Authorship：Last author   Language：Japanese   Publishing type：Research paper (scientific journal)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER  

Melon is a fruit/vegetable that has been grown in Japan for at least 2000 years. To obtain a better understanding of melon crop evolution in this island country, we measured the seed size and determined the cytoplasmic genotype of 135 modern melon accessions and 12 populations of ancient melon seed remains from archaeological sites for a 2000-year period in Japan. Based on differences in seed length, populations of melon seed remains at the Shikata site (Okayama Prefecture, Japan) consisted of seed types corresponding to those of modern East and South Asian melon. Although several types of melon seeds were found in and around the Shikata site, only Agrestis-type seeds, < 6.1 mm in length, were found in melon populations from 1 CE. Intra-population length variation was higher in 1050 CE than in 1530-1680 CE. Ancient DNA from archaeological melon was analysed for SNPs in the chloroplast genome. These revealed that cytoplasm type was heterogeneous and consisted of Ia and Ib types in melon populations prior to ca. 1600 CE, and thereafter becoming homogenous by genetic erosion of Ib, which is absent in modern endemic Japanese melon accessions. The decrease in variation of both seed length and cytoplasm type together with historical records indicates that artificial selection in the Japanese melons for desired fruit traits intensified in the past 1000 years.

DOI： 10.1007/s10722-015-0314-7

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Triticum aestivum L. cv 'Chogokuwase' is an extra-early flowering common wheat cultivar that is insensitive to photoperiod conferred by the photoperiod insensitive alleles at the Photoperiod-B1 (Ppd-B1) and Ppd-D1loci, and does not require vernalization for flowering. This reduced vernalization requirement is likely due to the spring habitat allele Vrn-D1 at the VERNALIZATION-D1 locus. Genotypes of the Ppd-1 loci that determine photoperiod sensitivity do not fully explain the insensitivity to photoperiod seen in 'Chogokuwase'. We detected altered expression patterns of clock and clock-output genes including Ppd-1 in 'Chogokuwase' that were similar to those in an einkorn wheat mutant that lacks the clock-gene homologue, wheat PHYTOCLOCK 1 (WPCL1). Presumptive loss-of-function mutations in all WPCL1 homoeologous genes were found in 'Chogokuwase' and 'Geurumil', one of the parental cultivars. Segregation analysis of the two intervarietal F-2 populations revealed that all the examined F-2 plants that headed as early as 'Chogokuwase' had the loss-of-function wpcl1 alleles at all three homoeoloci. Some F-2 plants carrying the wpcl1 alleles at three homoeoloci headed later than 'Chogokuwase', suggesting the presence of other loci influencing heading date. Flowering repressor Vrn-2 was up-regulated in 'Chogokuwase' and 'Geurumil' that had the triple recessive wpcl1 alleles. An elevated transcript abundance of Vrn-2 could explain the observation that 'Geurumil' and some F-2 plants carrying the three recessive wpcl1 homeoealleles headed later than 'Chogokuwase'. In spite of the up-regulation of Vrn-2, 'Chogokuwase' may have headed earlier due to unidentified earliness genes. Our observations indicated that loss-of-function mutations in the clock gene wpcl1 are necessary but are not sufficient to explain the extra-early heading of 'Chogokuwase'.

DOI： 10.1371/journal.pone.0165618

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Plants commonly rely on photoperiodism to control flowering time. Rice development before floral initiation is divided into two successive phases: the basic vegetative growth phase (BVP, photoperiod-insensitive phase) and the photoperiod-sensitive phase (PSP). The mechanism responsible for the transition of rice plants into their photoperiod-sensitive state remains elusive. Here, we show that se13, a mutation detected in the extremely early flowering mutant X61 is a nonsense mutant gene of OsHY2, which encodes phytochromobilin (P Phi B) synthase, as evidenced by spectrometric and photomorphogenic analyses. We demonstrated that some flowering time and circadian clock genes harbor different expression profiles in BVP as opposed to PSP, and that this phenomenon is chiefly caused by different phytochrome-mediated light signal requirements: in BVP, phytochrome-mediated light signals directly suppress Ehd2, while in PSP, phytochrome-mediated light signals activate Hd1 and Ghd7 expression through the circadian clock genes' expression. These findings indicate that light receptivity through the phytochromes is different between two distinct developmental phases corresponding to the BVP and PSP in the rice flowering process. Our results suggest that these differences might be involved in the acquisition of photoperiod sensitivity in rice.

DOI： 10.1038/srep07709

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPRINGER HEIDELBERG  

Wheat vernalization requirement is mainly controlled by the VRN1, VRN2, VRN3, and VRN4 genes. The first three have been cloned and have homoeologs in all three genomes. VRN4 has been found only in the D genome (VRN-D4) and has not been cloned. We constructed a high-density genetic map of the VRN-D4 region and mapped VRN-D4 within a 0.09 cM interval in the centromeric region of chromosome 5D. Using telocentric 5D chromosomes generated from the VRN-D4 donor Triple Dirk F, we determined that VRN-D4 is located on the short arm. The VRN-D4 candidate region is colinear with a 2.24 Mb region on Brachypodium distachyon chromosome 4, which includes 127 predicted genes. Ten of these genes have predicted roles in development but we detected no functional polymorphisms associated to VRN-D4. Two recombination events separated VRN-D4 from TaVIL-D1, the wheat homolog of Arabidopsis vernalization gene VIL1, confirming that this gene is not a candidate for VRN-D4. We detected significant interactions between VRN-D4 and other four genes controlling vernalization requirement (Vrn-A1, Vrn-B1, Vrn-D1, and Vrn-B3), which confirmed that VRN-D4 is part of the vernalization pathway and that it is either upstream or is part of the regulatory feedback loop involving VRN1, VRN2 and VRN3 genes. The precise mapping of VRN-D4 and the characterization of its interactions with other vernalization genes provide valuable information for the utilization of VRN-D4 in wheat improvement and for our current efforts to clone this vernalization gene.

DOI： 10.1007/s00438-013-0788-y

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The spring-type near isogenic line (NIL) of the winter-type barley (Hordeum vulgare ssp. vulgare) var. Hayakiso 2 (HK2) was developed by introducing VERNALIZATION-H1 (Vrn-H1) for spring growth habit from the spring-type var. Indo Omugi. Contrary to expectations, the spring-type NIL flowered later than winter-type HK2. This phenotypic difference was controlled by a single gene, which cosegregated only with phytochrome C (HvPhyC) among three candidates around the Vrn-H1 region (Vrn-H1, HvPhyC, and CASEIN KINASE IIα), indicating that HvPhyC was the most likely candidate gene. Compared with the late-flowering allele HvPhyC-l from the NIL, the early-flowering allele HvPhyC-e from HK2 had a single nucleotide polymorphism T1139C in exon 1, which caused a nonsynonymous amino acid substitution of phenylalanine at position 380 by serine in the functionally essential GAF (39, 59-cyclic-GMP phosphodiesterase, adenylate cyclase, formate hydrogen lyase activator protein) domain. Functional assay using a rice (Oryza sativa) phyA phyC double mutant line showed that both of the HvPhyC alleles are functional, but HvPhyC-e may have a hyperfunction. Expression analysis using NILs carrying HvPhyC-e and HvPhyC-l (NIL [HvPhyC-e] and NIL [HvPhyC-l], respectively) showed that HvPhyC-e up-regulated only the flowering promoter FLOWERING LOCUS T1 by bypassing the circadian clock genes and flowering integrator CONSTANS1 under a long photoperiod. Consistent with the up-regulation, NIL (HvPhyC-e) flowered earlier than NIL (HvPhyC-l) under long photoperiods. These results implied that HvPhyC is a key factor to control long-day flowering directly. © 2013 American Society of Plant Biologists. All Rights Reserved.

DOI： 10.1104/pp.113.222570

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The Ppd-A1 genotype of 240 Japanese wheat cultivars and 40 foreign cultivars was determined using a PCR-based method. Among Japanese cultivars, only 12 cultivars, all of which were Hokkaido winter wheat, carried the Ppd-A1a allele, while this allele was not found in Hokkaido spring wheat cultivars or Tohoku-Kyushu cultivars. Cultivars with a photoperiod-insensitive allele headed 6.9-9.8 days earlier in Kanto and 2.5 days earlier in Hokkaido than photoperiod-sensitive cultivars. The lower effect of photoperiod-insensitive alleles observed in Hokkaido could be due to the longer day-length at the spike formation stage compared with that in Kanto. Pedigree analysis showed that 'Purple Straw' and 'Tohoku 118' were donors of Ppd-A1a and Ppd-D1a in Hokkaido wheat cultivars, respectively. Wheat cultivars recently developed in Hokkaido carry photoperiod-insensitive alleles at a high frequency. For efficient utilization of Ppd-1 alleles in the Hokkaido wheat-breeding program, the effect of Ppd-1 on growth pattern and grain yield should be investigated. Ppd-A1a may be useful as a unique gene source for fine tuning the heading time in the Tohoku-Kyushu region since the effect of Ppd-A1a on photoperiod insensitivity appears to differ from the effect of Ppd-B1a and Ppd-D1a.

DOI： 10.1270/jsbbs.63.309

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOC BREEDING  

Molecular analysis encouraged discovery of genetic diversity and relationships of cultivated melon (Cucumis melo L.). We sequenced nine inter- and intra-genic regions of the chloroplast genome, about 5500 bp, using 60 melon accessions and six reference accessions of wild species of Cucumis to show intra-specific variation of the chloroplast genome. Sequence polymorphisms were detected among melon accessions and other Cucumis species, indicating intra-specific diversification of the chloroplast genome. Melon accessions were classified into three subclusters by cytoplasm type and then into 12 subgroups. Geographical origin and seed size also differed between the three subclusters. Subcluster Ia contained small-seed melon from Southern Africa and South and East Asia and subcluster Ib mainly consisted of large-seed melon from northern Africa, Europe and USA. Melon accessions of subcluster Ic were only found in West, Central and Southern Africa. Our results indicated that European melon groups and Asian melon groups diversified independently and shared the same maternal lineage with northern African large-seed melon and Southern African small-seed melon, respectively. Cultivated melon of subcluster Ic may have been domesticated independently in Africa. The presence of 11 cytoplasm types in Africa strongly supported African origin of cultivated melon and indicated the importance of germplasm from Africa.

DOI： 10.1270/jsbbs.63.183

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For genetic analysis of Ppd-1 homoeologs controlling photoperiodic response of wheat (Triticum aestivum L.), bulk segregant analysis was performed using a doubled haploid (DH) population derived from a cross of Japanese wheat genotypes Winter-Abukumawase and Chihokukomugi. Based on the segregation of simple sequence repeat markers linked to the Ppd-1 homoeologs, Winter-Abukumawase carried insensitive alleles Ppd-B1a and Ppd-D1a and Chihokukomugi carried a single insensitive allele (Ppd-A1a) that was first found in common wheat. The genomic sequence of Ppd-1 homoeologs including the 5′ upstream region was determined and compared between the two genotypes. Ppd-D1a of Winter-Abukumawase had a deletion of 2,089 bp that was already reported for Ciano 67. Critical sequence polymorphism causing photoperiod insensitivity was not detected from the translation start codon to the 3′ untranslated region of Ppd-A1 and Ppd-B1. However, novel mutations were found in the 5′ upstream region. Ppd-A1a of Chihokukomugi had a deletion of 1,085 bp and Ppd-B1a of Winter-Abukumawase had an insertion of 308 bp. A total of 80 DH lines were classified into eight genotypes by PCR-based genotyping using specific primer sets to detect the In/Dels in the 5′ upstream region of three Ppd-1 genes. The heading dates of the DH lines differed significantly between the eight genotypes, showing that each of the three insensitive alleles accelerates heading by 7-9 days compared with the photoperiod-sensitive genotype. Interaction between the three genes was also significant. © 2012 Springer Science+Business Media B.V.

DOI： 10.1007/s11032-012-9765-0

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The genotypes of photoperiod response genes Ppd-B1 and Ppd-D1 in Japanese wheat cultivars were determined by a PCR-based method, and heading times were compared among genotypes. Most of the Japanese wheat cultivars, except those from the Hokkaido region, carried the photoperiod-insensitive allele Ppd-D1a, and heading was accelerated 10.3 days compared with the Ppd-D1b genotype. Early cultivars with Ppd-D1a may have been selected to avoid damage from preharvest rain. In the Hokkaido region, Ppd-D1a frequency was lower and heading date was late regardless of Ppd-D1 genotype, suggesting another genetic mechanism for late heading in Hokkaido cultivars. In this study, only 11 cultivars proved to carry Ppd-B1a, and all of them carried another photoperiod-insensitive allele, Ppd-D1a. The Ppd-B1a/Ppd-D1a genotype headed 6.7 days earlier than the Ppd-B1b/Ppd-D1a genotype, indicating a significant effect of Ppd-B1a in the genetic background with Ppd-D1a. Early-maturity breeding in Japan is believed to be accelerated by the introduction of the Ppd-B1a allele into medium-heading cultivars carrying Ppd-D1a. Pedigree analysis showed that Ppd-B1a in three extra-early commercial cultivars was inherited from 'Shiroboro 21' by early-heading Chugoku lines bred at the Chugoku Agriculture Experimental Station.

DOI： 10.1270/jsbbs.61.405

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC HORTICULTURAL SCI  

Chinese Hami melon consists of the varieties cassaba, chandalak, amen, and zard. To show their genetic diversity, 120 melon accessions, including 24 accessions of Hami melon, were analyzed using molecular markers of nuclear and cytoplasmic genomes. All Hami melon accessions were classified as the large-seed type with seed length longer than 9 mm, like US and Spanish Inodorus melon. Conomon accessions grown in east China were all the small-seed type. Both large- and small-seed types were in landraces from Iran, Afghanistan, Pakistan, and Central Asia. Analysis of an SNP in the PS-ID region (Rpl16-Rpl14) and size polymorphism of ccSSR7 showed that the melon accessions consisted of three chloroplast genome types, that is, maternal lineages. Hami melon accessions were T/338 bp type, which differed from Spanish melon and US Honey Dew (T/333 bp type), indicating a different maternal lineage within group Inodorus. The gene diversity (D), calculated from random amplified polymorphic DNA (RAPD) and simple sequence repeat (SSR) polymorphism, was 0.476 in 120 melon accessions; the largest diversity was in Central Asian accessions (D = 0.377) but was low for Hami melon accessions (D = 0.243), even though Hami melon has diverse morphological traits, earliness, and shelf life. Reflecting such small genetic diversity, Hami melon accessions of vars. ameri and zard were grouped into cluster II, except for one accession, by the unweighted pair group method and the arithmetic mean (UPGMA) cluster analysis. Variety chandalak with distinct characters, such as early maturing and poor shelf life, was assigned to clusters IV and VI, indicating inter-varietal genetic differentiation within Hami melon. Three accessions from Turkmenistan and Afghanistan, with large seeds and T/338 bp type of chloroplast genome, were classified as cluster II with Hami melon accessions of vars. ameri and zard. We therefore concluded that Hami melon may have been transmitted from the west. The small-seed type melon of group Conomon grown in east China may have been introduced into China independently of Hami melon, because it had the A/338 bp type of the chloroplast genome and was clustered distantly from Hami melon according to nuclear genome analysis.

DOI： 10.2503/jjshs1.80.52

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In rice (Oryza sativa), a short-day plant, photoperiod is the most favorable external signal for floral induction because of the constant seasonal change throughout the years. Compared with Arabidopsis, however, a large part of the regulation mechanism of the photoperiodic response in rice still remains unclear due mainly to the lack of induced mutant genes. An induced mutant line X61 flowers 35 days earlier than its original variety Gimbozu under a natural photoperiod in Kyoto (35A degrees 01'N). We attempted to identify the mutant gene conferring early heading to X61. Experimental results showed that the early heading of X61 was conferred by a complete loss of photoperiodic response due to a novel single recessive mutant gene se13. This locus interacts with two crucial photoperiod sensitivity loci, Se1 and E1. Wild type alleles at these two loci do not function in coexistence with se13 in a homozygous state, suggesting that Se13 is an upstream locus of the Se1 and E1 loci. Linkage analysis showed that Se13 is located in a 110 kb region between the two markers, INDEL3735_1 and INDEL3735_3 on chromosome 1. A database search suggested that the Se13 gene is identical to AK101395 (=OsHY2), which encodes phytochromobilin synthase, a key enzyme in phytochrome chromophore biosynthesis. Subsequent sequence analysis revealed that X61 harbors a 1 bp insertion in exon 1 of OsHY2, which induces a frame-shift mutation producing a premature stop codon. It is therefore considered that the complete loss of photoperiodic response of X61 is caused by a loss of function of the Se13 (OsHY2) gene involved in phytochrome chromophore biosynthesis.

DOI： 10.1007/s00122-010-1426-2

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Language：English   Publisher：The Society of Crop Science and Breeding in Kinki, Japan  

The flowering traits of 'Emmer' and 'Pyramidale', two ancestral wheat varieties that are now used to make two types of beer brewed in partnership with Kyoto University scientists, were investigated in detail. These varieties are classified as T. turgidum L. ssp. dicoccon and ssp. turanicum, respectively, and little information is available about their agronomic characteristics. Through evaluation of the internal factors determining their flowering time (photoperiodic response, vernalization requirement and narrow-sense earliness), we revealed that the two varieties are spring-habit and photoperiod-sensitive. While the narrow-sense earliness of 'Emmer' is less intense than that of 'Pyramidale', the photoperiodic response of 'Emmer' is more intense than that of 'Pyramidale'. Based on a genetic analysis using the F₂ population of the two varieties, we concluded that 'Pyramidale' harbors a photoperiod-insensitive allele in the Ppd-A1 locus, the same allele reported by Wilhelm et al. (2009). This photoperiod-insensitive allele is expected to be a useful genetic resource in the breeding of tetraploid and hexaploid wheat.

DOI： 10.18964/jcr.56.0_67

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOC BREEDING  

Genetic diversity among 59 melon landraces from Vietnam was studied by analyzing morphological traits and molecular markers. The morphological characters of the melon landrace fruits were highly diversified. Among the five types of cultivated melon, "Dua le" and "Dua yang" were classified as Conomon var. makuwa, whereas "Dua gang" was classified as Conomon var. conomon, and "Dua bo" was classified as Momordica. However, "Dua thom" could not be classified into a proper group or variety. The gene diversity based on random amplified polymorphic DNA (RAPD) and single sequence repeat analyses was small and equivalent to that of Chinese Conomon. A cluster analysis revealed that "Dua bo", "Dua le", "Dua yang", and "Dua gang" were grouped in cluster II. Clusters III and IV consisted mainly of Conomon accessions from China and Japan. "Dua thom" was classified into cluster V with landraces from Yunnan Province, China. The comparison of a RAPD profile with 291 melon accessions from Africa and Asia clearly showed that "Dua thom" and Yunnanese landraces were closely related with the small-seed type melons from Myanmar, Bangladesh, and northeastern India. The other four types were related closely with Conomon and Agrestis accessions from China, Korea, and Japan, indicating their involvement in the differentiation and establishment of the Conomon group in East Asia.

DOI： 10.1270/jsbbs.60.255

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Natural variation in wheat requirement of long exposures to cold temperatures to accelerate flowering (vernalization) is mainly controlled by the Vrn-1, Vrn-2, Vrn-3, and Vrn-4 loci. The first three loci have been well characterized, but limited information is available for Vrn-4. So far, natural variation for Vrn-4 has been detected only in the D genome (Vrn-D4), and genetic stocks for this gene are available in Triple Dirk (TDF, hereafter). We detected heterogeneity in the Vrn-1 alleles present in different TDF stocks, which may explain inconsistencies among previous studies. A correct TDF seed stock from Japan carrying recessive vrn-A1, vrn-B1, and vrn-D1 alleles was crossed with three different winter cultivars to generate F(2) mapping populations. Most of the variation in flowering time in these three populations was controlled by a single locus, Vrn-D4, which was mapped within a 1.8 cM interval flanked by markers Xcfd78 and Xbarc205 in the centromeric region of chromosome 5D. A factorial ANOVA for heading time using Vrn-D4 alleles and vernalization as factors showed a significant interaction (P < 0.0001), which confirmed that the Vrn-D4 effect on flowering time is modulated by vernalization. Comparison of the different Triple Dirk stocks revealed that Vrn-B1, Vrn-D1, and Vrn-D4 all have a small residual response to vernalization, but Vrn-D4 differs from the other two in its response to short vernalization periods. The precise mapping and characterization of Vrn-D4 presented here represent a first step toward the positional cloning of this gene.

DOI： 10.1007/s00122-009-1174-3

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Genetic diversity of Myanmar melon was evaluated by analysis of 27 RAPD markers and morphological characters using 41 accessions of melon landraces of which 36 accessions were small-seed type. The gene diversity was 0.239, higher than for group Conomon from East Asia and equivalent to Indian melon populations. Melon accessions were classified into six major clusters. The largest cluster IV comprised mainly group Conomon which was closely related to cluster V consisting of mainly group Agrestis. Most of the accessions of group Cantalupensis were grouped into clusters II or VII and were distantly related to groups Conomon and Agrestis. The genetic relationship to melon accessions from neighboring countries was analyzed. The 24 accessions of clusters IV and V were mostly clustered together with small-seed type melon of India, but the 14 accessions of clusters VI and VII were mostly clustered together with large-seed type melon of India. These results indicated that the genetic diversity of Indian melon is conserved in Myanmar. Genetic introgression among melon groups through spontaneous hybridization was also indicated and was considered important to maintain or increase the genetic diversity in Myanmar.

DOI： 10.1007/s10722-009-9438-y

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A late heading-time mutant line, HS276, which was induced by gamma-irradiation of seeds of the japonica rice (Oryza sativa L.) variety Gimbozu, exhibits an extremely long basic vegetative growth phase (BVP). A genetic analysis using the F(2) population from the cross between HS276 and Gimbozu revealed that the late heading of HS276 is governed by a single recessive mutant gene. The subsequent analysis on heading responses of HS276 and Gimbozu to four photoperiods (12, 13, 14, and 15 h) and to the photoperiodic transfer treatment from a short photoperiod to a long photoperiod revealed that the mutant gene confers an extremely long BVP and increases photoperiod sensitivity under long photoperiod (14 and 15 h). The BVP durations of HS276 and Gimbozu were estimated at 30.1 and 16.0 days, respectively; the mutant gene, compared with its wild type allele, elongates the duration of BVP by 14 days. Linkage analysis showed that the mutant gene is located in the 129 kb region between the two INDEL markers, INDELAP0399_6 and INDELAP3487_2, on the distal part of the short arm of chromosome 6. None of the other BVP genes are located in this region; therefore, we declared this a newly detected mutant gene and designated it ef7. A recently established program to breed rice suitable for low latitudes, where short photoperiodic conditions continue throughout the year, aims to develop varieties with extremely long BVPs and weak photoperiod sensitivities; the mutant gene ef7, therefore, will be quite useful in these programs because it confers an extremely long BVP and little enhances photoperiod sensitivity under short photoperiod.

DOI： 10.1007/s00122-009-1078-2

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The genetic diversity and relationship among South and East Asian melon Cucumis melo L. were studied by using RAPD analysis of 69 accessions of melon from India, Myanmar, China, Korea, and Japan. The genetic diversity was large in India, and quite small in Group Conomon var. makuwa and var. conomon from East Asia, clearly indicating a decrease in genetic variation from India toward the east. Cluster analysis based on genetic distance classified 17 groups of accessions into two major clusters: cluster I comprising 12 groups of accessions from India and Myanmar and cluster II that included five groups of accessions of Group Conomon var. makuwa and var. conomon from East Asia. Cluster I was further divided into three subclusters, of which subclusters Ib and Ic included small- and large-seed type populations, respectively. Therefore, this division was based on their seed size, not cultivation area. The large-seed type from east India was differently included in the subcluster of small-seed type (Ib). A total of 122 plants of 69 accessions were classified into three major clusters and subclusters: clusters I and II comprised melon accessions mostly from India and Myanmar, and cluster III comprised Group Conomon var. makuwa and var. conomon from East Asia. The frequency of large- and small-seed types was different between clusters I and II, also indicating genetic differentiation between large- and small-seed types. One plant of the small-seed type from east India was differently included in cluster III, and two plants from east India were classified into subcluster IV. These results clearly showed that South Asian melon is genetically differentiated by their seed size, and that small-seed type melon in east India is closely related to Group Conomon var. makuwa and var. conomon.

DOI： 10.1007/s10681-006-9259-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOC BREEDING  

Genetic diversity and genetic structure of East Asian wheat populations were studied based on the analysis of five isozymes using 324 wheat landraces. Gene diversity value calculated from the frequency of 31 isozyme bands varied within China, being higher in the western part than in the eastern part. Twenty populations of wheat landraces were classified into three major groups by cluster analysis, and wheat populations from the neighboring areas were clustered together. The first group comprised most of the populations from China (West), though two populations from Xinjiang and Gansu & Ningxia were rather distantly related to the populations from Tibet, Sichuan (West) and Yunnan. These results indicated the transmission of wheat from Nepal to the Tibetan area of China. The second group included the northern populations, from Mongolia to Japan (Northeast), indicating the transmission of wheat through the northern route of the "Silk road". The third group consisted of wheat populations from Shaanxi, China (Southeast) and Japan (Southwest). Wheat population from Shaanxi was also related to the population from Hebei and Gansu & Ningxia, strongly suggesting the transmission of wheat through the "Silk road": Xinjiang-Gansu & Ningxia-Shaanxi-Shandong. In addition, in the eastern part of China, genetic differentiation among wheat populations from northern and southern parts was observed, and a similar geographical differentiation was also recorded in Korea and Japan.

DOI： 10.1270/jsbbs.56.379

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Language：Japanese  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Rice (Oryza sativa L.) is an important crop worldwide and, with the availability of the draft sequence(1,2), a useful model for analysing the genome structure of grasses(3),(4). To practice efficient rice breeding through genetic engineering techniques, it is important to identify the economically important genes in this crop. The use of mobile transposons as gene tags in intact plants is a powerful tool for functional analysis because transposon insertions often inactivate genes(5). Here we identify an active rice transposon named miniature Ping (mPing) through analysis of the mutability of a slender mutation of the glume(6)-the seed structure that encloses and determines the shape of the grain. The mPing transposon is inserted in the slender glume (slg) mutant allele but not in the wild-type allele. Search of the O. sativa variety Nipponbare genome identified 34 sequences with high nucleotide similarity to mPing, indicating that mPing constitutes a family of transposon elements. Excision of mPing from slg plants results in reversion to a wild-type phenotype. The mobility of the transposon mPing in intact rice plants represents a useful alternative tool for the functional analysis of rice genes.

DOI： 10.1038/nature01219

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：CROP SCIENCE SOC AMER  

A late-heading mutant line, HS169, which was induced by gamma-ray irradiation to seeds of the japonica rice (Oryza sativa L.) cultivar Gimbozu, has an extremely long basic vegetative growth (BVG) period. A genetic analysis using the F-2 poptilation from the crossHS169 x Gimbozu showed that the late heading of HS169 is governed by a recessive mutant gene. The subsequent analysis of heading responses of HS169, Gimbozu, and six heading-time tester lines to five photoperiods (10, 13, 14, 15, and 16 h) revealed that the mutant gene confers an extremely long BVG period by itself. A recessive allele, ef1, at the heading-time locus Ef1 has been considered to confer an extremely long BVG period, but experimental results showed that the effect of ef1 is modified by the allelic constitution at the photoperiod sensitivity locus Se1. The allele ef1 increases the BVG period markedly only when coexisting with the nonfunctional allele Se1-e at the Se1 locus. As a result of allelism test and subsequent trisomic analysis, the mutant gene was found to he a nonfunctional allele at the Ef1 locus on chromosome 10. We designated this mutant gene ef1-h. On the basis of the results, causal genetic pathways to flowering in rice and the significance of ef1-h in recent rice breeding in the low latitudes were discussed.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

The interaction between the Se1 and the Ef1 loci, which chiefly control the photoperiod sensitivity (PS) and the basic vegetative growth (BVG) period of rice (Oryza sativa L.) respectively, was investigated using four tester lines different in genotype for the two heading time loci from each other. The four tester lines were grown under 10, 13, 14, 15, and 16h daylengths to estimate their BVG period and PS. The Taiwanese cultivar Taichung 65 (T65), one of the tester lines, has an extremely long BVG period that has been considered to be conferred by a late heading-time allele ef1 at the Ef1 locus. Experimental results, however, showed that the extremely long BVG of T65 was conferred not by a single effect of ef1 but by a complementary effect of ef1 and Se1-e, a photoperiod insensitivity allele, at the Se1 locus. It was also found that a complementary effect of a PS allele Se1-n at the Se1 locus and ef1 stimulates the PS of rice. Gene analysis for heading time under an optimum daylength (10 h) as well as under natural daylength confirmed the presence of the complementary effect of the two nonallelic genes on BVG, which was found only with homozygosity of both the genes. Based on these results and earlier reports on the Se1 locus, the roles of the Se1 and Ef1 loci on the durations of pre-flowering developmental phases in rice were discussed.

DOI： 10.1023/A:1016357511738

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ACADEMIC PRESS LTD  

Sixteen heading-time tester lines of rice (Oryza sativa L.) for the E1, E2, E3, Se1, Ef1 and U loci were subjected to transfer treatments from short (10 h) to long photoperiods (24 h) and vice versa at various times after sowing. Based on heading response, the 16 lines were classified into four groups, which corresponded well to the genotype at the Se1, Ef1 and E1 loci. Using an analytical model, we estimated seven parameters for the three pre-flowering developmental phases of each line, the basic vegetative phase (BVP), the subsequent photoperiod-sensitive phase (PSP), and the post photoperiod-sensitive phase until heading (PPP). The Se1 locus had an extremely large effect on PSP and large effects on BVP and PPP; Ef1 had a large effect on BVP and a considerable effect on PPP; and E1 had a considerable effect on PSP, although effects were modified by non-allelic interactions at these three loci. The effects of three other loci were almost negligible. Thus the Se1, Ef1 and E1 loci play principal roles in determining the heading time of rice, which is further diversified not only by the action of genes of other heading-time loci but also by non-allelic interactions. Based on these results, causal genetic pathways to flowering (heading) in rice are proposed. (C) 2001 Annals of Botany Company.

DOI： 10.1006/anbo.2001.1490

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPANESE SOC BREEDING  

An early heading time gene tentatively designated as 'v' and nonallelic to E-1, E-2, E-3 and Ef-1 was detected in the Taiwanese rice cultivar Taichung 65 (T65) (Okumoto et al. 1992b). This gene remarkably accelerated heading time. The allelism test of this gene to a photoperiod insensitivity gene Se - 1(e) at the Se - 1 locus was per formed using the progenies from reciprocal crosses between T65 and a heading time tester line ER. The role of this gene in the rice cultivation in Taiwan was also discussed on the basis of photoperiod responses of T65: ER and a heading time tester line LR. T65 was found tee have the genotype E1E1E2E2E3E3 vv ef - 1ef - 1, while ER and LR had the genotypes E(1)E(1)e(2)e(2)E(3)E(3)Se - 1(e)Se - 1(e)Ef-1Ef-1 and E(1)E(1)e(2)e(2)E(3)E(3)Se - 1(u)Se - 1(u)Ef - 1Ef - 1, respectively. ER also carried a rice blast resistance gene Pi - z(t) closely linked to Se - 1(e) on chromosome 6. E-1, E-2, E-3 and Se -1(u) were all photoperiod sensitivity genes, and ef - 1 at the Ef - 1 locus remarkably increased the duration of the basic vegetative growth period (BVG). In the F-2, no distinct transgressive segregants appeared, and the three genotypes (Pi - z(t) Pi - z(t), Pi - z(t) +, ++) for the Pi-z locus in the Fa exhibited almost the same range and the same mean for heading time. These facts imply that 'v' is identical with Se - 1(e). T65 exhibited a far longer BVG than the two tester lines. The critical day-lengths (CDLs) of T65 and ER were longer than 16 h, while the CDL of LR ranged between 14 h and 15 h : the CDL of LR was shorter than those of T65 and ER. When compared to LR, T65 and ER exhibited a small retarding effect under super optimum photoperiod (RES), and did not differ in RES. These results indicate that the low photoperiod sensitivity of T65 is due to the action of 'v' (=Se - I-e). Since the long BVG of T65 is attributed to the action of ef - 1, it is considered that 'v' (=Se - I-e) and ef - 1 are very important genes for rice cultivation in Taiwan, where natural day-length is short even in summer and seasonal changes are negligible.

DOI： 10.1270/jsbbs1951.48.103

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DOI： 10.1270/jsbbr.16.93

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Language：Japanese   Publisher：岡山大學農學部  

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DOI： 10.1270/jsbbs1951.48.103

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