Genotypic Analysis of Heading Time on an Indica Rice Cultivar,Nanjing 11

In this paper, the genotype of heading time in Nanjing 11, an indica variety, was analyzed by crossing with tester varieties, Akihikari (e1e1e2e2e3e3SeleSele), Koshihikari (E1E1E2E2 e3e3 SeleSele), Nipponbare(E1E1e2e2e3e3Se1Se1 )and HinohikarKEjE^ E2E2 e3e3 SelSel), of which the genotypes of heading time were well known. The results showed genotype of heading time in Nanjing 11 was E1E1 e2e2 E3E3 SelSel and also included a recessive inhibitor i-Sel for photoperiod-sensitivity as well. Meanwhile, the two photoperiod-sensitive genes, E1 and Sel, in Nanjing 11 were also identified by crossing with QTL nearly isogenic lines of Nipponbare, NIL(Hdl )and NIL(Hd4)which have complementary effects.

Characterization and distribution of novel alleles of the vernalization gene Vrn-A1 in Chinese wheat(Triticum aestivum L.) cultivars

The ability of wheat to adapt to a wide range of environmental conditions is determined mostly by allelic diversity among genes regulating vernalization requirement.Vrn-1 is a major regulator of this requirement.In this study,two novel alleles of Vrn-A1 were discovered in Chinese cultivars:vrn-A1n was identified in two landraces,Jiunong 2 and Ganchun 16,and Vrn-A1o was detected in Duanhongmangmai.Both novel alleles showed a linked duplication in the promoter region.The common copy of these two alleles was identical to the recessive allele vrn-A1.Compared with the recessive allele vrn-A1,the other copy of vrn-A1n contained a 54-bp deletion in the promoter region and the distinct copy of Vrn-A1o contained an11-bp deletion in the promoter region.In segregating populations in the greenhouse under nonvernalizing(20–25°C)and long-day(16 h light)conditions,plants with the novel vrn-A1n allele did not head earlier than those with the recessive vrn-A1 allele.However,plants that were either homozygous or heterozygous for the novel Vrn-A1o allele headed earlier than those with the recessive vrn-A1 allele.To identify the novel allele with the small-sized product and facilitate screening,a DNA marker for the novel dominant allele Vrn-A1o was designed.Analysis of the novel-allele distribution showed that two cultivars carrying the vrn-A1n allele were dispersed in the northwestern spring wheat zone,and 12 cultivars carrying the dominant Vrn-A1o allele were widely distributed in the northwestern spring wheat zone,Xinjiang winter and spring wheat zone,Yellow and Huai River valley winter wheat zone,and QinghaiTibetan Plateau spring and winter wheat zone.Our study identifies useful germplasm and a DNA marker for wheat breeding.

Genetic Mechanism of Dominant Earliness in Kefeng A,a New Rice Cytoplasmic Male Sterile Line

Kefeng A is an early maturing indica cytoplasmic male sterile （CMS） line of rice. Combinations derived from Kefeng A and late maturing indica restorer lines showed dominant earliness to various extents. To understand the genetic basis of dominant earliness, the genotype of photoperiod-sensitive genes in Kefeng A was analyzed using a complete set of heading time near isogenic lines （NILs） EGO to EG7, ER, LR, T65, T65E^b, T65E^bm, T65m, NIL（Hd1） and NIL（Hd4）. Results indicated that Kefeng A contained two dominant photoperiod-sensitive alleles E1 and Se-1^U on E1 and Se-1 loci, respectively, and the genotype of photoperiod-sensitivity genes for heading time in Kefeng A was E1E1e2e2E3E3Se-1^USe-1UEf-1Ef-1. Based on the detected heading time genotype, in combination with the heading time of Kefeng A and the early maturing phenomenon in its derived F1 hybrids, it is speculated that Kefeng A might carry a dominant inhibitor gene Su-E7 for the dominant photoperiod- sensitive gene E1, and a recessive inhibitor gene i-Se-1 for another dominant photoperiod-sensitive gene Se-1. The reason why F1 hybrids from Kefeng A exhibited early maturing was hereby analyzed and the breeding value of dominant earliness related genes in Kefeng A was discussed.