QTL effects and epistatic interaction for flowering time and branch number in a soybean mapping population of Japanese×Chinese cultivars

Flowering time and branching type are important agronomic traits related to the adaptability and yield of soybean. Molecular bases for major flowering time or maturity loci, E1 to E4, have been identified. However, more flowering time genes in cultivars with different genetic backgrounds are needed to be mapped and cloned for a better understanding of flowering time regulation in soybean. In this study, we developed a population of Japanese cultivar（Toyomusume）×Chinese cultivar（Suinong 10） to map novel quantitative trait locus（QTL） for flowering time and branch number. A genetic linkage map of a F_2 population was constructed using 1 306 polymorphic single nucleotide polymorphism（SNP） markers using Illumina Soy SNP8 ki Select Bead Chip containing 7 189（SNPs）. Two major QTLs at E1 and E9, and two minor QTLs at a novel locus, qFT2_1 and at E3 region were mapped. Using other sets of F_2 populations and their derived progenies, the existence of a novel QTL of qFT2_1 was verified. qBR6_1, the major QTL for branch number was mapped to the proximate to the E1 gene, inferring that E1 gene or neighboring genetic factor is significantly contributing to the branch number.

Characterization and Identification of a Novel Mutant fon(t) on Floral Organ Number and Floral Organ Identity in Rice

The floral-organ-number mutant fon（t） was firstly discovered in the progeny of a cross between a diploid （Chunjiang 683） and a haploid （SARⅣ/-620-A） rice cultivar. The fon（t） mutant showed normal vegetative development and produced normal inflorescence structures. Difference between the mutant and the wild type was observed when the stamen primordia began to form. The mature flowers offon（t） mutant showed open-hull phenotypes, which resulted in the exposure of stamens and stigmas. Normally, a single fon（t） floret consisted of six to nine stamens and one or two pistils. In addition, stamen/pistil-like structures and bulged tissues near ovaries were also observed in a few fon（t） florets. But homeotic transformation of lodicules into palea/lemma-like organs was observed almost in all the open-hull florets. The phenotypes offon（t） flowers also suggested thatfon（t） gene might affect flower organ identity in the inner whorls. Genetic analysis showed that thefon（t） mutant was controlled by a single recessive gene.

Heterosis Study on Developmental Behavior of Flowering and Boll Setting in Upland Cotton

The developmental behavior was examined for flowering and boll setting in upland cotton （Gossypium hirsutum L.） at different boll-setting sites and blooming periods. Conventional and conditional methods were applied to analyze heterosis by an additive-dominance model with genotype by environment （GE） interaction effects. Positive general heterosis was significantly detected on middle-lower nodes at positions 1 and 2 for a number of flowers and bolls per plant. Deviation between HPBE1 and HPBE2 was relatively large for a number of flowers per plant at positions 3, 4, and 5, but much smaller for number of bolls per plant. There was increase of heterosis before the end of July, and the highest heterosis was observed at 22 DAF （22 days after flowering） for flowers and at 16 DAF for bolls, and then declined. There existed significant diversity of interaction heterosis for flowers as well as for bolls during blooming stages, but deviation between HPBE1 and HPBE2 was smaller for number of bolls per plant than that of flowers per plant. The cross of DP-15 （late-season variety）＇ HG-H-12 had positive general heterosis since 19 DAF, and negative HPB was observed for the cross of GL-5 （early-season variety）＇ HG-H-12 after 37 DAF. Interaction heterosis was mostly not significant for cross DP-15＇ HG-H-12, but the reverse was true for cross GL-5＇ HG-H-12. Positive conditional HPB was detected since 16 DAF until 43 DAF for cross DP-15＇ HG- H-12, and before 13 DAF for cross GL-5＇ HG-H-12.

Identification of Quantitative Trait Loci （QTLs） Determining Flowering in the Robusta Coffee （Coffea canephora Pierre）

The quantitative trait loci （QTLs） analysis for flower traits were performed based on three crossing of Coffea canephora in Indonesia. This study successfully identified 19 QTLs related to flowering. These QTLs consisted of 1） three QTLs associated with green candle flowering time located at linkage groups of A and D; 2） one QTL associated to white candle flowering time located at linkage groups of B; 3） two QTLs associated to blossom flowering time located at linkage groups of B; 4） two QTLs associated to number of flowers located at linkage groups of G and H; 5） five QTLs associated to score of flowers quality located at linkage groups of A, C and D; 6） five QTLs associated to number of star flowers located at linkage groups of D, E, F and G. Due to some QTLs are overlapping on the same linkage group, thus, these 19 QTLs for flower traits might be considered as 15 different ones which distributed on 14 regions of the eight linkage groups. Although pleiotropic genes might be the most likely explanation for the collocation of these QTLs, the present data are not sufficient to distinguish between a pleiotropic gene and a cluster of different loci controlling several traits. These results can be a first step for molecular breeding on Robusta coffee mainly in order to improve potential suitable characteristics such as number of flowers and number of normal flowers as well as to reduce adverse characteristics such as number of star flowers.

Capsule Development Characters at Different Positions of Sesame(Sesamum indicum)

[Objective] This study aimed to explore the capsule development at differ-ent positions of sesame （Sesamum indicum）. [Method] The number of flowers and capsules at lower part （below the 8th node from the bottom）, middle part （at 9th-20th nodes from the bottom） and upper part （above the 20th node） of sesame plants （Zhengzhi 98N09） was counted. The length, width, fresh weight of the capsules, fresh and dry weight of the seeds, and the dry weight of the capsule shel s at dif-ferent growth stages were measured. [Result] From the bottom to the top of sesame plants, the numbers of flowers and capsules at each node showed a trend of first increasing and then decreasing. The 15th and the 12th node had the maxi-mum flower number （9.3 flowers per node on average） and the maximum capsule number （4.2 capsules per node on average）, respectively. The middle nodes had the highest capsule setting rate, up to 45.1%, fol owed by that at upper nodes, 30.1%, and the capsule setting rate at lower nodes was the smal est, only 25.0%. The capsule length, width, fresh weight, seed fresh weight, dry weight and capsule shel dry weight at middle part were higher than that at lower and upper part. Moreover, grain fil ing rates of the lower, middle and upper capsules were 0.003 5, 0.004 4 and 0.003 0 g/（capsule·d）. It suggests that the substances gave priority to supply the middle capsules during the development of capsules. [Conclusion] This study wil provide theoretical basis for the cultivation of high-yielding sesame.

Identification of genomic regions determining flower and pod numbers development in soybean (Glycine max L.)

Flower and pod numbers per plant are important agronomic traits underlying soybean yield. So far quantitative trait loci （QTL） de- tected for flower and pod-related traits have mainly focused on the final stage, and might therefore have ignored genetic effects expressed during a specific developmental stage. Here, dynamic expressions of QTL for flower and pod numbers were identified using 152 recom- binant inbred lines （RILs） and a linkage map of 306 markers. Wide genetic variation was found among RILs; 17 unconditional and 18 conditional QTL were detected for the two traits at different developmental stages over two years. Some QTL were detected only at one stage and others across two or more stages, indicating that soybean flower and pod numbers development may be governed by time-dependent gene expression. Three main QTL （qfn-Chrl8-2, qfn-Chr20-1, and qfn-Chr19） were detected for flower number, and two main QTL （qpn-Chrll and qpn-Chr20） were detected for pod number. The phenotypic variation explained by them ranged from 6.1% to 34.7%. The markers linked to these QTL could be used in marker-assisted selection for increasing soybean flower and pod numbers, with the ultimate aim of increasing soybean yield. Comparison of the QTL regions for flower and pod numbers traits with the related genes reported previously showed that seven and four related genes were located in the QTL regions of qfn-Chr11 and qfn-Chr19, respectively. These results provide a basis for free mapping and cloning of flower and pod development-related genes.