Cell ar chi tec ture in microspore de vel op men tal programmes Ab stractIn this work, the cell ar chi tec ture of the microspore fol low ing both gametophytic and embryogenic de vel op men tal path ways in vi tro was com pared with the gametophytic de vel op ment in vivo in Bras sica napus, at both light and elec tron mi cros copy level. The microspore re pro gram ming to embryo genesis involves de fined changes af fect ing cell ac tiv i ties and struc tural or ga ni za tion which can be con sid ered as mark ers of the microspore embryogenic path way, but less is known about oth ers de vel op men tal programmes fol lowed by the microspore in vi tro af ter both, in duc tive and non-in duc tive con di tions. Low-tem per a ture pro cess ing of the sam ples, cytochemical and immunocytochemical ap proaches to identify var i ous cell com po nents were per formed. Dif fer ences in spe cific cel lu lar fea tures such as cel lu lar size and shape, nuclear ar chi tec ture, starch ac cu mu la tion, pres ence of vac u oles and ri bo somal pop u la tion were stud ied to char ac ter ize se quential stages of microspore embryogenesis and other path ways oc cur ring in vi tro. The pres ence of abun dant starch grains in a de fined cy to plas mic re gion ap peared as a spe cific fea ture of the in vi tro gametophytic de vel op ment, as well as of the non-in duced micro spores of in vi tro cul tures un der embryogenic-in duc tive con di tions. In tro duc tionThe microspore, un der stress con di tions in vi tro, can switch its de vel op men tal programme to wards embryogenesis by pro lif er a tion and to form haploid em bryos and plants (Chupeau et al. 1998). In most spe cies, the re pro gram ming of the microspore is only pos si ble at spe cific de vel op men tal stages such as the late vacuolate microspore (González-Melen di et al. 1995, 1996. The compar i son of the game tophytic and embryogenic path ways of the micro spore, per mit ted to ana lyse the subcellular changes in plant dif fer en ti at ing cells switched to pro lif er a tion. The search of mo lec u lar and cel lu lar mark ers dur ing early stages of microspore embryogenesis con sti tutes an im portant goal to mon i tor the phys i o log i cal pro cesses involved in the in duc tion and to iden tify cells commit ted to the new de vel op men tal programme. This re pro gram ming is ac com pa nied by de fined 665 ACTA PHYSIOLOGIAE PLANTARUM

Soybean [Glycine max (L.) Merr.] is the leading Indian oilseed crop grown under rainfed conditions. Meticulous understanding of genotype × environment interaction patterns is essential to develop superior and widely adaptable soybean varieties. In the current study, 32 soybean genotypes were evaluated at eight locations for two consecutive years. Additive main effect and multiplicative interaction ANOVA revealed that only 41.6% of variance was explained by the first two interaction principal component axes (IPCAs), leaving 58.4% to the remaining 13 IPCs. The weighted average of absolute scores (WAASB) stability index, a best linear unbiased prediction–based mixed model that takes in to account all the IPCAs, has been used in stability analysis. SL1171 (WAASB score, 4.09) was found to be highly stable among the genotypes under study, with grain yield (2,050.87 kg ha−1) lower than the grand mean (2,082.50 kg ha−1). A superiority index that allows weighting between mean performance and stability (WAASBY) was used to select stable and high yielding genotypes. MACS 1620 (WAASBY score, 74.47) was found to be high yielding (2,476.05 kg ha−1) and widely adaptable. A simultaneous selection index (i.e., multi‐trait stability index [MTSI]) has been used for selecting early‐maturing and high‐yielding genotypes. DSb 33 was found to have the lowest MTSI (0.001) and can be used as a parent for breeding for early maturity and higher yield. The 100‐seed weight was found to be positively correlated with grain yield and can be used in direct selection for grain yield. Through genotypic cluster analysis, NRC 146 was found to be more divergent, with the highest mean 100 seed weight (16.39 g), and therefore can be used as a parent for breeding solely for grain yield.

Soybean is a leading oilseed crop in India, which contains about 40% of protein and 20% of oil. Core collection will accelerate the management and utilization of soybean genetic resources in breeding programmes. In the present study, eight agromorphological traits of 3443 soybean germplasm were analysed for the development of core collection using the principal component score (PCS) strategy and the power core method. The PCS strategy yielded core collection (CC1) of 576 accessions, which accounted for 16.72% of the entire collection (EC). The analysis based on the power core programme resulted in CC2 of 402 accessions, which accounted for 11.67% of the EC. Statistical analysis showed similar trends for the mean and range estimated in both core collections and EC. In addition, the variance, standard deviation and coefficient of variance were in general higher in core collections than in the EC. The correlations observed in the EC in general were preserved in core collections. A total of 311 and 137 unique accessions were found in CC1 and CC2 in addition to 265 accessions that were found to be common in both core collections. These 265 common accessions were the most diverse core sets, which accounted for 7.64% of the EC. We proposed to constitute an integrated core collection (ICC) by integrating both common and unique accessions. The ICC comprised 713 accessions, which accounted for about 20.62% of the EC. Statistical analysis indicated that the ICC captured maximum variation than CC1 and CC2. Therefore, the ICC can be extensively evaluated for a large number of economically important traits for the identification of desirable genotypes and for the development of mini core collection in soybean.

Food legumes play an important role in attaining both food and nutritional security along with sustainable agricultural production for the well-being of humans globally. The various traits of economic importance in legume crops are complex and quantitative in nature, which are governed by quantitative trait loci (QTLs). Mapping of quantitative traits is a tedious and costly process, however, a large number of QTLs has been mapped in soybean for various traits albeit their utilization in breeding programmes is poorly reported. For their effective use in breeding programme it is imperative to narrow down the confidence interval of QTLs, to identify the underlying genes, and most importantly allelic characterization of these genes for identifying superior variants. In the field of functional genomics, especially in the identification and characterization of gene responsible for quantitative traits, soybean is far ahead from other legume crops. The availability of genic information about quantitative traits is more significant because it is easy and effective to identify homologs than identifying shared syntenic regions in other crop species. In soybean, genes underlying QTLs have been identified and functionally characterized for phosphorous efficiency, flowering and maturity, pod dehiscence, hard-seededness, α-Tocopherol content, soybean cyst nematode, sudden death syndrome, and salt tolerance. Candidate genes have also been identified for many other quantitative traits for which functional validation is required. Using the sequence information of identified genes from soybean, comparative genomic analysis of homologs in other legume crops could discover novel structural variants and useful alleles for functional marker development. The functional markers may be very useful for molecular breeding in soybean and harnessing benefit of translational research from soybean to other leguminous crops. Thus, soybean crop can act as a model crop for translational genomics and breeding of quantitative traits in legume crops. In this review, we summarize current status of identification and characterization of genes underlying QTLs for various quantitative traits in soybean and their significance in translational genomics and breeding of other legume crops.

Allelic combinations of major photoperiodic (E1, E3, E4) and maturity (E2) genes have extended the adaptation of quantitative photoperiod sensitive soybean crop from its origin (China ∼35◦N latitude) to both north (up to ∼50◦N) and south (up to 40◦S) latitudes, but their allelic status and role in India (6-35◦N) are unknown. Loss of function and hypoactive alleles of these genes are known to confer photoinsensitivity to long days and early maturity. Early maturity has helped to adapt soybean to short growing season of India. We had earlier found that all the Indian cultivars are sensitive to incandescent long day (ILD) and could identify six insensitive accessions through screening 2071 accessions under ILD. Available models for ILD insensitivity suggested that identified insensitive genotypes should be either e3/e4 or e1 (e1-nl or e1-fs) with either e3 or e4. We found that one of the insensitive accessions (EC 390977) was of e3/e4 genotype and hybridized it with four ILD sensitive cultivars JS 335, JS 95-60, JS 93-05, NRC 37 and an accession EC 538828. Inheritance studies and marker-based cosegregation analyses confirmed the segregation of E3 and E4 genes and identified JS 93-05 and NRC 37 as E3E3E4E4 and EC 538828 as e3e3E4E4. Further, genotyping through sequencing, derived cleaved amplified polymorphic sequences (dCAPS) and cleaved amplified polymorphic sequences (CAPS) markers identified JS 95-60 with hypoactive e1-as and JS 335 with loss of function e3-fs alleles. Presence of photoperiodic recessive alleles in these two most popular Indian cultivars suggested for their role in conferring early flowering and maturity. This observation could be confirmed in F2 population derived from the cross JS 95-60 × EC 390977, where individuals with e1-as e1-as and e4e4 genotypes could flower 7 and 2.4 days earlier, respectively. Possibility of identification of new alleles ormechanism for ILD insensitivity and use of photoinsensitivity in Indian conditions have been discussed.