Sorghum, a cereal of economic importance ensures food and fodder security for millions of rural families in the semi-arid tropics. The objective of the present study was to identify and validate quantitative trait loci (QTL) for grain yield and other agronomic traits using replicated phenotypic data sets from three post-rainy dry sorghum crop seasons involving a mapping population with 245 F9 recombinant inbred lines derived from a cross of M35-1 × B35. A genetic linkage map was constructed with 237 markers consisting of 174 genomic, 60 genic and 3 morphological markers. The QTL analysis for 11 traits following composite interval mapping identified 91 QTL with 5-12 QTL for each trait. QTL detected in the population individually explained phenotypic variation between 2.5 and 30.3 % for a given trait and six major genomic regions with QTL effect on multiple traits were identified. Stable QTL across seasons were identified. Of the 60 genic markers mapped, 21 were found at QTL peak or tightly linked with QTL. A gene-based marker XnhsbSFCILP67 (Sb03g028240) on SBI-03, encoding indole-3-acetic acid-amido synthetase GH3.5, was found to be involved in QTL for seven traits. The QTL-linked markers identified for 11 agronomic traits may assist in fine mapping, map-based gene isolation and also for improving post-rainy sorghum through marker-assisted breeding.

Forage sorghum cultivars grown in India are susceptible to various foliar diseases, of which anthracnose, rust, zonate leaf spot, drechslera leaf blight and target leaf spot cause severe damage. We report here the quantitative trait loci (QTLs) conferring resistance to these foliar diseases. QTL analysis was undertaken using 168 F 7 recombinant inbred lines (RILs) of a cross between a female parental line 296B (resistant) and a germplasm accession IS18551 (susceptible). RILs and parents were evaluated in replicated field trials in two environments. A total of twelve QTLs for five foliar diseases on three sorghum linkage groups (SBI-03, SBI-04 and SBI-06) were detected, accounting for 6.9-44.9% phenotypic variance. The morphological marker Plant color (Plcor) was associated with most of the QTL across years and locations. The QTL information generated in this study will aid in the transfer of foliar disease resistance into elite susceptible sorghum breeding lines through marker-assisted selection.

Genetic analysis of four in vitro characters (callus initiation, callus productivity, embryogenic callus percentage, and mean number of regenerated shoots per callus) was conducted using a 6 9 6 diallel cross among four cultivars of eggplant (Solanum melongena) and two related species (S. indicum, S. surattense) showing different in vitro responses. Among the 30 hybrid families, the in vitro performance exceeded the midparent in 19, 29, 18, and 22 cases, respectively, for callus initiation, callus productivity, embryogenic callus induction, and number of regenerated shoots. Both additive and dominant effects were significant and additive gene action was predominant for three of four in vitro characters with the exception of callus productivity. Different degrees of dominance were observed in the expression of the four characters. The broad and narrow sense heritabilities were 0.97 and 0.82 for callus initiation frequency, 0.99 and 0.42 for total amount of callus, 0.99 and 0.92 for E-callus productivity, and 0.99 and 0.73 for mean number of shoots, respectively, suggesting that these traits can be easily transferred into economically important cultivars with low tissue culture response or recalcitrance.

Three wild relatives Solanum: S. trilobatum L. (P1), S. indicum L. (P2), S. surattense Burm F. (P3) and four cultivars of S. melongena L.: 'Pusa Kranthi' (P4), 'Pusa purple long' (P5), 'Pusa purple cluster' (P6) and 'Green round' (P7) were evaluated for their callus induction frequency, total callus quantity, embryogenic callus quantity and plant regeneration ability. The present experiment revealed that in vitro response was significantly affected by the genotype, hormonal concentration and age of the explants (P<0.05). Cotyledon at walking stick stage of explants responded more than the opened leaves stage in all genotypes except in P1. Out of seven genotypes, P3 exhibited the highest callus induction, E-callus and regeneration response followed by P5 while highest total callus quantity obtained in P4. MS medium supplemented with 2 mg/l NAA+2.5 mg/l BAP was optimum for callus initiation, total callus quantity and embryogenic callus formation, and MS medium supplemented with 2.5 mg/l each BAP and KN were optimum for regeneration. Rooting of shoots occurred on half strength MS medium supplemented with 1 and 1.5 mg/l IBA respectively. The rooted plant lets were well accomplished with a survival frequency of 85.5±5%. Moreover, there were no phenotypic differences observed between the in vitro regenerated and in vivo plantlets.

No abstract