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.

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Three improved varieties of Sorghum bicolor (L) Moench SPV 475, CSV 13 and CSV 15 were studied for the regeneration and multiple shoot induction. Explants of young immature inflorescence were cultured on modified Murashige and Skoog medium supplemented with 2% sucrose, 0.8% agar and 1.5 mg/l 2,4-D for callus initiation. Within 9 to 11 d callus initiation was observed. During third week 2 types of calli were identified, one was white compact, nodular embryogenic callus, while the other was unorganized, non morphogenic and non embryogenic callus. After transferring the callus onto regeneration medium (MSϩBAP), somatic embryos were formed, shoot initiation was observed from somatic embryos and was maximum at 1 mg/l BAP (7-17 shoots per culture). For multiple shoot induction different combinations of plant growth regulators (MSϩBAPϩ2,4-D, MSϩGAϩNAA, MSϩBAPϩIAA, MSϩBAPϩGA) along with asparagine and proline (50 mg/l), were used. Among these combinations MSϩ1 mg/l BAPϩ1 mg/l IAA gave maximum shoot induction. In this combination about 11-69 shoots were obtained per culture. And subsequent root formation was obtained with half strength MSϩ1.0 mg/l NAA.

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