Identification of fertility restorers for A2 cytoplasm-based CGMS lines and development of short duration hybrids in pigeonpea (Cajanus cajan(L.) Millsp.).

Pigeonpea is the second most important legume crop grown in India after chickpea. India is the largest producer of pigeonpea in the world. However, the productivity of pigeonpea in India remains stagnant over the years. The productivity of pigeonpea can be improved through exploitation of heterosis. The cytoplasmic genetic male sterility is the predominant method employed in hybrid development in pigeonpea during the recent days owing to the advantages involved. The present study involved the identification of fertility restorers for three Cajanus scarabaeoides(A2) based short duration (120-130 days) male sterile lines, namely CORG 990047A, CORG 990052A and CORG 7A. A total of 77 inbreds were involved in the hybridization programme. The pollen fertility of the 186 hybrids ranged from 0.00 to 94.89%. The independent confirmation of fertility restoration based on pollen fertility and pod set by selfing showed that, the hybrids, namely CORG 990047A 9 AK 261322, CORG 990052A 9 AK 261322 and CORG 7A 9 AK 261322 were identified as fertile. The inbred AK 261322 was the potential restorer of fertility in A2 male sterile lines. The hybrids, namely CORG 990047A 9 AK 261322 (35.19%), CORG 990052A 9 AK 261322 (12.75%) and CORG 7A 9 AK 261322 (19.77%) showed high heterosis for single plant yield over CO(Rg)7, a commercial check variety. The hybrids identified in the present study can be exploited for commercial cultivation after evaluation under various yield trials to estimate its performance. The polymorphic SSR markers identified in the present study can be utilized in future to assess the genetic purity of the hybrids.

Characterization of betasatellite associated with the yellow mosaic disease of grain legumes in Southern India.

Yellow mosaic disease caused by mungbean yellow mosaic virus (MYMV) belonging to the genus Begomovirus (the family Geminiviridae) is a major constraint in cultivation of grain legumes in India. The urdbean (Vigna mungo (L.) Hepper) and mungbean (Vigna radiata (L.) R. Wilczek) samples affected with yellow mosaic disease exhibits yellow mosaic symptoms along with leaf puckering and leaf distortion in Tamil Nadu. Hence the study was performed to find out if there was any association and influence of betasatellite DNA on the symptom expression of MYMV. Full length viral clones of DNA A and DNA B were obtained through rolling circle amplification from YMD infected samples and identified as mungbean yellow mosaic virus. Interestingly, betasatellite was found to associate with MYMV, and its nucleotide sequence analysis showed its 95% identity with papaya leaf curl betasatellite (DQ118862) from cowpea. The present study represents the first report about the association of papaya leaf curl betasatellite with MYMV and represents a new member of the emerging group of bipartite begomovirus associated with betasatellite DNA.