Identification and characterization of sources for photo‐ and thermo‐insensitivity in Vigna species

Cultivation of the same varieties of mungbean and blackgram across different seasons and locations is constrained by their photo‐ and thermo‐sensitive behaviour. Developing insensitive genotypes, which can fit well across all seasons, requires robust donors which would provide genes imparting this trait. This study was undertaken to identify such donors in the Vigna species. Forty‐eight accessions belonging to 13 Vigna species and eight released cultivars were evaluated under natural field conditions. Among these, two accessions, viz. V. umbellata (IC251442) and V. glabrescens (IC251372) were found photo‐ and thermo‐insensitive as these were able to flower and set pods at temperatures as high as 43.9°C and as low as 2.7°C. Pollen viability studies indicated viable pollen (>75% at 2.7°C and >85% at 41.9°C) and normal pollen tube growth at both the extremes of temperature. The identified V. glabrescens accession has long, constricted pods and dark green, mottled seeds while V. umbellata has smooth, curved pods and shining, oval, large seeds. Both these accessions can be utilized in developing photo–thermo insensitive genotypes in cultivated Vigna species.     

Ontogeny of in vitro shoot organogenesis from axillary meristem explants in chickpea (Cicer arietinum L.)

Chickpea (Cicer arietinum L.) is a major food legume crops for the tropics and sub-tropical regions and is the main dietary protein source for vegetarians in developing countries. Besides several abiotic factors, its production is constrained by insect pests, as well as many fungal diseases. The success of any attempt to produce resistant varieties through genetic engineering to a large extent depends on the availability of efficient and reproducible regeneration and transformation procedures. Further, the transformation techniques can be more successfully applied if the ontogeny of shoot development is well understood. Ontogeny of shoot development from axillary meristem explants (AME) in chickpea has been studied with the optimization of conditions for high-frequency multiple shoot induction. Preculture of seeds in TDZ significantly enhances the frequency of multiple shoot induction from the explants. Ontogeny and early events of multiple shoot induction revealed direct adventitious origin of the shoots. The understanding of the regeneration process could be further utilized in the designing of efficient transformation methods.