Cytotaxonomy and gene introgression in wildArachis species

Abstract

Groundnut is considered as a gift for small and marginal farmers, who grow groundnut under low input conditions for food, oil, cattle feed and confectionery purposes. However, the crop suffers from many diseases and pests that cause serious yield reduction. Wild relatives of groundnut have reported to be the potential sources of resistance for number of diseases such as rust, late leaf spot, early leaf spot, bud and stem necrosis besides their tolerance to insect pests such as thrips and aphids. But, utilization of wild Arachis for genetic improvement of Groundnut along with their tolerance to major biotic stresses forms a key factor for groundnut research considering that those are lacking in cultivated Arachis hypogaea Linn. The cross compatibility in the Arachis genus identified that species within a section will usually hybridize but hybrids under different sections of same genus are difficult to hybridize and are usually sterile. The section, Arachis has immediate potential as sources for the genetic improvement of groundnut though the differences in ploidy levels seem to be the major bottleneck in gene transfer from wild diploid to cultivated tetraploid. The information furnished in this article establishes the complexity in the genetic improvement of the Arachis species. Tapping the genetic variability in any crop species will help a plant breeder to achieve his desired goal of varietal evolution. In this regard, the breeders can tap the secondary gene pool or tertiary gene pool rather tapping primary gene pool.