Conventional and Molecular Approaches towards Genetic Improvement in Pigeonpea for Insects Resistance

Abstract

Pigeonpea [Cajanus cajan (L.) Millspaugh] is an important food legume of the semi-arid tropics (SAT) sustaining livelihood of millions of people. Stagnant and unstable yield per hectare all over the world is the characteristic feature of this crop. This is primarily ascribed to its susceptibility/sensitivity to a number of biotic and abiotic factors. Among biotic factors, insects such as pod borer (Helicoverpa armigera), pod fly (Melanoagromyza obtusa) and spotted borer (Maruca vitrata) substantially damage the crop and result in significant economic losses. Management of these insects by genetic means has always been considered environment friendly approach. However, genetic improvement has always been impeded by limited genetic variability in the primary gene pool of pigeonpea. Wild species present in the secondary and tertiary gene pools have been reported to carry resistance for such insects. However, transfer of resistance through conventional backcrossing has not been much successful. It calls for gene introgression through marker assisted backcrossing (MABC) or advanced backcross breeding (AB breeding). In this review, we have attempted to assess the progress made through conventional and molecular breeding and suggested the ways to move further towards genetic enhancement for insects resistance in pigeonpea.

Biochemical composition of pigeonpea genotypes in Kenya

“…Pigeonpea [Cajanus cajan (L.) Millsp.] is a legume crop mainly grown in the semi-arid tropics (Saxena et al, 2002) where millions of people are living below the poverty line and their livelihood primarily depends on the rain fed agriculture (Choudhary et al, 2013). Pigeonpea is a drought tolerant crop and produces reasonable grain yield during the dry spell when other legumes have dried up.…”

Assessment of phenotypic and genetic variation against pod borer among a subset of elite pigeonpea (Cajanus cajan) genotypes in Kenya

“…It has a diploid number of chromosome 2n=2x=22 and genome size of 833.1 Mbp (Varshney et al, 2012). Insect pests are among the major constraints to pigeonpea production in Eastern Africa especially pod borer (Helicoverpa armigera), pod fly (Melanagromyza cholcosoma) and sucking bug (Clavigralla tomentosicollis) (Minja et al, 1999) which substantially damage the crop and result to significant economic losses (Choudhary et al, 2013). Field evaluation of genotypes for response to insect pests can give breeders information on host plant resistance but is not sufficient in providing the extent of genetic diversity that is required in the field for improved productivity that results from selection.…”

Distinguishing Proof and Utilization of Resistance of Insect Pests in Grain Legumes: Progress and Limitations

“…However, till date deployment of resistance genes through conventional backcrossing has not been much successful. So now it especially calls for development of gene introgression through marker-assisted backcrossing (MABC) or advanced backcross breeding (AB breeding) for the development of improved insect pest-resistant cultivars (Choudhary et al 2013). A cross among an aphid (A. craccivora)-resistant cultivated cowpea (IT 84S-2246-4) and susceptible wild cowpea (NI 963) has also been evaluated for aphid screening resistance and RFLP (restricted fragment length polymorphism) marker segregation (Myers et al 1996).…”