American Journal of Plant Sciences, 2013, 4, 372-385 doi:10.4236/ajps.2013.42A049 Published Online February 2013 (http://www.scirp.org/journal/ajps) Conventional and Molecular Approaches towards Genetic Improvement in Pigeonpea for Insects Resistance Arbind K. Choudhary 1 , Ranjeet Sharad Raje 2 , Subhojit Datta 3 , Rafat Sultana 4 , Timmanna Ontagodi 5 1 Indian Institute of Pulses Research, Regional Research Station Cum Offseason Nursery, Dharwad, India; 2 Division of Genetics, Indian Agricultural Research Institute, New Delhi, India; 3 Indian Institute of Pulses Research, Kanpur, India; 4 Department of Plant Breeding and Genetics, Bihar Agricultural University, Sabour, India; 5 Department of Genetics and Plant Breeding, University of Agricultural Sciences, Dharwad, India. Email: akiipr23@yahoo.com Received December 18 th , 2012; revised January 20 th , 2013; accepted January 28 th , 2013 ABSTRACT Pigeonpea [Cajanus cajan (L.) Millspaugh] is an important food legume of the semi-arid tropics (SAT) sustaining live- lihood 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 al- ways 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 resis- tance 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. Keywords: Cajanus cajan; Insects Resistance; Wild Species; Secondary Gene Pool; MABC; AB Breeding 1. Introduction Millions of people in the semi-arid tropics (SAT) are living below poverty line and their livelihoods primarily depends on rainfed agriculture. Pigeonpea [Cajanus ca- jan (L.) Millsp.] plays an important role in sustaining the livelihood of poor people in the SAT regions by forming an integral component of rainfed agriculture [1]. It is a multi-purpose legume, which not only provides food and domestic fuel wood, but also enriches soil by improving water infiltration and conserving valuable nutrients and water. It is endowed with several unique features that allow its plants thrive well in drought prone degraded soils. Therefore, the cultivation of pigeonpea is likely to contribute to the overall economic development of the SAT regions by promoting a sustainable and eco-friendly agriculture that is subject to easy adoption by the resource poor farmers. Pigeonpea is an often cross-pollinated diploid (2n = 2x = 22) crop with 833.07 Mb genome size [2]. Globally, pi- geonpea is cultivated on an area of 4.92 M ha yielding a production of 3.65 Mt with an average productivity of 800 kg/ha [3]. Besides India, Kenya, Uganda, Malawi, Tanzania, Myanmar, Nepal, Puerto Rico, Dominican Re- public, and Venezuela are the major pigeonpea-produc- ing countries. In India, it is mainly cultivated as rainfed crop in about 3.92 Mha, accounting for more than 80% of the global pigeonpea production. In the states of Ma- harashtra, Karnataka and Andhra Pradesh, which account for >50% of the total pigeonpea area, pigeonpea is grown almost exclusively as a rainfed crop. From 1950 to 2010, the area under pigeonpea in India has increased from 2.18 to 3.92 Mha. However, despite its importance in subsistence and sustainable agriculture and continued breeding efforts to- wards genetic improvement, the average global produc- tivity of pigeonpea has remained static over the last three decades. The yield gap observed between the potential yield and on-farm yield is mainly due to prevalence of various abiotic [4] and biotic factors together with the cultivation of pigeonpea in marginal lands with low input supply and lack of efficient management practices [2]. There has been observed wide yearly fluctuations in total production mainly due to attack by insect pests including Copyright © 2013 SciRes. AJPS