Genomics for greater efficiency in pigeonpea hybrid breeding

Abstract

Pigeonpea [Cajanus cajan (L.) Millspaugh] is an important pulse crop of rainfed and semi-arid regions of Asia, Africa and the Caribbean islands. India accounts for over 85% of the global area of 4.6 million hectares (Table 1). Globally, it is grown under low input environments, primarily as an intercrop with early maturing cereals. Pigeonpea is a major protein supplement for small holding farming families. Pigeonpea is also known for improving soil nutrition by fixing atmospheric nitrogen, releasing soil-bound phosphorus and recycling micro-nutrients. Its extensive root mass and leaf fall are known for improving soil structure and water infiltration in the soil (Saxena, 2008). Pigeonpea varietal improvement program started in India in 1931 with selection from landraces for traits such as seed size, fusarium wilt, plant type, and yield (Ramanujam and Singh, 1981). During this period over 100 pigeonpea cultivars have been released in India (http://www.iipr.res.in/aicrp.html); but the crop productivity remained stagnant (Figure 1). This is a matter of concern in view of increasing population and reducing per capita availability of protein that led to malnutrition among growing children and women, in particular. Considering the above mentioned constraints, new scientific approaches and tools are needed to raise the productivity of this important pulse crop. In this context, cytoplasmic male sterility (CMS)-based hybrid technology was developed and the world’s first pigeonpea commercial hybrid namely; ICPH 2671 was released, with 46% yield advantage in farmers’ field (Saxena et al., 2013). This is considered a milestone in the history of pulse breeding so far. In order to popularize hybrids, it is necessary that new high yielding hybrids are bred for different climatic conditions. Besides this, the technology be made grower-friendly. In this regard the new developments in genomics science can be of great help. Beyond doubt, integration of genomics with breeding can enhance the pace of breeding new widely adopted hybrids. The genomics science can be effectively used in the selection of heterotic hybrid male and female parents, incorporation of resistances and stability in the performance, assessment of purity of hybrids and their parents. In this paper, an effort has been made to highlight the potential role that genomics can play in accelerating the pace of hybrid breeding in pigeonpea (Figure 2).