R.K. Gill

Gene Pyramiding and Multiple Character Breeding

Abstract Plant breeders are often interested in improving several quantitative traits including yield, quality, and resistance to both biotic and abiotic stresses simultaneously. However, breeding for multiple traits together is challenging and largely depends on the choice of germplasm, and the genetics and genetic relationships among the traits under selection. Both conventional and molecular breeding approaches have been used to breed for multiple traits simultaneously. Several selection schemes including independent culling levels, tandem selection, and index selection have been developed and used to improve and integrate traits simultaneously. Of these, selection index was preferred in the past and has been used to improve the overall genotypic performance based simultaneously on several quantitative traits, even for traits with unfavorable associations. With the recent development and advancement in molecular marker technologies, molecular breeding has become preferred for targeted breeding and product development. Molecular breeding technologies including marker-assisted selection, marker-assisted backcrossing, marker-assisted recurrent selection, gene pyramiding, marker-assisted backcross gene pyramiding, and genomic selection have been used to introgress single or multiple genes. Multiple trait selection using selection indices based on information from both phenotypes and markers distributed across the whole genome has recently been practiced in various crops. Multiple trait selection is a realistic approach that can be exploited in lentil breeding programs to simultaneously improve multiple traits. In this chapter, we discuss various conventional and molecular approaches to breeding, improving, and integrating multiple traits into a single genetic background with relevance to lentil crops.

Genetic variation for tolerance to post-emergence herbicide, imazethapyr in lentil (Lens culinaris Medik.)

ABSTRACT Weeds pose a serious constraint to lentil production. Identification and deployment of post-emergence herbicide tolerance in improved varieties can help reduce the production cost and increase the productivity and area under lentil cultivation. Imazethapyr, a post-emergence herbicide was tested on 180 lentil genotypes for two consecutive years. Significant variation among the genotypes was observed for tolerance to imazethapyr. On a 1–5 scale, 12 genotypes were found tolerant, 46 moderately tolerant, 112 sensitive and 10 highly sensitive during the first season, and 11 genotypes were found tolerant, 51 moderately tolerant, 110 sensitive and 8 highly sensitive during the second season. Based on the first year’s result, 30 genotypes, representing tolerant, moderately tolerant, sensitive and highly sensitive reactions, were evaluated to determine the effect of herbicide on morpho-physiological and yield traits. The adverse effect of imazethapyr was significant on growth and yield attributes of lentils. Five genotypes namely LL699, LL1397, IPL406, EC78452 and LL1203 demonstrated tolerance to imazethapyr with limited phytotoxic effect on various morpho-physiological traits. These genotypes showed less reduction (<19%) for seed yield in imazethapyr treated plots as compared to control. These genotypes offer scope for developing post-emergence herbicide tolerant cultivars in lentil.

Comparative assessment of ssr markers derived from different sources in genetic diversity analysis of Vigna genotypes

Mung bean (Vigna radiata (L.) Wilczek), also known as green gram, is an important food legume crop and provides an inexpensive source of dietary protein. Due to lack of sufficient variability and its importance in Asian countries there is need of broadening its genetic base. Genetic diversity among 21 Vigna genotypes of mung bean, rice bean and urd bean was assessed using SSR markers derived from genomic sequences of azuki bean (Ced) and mung bean (VR) and EST sequences of mung bean (MBM). Of the 67 SSR markers selected, 45 were found polymorphic among different genotypes which yielded 138 alleles of which 16 were mung bean specific, 27 urd bean specific and 17 rice bean specific alleles. Azuki bean derived SSRs (Ced) were more polymorphic. PIC value was similar in three sets of SSRs. Number of observed and effective alleles were more in Ced markers along with high value of various other parameters like EMR (3.6), MI (1.26), RP (2.7), H(0.33), H(0.62), and H(0.6), calculated to identify effectiveness of markers. Dissimilarity analysis divided mung bean and rice bean genotypes into two subclusters while 12 genotypes of urd bean formed two clusters.

Studies on Combining Ability for Grain Yield and Component Traits in Kharif Urdbean

Combining ability studies were carried out through line x tester analysis involving six lines and three testers for ten quantitative traits in kharif urdbean. The relative estimates of variance due to specific combining ability (sca) were higher than variance due to general combining ability (gca) for days to maturity, plant height and number of pods per plant indicating the pre-dominance of nonadditive gene action for these traits. The parents Mash 479 and KUG 489 were good general combiners for days to flowering, days to maturity and number of pods per plant. The cross ‘Mash 479 x Mash 1008’ exhibited significant positive sca effects for number of pods per plant, grain yield per plant and harvest index (%) alongwith high per se performance. The crosses; KUG 216 x Pant U 19, KUG 489 x Mash 338 and Mash 114 x Mash 1008 recorded highly significant sca effects as well as high per se performance for number of pods per plant. These crosses could be further exploited to obtain transgressive segregants in the breeding programme.