Mining legume germplasm for genetic gains: An Indian perspective

Abstract

Legumes play a significant role in food and nutritional security and contribute to environmental sustainability. Although legumes are highly beneficial crops, it has not yet been possible to enhance their yield and production to a satisfactory level. Amid a rising population and low yield levels, per capita average legume consumption in India has fallen by 71% over the last 50 years, and this has led to protein-related malnutrition in a large segment of the Indian population, especially women and children. Several factors have hindered attempts to achieve yield enhancement in grain legumes, including biotic and abiotic pressures, a lack of good ideotypes, less amenability to mechanization, poorer responsiveness to fertilizer input, and a poor genetic base. Therefore, there is a need to mine the approximately 0.4 million ex situ collections of legumes that are being conserved in gene banks globally for identification of ideal donors for various traits. The Indian National Gene Bank conserves over 63,000 accessions of legumes belonging to 61 species. Recent initiatives have been undertaken in consortia mode with the aim of unlocking the genetic potential of ex situ collections and conducting large-scale germplasm characterization and evaluation analyses. We assume that large-scale phenotyping integrated with omics-based science will aid the identification of target traits and their use to enhance genetic gains. Additionally, in cases where the genetic base of major legumes is narrow, wild relatives have been evaluated, and these are being exploited through pre-breeding. Thus far, >200 accessions of various legumes have been registered as unique donors for various traits of interest.

Keywords: biotic and abiotic stresses; crop domestication; legume collections; legume genomics; pulse production.

FIGURE 1

A graphical comparison of cereals and pulses in terms of total area harvested (A), total production (B), and yield (C) in India and the world. The graph indicates how the onset of the green revolution has tremendously enhanced the production of cereals in India and worldwide, which can be primarily attributed to yield improvement in these crops. By comparison, yield and production improvements in pulses have remained insignificant during this period (Data source: FAOSTAT, 2022).

FIGURE 2

Strategy to enhance genetic gains through utilization of advanced phenotyping tools, efficient operational tools, and advanced selection methods and technologies. A strategy to achieve higher genetic gains by broadening the genetic base through the infusion of increasing levels of variability from diverse sources into the target breeding populations is illustrated. The integration of improved crossing program strategies and advanced tools for phenotyping, operations, and desired genotype selection will further enhance the genetic gains made. This strategy will help with the attainment of greater genetic gains along with enhanced crop adaptability to changing climatic conditions.

FIGURE 3

Highlights of various important agro-morphological variations. Genotype (ICC16358) with a large number of branches per plant (A); genotype (IC486088) having upright peduncle and pods (B); genotype (ICC15559) with two to three flowers/peduncle (C); genotype (EC398937) with greater pod length (>15 cm) and a higher number of seeds/pod (D); leaflet size variation (E); leaf size variation (F); genotype with short internode length and compact phenotype (G); genotype (IC24417) with erect and tall growth habit (H); an erect genotype (NBeG 47) in chickpea (I); early-maturing (IC347181) (J) and erect type (VLG 39) (K) genotypes of horse gram; sona mung with bright yellow seeds having superior visual appeal (L) in green gram; a common bean germplasm (IC341862) having pea-shaped, bright white-colored seed with superior visual appeal (M); and a pigeon pea genotype with determinate growth habit (N).

FIGURE 4

Several promising newly identified resistance donors: IC486215 (A) for resistance against dry root rot in chickpea; IC275447 (B) for resistance against ascochyta blight in chickpea; IC118998 (C) for yellow mosaic disease (YMD) resistance in green gram; and IC278261 (D) for powdery mildew resistance in field pea.