In plant breeding, genetic gain is used to quantify the benefit of selection. It may be described as the increase in a population's average genetic value or average phenotypic value brought about by selection acting within the population throughout successive breeding cycles. Genetic gain (GG) is calculated from breeder’s equation, which is directly proportional to selection intensity (i), accuracy (r) and additive genetic variance (σA) and inversely proportional to cycle time (t)2. A high and sustained rate of genetic gain is a key component of agriculture transformation; the genetic gain delivered in farmers’ fields is the key measure of effectiveness of a crop improvement system. Conventional plant breeding approaches helped the breeders in achieving genetic gain to certain extent. Changing climate, malnutrition and growing population demands magnificent rise in genetic gain, it can be achieved through supplementing the conventional breeding with advanced molecular breeding approaches.

Modern molecular breeding approaches like doubled haploid technology, speed breeding (SB),genomic selection coupled with phenotypic selection minimises the cycle length thereby maximises the gain. Application of high throughput phenotyping and improved field experimentations are known to enhance the selection accuracy there by genetic gain3.

Development of transgenics in pigeon pea remains dogged by poor plant regeneration in vitro from transformed tissues and low frequency transformation protocols. Hence the plumular and intercotyledonary meristems of the seedling axes are targeted for transformation, pricking of the apical and intercotyledonary region of the seedling axes of two-day old germinating seedlings with a sewing needle, infection with Agrobacterium, further harvesting seeds directly eliminates the tissue culture requirements thus reducing time required for breeding cycle. Effect of targeted recombination on improving the genetic gain was studied in different mapping populations of self-pollinated crops like soybean, wheat, barley and pea. Targeted recombination significantly (P = 0.05) increased the predicted genetic gain compared to nontargeted recombination for all traits studied and, in all populations, except for plant height in barley. For most traits and populations, having targeted recombination on less than a third of all the chromosomes led to the same or higher predicted gain than nontargeted recombination. Results from the study proved that targeted recombination could enhance genetic gain in both self and cross pollinated crops1.

Various studies have thoroughly indicated that integration of both conventional and modern molecular approaches can contribute to enhanced genetic gain to cope up the climate change, malnutrition and growing population4.

References

1. RU, S. AND BERNARDO, R., 2019, Targeted recombination to increase genetic gain in self‑pollinated species. Theor. Appl. Genet., 132:289–300. https://doi.org/10.1007/s00122-018-3216-1

2. SINHA, P., SINGH, V. K., BOHRA, A., ARVIND KUMAR, REIF, J. C. AND VARSHNEY, R. K., 2021, Genomics and breeding innovations for enhancing genetic gain for climate resilience and nutrition traits. Theor. Appl. Genet., 134:1829–1843 https://doi.org/10.1007/s00122-021-03847-6

3. XU, Y., LI, P., ZOU, C., LU, Y., XIE, C., ZHANG, X., PRASANNA, B. M. AND OLSEN, M. S., 2017, Enhancing genetic gain in the era of molecular breeding. J. Exp. Bot., 68(11): 2641–2666. doi:10.1093/jxb/erx135

4. SANKARA RAO, K., SREEVATHSA, R., SHARMA, P.D., KESHAMMA, E. AND UDAYA KUMAR, M., 2008, In planta transformation of pigeon pea: a method to overcome recalcitrancy of the crop to regeneration in vitro. Physiol. Mol. Biol. Plants, 14:321-328.