The reward to selection in plant breeding is measured in terms of genetic gain. It is defined as the improvement in average genetic value in a population or the improvement in average phenotypic value due to selection within a population over cycles of breeding. 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)3. 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 gain4.

Genomic selection and speed breeding methods in combination (SpeedGS) could be effectively used to accelerate genetic gain in different crops. A simulation study in tall fescue for five different traits (heading date, fodder yield, seed yield, quality and persistency) with different genetic architecture was carried out and genetic gain from phenotypic selection and three different speedGS schemes was compared. SpeedGS schemes resulted in higher genetic gain per year for all traits especially for traits with low heritability such as persistency. Results from the study indicated that running more SB rounds resulted in higher genetic gain per cycle when compared to phenotypic or GS only schemes and this increase was more pronounced per year when cycle time was shortened1.

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 crops2.

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 apopulation4.

References

1. JIGHLY, A., LIN, Z., PEMBLETON, L. W., COGAN, N. O. I., SPANGENBERG, G. C., HAYES, B. J. AND DAETWYLER, H. D., 2019, Boosting genetic gain in allogamous crops via speed breeding and genomic selection. Front. Plant Sci., 10:1364. doi: 10.3389/fpls.2019.01364

2. 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

3. 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

4. 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