Genetic gains with rapid‐cycle genomic selection for combined drought and waterlogging tolerance in tropical maize (Zea mays L.)

Abstract

Rapid cycle genomic selection (RC-GS) helps to shorten the breeding cycle and reduce the costs of phenotyping, thereby increasing genetic gains in terms of both cost and time. We implemented RC-GS on two multi-parent yellow synthetic (MYS) populations constituted by intermating ten elite lines involved in each population, including four each of drought and waterlogging tolerant donors and two commercial lines, with proven commercial value. Cycle 1 (C 1) was constituted based on phenotypic selection and intermating of the top 5% of 500 S 2 families derived from each MYS population, test-crossed and evaluated across moisture regimes. C 1 was advanced to the next two cycles (C 2 and C 3) by intermating the top 5% selected individuals with high genomic estimated breeding values (GEBVs) for grain yield under drought and waterlogging stress. To estimate genetic gains, population bulks from each cycle were test-crossed and evaluated across locations under different moisture regimes. Results indicated that the realised genetic gain under drought stress was 0.110 t ha −1 yr −1 and 0.135 t ha −1 yr −1 , respectively, for MYS-1 and MYS-2. The gain was less under waterlogging stress, where MYS-1 showed 0.038 t ha −1 yr −1 and MYS-2 reached 0.113 t ha −1 yr −1. Genomic selection for drought and waterlogging tolerance resulted in no yield penalty under optimal moisture conditions. The genetic diversity of the two populations did not change significantly after two cycles of GS, suggesting that RC-GS can be an effective breeding strategy to achieve high genetic gains without losing genetic diversity.

Opportunities for Improving Waterlogging Tolerance in Cereal Crops—Physiological Traits and Genetic Mechanisms

“…Genomic selection was applied to predict genetic value by combining genome-wide marker and phenotyping data of a training population to obtain genomic estimated breeding value (GEBV) [ 158 ]. In maize, rapid-cycle genomic selection (RCGS) for waterlogging tolerance in two multi-parent yellow synthetic populations showed a genetic gain of 38–113 kg ha −1 year −1 under waterlogging stress [ 159 ]. The results suggested that RCGS is an effective approach to breed varieties with superior qualities by introgressing parents with traits of interest [ 160 ].…”

Multi-trait genomic prediction using in-season physiological parameters increases prediction accuracy of complex traits in US wheat

“…Genomic selection will also likely increase gain per unit cost by reduced genotyping cost per data point and reduced number of lines to be phenotyped [ 4 , 13 ]. As a result, GS is being implemented widely in breeding programs to improve genetic gain and expedite cultivar development by reducing cycles of selection [ 1 , 14 ]. Prediction accuracy is estimated as a correlation between GEBV and the phenotypic value of a trait [ 13 ].…”

Genomic Selection: A Tool for Accelerating the Efficiency of Molecular Breeding for Development of Climate-Resilient Crops

“…This increased the genetic gain as the time required for selection was reduced significantly as compared to that of the conventional breeding scheme, where it was three times higher with phenotypic selection. Similarly, Das et al (2020) reported a genetic gain of 0.110 and 0.135 t/ha/yr for grain yield under drought and 0.038 and 0.113 t/ha/yr under water logging in two maize populations, viz., Maize Yellow Synthetic 1 and Maize Yellow Synthetic 2, respectively, following rapid cycling genomic selection. Vivek et al (2017) compared the performances of second cycle selection through phenotypic and rapid cycle genomic selection and found 10–20% superiority using the latter.…”