Priscilla Glenn, Junli Zhang, Gina Brown-Guedira, Noah DeWitt, Jason P. Cook, Kun Li, Eduard Akhunov & Jorge Dubcovsky

Theoretical and Applied Genetics; Februcery 2022; vol. 135: 679–692

Key message

We discovered a natural FT-A2 allele that increases grain number per spike in both pasta and bread wheat with limited effect on heading time.

Abstract

Increases in wheat grain yield are necessary to meet future global food demands. A previous study showed that loss-of-function mutations in FLOWERING LOCUS T2 (FT2) increase spikelet number per spike (SNS), an important grain yield component. However, these mutations were also associated with reduced fertility, offsetting the beneficial effect of the increases in SNS on grain number. Here, we report a natural mutation resulting in an aspartic acid to alanine change at position 10 (D10A) associated with significant increases in SNS and no negative effects on fertility. Using a high-density genetic map, we delimited the SNS candidate region to a 5.2-Mb region on chromosome 3AS including 28 genes. Among them, only FT-A2 showed a non-synonymous polymorphism (D10A) present in two different populations segregating for the SNS QTL on chromosome arm 3AS. These results, together with the known effect of the ft-A2 mutations on SNS, suggest that variation in FT-A2 is the most likely cause of the observed differences in SNS. We validated the positive effects of the A10 allele on SNS, grain number, and grain yield per spike in near-isogenic tetraploid wheat lines and in an hexaploid winter wheat population. The A10 allele is present at very low frequency in durum wheat and at much higher frequency in hexaploid wheat, particularly in winter and fall-planted spring varieties. These results suggest that the FT-A2 A10 allele may be particularly useful for improving grain yield in durum wheat and fall-planted common wheat varieties.

See: https://link.springer.com/article/10.1007/s00122-021-03992-y

Figure 1: Comparison between FT-A2 A10 (SS-MVP57) and D10 (LA95135) alleles in winter wheat. a Days to heading. b Spikelet number per spike. c Grain number per spike. d Grain number per spikelet (fertility). e Average spike yield. Bars are least square means from a factorial ANOVA including PPD-D1, RHT-D1 and WAPO-A1 as factors. Error bars are s.e.m. ns not significant, *P = 0.05, **P = 0.01, ***P = 0.001