Insight into the genetic contribution of maximum yield potential, spikelet development and abortion in barley

Societal Impact Statement To feed the world's ever-increasing population, new genetic approaches are required. Increasing the number of living spikelets is one promising way to improve grain yield. This, in turn, increases the number of spikelets per plant, thereby increasing the total yield. We present the first evidence for genetic control of alive spikelets in barley. Discovering natural variation as well as genomic regions associated with these traits will serve as a benchmark in future breeding for improving grain yield. The primary goal of most breeding programmes is to increase grain yield. However, one of the many methods for raising yield that is yet to be fully investigated is increasing the number of spikelets by minimising spikelet abortion. Spikelet abortion dramatically increases during the late reproductive phase, but the molecular and genetic mechanisms remain unknown. Here, we employed a phenotyping approach in which developed and undeveloped spikelets were detected and counted during spike development and their maximum yield potential (MYP) was investigated. We studied 20 agronomic and spikelet-related traits using a set of 184 diverse spring barley accessions under field conditions. By employing a set of >125K SNPs, GWAS was conducted. Our analysis revealed 26 genetic clusters associated with MYP and the number of developed and undeveloped spikelets. Most of the significant associated genomic regions were co-located near the candidate genes of phytohormones such as ABA, auxin, and cytokinin suggesting the importance of phytohormones in keeping spikelets alive, their development, and MYP. Our findings point to a potential link between jasmonic acid and the MYP, development and abortion of spikelets. We further provide genetic evidence that sugar-related genes and sucrose have the potential to regulate MYP, spikelet development and spikelet survival. Our findings can be used for marker-assisted breeding and as a resource for future molecular and genetic validation. Collectively, we propose a new genetic network linking spikelet-related traits to grain yield determinants.