The Grain Number Increase 1 alleles GNI-A1-105Y and -105K increase grain number in spring wheat

Abstract

Wheat (Triticum aestivum L.) has inflorescences made up of multiple spikelets arranged along a central rachis, with each spikelet producing between one and four grains. The Grain Number Increase 1 (GNI-A1) gene wheat directly influences grain number per spikelet and grain size. Three naturally occurring alleles have been described previously: GNI-A1-105N, 105Y, and 105K. This project's goal was to characterize the impact of these alleles within hard red spring wheat cultivars in Montana, where each of the alleles is common. The 105N allele and the 105K allele were compared through analysis of an F5 Vida by Spring-Yellowstone recombinant inbred line (RIL) population, and with near isogenic lines (NILs) derived from the same population. The 105N allele and the 105Y allele were compared with NILs derived from an F4 Lanning by Egan RIL population. We analyzed the impact of each of the three alleles and compared their effects on inflorescence architecture, grain size, grain yield, grain quality, and milling quality under Bozeman, MT, field conditions. Data show that either loss-of-function alleles (105Y and 105K) increased grain number per spikelet by 5% when compared to the more functional allele (105N) across all years and environments tested. Overall grain size was not significantly reduced and there was also not a significant increase in overall grain yield.