Mutations in Barley Row Type Genes Have Pleiotropic Effects on Shoot Branching

Abstract

Cereal crop yield is determined by different yield components such as seed weight, seed number per spike and the tiller number and spikes. Negative correlations between these traits are often attributed to resource limitation. However, recent evidence suggests that the same genes or regulatory modules can regulate both inflorescence branching and tillering. It is therefore important to explore the role of genetic correlations between different yield components in small grain cereals. In this work, we studied pleiotropic effects of row type genes on seed size, seed number per spike, thousand grain weight, and tillering in barley to better understand the genetic correlations between individual yield components. Allelic mutants of nine different row type loci (36 mutants), in the original spring barley varieties Barke, Bonus and Foma and introgressed in the spring barley cultivar Bowman, were phenotyped under greenhouse and outdoor conditions. We identified two main mutant groups characterized by their relationships between seed and tillering parameters. The first group comprises all mutants with an increased number of seeds and significant change in tiller number at early development (group 1a) or reduced tillering only at full maturity (group 1b). Mutants in the second group are characterized by a reduction in seeds per spike and tiller number, thus exhibiting positive correlations between seed and tiller number. Reduced tillering at full maturity (group 1b) is likely due to resource limitations. In contrast, altered tillering at early development (groups 1a and 2) suggests that the same genes or regulatory modules affect inflorescence and shoot branching. Understanding the genetic bases of the trade-offs between these traits is important for the genetic manipulation of individual yield components.

Six-Rowed Spike3 (VRS3) Is a Histone Demethylase That Controls Lateral Spikelet Development in Barley

“…1; Supplemental Fig. S1), corroborating previous reports Koppolu et al, 2013;Liller et al, 2015). The development of additional lateral spikelets, which mainly occurred at the middle part of the spike, was not associated with a significant change in rachis internode number (Supplemental Fig.…”

“…In addition, many of these mutant phenotypes were intercrossed to identify allelic mutant series for different morphological, developmental, and physiological traits. The collection has proven particularly valuable for studying the genetic control of plant and spike architecture Koppolu et al, 2013;Liller et al, 2015).…”

“…Double mutants of different int loci lead to typical six-rowed plants, suggesting that int genes and VRS1 might interact in the same pathway . In a comprehensive analysis, we have classified 36 different row-type mutants based on their shoot and spike architecture (Liller et al, 2015). Allelic vrs3/int-a, int-c, vrs1, and vrs4 mutants and derived introgression lines showed comparable macroscopic phenotypes, such an increase in the number of seeds per spike and a reduction in tiller number at maturity compared to their two-rowed wild-type parents.…”

Genetics of barley tiller and leaf development

“…A considerable effect of row type on tiller number was demonstrated under various growth conditions (Alqudah and Schnurbusch 2013). Consistent with this finding, tiller number was shown to be affected by the allelic status of the VRS1 gene (Liller et al 2015).…”

Fine mapping of a major QTL for awn length in barley using a multiparent mapping population

“…The plants were irrigated using a sprinkler robot. For QTL confirmation and additional experiments performed in 2012, 2013 and 2014 the plot was set-up using 12 L pots as described previously (Liller et al 2015) only in this study the plot was divided into two blocks.…”