Abstract
Exploring genes with impact on yield-related phenotypes is the preceding step to accomplishing crop improvements while facing a growing world population. A genome-wide association scan on leaf blade area (LA) in a worldwide spring barley collection (Hordeum vulgare L.), including 125 two- and 93 six-rowed accessions, identified a gene encoding the homeobox transcription factor, Six-rowed spike 1 (VRS1). VRS1 was previously described as a key domestication gene affecting spike development. Its mutation converts two-rowed (wild-type VRS1, only central fertile spikelets) into six-rowed spikes (mutant vrs1, fully developed fertile central and lateral spikelets). Phenotypic analyses of mutant and wild-type leaves revealed that mutants had an increased leaf width with more longitudinal veins. The observed significant increase of LA and leaf nitrogen (%) during pre-anthesis development in vrs1 mutants also implies a link between wider leaf and grain number, which was validated from the association of vrs1 locus with wider leaf and grain number. Histological and gene expression analyses indicated that VRS1 might influence the size of leaf primordia by affecting cell proliferation of leaf primordial cells. This finding was supported by the transcriptome analysis of mutant and wild-type leaf primordia where in the mutant transcriptional activation of genes related to cell proliferation was detectable. Here we show that VRS1 has an independent role on barley leaf development which might influence the grain number.
Highlights
Feeding the growing population along with reducing agriculture’s environmental footprint is a crucial challenge posed to the scientific community in this century, which can be achieved by increasing cropping efficiency and yield (Foley et al, 2011)
Barley exists in two morphologically distinct spike forms, referred to as ‘two-rowed’ and ‘six-rowed’, which differ in their leaf blade area (LA) (Alqudah and Schnurbusch, 2015)
High broad-sense heritability (H2) for the studied trait (≥0.85) indicated that LA is predominantly genetically controlled at the examined developmental stages
Summary
Feeding the growing population along with reducing agriculture’s environmental footprint is a crucial challenge posed to the scientific community in this century, which can be achieved by increasing cropping efficiency and yield (Foley et al, 2011). The Plant Journal published by John Wiley & Sons Ltd and Society for Experimental Biology. It has already been reported that VRS1 is the result of a recent gene duplication that occurred only in tribe Triticeae (found in Wheat and Rye), and its paralog is known as HvHOX2. Both genes’ tissue-specific expression has been shown, their molecular functions are yet to be described (Komatsuda et al, 2007; Sakuma et al, 2010, 2013)
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