Journal Article

Six-rowed spike4 (Vrs4) controls spikelet determinacy and row-type in barley

Tagiri, Akemi, Anwar, Nadia, Ariyadasa, Ruvini, Rutten, Twan, Lundqvist, Udda, Stein, Nils, Pourkheirandish, Mohammad, Himmelbach, Axel, Youssef, Helmy Mohamad, Sreenivasulu, Nese, Koppolu, Ravi, Komatsuda, Takao, Schnurbusch, Thorsten, Sakuma, Shun, Seiler, Christiane

2013

Overview

Inflorescence architecture of barley (Hordeum vulgare L.) is common among the Triticeae species, which bear one to three singleflowered spikelets at each rachis internode. Triple spikelet meristem is one of the unique features of barley spikes, in which three spikelets (one central and two lateral spikelets) are produced at each rachis internode. Fertility of the lateral spikelets at triple spikelet meristem gives row-type identity to barley spikes. Sixrowed spikes show fertile lateral spikelets and produce increased grain yield per spike, compared with two-rowed spikes with sterile lateral spikelets. Thus, far, two loci governing the row-type phenotype were isolated in barley that include Six-rowed spikei (Vrs1) and Intermedium-C. In the present study, we isolated Six-rowed spike4 (Vrs4), a barley ortholog of the maize (Zea mays L.) inflorescence architecture gene RAMOSA2 (RA2). Eighteen coding mutations in barley RA2 (HvRA2) were specifically associated with lateral spikelet fertility and loss of spikelet determinacy. Expression analyses through mRNA in situ hybridization and microarray showed that Vrs4 (HvRA2) controls the row-type pathway through Vrs1 (HvHox1) a negative regulator of lateral spikelet fertility in barley. Moreover, Vrs4 may also regulate transcripts of barley SISTER OF RAMOSA3 (HvSRA), a putative trehalose-6-phosphate phosphatase involved in trehalose-6-phosphate homeostasis implicated to control spikelet determinacy. Our expression data illustrated that, although RA2 is conserved among different grass species, its down-stream target genes appear to be modified in barley and possibly other species of tribe Triticeae.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Alleles / Amino Acid Sequence / Barley / Base Sequence / Biological Sciences / Chromosome Mapping / Chromosomes, Plant - genetics / Corn / Cytokinins / Determinacy / Fertility / Fertility - genetics / Gene expression / Gene Expression Profiling / Gene Expression Regulation, Plant / Genes / Genotype & phenotype / grain yield / grasses / Haplotypes / Homeostasis / Hordeum - genetics / Hordeum - metabolism / Hordeum - ultrastructure / Hordeum vulgare / in situ hybridization / Inflorescence - genetics / Inflorescence - metabolism / Inflorescence - ultrastructure / Inflorescences / loci / Meristems / messenger RNA / microarray technology / Microscopy, Electron, Scanning / Molecular Sequence Data / Mutation / Nonnative species / Oligonucleotide Array Sequence Analysis / Phenotype / Phenotypes / Phylogeny / Plant Proteins - classification / Plant Proteins - genetics / Plant Proteins - metabolism / Reverse Transcriptase Polymerase Chain Reaction / Sequence Homology, Amino Acid / Spikelets / Zea mays