Repeat-length variation in a wheat cellulose synthase-like gene is associated with altered tiller number and stem cell wall composition.

J Hyles,H Berges,F Pettolino,J Breen,Z Stachurski,T Wicker,W Spielmeyer,C Macmillan,S Vautrin

doi:10.1093/jxb/erx051

Abstract

The tiller inhibition gene (tin) that reduces tillering in wheat (Triticum aestivum) is also associated with large spikes, increased grain weight, and thick leaves and stems. In this study, comparison of near-isogenic lines (NILs) revealed changes in stem morphology, cell wall composition, and stem strength. Microscopic analysis of stem cross-sections and chemical analysis of stem tissue indicated that cell walls in tin lines were thicker and more lignified than in free-tillering NILs. Increased lignification was associated with stronger stems in tin plants. A candidate gene for tin was identified through map-based cloning and was predicted to encode a cellulose synthase-like (Csl) protein with homology to members of the CslA clade. Dinucleotide repeat-length polymorphism in the 5'UTR region of the Csl gene was associated with tiller number in diverse wheat germplasm and linked to expression differences of Csl transcripts between NILs. We propose that regulation of Csl transcript and/or protein levels affects carbon partitioning throughout the plant, which plays a key role in the tin phenotype.

Highlights

The development of tillers from basal nodes of shoots has major effects on the above-ground architecture and biomass of monocots
The near-isogenic line Banks+tin that was previously used for agronomic assessment of tin was developed by transferring the gene from the ‘492’ donor line into the Australian wheat cultivar ‘Banks’ (Richards, 1988)
We studied the allelic diversity of the repeat-length variation in the 5 ́UTR region and possible association with tillering by assaying the polymorphism detected by gwm136 in diverse and historical wheat landraces contained within the Watkins collection

Summary

Introduction

The development of tillers from basal nodes of shoots has major effects on the above-ground architecture and biomass of monocots. Buds in the leaf axils of basal nodes can grow out to form tillers (branches) that determine the yield potential of temperate cereals such as wheat (Triticum aestivum). A gene was reported in wheat that reduces tillering by preventing tillerbud outgrowth and is named ‘tiller inhibition’ gene (tin). (Atsmon and Jacobs, 1977; Kebrom et al, 2012). The tin gene was associated with larger spikes and increased grain weight along with thicker leaves and stems, which were collectively referred to as Gigas characteristics (Atsmon and Jacobs, 1977). Several agronomic studies concluded that tin was associated with 1520 | Hyles et al

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