The non-gibberellic acid-responsive semi-dwarfing gene uzu affects Fusarium crown rot resistance in barley

Guangdeng Chen,Chunji Liu,You-Liang Zheng,Wei Yan,John M Manners,Yuming Wei,Yaxi Liu,Meixue Zhou

doi:10.1186/1471-2229-14-22

Abstract

BackgroundStudies in Arabidopsis show that DELLA genes may differentially affect responses to biotrophic and necrophic pathogens. A recent report based on the study of DELLA-producing reduced height (Rht) genes in wheat and barley also hypothesized that DELLA genes likely increased susceptibility to necrotrophs but increased resistance to biotrophs.ResultsEffects of uzu, a non-GA (gibberellic acid)-responsive semi-dwarfing gene, on Fusarium crown rot (FCR) resistance in barley were investigated. Fifteen pairs of near isogenic lines for this gene were generated and assessed under two different temperature regimes. Similar to its impacts on plant height, the semi-dwarfing gene uzu also showed larger effects on FCR severity in the high temperature regime when compared with that in the low temperature regime.ConclusionsResults from this study add to the growing evidence showing that the effects of plant height on Fusarium resistances are unlikely related to DELLA genes but due to direct or indirect effects of height difference per se. The interaction between these two characteristics highlights the importance of understanding relationships between resistance and other traits of agronomic importance as the value of a resistance gene could be compromised if it dramatically affects plant development and morphology.

Highlights

Studies in Arabidopsis show that DELLA genes may differentially affect responses to biotrophic and necrophic pathogens
Development and assessment of near isogenic lines for the semi-dwarfing gene uzu With the use of the SSR marker HMV33, ten heterozygous plants were identified from the TX9425/Franklin population and five from the TX9425/Gairdner population
The two isolines for each of the 15 pairs of near isogenic lines (NILs) developed from these heterozygous individuals showed highly significant difference in height under both temperature regimes assessed (Figure 1)

Summary

Introduction

Studies in Arabidopsis show that DELLA genes may differentially affect responses to biotrophic and necrophic pathogens. One of the critical considerations in cereal breeding is the selection of reduced height (Rht) genes. This is because different Rht genes do affect height differently but may have different effects on other morphological and agronomic traits of importance [1,2]. Two of the most widely used Rht genes in wheat, Rht-B1b and Rht-D1b, are known to encode DELLA proteins which repress GA responsive growth. They are thought to confer dwarfism by producing constitutively active forms of these growth repressors [3].

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