An autoactive <i>NB-LRR</i> gene causes <i>Rht13</i> dwarfism in wheat.

Abstract

Semidwarfing genes have greatly increased wheat yields globally, yet the widely used gibberellin (GA)-insensitive genes <i>Rht-B1b</i> and <i>Rht-D1b</i> have disadvantages for seedling emergence. Use of the GA-sensitive semidwarfing gene <i>Rht13</i> avoids this pleiotropic effect. Here, we show that <i>Rht13</i> encodes a <i>nucleotide-binding site/leucine-rich repeat</i> (<i>NB-LRR</i>) gene. A point mutation in the semidwarf <i>Rht-B13b</i> allele autoactivates the <i>NB-LRR</i> gene and causes a height reduction comparable with <i>Rht-B1b</i> and <i>Rht-D1b</i> in diverse genetic backgrounds. The autoactive <i>Rht-B13b</i> allele leads to transcriptional up-regulation of pathogenesis-related genes including class III peroxidases associated with cell wall remodeling. <i>Rht13</i> represents a new class of reduced height (<i>Rht</i>) gene, unlike other <i>Rht</i> genes, which encode components of the GA signaling or metabolic pathways. This discovery opens avenues to use autoactive <i>NB-LRR</i> genes as semidwarfing genes in a range of crop species, and to apply <i>Rht13</i> in wheat breeding programs using a perfect genetic marker.