Poaceae-specific<i>MS1</i>encodes a phospholipid-binding protein for male fertility in bread wheat

Abstract

Male sterility is an essential trait in hybrid seed production for monoclinous crops, including rice and wheat. However, compared with the high percentage of hybrid rice planted in the world, little commercial hybrid wheat is planted globally as a result of the lack of a suitable system for male sterility. Therefore, understanding the molecular nature of male fertility in wheat is critical for commercially viable hybrid wheat. Here, we report the cloning and characterization of <i>Male Sterility 1</i> (<i>Ms1</i>) in bread wheat by using a combination of advanced genomic approaches. <i>MS1</i> is a newly evolved gene in the Poaceae that is specifically expressed in microsporocytes, and is essential for microgametogenesis. Orthologs of <i>Ms1</i> are expressed in diploid and allotetraploid ancestral species. Orthologs of <i>Ms1</i> are epigenetically silenced in the A and D subgenomes of allohexaploid wheat; only <i>Ms1</i> from the B subgenome is expressed. The encoded protein, Ms1, is localized to plastid and mitochondrial membranes, where it exhibits phospholipid-binding activity. These findings provide a foundation for the development of commercially viable hybrid wheat.