Pollen Development in Crops - Barley and Wheat

Pollen development is a fundamental stage in the higher plant life cycle that is pivotal for breeding and seed production. The detailed regulation of this pathway has been extensively studied in Arabidopsis. Recent work has shown a high degree of conservation in this pathway in monocots (Wilson & Zhang, 2009). This has been greatly facilitated by the barley whole genome sequence and the availability of an increasing array of wheat genomic resources. Extending knowledge of these pathways into commercial crops such as barley and wheat therefore offers a mechanism to improve production, breeding and hybrid generation in crops.

Bioinformatics analysis has allowed the identification of barley and wheat orthologues to genes involved in anther and pollen development.  A detailed morphological characterization of barley (Fernandez and Wilson, 2012) and wheat reproductive development has facilitated the characterisation of orthologous genes that are highly tissue/stage specific. Molecular analysis of a number of barley genes showed functional similarities to their orthologues in Arabidopsis and rice. Recently, an orthologue to Arabidopsis Male Sterility1 (AtMS1) has been characterized in barley, HvMS1 (Fernandez and Wilson, 2014). MS1 is an anther specific PHD transcription factor that is essential for viable pollen formation in Arabidopsis. Characterization of this barley gene has indicated expression exclusively in the tapetum during microspore release from the tetrads. Moreover, the over-expression of HvMS1 in barley caused complete sterility, with no vegetative developmental effects. This phenotype is highly desirable in hybrid systems and shows the potential of anther and pollen gene characterization for commercial applications.