halfman, an Arabidopsis male gametophytic mutant associated with a 150 kb chromosomal deletion adjacent to an introduced Ds transposable element

To identify genes that play an important gametophytic role during pollen development, an Arabidopsis transposon (DsE) mutagenised population was screened for marker segregation ratio distortion. We report the characterisation of a male gametophytic mutant termed halfman (ham) that results in an aborted pollen phenotype in mature anthers. The genetic transmission efficiency of DsE was 6.6% through the male and 98.4% through the female, which suggested that HAM may encode essential male-specific component(s) required for pollen development. Molecular analysis of the insertion site revealed a single copy of the DsE element inserted into the second exon of the RLK5 gene that was adjacent to a large (∼150 kb) genomic deletion. The deleted region is predicted to encode 38 genes and to include one or more genes with important function(s) during pollen maturation and seed development.