Genes Expressed in Pinus radiata Male Cones Include Homologs to Anther-Specific and Pathogenesis Response Genes

We describe the isolation and characterization of 13 cDNA clones that are differentially expressed in male cones of Pinus radiata (D. Don). The transcripts of the 13 genes are expressed at different times between meiosis and microspore mitosis, timing that corresponds to a burst in tapetal activity in the developing anthers. In situ hybridization showed that four of the genes are expressed in the tapetum, while a fifth is expressed in tetrads during a brief developmental window. Six of the seven cDNAs identified in database searches have striking similarity to genes expressed in angiosperm anthers. Seven cDNAs are homologs of defense and pathogen response genes. The cDNAs identified are predicted to encode a chalcone-synthase-like protein, a thaumatin-like protein, a serine hydrolase thought to be a putative regulator of programmed cell death, two lipid-transfer proteins, and two homologs of the anther-specific A9 genes from Brassica napus and Arabidopsis. Overall, our results support the hypothesis that many of the reproductive processes in the angiosperms and gymnosperms were inherited from a common ancestor.