Abstract
Arabidopsis SHEPHERD (SHD) gene encodes a Hsp90-type molecular chaperon resident in the endoplasmic reticulum. The shd mutant shows a defect in formation of pollen exine. When we joined SHD cDNA to tapetum-specific promoters, SP11p and FBP1p, and introduced them into the shd mutant, only FBP1p:SHD restored the exine structure. This suggested that the the SHD is required for the exine formarion in tapetal cells of tetrad stage, in which FBP1p, but not SP11p, is active. It is supposed that the SHD participates in the secretion of prime exine components from tapetal cells. The shd also shows a defect in pollen tube elongation. It was recovered when the SHD was driven by the pollen-specific LAT52 promoter, whereas not by FBP1p, suggesting that the SHD expression in pollen grains is important for the pollen fertility, and that the correct exine structure is not necessary for the pollen fertility.
