An anther‐specific lipid transfer protein gene in sugar beet: its expression is strongly reduced in male‐sterile plants with Owen cytoplasm

Abstract

Differential screening of a sugar beet (normal cytoplasm line TK81‐O) cDNA library made with anther tissues of various stages resulted in the isolation of a clone (#74‐29) that hybridized to flower bud RNA but did not hybridize to RNA of vegetative organs. The clone contained an open reading frame (ORF) (designated bvLTP‐1) that encoded a putative lipid transfer protein. We also identified a second copy (bvLTP‐2) of the gene. In situ hybridization analysis demonstrated that expression of bvLTP‐1 was confined to the tapetal cells of the anthers at the young microspore stage. Flower bud RNA was prepared from male‐sterile sugar beet with Owen cytoplasm and fertility‐restored plants and used for northern hybridization with the bvLTP‐1 probe. Interestingly, bvLTP‐1 was found to be expressed in the flower buds from the restored plants producing 30% or more stainable pollen, but not in the flower buds from completely sterile or poorly fertility‐restored plants. These results lead us to suppose that the expression of bvLTP‐1 is strongly reduced in the tapetum in response to mitochondrial dysfunction and subsequent physiological changes caused by the Owen cytoplasm.