A PISTIL-SPECIFIC GENE OF SOLANUM-TUBEROSUM IS PREDOMINANTLY EXPRESSED IN THE STYLAR CORTEX

In a program aimed at studying genes expressed in pistils, the cDNA cl one STSI5 was isolated from a cDNA library of pollinated pistils of So lanum tuberosum and was found to be expressed only in pistils. During development of the pistil, the accumulation of STS15 transcripts, whic h are 0.7 kb long, reached a maximum just before anthesis and declined in fully open flowers. Southern blot analysis revealed that sts15 was present as a small gene family in dihaploid potato. In situ hybridiza tion experiments indicated that STS15 was strongly expressed in the co rtex of the style and at a low level in the stigma. No hybridization s ignal was observed in the transmitting tissue. The temporal and spatia l expression patterns of STS15 indicate that the gene products of the sts15 gene might be involved in the function of the stylar cortex or i n making the pistil competent for pollination.