21 Differential screening and suppression subtractive hybridization identifies genes differentially expressed in male and female plants of aglaothamnion oosumiense (rhodophyta)

Abstract

Sex determination and development of reproductive structures in Aglaothamnion oosumiense were examined by cytogenetic and molecular studies. Chromosome studies of male and female reproductive cells indicated that the sexuality of this species might be determined by a sex chromosome. Chromosome counts in female and male gametophytes were 37 and 36, respectively. The sex ratio of the gametophytes was 1:1. Also male‐derived bisexual plants were observed. They were different in morphology, position of carpogonial branches and chromosome number. Some male plants also developed parasporangia. Chromosome number of the paraspore germlings was the same as in the male plants. A novel method combining element of suppression subtractive hybridization (SSH) with high throughput differential screening permitted an efficient and rapid cloning of rarely transcribed differentially expressed genes. Potential of the method is demonstrated by the isolation of 212 subtractive clones that were differentially expressed in male and female plants. About 18 subtractive clones were confirmed by reverse northern blotting. Two genes, AOMS‐1 and AOMS‐2, which showed male specific expression were analyzed. These genes seem to be involved in differentiation of male reproductive structures.