동질사배체 탱자에서 염색체 배가와 수체 표현형의 변이

Abstract

The study was conducted to investigate the possibility that epigenetic DNA methylation might cause tree phenotypic variation in autotetraploids through evaluating the phenotypic variation and DNA methylation in autotetraploids occurred spontaneously from diploid trifoliate orange. Chromosome analysis confirmed that fourteen plants of trifoliate oranges selected by flow cytometry were tetraploids (2n=36) without any aneuploid. CMA staining determined that these plants were all autotetraploids with double chromosome set. Tree phenotypes, such as tree height, tree width, branching number, branching length, branching angle, internode length, and leaf characteristic, were varied in the autotetraploids. There was no significant difference in the photosynthetic rate, however, chlorophyll indexes were diverse in the autotetraploids. In addition, a wide range of variation was observed in stoma density and guard cell length. Analysis of global cytosine DNA methylation showed that there was a variation of the methylation level in population. More than half of 14 autotetraploids had at least 2 times higher than that of diploid trifoliate orange. The results indicated that tree phenotypic variation in autotetraploids might be related to global DNA methylation for reducing gene redundancy.