陆地棉抗凋亡基因DAD1同源拷贝的非对称性驯化改变

Asymmetric domesticated changes of DAD1 homoeologs in Gossypium hirsutum

抗凋亡基因DAD1是细胞程序性死亡的抑制基因,在植物生长发育中发挥重要作用。为探讨该基因在具有AADD基因组的异源四倍体陆地棉驯化过程中的遗传改变,本研究选取了陆地棉的野生和栽培样品作为研究对象,结合分子克隆、测序以及棉纤维不同发育阶段的转录组数据分析等方法,对二者在DAD1基因序列和表达水平的差异进行了深入比较,结果显示:陆地棉中,DAD1基因同时具有A和D基因组的2个同源拷贝;驯化对这2个拷贝的影响是不均衡的,其中A基因组的拷贝在基因序列上保持一致,但在表达上出现分化;D基因组拷贝在基因序列上出现了5个核苷酸的变异,包括1个发生在外显子区的同义突变,但在表达上却未出现明显变化。我们目前的研究结果展示了驯化对多倍体植物重要功能基因同源组分的影响是独立的,非对称性的。

Anti-apoptotic gene（defender against apoptotic death 1, DAD1）, an inhibitor of programmed cell death, plays an important role in plant growth and development. In this study, we chose an AADD genome allopolyploid species Gossypium hirsutum as the plant materials to investigate domesticated changes of DAD1 gene. We analyzed and compared the sequence differences of the DAD1 genes between cultivated and wild cottons by using the methods of molecular cloning and sequencing. Meanwhile, using our previous transcriptome data, we compared the expression statuses of DAD1 gene in two kinds of cottons. As a result, we found that both A and D genomic homoeologs were maintained in G. hirsutum, and an unequal impact derived by domestication was revealed on different genomic homoeologs. The consistent nucleotide sequences, but divergent expression levels were found in A genomic homoeologs of wild and cultivated cottons; whereas five nucleotide mutations, including one synonymous mutation occurred in exonic region, and the unchanged expression levels were found in D genomic homoeologs of wild and cultivated cottons. Our present result implies that domestication would make independent and asymmetric impacts on the duplicated homoeologs of some important functional genes in polyploids.