猕猴桃果实乙烯受体基因Ad-ETR1的克隆及其表达

以"布鲁诺"美味猕猴桃(Actinidia deliciosa cv.Bruno)果实为材料,根据其它植物乙烯受体氨基酸保守区序列,设计简并引物,通过RT-PCR扩增出1个657bp大小的cDNA片段(Ad-ETR1)该片段编码219个氨基酸,与其它植物乙烯受体及其基因的氨基酸及核苷酸同源性在72%～90%之间.Northern杂交结果表明,猕猴桃果实成熟衰老进程中Ad-ETR1 mRNA的积累趋于增加.这种积累的最大值出现在乙烯进入跃变之后;乙烯处理可以促使Ad-ETR1 mRNA最大值提前出现,乙酰水杨酸(ASA)处理则显著抑制Ad-ETR1表达.

Cloning and Expression of Ethylene Receptor Gene Ad- ETR1 from Kiwifruit

According to the conserved amino acid sequence from ethylene receptors in other plants, a pair of degenerate primers was designed and a 657-bp cDNA fragment encoding an ethylene receptor fruit was obtained by RT-PCR from ripening kiwifruit (Actinidia deliciosa cv. Bruno) (Fig.1). The cDNA fragment encoding 219 amino acids was named Ad-ETR1, and its sequences shared high similarity at both nucle-otide and polypeptide level with the sequences from the plants of Arabidopsis, tomato, persimmon, avocado, citrus and peach (Fig.2, Table 1). Northern blot analysis indicated that the levels of Ad-ETR1 mRNA increased during kiwifruit ripening and reached peak at 144 h after treatment, then dropped immediately. The expression of Ad-ETR1 could be induced by ethyl-ene treatment, while acetylsalicylic acid (ASA) treatment inhibited its expression (Fig.4). In consistence with the changes of Ad-ETR1 mRNA, ethylene or ASA treatment had marked effects on the kiwifruit ethylene production and fruit softening (Fig.3). The significance of these results was discussed.