拟南芥ABA不敏感型突变体及其ABA结合特性

Characterization of ABA Binding in ABA-insensitive Mutant abi2 of Arabidopsis thaliana

拟南芥的脱落醚（ABA）不敏感型突变体abi2，在对ABA的敏感性、气孔开度及种子休眠方面，与野生型有明显差异。通过3H－ABA与野生型对的亚细胞组分的结合分析，表明38000×g组分特异结合活性最高，结合最适温度为20℃，最适保温时间：20℃时为70min；0℃时为90min。由饱和曲线的Scatchard分析表明：abi2存在一种ABA结合位点，野生型有两种ABA结合位点。对3H－ABA结合的38000×g组分的SDS－PAGE电泳分析表明：野生型有3个结合活性峰，而abi2只有1个结合活性峰。

There are distinct differences inphysiological characteristics, such asseed domancy, sensitivity to ABA andaperture of the stomata between wildtype and the ABA-insensitive mutantabi2 from Arabidopsis thaliana(Landsberg ) (Figs. 1 - 3, Table 1 ).AH-ABA binding in subcellular fractions(4 000 - 100 000 × g) of wild-typeand abi2 showed that the strongestspecifically-bound activity was in the38 000 × g pellet fraction (Table 2 ),the optimum temperature of ABA binding was 20C (Fig. 4 ). Scatchard plotof saturation kinetics showed that therewas one kind of binding site in abi2,but two in wild-type (Figs. 5, 6 ). Byanalysis of electropherogram un SDSPAGE of 3H-ABA-labelled 38 000 × gfractions from leaves of abi2 and wildtype (Fig. 7 ), three peaks of 3H-ABAbinding activity were found in wildtype (Fig. 8A), but only one in abi2(Fig. 8B). These results suggest that theinsensitivity to ABA of abi2 might becaused by mutation of ABA-bindingsites.