去胚轴对花生子叶肽链内切酶和贮藏蛋白质降解的影响

The Influences of Axis Removal on Endopeptidase Activity and Storage Protein Degradation in Cotyledon of Peanut (Arachis hypogaea L.) Seed

从离体子叶与连体子叶在水中培养一段时间后的比较 ,看到它们之间在肽链内切酶活性和盐溶蛋白及花生球蛋白降解上的差异并不大 ,这表明去除胚轴对子叶肽链内切酶活性和贮藏蛋白降解的影响很轻微。亚胺环己酮 (蛋白质合成抑制剂 )不能完全抑制离体子叶肽链内切酶活性的提高 ,子叶的大部分大分子贮藏蛋白同样被降解。这表明 ,在花生种子萌发过程中降解大部分贮藏蛋白的子叶肽链内切酶并非全部是在种子萌发时新合成的 ,子叶贮藏蛋白降解和肽链内切酶活性基本不受胚轴调控 。

The endopeptidase activity and storage protein degradation in cotyledon of peanut seed 0～10 days after sowing were investigated. Compared with undetached cotyledon, detached one incubated in distilled water showed only a slightly lower enzyme activity (Fig.1) and rate of degradation of salt soluble protein(SSP) (Fig.5) and arachin (Fig.6), while strong but not total inhibitions of both the endopeptidase activity (Figs.1,2,4B) and the degradation of proteins (Figs.2,5～7) were observed when detached cotyledons were incubated in cycloheximide solution(0.05～1 mmol/L). Peanut cotyledon has two isoenzymes of endopeptidase, with the difference that the activity of the one near anode is delayed for one day in sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS PAGE), while the one near cathode is unaffected (Fig.4A) . SDS PAGE of SSP of detatched cotyledons showed that its mobilization pattern was very similar to that in normal germinating seeds, and there was almost no protein of large molecular weight in gel of SDS PAGE of SSP of detached cotyledons cultured in CHM 1 mmol/L (Fig. 7). The results obtained suggest that the endopeptidase which degrades most storage proteins in peanut cotyledon during seed germination is not synthesized de novo and the endopeptidase activity and storage protein degradation are not induced by the embryonic axis. The mode in which storage matter in peanut cotyledon is mobilized during seed germination may be a new one.