Plastidial starch phosphorylase is highly associated with starch accumulation process in developing squash (Cucurbita sp.) fruit
Plastidial starch phosphorylase is highly associated with starch accumulation process in developing squash (Cucurbita sp.) fruit
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DOI：
10.1111/ppl.12886
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发表时间：
2019-10-01
影响因子：
6.4
通讯作者：
Tateishi, Akira
中科院分区：
文献类型：
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作者：
Mizuno, Shinji;Kamiyoshihara, Yusuke;Tateishi, Akira
我们研究了南瓜发育和采后淀粉代谢酶活性的变化，它们分别积累了高水平和低水平的淀粉。西葫芦(C.Maxima)、西葫芦(C.Moschata)和西葫芦(C.Pepo)果实发育过程中淀粉磷酸化酶总活性与淀粉含量呈极显著正相关(r=0.99)。大叶锦鸡儿果实中一种胞质L形式的磷酸化酶的可分离活性随着淀粉的积累而显着增加。我们从极大黄瓜果实中分离到两个基因(CmPhoL1和CmPhoH1)，它们编码一个L形式的磷酸化酶和一个胞质H-型磷酸化酶。CmPhoL1在果实中的表达在淀粉积累开始时显著增加。重组CmPhoL1酶在葡聚糖合成和磷酸降解中表现出相似的动力学参数：该酶在体外可以催化可逆反应，这取决于底物的浓度。这些结果表明，CmPhoL1在南瓜发育过程中参与了淀粉的积累过程，但CmPhoL1在体内的葡聚糖合成反应中可能需要其他淀粉合成酶的辅助。指出了胞质淀粉磷酸化酶在果实器官淀粉积累中的重要作用。
We investigated changes in starch content and starch metabolic enzyme activities in developing and postharvest squash of distinct species, Cucurbita maxima and Cucurbita moschata, which accumulate high and low levels of starch, respectively. The total activity of starch phosphorylase in developing fruits significantly correlated (r = 0.99) to the amount of starch among Cucurbita species (C. maxima, C. moschata and C. pepo). Separable activity of a plastidial L-form phosphorylase in C. maxima fruit markedly increased corresponding with starch accumulation. We isolated two genes (CmPhoL1 and CmPhoH1) encoding an L-form and a cytosolic H-form phosphorylase from C. maxima fruit. The expression of CmPhoL1 in the fruit dramatically increased at the beginning of starch accumulation. Recombinant CmPhoL1 enzyme showed similar kinetic parameters in both glucan synthesis and phosphorolysis: this enzyme can catalyze the invertible reaction in vitro depending on the concentration of substrates. These results suggest that CmPhoL1 plays a role in the starch accumulation process during squash development, but the aid of other starch synthetic enzymes may be required for in vivo glucan synthesis reaction by CmPhoL1. An importance of plastidial starch phosphorylase in the starch accumulation in the fruit organ was indicated.