Amylases StAmy23, StBAM1 and StBAM9 regulate cold-induced sweetening of potato tubers in distinct ways.
Amylases StAmy23, StBAM1 and StBAM9 regulate cold-induced sweetening of potato tubers in distinct ways.
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淀粉酶 StAmy23、StBAM1 和 StBAM9 以不同的方式调节冷诱导的马铃薯块茎增甜
DOI：
10.1093/jxb/erx076
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发表时间：
2017-04-01
影响因子：
6.9
通讯作者：
Xie C
中科院分区：
文献类型：
--
作者：
Hou J;Zhang H;Liu J;Reid S;Liu T;Xu S;Tian Z;Sonnewald U;Song B;Xie C
StAmy23、StBAM1和StBAM9分别优先作用于不同亚细胞位置的可溶性植物糖原、可溶性淀粉和淀粉颗粒，在马铃薯低温甜化过程中发挥着不同的作用。马铃薯冷害甜化是影响马铃薯加工产品品质的重要因素。淀粉酶将淀粉转化为还原型糖(RS)被认为是独联体的主要途径之一，但尚未得到很好的研究。对淀粉酶基因StAmy23、StBAM1和StBAM9在马铃薯CIS中的功能进行了研究。StAmy23定位于细胞质，而StBAM1和StBAM9分别定位于叶绿体基质和淀粉颗粒。这些淀粉酶在马铃薯中的遗传转化表明，通过沉默StBAM1和集体沉默StBAM1和StBAM9可以降低冷藏块茎中β淀粉酶的活性。然而，沉默StBAM9并没有降低β淀粉酶的活性。沉默StBAM1和StBAM9导致淀粉积累和RS降低，这在同时沉默的品系中表现得更加明显，表明功能冗余。RNAi-StBAM1品系的可溶性淀粉含量增加，而RNAi-StBAM9品系的可溶性淀粉含量降低，提示StBAM1可能通过直接作用于淀粉粒而对可溶性淀粉和StBAM9的降解起调控作用。此外，StBAM9与StBAM1在淀粉粒上相互作用。StAmy23的沉默导致冷藏块茎中较高的植物糖原和较低的RS积累，这意味着StAmy23通过降解细胞液中的植物糖原来调节CIS。我们的研究结果表明，StAmy23、StBAM1和StBAM9在马铃薯CIS中的作用程度不同。
StAmy23, StBAM1 and StBAM9 play distinct roles in potato cold-induced sweetening by preferentially acting on soluble phytoglycogen, soluble starch and starch granules, respectively, in different subcellular locations. Cold-induced sweetening (CIS) in potato is detrimental to the quality of processed products. Conversion of starch to reducing sugars (RS) by amylases is considered one of the main pathways in CIS but is not well studied. The amylase genes StAmy23, StBAM1, and StBAM9 were studied for their functions in potato CIS. StAmy23 is localized in the cytoplasm, whereas StBAM1 and StBAM9 are targeted to the plastid stroma and starch granules, respectively. Genetic transformation of these amylases in potatoes by RNA interference showed that β-amylase activity could be decreased in cold-stored tubers by silencing of StBAM1 and collective silencing of StBAM1 and StBAM9. However, StBAM9 silencing did not decrease β-amylase activity. Silencing StBAM1 and StBAM9 caused starch accumulation and lower RS, which was more evident in simultaneously silenced lines, suggesting functional redundancy. Soluble starch content increased in RNAi-StBAM1 lines but decreased in RNAi-StBAM9 lines, suggesting that StBAM1 may regulate CIS by hydrolysing soluble starch and StBAM9 by directly acting on starch granules. Moreover, StBAM9 interacted with StBAM1 on the starch granules. StAmy23 silencing resulted in higher phytoglycogen and lower RS accumulation in cold-stored tubers, implying that StAmy23 regulates CIS by degrading cytosolic phytoglycogen. Our findings suggest that StAmy23, StBAM1, and StBAM9 function in potato CIS with varying levels of impact.