Robert H. Smith Faculty of Agriculture Food and Environment, Hebrew University, Rehovot 76100, Israel.
Department of Chemical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Int J Mol Sci. 2022 Dec 22;24(1):190. doi: 10.3390/ijms24010190.
Isoamylase (ISA) is a debranching enzyme found in many plants, which hydrolyzes (1-6)-α-D glucosidic linkages in starch, amylopectin, and β-dextrins, and is thought to be responsible for starch granule formation (ISA1 and ISA2) and degradation (ISA3). Lipid-modified PEI (lmPEI) was synthesized as a carrier for long double-stranded RNA (dsRNA, 250-bp), which targets the three isoamylase isoforms. The particles were applied to the plant via the foliar spray and were differentially effective in suppressing the expressions of ISA1 and ISA2 in the potato leaves, and ISA3 in the tubers. Plant growth was not significantly impaired, and starch levels in the tubers were not affected as well. Interestingly, the treated plants had significantly smaller starch granule sizes as well as increased sucrose content, which led to an early sprouting phenotype. We confirm the proposal of previous research that an increased number of small starch granules could be responsible for an accelerated turnover of glucan chains and, thus, the rapid synthesis of sucrose, and we propose a new relationship between ISA3 and the starch granule size. The implications of this study are in achieving a transgenic phenotype for endogenous plant genes using a systemic, novel delivery system, and foliar applications of dsRNA for agriculture.
异淀粉酶（ISA）是一种存在于许多植物中的支链酶，它可以水解淀粉、支链淀粉和β-糊精中的（1-6）-α-D 糖苷键，被认为是负责淀粉颗粒形成（ISA1 和 ISA2）和降解（ISA3）的酶。脂质修饰的聚乙烯亚胺（lmPEI）被合成作为长双链 RNA（dsRNA，250bp）的载体，该 RNA 靶向三种异淀粉酶同工型。通过叶面喷雾将颗粒应用于植物，在抑制马铃薯叶片中的 ISA1 和 ISA2 以及块茎中的 ISA3 的表达方面具有不同的效果。植物生长没有明显受损，块茎中的淀粉含量也没有受到影响。有趣的是，处理过的植物的淀粉颗粒尺寸明显变小，蔗糖含量增加，导致早期发芽表型。我们证实了先前研究的提议，即更多的小淀粉颗粒可能是导致葡聚糖链快速周转的原因，从而导致蔗糖的快速合成，并且我们提出了 ISA3 与淀粉颗粒大小之间的新关系。这项研究的意义在于利用系统的、新颖的传递系统和叶面施用 dsRNA 实现内源植物基因的转基因表型，用于农业。
