School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA, 5064, Australia.
South Australian Agricultural Research Institute, Waite Precinct, Glen Osmond, SA, Australia.
Planta. 2022 May 6;255(6):119. doi: 10.1007/s00425-022-03899-y.
α-Amylase synthesis by wheat aleurone during grain development (late maturity α-amylase) appears to be independent of gibberellin unlike α-amylase synthesis by aleurone during germination or following treatment with exogenous GA. Late-maturity α-amylase (LMA) in wheat (Triticum aestivum L.) involves the synthesis of α-amylase by the aleurone tissue during grain development. Previous research identified a putative ent-copalyl diphosphate synthase gene, coding for an enzyme that controls the first step in gibberellin biosynthesis, that underlies the major genetic locus involved in variation in LMA phenotype. The reported results for gene transcript analysis, preliminary gibberellin analysis and the effects of DELLA mutants on LMA phenotype appeared to be consistent with involvement of gibberellin but did not provide definitive proof of a causal link. Conversely, several observations do not appear to be consistent with this hypothesis. In this current study, LMA phenotype, gibberellin profiles and ABA content were recorded for experiments involving susceptible and resistant genotypes, gibberellin biosynthesis inhibitors, genetic lines containing different LMA quantitative trait loci and treatment of distal halves of developing grains with exogenous gibberellin. The results suggested that gibberellin may not be a prerequisite for LMA expression and further that the mechanism involved in triggering α-amylase synthesis did not correspond to the model proposed for germination and gibberellin challenged aleurone of ripe grain. The results provide new insight into LMA and highlight the need to investigate alternate pathways for the induction of α-amylase gene transcription, the function of novel 1-β-OH gibberellins and other functions of DELLA proteins in developing grains.
在谷物发育过程中（晚期成熟α-淀粉酶），小麦糊粉层中的α-淀粉酶合成似乎不依赖赤霉素，而在萌发或用外源 GA 处理后，糊粉层中的α-淀粉酶合成则依赖赤霉素。小麦（Triticum aestivum L.）中的晚期成熟α-淀粉酶（LMA）涉及到在谷物发育过程中糊粉层组织合成α-淀粉酶。先前的研究确定了一个假定的 ent-copalyl diphosphate 合酶基因，该基因编码控制赤霉素生物合成第一步的酶，该基因位于与 LMA 表型变异相关的主要遗传位点下方。基因转录分析、初步赤霉素分析以及 DELLA 突变体对 LMA 表型的影响的报告结果似乎表明与赤霉素有关，但并未提供因果关系的明确证据。相反，有几个观察结果似乎与该假说不一致。在本研究中，对于涉及敏感和抗性基因型、赤霉素生物合成抑制剂、含有不同 LMA 数量性状位点的遗传系以及用外源赤霉素处理发育中谷物的远端半部分的实验，记录了 LMA 表型、赤霉素图谱和 ABA 含量。结果表明，赤霉素可能不是 LMA 表达的必要条件，而且参与触发α-淀粉酶合成的机制与提出的用于萌发和赤霉素处理的成熟谷物糊粉层的模型不一致。研究结果为 LMA 提供了新的见解，并强调需要研究诱导α-淀粉酶基因转录的替代途径、新型 1-β-OH 赤霉素的功能以及 DELLA 蛋白在发育中的谷物中的其他功能。
