Main Conclusion Late-maturity α-amylase (LMA) expression in wheat grains can be induced by either a cool temperature shock close to physiological maturity or continuous cool maximum temperatures during grain development. Abstract Late-maturity α-amylase (LMA) is a genetic trait in wheat ( Triticum aestivum L.) involving the production of α-amylase during grain development, which can result in an unacceptably low Falling Number (FN) in mature grain and consequent grain downgrading. Comparison of the FN test, an α-amylase activity assay and a high pI α-amylase-specific ELISA on the same meal samples gave equivalent results; ELISA was used for further experiments because of its isoform specificity. A cool temperature shock during the middle stages of grain development is known to induce LMA and is used for phenotypic screening. It was determined that a cool temperature treatment of seven days was required to reliably induce LMA. Glasshouse studies performed in summer and winter demonstrated that temperature affected the timing of sensitivity to cool-shock by altering the rate and duration of grain development, but that the sensitive grain developmental stage was unchanged at 35–45% moisture content. Wheat varieties with Rht-B1b or Rht-D1b dwarfing genes responded to a cool-shock only from mid grain filling until physiological maturity, whilst genotypes with Rht8c or without a dwarfing gene expressed LMA in response to a cool-shock during a wider developmental range. A continuous cool maximum temperature regimen (23 °C/15 °C day/night) during grain development also resulted in LMA expression and showed a stronger association with field expression than the cool-shock treatment. These results clarify how genotype, temperature and grain developmental stage determine LMA expression, and allow for the improvement of LMA phenotypic screening methods.

中文翻译：

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小麦中晚熟α-淀粉酶的表达受基因型、温度和籽粒发育阶段的影响

主要结论 小麦籽粒中晚熟 α-淀粉酶 (LMA) 的表达可由接近生理成熟的低温冲击或谷物发育过程中持续低温的最高温度诱导。摘要 晚熟 α-淀粉酶 (LMA) 是小麦 (Triticum aestivum L.) 的一种遗传性状，涉及在籽粒发育过程中产生 α-淀粉酶，这会导致成熟籽粒中的下降数 (FN) 过低，从而导致粮食降级。FN 测试、α-淀粉酶活性测定和高 pI α-淀粉酶特异性 ELISA 对相同膳食样品的比较得出了相同的结果；由于其异构体特异性，ELISA 被用于进一步的实验。已知谷物发育中期的低温冲击可诱导 LMA 并用于表型筛选。确定需要 7 天的低温处理才能可靠地诱导 LMA。在夏季和冬季进行的温室研究表明，温度通过改变谷物发育的速率和持续时间来影响对冷休克敏感的时间，但敏感的谷物发育阶段在 35-45% 的水分含量下没有变化。具有 Rht-B1b 或 Rht-D1b 矮化基因的小麦品种仅在中粒灌浆至生理成熟期间对冷休克有反应，而具有 Rht8c 或没有矮化基因的基因型在更广泛的发育范围内表达 LMA 对冷休克的反应. 在谷物发育过程中，连续低温最高温度方案（23°C/15°C 白天/夜间）也导致 LMA 表达，并且与冷休克处理相比，与田间表达的相关性更强。这些结果阐明了基因型、温度和谷物发育阶段如何决定 LMA 表达，并有助于改进 LMA 表型筛选方法。