Drought represents a major constraint on maize production worldwide. Understanding the genetic basis for natural variation in drought tolerance of maize may facilitate efforts to improve this trait in cultivated germplasm. Here, using a genome-wide association study, we show that a miniature inverted-repeat transposable element (MITE) inserted in the promoter of a NAC gene (ZmNAC111) is significantly associated with natural variation in maize drought tolerance. The 82-bp MITE represses ZmNAC111 expression via RNA-directed DNA methylation and H3K9 dimethylation when heterologously expressed in Arabidopsis. Increasing ZmNAC111 expression in transgenic maize enhances drought tolerance at the seedling stage, improves water-use efficiency and induces upregulation of drought-responsive genes under water stress. The MITE insertion in the ZmNAC111 promoter appears to have occurred after maize domestication and spread among temperate germplasm. The identification of this MITE insertion provides insight into the genetic basis for natural variation in maize drought tolerance.

中文翻译：

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NAC基因中的转座因子与玉米幼苗的耐旱性有关。

干旱是全球玉米生产的主要制约因素。了解玉米抗旱性自然变化的遗传基础可能有助于改善栽培种质的这一性状。在这里，使用全基因组关联研究，我们表明，插入到NAC基因（ZmNAC111）启动子中的微型反向重复转座因子（MITE）与玉米耐旱性的自然变化显着相关。当在拟南芥中异源表达时，82 bp的MITE通过RNA定向的DNA甲基化和H3K9二甲基化抑制ZmNAC111的表达。ZmNAC111在转基因玉米中的表达增加，提高了幼苗期的耐旱性，提高了水分利用效率，并诱导了水分胁迫下干旱反应基因的上调。ZmNAC111启动子中的MITE插入似乎发生在玉米驯化后并在温带种质中传播。该MITE插入物的鉴定为玉米抗旱性自然变异的遗传基础提供了见识。