SummaryKernel row number (KRN) is a major yield related trait for maize (Zea mays L.) and is also a major goal of breeders, as it can increase the number of kernels per plant. Thus, identifying new genetic factors involving in KRN formation may accelerate improving yield‐related traits genetically. We herein describe a new kernel number‐related gene (KRN5b) identified from KRN QTL qKRN5b and encoding an inositol polyphosphate 5‐phosphatase (5PTase). KRN5b has phosphatase activity towards PI(4,5)P2, PI(3,4,5)P3, and Ins(1,4,5)P3 in vitro. Knocking out KRN5b caused accumulation of PI(4,5)P2 and Ins(1,4,5)P3, resulting in disordered kernel rows and a decrease in the number of kernels and tassel branches. The introgression of the allele with higher expression abundance into different inbred lines could increase the ear weight of the inbred lines and the corresponding hybrids by 10.1%–12.2% via increasing KRN, with no adverse effects on other agronomic traits. Further analyses showed that KRN5b regulates inflorescence development through affecting the synthesis and distribution of hormones. Together, KRN5b contributes to spikelet pair meristem development through inositol phosphate and phosphatidylinositols, making it a selecting target for yield improvement.

中文翻译：

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KRN5b 通过介导磷酸肌醇信号传导调节玉米籽粒行数


摘要籽粒行数 （KRN） 是玉米 （Zea mays L.） 的主要产量相关性状，也是育种者的主要目标，因为它可以增加每株植物的籽粒数量。因此，识别参与 KRN 形成的新遗传因素可能会加速遗传上改善产量相关性状。我们在此描述了一个新的内核数量相关基因 （KRN5b），该基因从 KRN QTL qKRN5b 中鉴定出来，编码肌醇多磷酸 5-磷酸酶 （5PTase）。KRN5b 在体外对 PI（4,5）P2、PI（3,4,5）P3 和 Ins（1,4,5）P3 具有磷酸酶活性。敲除 KRN5b 导致 PI（4,5）P2 和 Ins（1,4,5）P3 积累，导致籽粒行无序，籽粒和抽穗枝条数量减少。表达丰度较高的等位基因渗入不同的自交系，通过增加 KRN 可使自交系和相应杂交种的穗重增加 10.1%–12.2%，对其他农艺性状无不利影响。进一步分析表明，KRN5b 通过影响激素的合成和分布来调节花序发育。KRN5b 共同通过肌醇磷酸和磷脂酰肌醇促进小穗对分生组织的发育，使其成为提高产量的选择靶点。