Kernel 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调节玉米粒行数


籽粒行数 (KRN) 是玉米 ( Zea mays L.) 的一个主要产量相关性状，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，鉴定涉及 KRN 形成的新遗传因素可能会加速改善产量相关性状的遗传。我们在此描述了从 KRN QTL qKRN5b鉴定并编码肌醇多磷酸 5-磷酸酶 (5PTase) 的新籽粒编号相关基因 ( KRN5b )。 KRN5b在体外对 PI(4,5)P ₂ 、PI(3,4,5)P ₃和 Ins(1,4,5)P ₃具有磷酸酶活性。敲除KRN5b会导致PI(4,5)P ₂和Ins(1,4,5)P ₃积累，导致籽粒行无序，籽粒和雄穗分支数量减少。将表达丰度较高的等位基因渗入不同自交系中，可通过增加KRN使自交系及其杂种的穗重增加10.1%~12.2%，且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通过磷酸肌醇和磷脂酰肌醇共同促进小穗对分生组织的发育，使其成为提高产量的选择目标。