Rice is a typical monocotyledonous plant and an important cereal crop. The structural units of rice flowers are spikelets and florets, and floral organ development and spike germination affect rice reproduction and yield. In this study, we identified a novel long sterile lemma (lsl2) mutant from an EMS population. First, we mapped the lsl2 gene between the markers Indel7–22 and Indel7–27, which encompasses a 25-kb region. The rice genome annotation indicated the presence of four candidate genes in this region. Through gene prediction and cDNA sequencing, we confirmed that the target gene in the lsl2 mutant is allelic to LONG STERILE LEMMA1 (G1)/ELONGATED EMPTY GLUME (ELE), hereafter referred to as lsl2. Further analysis of the lsl2 and LSL2 proteins showed a one-amino-acid change, namely, the mutation of serine (Ser) 79 to proline (Pro) in lsl2 compared with LSL2, and this mutation might change the function of the protein. Knockout experiments showed that the lsl2 gene is responsible for the long sterile lemma phenotype. The lsl2 gene might reduce the damage induced by spike germination by decreasing the seed germination rate, but other agronomic traits of rice were not changed in the lsl2 mutant. Taken together, our results demonstrate that the lsl2 gene will have specific application prospects in future rice breeding. The lsl2 gene is responsible for the long sterile lemma phenotype and might reduce the damage induced by spike germination by decreasing the seed germination rate.

中文翻译：

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长不育外稃 (lsl2) 的克隆，这是一种调节水稻穗萌发的单一隐性基因 (Oryza sativa L.)

水稻是典型的单子叶植物，也是重要的谷类作物。水稻花的结构单元是小穗和小花，花器官发育和穗萌发影响水稻繁殖和产量。在这项研究中，我们从 EMS 群体中鉴定出了一种新型的长不育外稃 (lsl2) 突变体。首先，我们将 lsl2 基因定位在标记 Indel7-22 和 Indel7-27 之间，其中包含一个 25 kb 的区域。水稻基因组注释表明该区域存在四个候选基因。通过基因预测和cDNA测序，我们证实lsl2突变体中的靶基因与LONG STERILE LEMMA1 (G1)/ELONGATED EMPTY GLUME (ELE)等位基因，以下简称lsl2。对lsl2和LSL2蛋白的进一步分析显示，与LSL2相比，lsl2中存在一个氨基酸的变化，即第79位丝氨酸（Ser）突变为脯氨酸（Pro），这种突变可能会改变该蛋白的功能。敲除实验表明，lsl2 基因负责长不育外稃表型。lsl2基因可能通过降低种子发芽率来减少穗萌发引起的损害，但在lsl2突变体中水稻的其他农艺性状没有改变。综上所述，我们的结果表明lsl2基因在未来的水稻育种中将具有特定的应用前景。lsl2 基因负责长不育外稃表型，并可能通过降低种子发芽率来减少穗发芽引起的损害。