Cloning of long sterile lemma (lsl2), a single recessive gene that regulates spike germination in rice (Oryza sativa L.)

Abstract

Background: 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.Results: 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.Conclusions: 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.