OsLAP6/OsPKS1, an orthologue of Arabidopsis PKSA/LAP6, is critical for proper pollen exine formation

Abstract

BackgroundMale fertility is crucial for rice yield, and the improvement of rice yield requires hybrid production that depends on male sterile lines. Although recent studies have revealed several important genes in male reproductive development, our understanding of the mechanisms of rice pollen development remains unclear.ResultsWe identified a rice mutant oslap6 with complete male sterile phenotype caused by defects in pollen exine formation. By using the MutMap method, we found that a single nucleotide polymorphism (SNP) variation located in the second exon of OsLAP6/OsPKS1 was responsible for the mutant phenotype. OsLAP6/OsPKS1 is an orthologous gene of Arabidopsis PKSA/LAP6, which functions in sporopollenin metabolism. Several other loss-of-function mutants of OsLAP6/OsPKS1 generated by the CRISPR/Cas9 genomic editing tool also exhibited the same phenotype of male sterility. Our cellular analysis suggested that OsLAP6/OsPKS1 might regulate pollen exine formation by affecting bacula elongation. Expression examination indicated that OsLAP6/OsPKS1 is specifically expressed in tapetum, and its product is localized to the endoplasmic reticulum (ER). Protein sequence analysis indicated that OsLAP6/OsPKS1 is conserved in land plants.Conclusions OsLAP6/OsPKS1 is a critical molecular switch for rice male fertility by participating in a conserved sporopollenin precursor biosynthetic pathway in land plants. Manipulation of OsLAP6/OsPKS1 has potential for application in hybrid rice breeding.Electronic supplementary materialThe online version of this article (doi: 10.1186/s12284-017-0191-0) contains supplementary material, which is available to authorized users.

Wheat ms5 male‐sterility is induced by recessive homoeologous A and D genome non‐specific lipid transfer proteins

“…(), Zou et al . () and Tian et al . (), have shown the importance of exine development for pollen viability.…”

Molecular Cloning of Genic Male-Sterility Genes and Their Applications for Plant Heterosis via Biotechnology-based Male-sterility Systems

“…SNPs with sequence reads composed only of mutant sequences (SNP index of 1; SNP index is defined as the ratio between the number of reads of a mutant SNP and the total number of reads corresponding to the SNP) are closely linked to the causal SNP for the mutant phenotype [86]. The MutMap method was used for rice GMS gene cloning, e.g., OsLAP6/OsPKS1 [67]. Recently, a modified MutMap method was developed in rice male-sterility gene (OsMs55/MER3) cloning [87].…”

A Silent Exonic Mutation in a Rice Integrin-α FG-GAP Repeat-Containing Gene Causes Male-Sterility by Affecting mRNA Splicing

“…Spikelets with anthers at different developing stages were classified, and were fixed with Carnoy's fixative or 2.5% glutaraldehyde fixative according to the previous description [84]. The subsequent dehydration, semi-thin sections analysis, SEM and TEM analysis of the anther samples were performed as described previously [30].…”

“…The outer pollen wall, exine, is mainly composed of sporopollenin [5]. In rice, several genes involved in sporopollenin precursors synthesis and shipping have been found, such as CYP703A3 [24], CYP704B2 [25], Acyl-CoA Synthetase 12 (OsACOS12) [26,27], Polyketide synthase 1/2 (OsPKS1/2) [28][29][30][31], Tetraketide α-pyrone reductase 1 (OsTKPR1) [31,32], ATP Binding Cassette G 15 (OsABCG15) [16,33,34], and OsC4/6 [35]. Among them, CYP703A3, CYP704B2, OsACOS12, OsPKS1/2 and OsTKPR1 may form a sporopollenin metabolon similar to their orthologues in Arabidopsis [5,8,15,31,32,36].…”