Map-based Cloning Of The Lesion Mimic Mutant Spl5in Rice

Lesion mimic mutants (lmms) are mutunts which spontaneously necrotic lesions in the absence of pathogens. The phenotype of the lmms resembles that of the hypersensitive response (HR), and most of lmms often result in enhanced resistance to pathogen infection. Rice spotted leaf5(spl5) is a lesion mimic mutant. Analysis of the spl5resistance to21Xanthomonas oryzae pv. Oryzae(Xoo), exhibited a high resistance to Philippines races PXO86(P2), PXO99(P6),PXO280(P7), and Chinese races Zhe173、JSA06-8、JSA06-16、JSA06-40、YNA37-14、YNA37-18、HB17、 FJ28、Ⅱ-94、0167. Meanwhile, Expression analyses of the gene related with salicy licacid (SA) biosynthetic pathway (OsEDS1), the key controlling enzyme in jasmonate acid (JA) biosynthetic pathway (OsAOS2,OsLOX2) and the expression of pathogen-related (PR) genes OsPR1a, OsPR1b,OsPR5, were higher in spl5mutant than in wild-type. These data support that spl5mutation may activate the systemic-acquired resistance (SAR) and enhances resistance to pathogens.The phenotype of spl5mutant was controlled by a single recessive gene. Previously, the spl5gene was already mapped to the80-kb region,we continued using a map-based cloning approach to delimitated into a15.1-kb genomic region and predicted3genes.Subsequent sequencing in15.1-kb region of spl5mutant revealed that one candidate gene harbored a singlebase deletion, resulting in a frame-shift mutation and the others were the same as the oryza sativa Nipponbare. Complement test showed that wild-type SPL5did functionally complement the spl5phenotype. The data presented here clearly indicate that we had cloned this gene. Bioinformatic analysis showed that SPL5gene encodes a putative splicing factor3b subunit3(SF3b3), which contains one mono-functional DNA-alkylating methyl methanesulfonate (MMS1) domain in the N terminus and a cleavage and polyadenylation specificity factor A (CPSF_A) domain in the C terminus.It might be involved in splicing reactions of pre-mature RNAs participating in the regulation of cell death and resistance responses.