Characterization And Gene Cloning Of A Thermo-sensitive White Stripe Leaf11 (twsl11) Mutant In Rice

Photosynthesis is mainly occurred in chloroplasts,where light energy is converted into chemical energy for plant growth.Chloroplast is mainly distributed in the leaves of plants.Therefore,the development of chloroplast affects leaf development.In this study,we isolated a thermo-sensitive white stripe leaf 11(twsl11)mutant and cloned the TWSL11 gene.The main results are listed as follows:1.At the seedling stage,the twsl11 mutant plants exhibited different phenotypes with different times of sowing.When the twsl11 mutant plants were sown in May,they developed slightly white-striped leaves.And they exhibited severely white-striped leaves at tillering stage and restored at heading stage.When twsl11 plants were sown in June,their leaves exhibited albino and the mutant plants died one month after sowing.The contents of pigments in the white parts of leaf in the mutant were significantly lower than those of the wild-type.2.The agronomic traits investigation showed that compared with the wild-type,the twsl11 mutant showed shorter plant height,shorter panicle length,narrower grain width,more tillers,fewer secondary branches,lower seed setting rate and 1000-grain weight.In addition,the photosynthetic rate of the mutant was significantly lower than that of the wild-type.3.Temperature treatment revealed that the phenotype of the twsl11 mutant was similar to that of the wild-type under low temperature(25?C),but significantly different from the wild-type under high temperature(35?C)with albino leaves.The chlorophyll content of the mutant was significantly lower than that of the wild-type,and the ultrastructure of chloroplast was damaged under high temperature.4.Peroxide content determination and TdT-mediated DUTP nick end labeling(TUNEL)assay indicated that the twsl11 mutant accumulated a large amount of reactive oxygen species(ROS)and serious DNA damage than the wild-type under high temperature condition.Under low temperature condition,there was no significant difference in ROS content and DNA damage between twsl11 and the wild-type.5.Real-time RT-PCR experiments revealed that the expression level of genes related to chlorophyll synthesis,chloroplast development and photosynthesis in twsl11 were significantly decreased compared to the wild-type under high temperature.6.Genetic analysis suggested that the phenotype of the twsl11 mutant was controlled by a recessive nuclear gene.The TWSL11 gene was Fine mapped in 103 kb region between P2 and P3 markers.DNA sequencing of twsl11 revealed a missense mutation(G to A)in the eighth exon of LOC_Os11g39670 resulted in amino acid change(Glu to Lys).The complementation vector was constructed and transferred into the twsl11 mutant,and confirmed that LOC_Os11g39670 corresponds for the TWSL11 gene.Bioinformatics analysis showed that TWSL11 encodes seryl-tRNA synthetase involved in protein synthesis.7.The expression pattern analysis showed that the TWSL11 gene was expressed highest in leaves.Subcellular localization revealed that TWSL11 protein localized to chloroplast.