Identification And Map-Based Cloning Of Glume-Unclosed Mutant Lugl In Rice (Oryza Sativa L.)

Flower is sexual reproductive organ of Angiosperms, its biological function is a combination of male sperm and the female zygote cell to produce seeds. Seed is the next-generation of all plants, is the primary means of distribution for each species in nature. Born on the same plant with a combination of flowers called inflorescences. Rice flower organ known as glume,constituted of spikelets and rachis (including primary branches, secondary branches).Development of rice floral organs directly affect the yield and quality, so the research on rice flower organ development helps to improve the yield and quality of rice.Finding or creating artificial floral organ abnormalities mutants of rice through molecular genetics、genomics and systems biology approaches to explore the molecular genetic regulation mechanisms and molecular regulating signal pathways of rice flower organ development has become a hotspot of current research in plant molecular genetics.In this study, to further research the genetic mechanism of rice floral development, one rice mutant lugl with cultivar Nanjing35 background, was identified from the M2 mutant pool mutagenized by EMS (ethyl methane sulfonate).Field planting identification、 comparison between wild-type and mutant floral organs、segregation statistics of different hybridization phenotypes as well as gene mapping using map-based cloning method were used to study the mutant phenotype and gene fine mapping. Agronomic traits survey, compared with the wild type, the mutant seed setting rate and 1000-grain weigh decreased significantly, the differences were highly significant. Cytological observation, most lemma and palea of spikelets in lugl can not completely hooked together, spikelets cracking, both lemma and palea of spikelets become thinning, lemma slightly curved toward palea, other floral organs consistent with the wild-type phenotype.Genetic analysis showed the trait controlled by a recessive gene. Construction of mutant and indica cultivars 9311 hybrid populations, finding all mutants in the segregating population F2 and F2:3 as a mapping population, using two hundred pairs of SSR markers evenly distributed in twelve chromosomes of rice from our laboratory, detection the mutant phenotype individuals of the location groups, then OsLUGL gene was located on the long arm of rice chromosome 1. Subsequently developed a number of new SSR markers, and finally OsLUGL was located in 37kb physical distance position. There are three ORF in the physical distance predicted by the rice genome database. Verified by sequencing of the candidate gene, a single nucleotide deletion was found in the coding region of LOC_Os01g4226 in the mutant which caused premature termination of OsLUGL translation.We finally consider that LOC_Os01g42260 is our target gene resulting in a glume-unclosed phenotype in rice.Since LOC_Os01g42260 homologous with Arabidopsis LEUNIG(LUG), so that the rice gene named OsLUGL(Oryza Sativa LEUNIG-Like). Interference validation by transgene and transient expression pattern analysis further determine OsLUGL is the gene that controls our mutant phenotype.OsLUGL contains eighteen exons and seventeen introns, encoding a 876 amino acids protein. By protein domain predicting database SMART, we found OsLUGL encodes a glutamine-rich protein containing seven WD repeats domain.