Gene Mapping And Candidate-gene Screening Of A Clustered Spikelet Mutant Cll(t) In Rice

A clustered spikelets mutant, which was found in the rice mutant library of Minghui 86. The mutant is tentatively named cll(t)(clustered spikelets like), because it looks like Cl(clustered spikelets). The genetic analysis showed that cll(t) was not caused by T-DNA insertion. The mutant cll(t) exhibits a phenotype that most branch has two or more spikelets clustered together. Genetic analysis of the populations, which were from the crosses between cll(t) and Minghui 86, 93-11 or 02428, indicated that cll(t) was a recessive mutant controlled by a gene. We carried out gene mapping of the gene responsible for the mutated trait. The result showed that the mutated trait was located on the long arm of chromosome 4 between the marker InDel0406 and InDel0492, the physical region is 174kb, and finally cosegregated with the marker InDel0448,InDel0449,InDel0427. The mutant cll(t) is a new clustered spikelets material of rice,which is non-allele of mutant Cl located on the chromosome 6.Analysed the 174kb sequence, 23 putative genes were predicted protein. The co-segregating marker InDel0448 , InDel0449 , InDel0427 was near putative cytochrome P450-related gene. Comprehensived the morphological, physilogicaland biochemical characters of cll(t) mutant, and functions of plant cytochrome P450, the putative cytochrome P450-related gene was predicted as cll(t) candidate gene. Sequencing results showed that a change in exon 4 occurred in cll(t), a substitution of G1443 (wild-type) by A1443 , which resulted in a Q350 transformed to the stop coden.We found that the sequence of target region is the same as wild type according to sequencing Minghui72,Minghui 75,Minghui 88 and 02428,Zhonghua15, Zhonghua16. Above all, cytochrome P450 is the candidate gene.