Fine mapping and photosynthetic characteristics of the lower chlorophyll b 1 mutant in rice (Oryza sativa L.)

Chlorophylls absorb and transfer light energy to the photosynthetic system. Consequently, chlorophyll content is strongly related to crop biomass and yield. We isolated a rice spontaneous mutant, lower chlorophyll b 1 (lcb1), from a recombinant inbred line population. Under normal growth conditions, lcb1 plants produced yellow leaves with decreased total chlorophyll and chlorophyll b contents, but normal chlorophyll a content. Photosynthetic and fluorescence parameters differed between wild‐type and lcb1 plants. Compared with wild type, lcb1 had a higher electron transfer rate, a lower photochemical quenching coefficient and significantly reduced grain number, biomass and yield. A recessive nuclear gene controlled the mutant trait. Through map‐based cloning, we located the LCB1 gene in a 117.4‐kb region on the short arm of chromosome 3, close to the centromere, in a region containing 15 predicted candidate genes. None of these genes was directly related to chlorophylls or the chloroplast; therefore, lcb1 may be a mutation of a novel gene. These results will be useful for further research on the molecular mechanisms controlling biogenesis and chloroplast biochemical processes.