Genetic Mapping Of A Leaf Photooxidation Gene, LPO1(t) In Rice(Oryza Sativa L.)

Rice(Oryza sativa L.) was not only one of the most important food crops in China, but also a model plant for studying the developmental biology of monocots. Photosynthesis mostly took place in the leaves of plants, and chloroplasts were principal cell organs in the process of photosynthesis. When leaves absorbed in illumination which exceed to light saturation of photosynthesis, it would cause photo-inhibition and photo-oxidation. Photo-inhibition often happened in C3plants, when attacked by strong light, companying with other physical adversitys such as low or high temperature, drought, salinity, air pollution, it would prick up etiolation and leaves chlorosis.In the present research, we found a photo-oxidation mutant, designated as812HS, derived from a segregation population of an indica photo-thermo-sensitive male sterile line812S.812HS showed the same agronomic traits to812S, however, the leaves of812HS turned yellow from the top by photo-oxidation when attacked by strong sunlight companied with a lower temperature. The present paper analyzed photosynthetic physiological indexes and the heredity of the trait, and primarily mapped the gene.The main results were summarized as follows:1. The activity of PS II reaction center (RC) and PS II electron transport of the mutant were significantly reduced, in comparison with its wild-type, however, remaining energy of PS II reaction center was increased oppositely. It led to reduce light use efficiency. The leaves etiolation of the mutant was arised by chlorophyll hurt by photo-oxidation.2. Genetic analysis of F2populations from812HS/090028showed that, photo-oxidation plants:non-photo-oxidation plants in F2populationshowed a segregation ratio of3:1(green:virescent yellow plants, X2=0.167≤x20.05,1=3.84, P>0.05, in2010; x2=1.031≤x20.05,1=3.84, P>0.05, in2011). Therefore, the trait of812HS was controlled by a new dominant gene.3. Using SSR markers and BSA (bulk segregant analysis), LPO1(t) was mapped primarily between SSR markers, RM307and RM401, with genetic distances of4.3cM and4.5cM on Chromosome4, respectively. LPO1(t) gene was a new gene distinguished from all other genes which connected with leaf photo-oxidation in rice.