Physiological Analysis And Mapping Of A Lesion Mimic Mutant In Rice(Oryza Sativa L.)

In this paper, a mutant in rice discovered by artificial mutation was used to observe thephysiological characters and morphology and map the mutant gene. On this basis, everyone willaccurately locate the mutant gene and analyze its function. The results showed as follows:(1) Observed through the comparison of the mutant and the wild type, the formation of thelesion began in the period of three or four leaves on the rice. Since then leaves performed theexpansion of the lesion area and the formation of new lesions. Formation of different temperatureon lesion studies confirmed the formation of this lesion was independent of temperature.Mutantunder the shading was not the formation of the lesion, the lesion with light there was no directcontact. Lesion leaves DAB and trypan blue staining experiments confirmed that the lesion at thedeath cell belongs to a class of programmed cell death.(2) Mutant and wild-type SPAD value measurement and leaf cell ultrastructure observationstudy confirmed that the photosynthetic capacity of mutant plants was weaker than wild-typeplants. This may be the chlorophyll of a large number of missing,chloroplast damage or dissolveresulting in dysfunction, thylakoidslayer of the overall number of significantly less thanwild-type, and part of the thylakoid lamellae dissolved caused.(3) The active oxygen metabolism studies have shown that SOD, POD, CAT and MDAactivity of mutant plants was significantly higher than the wild-type plants. It can be seen that theaccumulation of reactive oxygen species in the mutant plants is obvious. The accumulation oflarge amounts of reactive oxygen species and SOD activity to improve and produce O₂and H₂O₂.The increase of H₂O₂stimulated the improvement of the POD and SOD activities. Theaccumulation of reactive oxygen broke the free radical balance.Unsaturated fatty acids in themembrane lipid bilayer is easily oxidized.(4) Photosynthetic characteristics of studies have shown that: F0, Fm, F0', Fm',Fv'/Fm' and Pn rate ofmutant leaves was significantly lower than the wild type. However, ETR, qP, Gs and Ci level of mutantleaves higher than the wild type. This shows that compared with the wild type,photochemical efficiency isnot the main reason leading to the decline of net photosynthetic capacity of the mutant. The reduction ofCO₂utilization efficiency and enhancement of the false loop electronic passment are the main reasonleading to the reducment of photosynthetic capacity of the mutant.(5) The initial positioning of the mutant gene variation experiments confirmed that: Theperformance of lesion and the physiological characteristics are all due to the mutant gene. Thismutant gene has been initially positioned in a148kb region of the chromosome6in rice.Bioinformatics initially concluded that this mutant gene is a new gene which has not beenreported. Precise mapping and functional analysis of the mutant gene will be studied further.