Analysis Of Photosynthesis Characteristics And Metabolites In A Yellow-leaf Mutant Of Tobacco

Flue-cured tobacco is a kind of economic crop which belongs to solanaceae. The index of havesting and grading base on leave colour which plays an important role in appearance qualities of tobacco leaves. Lower content of chlorophyll make it possible to promote colour shift during tobacco curing, bring labor costs down on the premise of ripe tobacco. A yellow-mutant of tobacco which was breeded b y doubling the chromosome of xanthan mutant found in F2 generation of G28 and NC2326, growed normally except its leaves were green. It had the potential as a new material in breeding and production by reason of that it could be used for research on photosynthetic mechanism, chlorophyll biosynthesis pathway and function of specific gene.Chlorophyll fluorescence characteristics, photosynthesis characteristic, content of photosynthetic pigments, neutral aroma components and metabolites in normal green variety K326,yellow- mutant and yellow- mutant K326 developed by backcrossing K326 and the yellow- mutant were determined to provide theory basis for illuminating biological mechanism of photosynthesis of yellow leaf mutant, interaction between the mutant gene and others, breeding application and oriented cultivation of xanthan gene by revealing yellow leaf mutation effect on photosynthetic efficiency, content of photosynthetic pigments and neutral aroma, metabolic pathways and metabolites. In the conclusion part of this study, some results were given as follows:1. Content of chlorophyll a and b, carotenoid, total pigment in yellow-mutant was only 37-50% of K326, the result also suggested that the decline in content of chlorophyll directly caused yellow leaf.Yellow-mutant would offset the influence of lower content of chlorophyll by more light absorption according to result that yellow- mutant and yellow-mutant K326 presented higher light saturation point(LSP) and intercellular CO2 concentration than K326.2.The decline in content of chlorophyll may not impact the photochemistry activity of yellow- mutant for it had no significant difference with K326 in Fv/Fm; the PSII photochemical quantum yield(Y), electron transfer chain(ETR) in yel ow-mutant and K326 was at the same level.Yellow-mutant had higher heat dissipation as its non-photochemical quenching(qN) was significantly higher than K326 and yellow- mutant K326. The above results suggested that photosynthetic efficiency and productivity of yellow- mutant wasn’t effected by the decline of content of chlorophyll.3. The result suggested that the content of all kinds of neutral aroma components in K326 was significantly higher than yellow- mutant and yellow- mutant K326. The content of neophytadiene in the xanthan mutant were significantly different while the else kinds of aroma were not; difference of the content of the same aroma substance in different tobacco varieties might be a reason for quality of aroma differed from different tobacco varieties; decline in content of chlorophyll and caro may lead to decrease of neophytadiene and carotenoid of neutral aroma constituent while the absence of phenylalanine group may be caused by gene mutation.4. Metabolites mainly consisted of sugar, alkaloid, organic acid, amino acid and organic phenol were detected in tobacco. Malic acid, nicotine and inositol, scopolin could be used as characteristic metabolites to discriminate the 3 kinds of tobacco according to the result of PCA(principal component analysis).