Comparative Analysis Of Photosynthetic Characteristics Of Two Species Of Tung Oil Palm And Preliminary Study On The Mechanism Of Leaf Development Regulation By Related Gene

Improving the photosynthetic capacity of crops by regulating the morphological structure of leaves has become an important strategy to deal with the food and energy crisis and plants to adapt to global climate change in the future.As a potential energy tree species,Jatropha curcas L.is widely planted in China.However,low seed yield has become an important factor restricting its development.Therefore,the study on the relationship between leaf morphological structure and photosynthetic characteristics has certain theoretical and practical significance for properly regulating leaf anatomical structure to enhance photosynthetic capacity so as to increase the yield of paulownia.It can not only provide a new direction for the genetic improvement strategy of Jatropha curcas L.,but also provide a reference for the regulation of leaf anatomical structure of other crops.In this study,Jatropha curcas L.(Jc)and its natural leaf mutant,Jatropha nigroviensrugosus CV Yang(Jn),were used as experimental materials to compare and analyze the differences of leaf morphology and photosynthetic characteristics between the two trees.Using the whole genome sequence of Jatropha curcas L.,the TCP transcription factors involved in regulating the growth and development of plant leaves were systematically identified and analyzed.According to the previous transcriptome data of the research group,Jc CYCD3;1 and JnCYCD3;1 genes were successfully cloned from 2 trees.And their biological functions were preliminarily verified.The main results are as follows:(1)There are significant differences in morphology and structure between the two leaf types of Jatropha curcas.The phenotypic analysis of functional leaves showed that the leaf length,leaf width and leaf area of Jn were significantly smaller than those of Jc(P<0.05),while the petiole was on the contrary.Leaf color analysis showed that the L-RGB value of Jn was significantly lower than that of Jc,and its color was close to dark green.And Jc was closer to bright green.The scanning electron microscope and anatomical analysis of the leaf surface showed that the leaf surface of Jn was rough,the cell density was high and there were different degrees of wrinkles.The anatomical structures such as leaf thickness,palisade tissue and spongy tissue of Jn are significantly different from those of Jc.The mesophyll cells of Jn were significantly smaller than those of Jc(P<0.05),and the morphology of mesophyll cells was significantly different.In addition,the ultrastructural observation of chloroplast showed that the chloroplast shape and intracellular distribution of the two leaf types were also significantly different.The above results show that at the DNA level,the difference in the morphology and size of mesophyll cells is the main reason for the difference in morphological structure between the two leaf types.(2)The difference of leaf morphology and structure significantly affected the photosynthetic characteristics of the two leaf types.The photosynthetic area of Jc was significantly larger than that of Jn.The pigment content analysis showed that the photosynthetic pigment content of Jn was significantly higher than that of Jc.Spectral reflectance analysis showed that both Jn and Jc had typical leaf reflectance characteristics,but the reflectivity of Jn in green and near infrared bands was significantly lower than that of Jc.The analysis of chlorophyll fluorescence characteristics showed that the effective photosynthetic quantum yield(Y(II))and the actual photosynthetic quantum yield(F’_v/F’_m)of Jn were higher than those of Jc.The two leaf types all had the phenomenon of"photosynthetic lunch break".The diurnal variation trend of photosynthetic parameters was about the same,but the photosynthetic parameters such as Pn of Jn were slightly higher than those of Jc.The above results showed that the photosynthetic ability of Jn was stronger than that of Jc.(3)A total of 18 TCP members were identified in the whole genome sequence of Jatropha curcas L.The bioinformatics analysis of 18 TCP showed that there were great differences in protein properties among the members of Jc TCP gene,which could be divided into two categories:Class I and Class II.The Jc TCP genes in the same branch had similar structure and conservative motifs,which indicated that they might have similar biological functions.The results of q PCR analysis showed that most of Jc TCP genes were differentially expressed at different stages of leaf development.Jc TCP4,Jc TCP5,Jc TCP8,Jc TCP13,Jc TCP14 and Jc TCP16 were significantly differentially expressed in leaves,which could be used as candidate genes to regulate leaf morphology.(4)Using the whole genome sequence and transcriptome data of Jatropha curcas L to design primers,it was found that the expression of CYCD3;1 gene in all stages of leaf development of Jn was significantly higher than that of Jc.JnCYCD3;1played an important role in the development of wrinkled leaves.At the same time,JnCYCD3;1 and Jc CYCD3;1 genes were cloned.The overexpression vector and RNAi silencing expression vector of 2 gene was successfully constructed for follow-up research.In addition,the results of chloroplast genome analysis showed that there was no significant mutation in the chloroplast genomes of the two trees.It suggested that the difference in leaf types was not caused by chloroplast genomes at the DNA level.