Study On Relation Between Lignin And Shoot Tendness Of Camellia Sinensis

Tea plant [Camellia sinensis(L.)O.Kuntze] belongs to the perennial evergreen trees,and is one of the important economic crops for leaves in China.‘Tenderness-keeping ability’ is an important biological trait of tea plant,reflecting the ability of keeping tenderness in shoots of tea plant.Tenderness not only has an important impact on the picking of tea and the quality of finished tea,but also the premise and basis for measuring the shoot’s ’tenderness-keeping ability’ of tea plant.In this study,the relationship between lignin content and tenderness of tea shoots was studied by physiological,biochemical and molecular biological methods.In this study,the relationship between lignin content and tenderness of tea shoots was studied by physiological,biochemical and molecular biological methods.The laccase gene of tea plant was cloned and its mechanism of lignin synthesis and tenderness in tea shoots was studied.This research is expected to promote the application of molecular biology in the field of tea plant tenderness research,and provide a theoretical basis for the research on the tea plant’s tenderness and the ’tenderness-keeping ability’ of new shoots.1.The shearing force of the new shoots of ’Zhongcha 108’ variety tea plant was determined by texture analyzer.The results showed that the shear force increased with the decrease of tenderness of tea shoots,indicating that shear force and new shoot tenderness were negative.That is,as the shoots’ s tenderness decreases,the shear force gradually increases.The results of histochemical staining showed that the lignin in the leaves and corresponding stems of tea plant was mainly distributed in xylem and vascular bundle sheath cells,and the accumulation increased with the decrease of tenderness,and the new shoots were in third leaves and corresponding stems.A large amount of lignin is accumulated in the middle.Similarly,the determination of the acetyl bromide lignin content of the new shoots also showed a significant increase with the decrease in the tenderness of the new shoot leaves and their corresponding stems.In addition,correlation analysis showed that the shear stress of new shoots was significantly positively correlated with the corresponding lignin content,that is,the lignin content was negatively correlated with the tenderness of tea shoots,indicating that the lignin accumulation of tea shoots was closely related to the tenderness of new shoots.2.Three tea laccase genes were cloned and named CsLAC11,CsLAC17-1 and CsLAC17-2.Bioinformatics analysis showed that CsLAC11,CsLAC17-1 and CsLAC17-2 encoded 571,579 and 585 amino acids,respectively.The molecular weight of the encoded protein was 63.46 kDa,64.15 kDa and 64.69 kDa,all of which were hydrophilic proteins.The structural analysis of the encoded protein showed that CsLAC11,CsLAC17-1 and CsLAC17-2 contained three highly conserved Cu-oxidase domains,belonging to the typical laccase family proteins.qRT-PCR analysis showed that the expression of three CsLAC genes in 3 leaves and 5 leaves or their corresponding stems increased to different degrees compared with 1 leaf and its corresponding stem,and The consistent trend of CsLAC17-1’expression in leaves and corresponding stems was found.At the same time,correlation analysis showed that there was a significant correlation between gene expression level and lignin content in shoots or their corresponding stems.It is speculated that CsLAC11,CsLAC17-1 and CsLAC17-2 play a role in the synthesis and accumulation of lignin in tea shoots.In addition,prokaryotic expression analysis showed that the expression of CsLAC11,CsLAC17-1 and CsLAC17-2 protein was not detected in the supernatant after IPTG induction,suggesting that it may exist in the form of inclusion bodies in the precipitate.