| Camellia sinensis.’Baiye1’.is a typical albino tea variety.The increasing amino acid content in the albino stage makes it have considerable nutritional value.Therefore,it is of great significance to study the molecular mechanism of its albinism.In this study,the development of chloroplast and the synthesis of chlorophyll in Camellia sinensis.’Baiye1’.were analyzed,and the sequence of transcript and genome were analyzed,which provided a theoretical basis for the study of color mutation mechanism of Camellia sinensis.’Baiye1’.The following results are obtained:1.Observation on the ultrastructure of chloroplasts in albino leaves and green leaves of Camellia sinensis.’Baiye1’Camellia sinensis.’Baiye1’ albino leaves and green leaves were sliced and the chloroplast ultrastructure was observed.The internal structure of albino leaf chloroplasts was poorly developed,the granules were scattered or even broken,the chloroplasts of the green leaves were well developed,and the granules were tightly folded and clear.2.Determination of chlorophyll and its precursors in albino leaves and green leaves of Camellia sinensis.’Baiye1’Determination of chlorophyll,carotenoids,δ-aminolevulinic acid(ALA),porphobilinogen(PGB),Urogen III and Coprogen III,ProtoIX,and the content of the original chlorophyll a(Pchlide a),Mg-proto IX(Mg-proto IX)is higher than that of the green leaves,and the difference is significant.The contents of δ-aminolevulinic acid(ALA),bile pigment(PGB),CoprogenIII,Pchlide a,Chlorophyll a,Chlorophyll b and Carotenoid in green leaves were higher than those in albino leaves.3.Transcriptome sequencing analysisThe expression pattern in the albino period differs greatly from the green-back phase.The important structure of the chloroplast basal(photosynthetic membrane)-light-harvesting complex,oxygen-releasing complex(OEC),electron transport chain,cytochrome b6/f complex,The expression of F-type H+transport ATPase and other synthetic genes was down-regulated in the whitening stage,such as iron-thio-cytochrome B6-F complex synthesis gene(PetC)andferredoxin synthesis gene(PetF),plastocyanin synthesis.Gene(PetE)and the like.The synthetic genes of key enzymes in the chlorophyll synthesis process also showed a downward trend in the whole whitening stage,such as uroporphyrinogen-III synthase(UROS),magnesium chelatase(Chl),and protochlorophyllin reductase(PORA).),chlorophyll synthase(CHLG),and the like.From the level of gene expression,the whitening of Camellia sinensis.’Baiye1’ is affected by both chloroplast development and chlorophyll synthesis.Through the analysis of the transcriptome,the whitening of Camellia sinensis.’Baiye1’ also affects the regulation related to photosynthesis and disease resistance.During the whitening period,except for the down-regulation of genes related to photosynthesis in the photoreaction phase,the expression of related genes in the dark reaction phase is also overall.Down-regulation;while the expression of genes associated with disease resistance has an overall upward trend.4.Camellia sinensis.’Baiye1’ genome resequencing resultsThe re-sequencing results of Camellia sinensis.’Baiye1’ genome(Camellia sinensis.cv.shuchazao as a sequencing reference genome)were found and referenced to the albino to green gene of rice,and it was found that SNP(non-synonymous)mutation occurred in RNRL1(ribonucleic acid reducase large subunit gene can affect the formation of dNTP and thus the replication of chloroplast DNA.)of Camellia sinensis.’Baiye1’,and the translated protein was in these variations.The hydrogen bond between the amino acid residue and the nearby amino acid residue is reduced,and the active site of the translated protein is predicted to be different from that of Camellia sinensis.cv.shuchazao.It is speculated that the mutation of RNRL1 reduced the activity of RNRL1 and affected the chlorophyll synthesis during leaf development,resulting in the character of albinism and green leaves in Camellia sinensis.’Baiye1’.5.Analysis of Gene expression related to Albino-reversion of Camellia sinensis.’Baiye1’Through the quantitative analysis of the expression of some related genes in the leaves of Camellia sinensis.’Baiye1’.During the albinism and greening stages,we found that RNRL1.The expression of RNRL1 in albino leaves was the lowest in albino leaves,and the expression level in albino leaves was 0.58 times higher than that in green leaves.Therefore,we further speculate that the phenomenon of whitening and returning green of Camellia sinensis.’Baiye1’,may be related to RNRL1. |
