| Actinidia erientha Benth is a unique resource in our country, which has rich antioxidants, high content of ascorbic acid and other nutrients. Its flowers and fruits have strong ornamental value, which more, the fruit is easy-peeling and resistance of the tree is strong. With all these advantages, A. eriantha has a broad prospect of development and utilization. At present, the flesh color of kiwifruit has got more and more attention, but the color analysis research of green-flesh kiwifruit during the whole development process has not yet been reported. In this paper, A. eriantha‘Ganmi 6’ was used to observe the flesh color changes and test the contents of chlorophyll and carotenoids, then analyze the correlation between measured indexes.Then we used RT-qPCR and cloning technologies to explore the dynamic changes of pigment in the various periods of full bloom and Chlorophyll synthesis-related genes expression, which can lay a good foundation for molecular breeding and germplasm of kiwifruit. The main findings are as follows:1. The hue angle of flesh in the process of ‘Ganmi 6’ fruits development(20DAFB-70 DAFB) rose stably. Chlorophyll content was about 6 mg/100 g before 90 DAFB, then rose to the maximum content(9.2 mg/100 g) rapidly until 140 DAFB,and the consequence made by chlorophyll a was weighed more than chlorophyll b.Carotenoids contents remained stable before 110 DAFB, then it showed a up--down trend with rose to the maximum(2.63 mg/100 g) at 140 DAFB. Chlorophyll and carotenoid were significantly correlated with chlorophyll a, chlorophyll b and hue angle, the two were also had significant correlation with each other. The results showed that it was the high expression level of chlorophyll that kept the flesh color green throughout the development of A. eriantha.2. Based on the early stage of the pigment content analysis results, we selected 6major periods to extract RNA. Then using RT-qPCR technique to explore the chlorophyll synthesis related gene expression. 12 genes of the related chlorophyll synthesis were found to be expressed in the flesh, but their expression levels varied.Correlation analysis showed a significant positive correlation existed between the chlorophyll contents with gene Unigenes25176(P < 0.05) expression; the cluster analysis showed that Unigenes25176 had the highest level expression in chlorophyll synthesis and clustered a category, different from other genes. Based on all the above results, Unigenes25176 might be the key gene during the chlorophyll synthesis in green-flesh kiwifruit. Unigene25176 was predictively noted encoding ferredoxin-NADP+ oxidoreductase of chromophores in grapes. Not only phytochrome influences the morphology of plants, but also controls gene expression by adjusting plant hormones and other chemicals. FNR is the protein to catalytic electrons fromreduced state ferredoxin passed to NADP+ which is on the surface of thylakoid membrane. Generated NADPH mainly acts on CO2 fixation, nitrogen assimilation,chlorophyll synthesis and other responses in Calvin cycle.3. By cloning and RNA-Seq analysis of Unigenes25176 which was the candidate key genes of chlorophyll synthesis in green-flesh A. eriantha ‘Ganmi 6’, the results as follows: Unigene25176 contains a 885 bp open reading frame and encode 294 amino acids, phylogenetic analysis showed that the gene has close distance with graps, the similarity of homologous protein amino acid sequence alignment was 65.45%, while far from the Arabidopsis. Through protein structure domain, we found it belongs to Fe_ bilin_red super family, and related to the FNR. So we concluded that it may be the key gene of chlorophyll synthesis. |
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