Transcriptomic Analyses Reveal Leaf Colour Changes and L-theanine Accumulation in Variegated Tea

Abstract Background Camellia sinensis ‘Yanlinghuayecha’ (YHC) is a variegated mutant developed recently in China. To dissect the physiological and molecular mechanisms of leaf variegation, we compared the leaf pigmentation, cellular ultrastructure, amino acid content, and transcriptome between the albino (A), mosaic (M), and green (G) sectors.Results The contents of photosynthetic pigments were significantly lower in sector A and higher in sector G than in sector M. Chloroplasts with well-organized thylakoids were found only in the mesophyll cells of the G sector but not in those of the A sector. The A sector had a significantly higher content of total and free amino acids. In particular, the levels of theanine, glutamate, and alanine in the A sector were higher than those in the G sector. Transcriptomics analysis showed that a total of 44,908 unique transcripts were identified. Comparing the differentially expressed genes (DEGs) in the three sectors, we conducted an in-depth study on chloroplast biogenesis, chlorophyll biosynthesis, and theanine synthesis pathways. The expression of CsPPOX in “porphyrin and chlorophyll metabolism” was significantly downregulated in the A sector. CsLHCB6 in “Photosynthesis - antenna proteins” and CsSCY1 in “Protein processing in endoplasmic reticulum”, both of which were associated with chloroplast biogenesis, were significantly downregulated in the A sector. The expression of CsTS1 was notably upregulated in the A sector.Conclusion Taken together, variegation alters the gene activities involved in chloroplast biogenesis, and our results suggest that leaf colour change in the A sector incorporates three aspects compared with that in the G sector: (1) Decreased CsPPOX expression slows the rate of chlorophyll synthesis, resulting in a decrease in chlorophyll content; (2) downregulated expression of CsLHCB6 and CsSCY1 inhibits chloroplast biogenesis, decreasing thylakoid morphogenesis and grana stacking; and (3) the metabolic flow of glutamate changes, possibly from chlorophyll biosynthesis to theanine biosynthesis. The accumulation of precursor synthetic substances and the high expression of CsTS1 generates a high theanine content. These analyses provide valuable insights into variegation in tea plants with regard to leaf colour change and L-theanine accumulation.

Download Full-text

iTRAQ-based comparative proteomic analysis of differences in the protein profiles of stems and leaves from two alfalfa genotypes

10.21203/rs.3.rs-36055/v4 ◽

2020 ◽

Author(s):

Hao Sun ◽

Jie Yu ◽

Fan Zhang ◽

Junmei Kang ◽

Mingna Li ◽

...

Keyword(s):

Leaf Development ◽

Proteomic Analysis ◽

Regulatory Networks ◽

Carbon Fixation ◽

Chlorophyll Biosynthesis ◽

Chlorophyll Synthesis ◽

Phenylpropanoid Pathway ◽

Chlorophyll Metabolism ◽

Phenylpropanoid Biosynthesis ◽

Proteomic Study

Abstract Background: To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves.Results: Based on fold-change thresholds of >1.20 or <0.83 (p<0.05), a large number of proteins were identified as being differentially enriched between the M and F genotypes: 249 downregulated and 139 upregulated in stems and 164 downregulated and 134 upregulated in leaves. The differentially enriched proteins in stems were mainly involved in amino acid biosynthesis, phenylpropanoid biosynthesis, carbon fixation, and phenylalanine metabolism. The differentially enriched proteins in leaves were mainly involved in porphyrin and chlorophyll metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and carbon fixation in photosynthetic organisms. Six differentially enriched proteins were mapped onto the porphyrin and chlorophyll metabolism pathway in leaves of the M genotype, including five upregulated proteins involved in chlorophyll biosynthesis and one downregulated protein involved in chlorophyll degradation. Eleven differentially enriched proteins were mapped onto the phenylpropanoid pathway in stems of the M genotype, including two upregulated proteins and nine downregulated proteins. Conclusion: Enhanced chlorophyll synthesis and decreased lignin synthesis provided a reasonable explanation for the larger leaves and lower levels of stem lignification in M genotype alfalfa. This proteomic study aimed to classify the functions of differentially enriched proteins and to provide information on the molecular regulatory networks involved in stem and leaf development.

Download Full-text

iTRAQ-based comparative proteomic analysis of differences in the protein profiles of stems and leaves from two alfalfa genotypes

BMC Plant Biology ◽

10.1186/s12870-020-02671-2 ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Hao Sun ◽

Jie Yu ◽

Fan Zhang ◽

Junmei Kang ◽

Mingna Li ◽

...

Keyword(s):

Leaf Development ◽

Proteomic Analysis ◽

Regulatory Networks ◽

Carbon Fixation ◽

Chlorophyll Biosynthesis ◽

Chlorophyll Synthesis ◽

Phenylpropanoid Pathway ◽

Chlorophyll Metabolism ◽

Phenylpropanoid Biosynthesis ◽

Proteomic Study

Abstract Background To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves. Results Based on fold-change thresholds of > 1.20 or < 0.83 (p < 0.05), a large number of proteins were identified as being differentially enriched between the M and F genotypes: 249 downregulated and 139 upregulated in stems and 164 downregulated and 134 upregulated in leaves. The differentially enriched proteins in stems were mainly involved in amino acid biosynthesis, phenylpropanoid biosynthesis, carbon fixation, and phenylalanine metabolism. The differentially enriched proteins in leaves were mainly involved in porphyrin and chlorophyll metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and carbon fixation in photosynthetic organisms. Six differentially enriched proteins were mapped onto the porphyrin and chlorophyll metabolism pathway in leaves of the M genotype, including five upregulated proteins involved in chlorophyll biosynthesis and one downregulated protein involved in chlorophyll degradation. Eleven differentially enriched proteins were mapped onto the phenylpropanoid pathway in stems of the M genotype, including two upregulated proteins and nine downregulated proteins. Conclusion Enhanced chlorophyll synthesis and decreased lignin synthesis provided a reasonable explanation for the larger leaves and lower levels of stem lignification in M genotype alfalfa. This proteomic study aimed to classify the functions of differentially enriched proteins and to provide information on the molecular regulatory networks involved in stem and leaf development.

Download Full-text

Physiological and transcriptome analyses of photosynthesis and chlorophyll metabolism in variegated Citrus (Shiranuhi and Huangguogan) seedlings

Scientific Reports ◽

10.1038/s41598-019-52276-5 ◽

2019 ◽

Vol 9 (1) ◽

Cited By ~ 1

Author(s):

Bo Xiong ◽

Xia Qiu ◽

Shengjia Huang ◽

Xiaojia Wang ◽

Xu Zhang ◽

...

Keyword(s):

Molecular Mechanisms ◽

Chlorophyll Biosynthesis ◽

Expression Patterns ◽

Sequencing Error ◽

Sequencing Data ◽

Chlorophyll Metabolism ◽

Regulatory Pathways ◽

Chlorophyll Contents ◽

Kegg Pathways ◽

And Function

Abstract Citrus species are among the most economically important fruit crops. Physiological characteristics and molecular mechanisms associated with de-etiolation have been partially revealed. However, little is known about the mechanisms controlling the expression and function of genes associated with photosynthesis and chlorophyll biosynthesis in variegated citrus seedlings. The lower biomass, chlorophyll contents, and photosynthetic parameter values recorded for the variegated seedlings suggested that chlorophyll biosynthesis was partially inhibited. Additionally, roots of the variegated seedlings were longer than the roots of green seedlings. We obtained 567.07 million clean reads and 85.05 Gb of RNA-sequencing data, with more than 94.19% of the reads having a quality score of Q30 (sequencing error rate = 0.1%). Furthermore, we detected 4,786 and 7,007 differentially expressed genes (DEGs) between variegated and green Shiranuhi and Huangguogan seedlings. Thirty common pathways were differentially regulated, including pathways related to photosynthesis (GO: 0015979) and the chloroplast (GO: 0009507). Photosynthesis (44 and 63 DEGs), photosynthesis-antenna proteins (14 and 29 DEGs), and flavonoid biosynthesis (16 and 29 DEGs) pathways were the most common KEGG pathways detected in two analyzed libraries. Differences in the expression patterns of PsbQ, PetF, PetB, PsaA, PsaN, PsbP, PsaF, Cluster-2274.8338 (ZIP1), Cluster-2274.38688 (PTC52), and Cluster-2274.78784 might be responsible for the variegation in citrus seedlings. We completed a physiological- and transcriptome-level comparison of the Shiranuhi and Huangguogan cultivars that differ in terms of seedling variegation. We performed mRNA-seq analyses of variegated and green Shiranuhi and Huangguogan seedlings to explore the genes and regulatory pathways involved in the inhibition of chlorophyll biosynthesis and decreases in Chl a and Chl b contents. The candidate genes described herein should be investigated in greater detail to further characterize variegated citrus seedlings.

Download Full-text

Identification of two recessive etiolation genes (py1, py2) in pakchoi (Brassica rapa L. ssp. chinensis)

10.21203/rs.2.15677/v3 ◽

2020 ◽

Author(s):

Kun Zhang ◽

Yu Mu ◽

Weijia Li ◽

Xiaofei Shan ◽

Nan Wang ◽

...

Keyword(s):

Molecular Mechanisms ◽

Crop Yields ◽

Microspore Culture ◽

Chlorophyll Biosynthesis ◽

Differentially Expressed Gene ◽

Nuclear Genes ◽

Single Amino Acid ◽

Leaf Color ◽

Chlorophyll Metabolism ◽

Metabolism Regulation

Abstract Background: Leaf color is a major agronomic trait, which has a strong influence on crop yields. Isolating leaf color mutants can represent valuable materials for research in chlorophyll biosynthesis and metabolism regulation.Results: In this study, we identified a stably inherited yellow leaf mutant derived from ‘Huaguan’ pakchoi variety via isolated microspore culture and designated as pylm. This mutant displayed yellow leaves after germination. Its etiolated phenotype was nonlethal and stable during the whole growth period. Its growth was weak and its hypocotyls were markedly elongated. Genetic analysis revealed that two recessive nuclear genes, named py1 and py2, are responsible for the etiolation phenotype. Bulked segregant RNA sequencing (BSR-Seq) showed that py1 and py2 were mapped on chromosomes A09 and A07, respectively. The genes were single Mendelian factors in F3:4 populations based on a 3:1 phenotypic segregation ratio. The py1 was localized to a 258.3-kb interval on a 34-gene genome. The differentially expressed gene BraA09004189 was detected in the py1 mapping region and regulated heme catabolism. One single-nucleotide polymorphism (SNP) of BraA09004189 occurred in pylm. A candidate gene-specific SNP marker in 1,520 F3:4 yellow-colored individuals co-segregated with py1. For py2, 1,860 recessive homozygous F3:4 individuals were investigated and localized py2 to a 4.4-kb interval. Of the five genes in this region, BraA07001774 was predicted as a candidate for py2. It encoded an embryo defective 1187 and a phosphotransferase related to chlorophyll deficiency and hypocotyl elongation. One SNP of BraA07001774 occurred in pylm. It caused a single amino acid mutation from Asp to Asn. According to quantitative real-time polymerase chain reaction (qRT-PCR), BraA07001774 was downregulated in pylm. Conclusions: Our study identified a Chl deficiency mutant pylm in pakchoi. Two recessive nuclear genes named py1 and py2 had a significant effect on etiolation. Candidate genes regulating etiolation were identified as BraA09004189 and BraA07001774, respectively. These findings will elucidate chlorophyll metabolism and the molecular mechanisms of the gene interactions controlling pakchoi etiolation.

Download Full-text

iTRAQ-based comparative proteomic analysis of differences in the protein profiles of stems and leaves from two alfalfa genotypes

10.21203/rs.3.rs-36055/v3 ◽

2020 ◽

Author(s):

Hao Sun ◽

Jie Yu ◽

Fan Zhang ◽

Junmei Kang ◽

Mingna Li ◽

...

Keyword(s):

Leaf Development ◽

Proteomic Analysis ◽

Regulatory Networks ◽

Carbon Fixation ◽

Chlorophyll Biosynthesis ◽

Chlorophyll Synthesis ◽

Phenylpropanoid Pathway ◽

Chlorophyll Metabolism ◽

Phenylpropanoid Biosynthesis ◽

Proteomic Study

Abstract Background: To explore the molecular regulatory mechanisms of early stem and leaf development, proteomic analysis was performed on leaves and stems of F genotype alfalfa, with thin stems and small leaves, and M genotype alfalfa, with thick stems and large leaves.Results: Based on fold-change thresholds of >1.20 or <0.83 (p<0.05), a large number of proteins were identified as being differentially enriched between the M and F genotypes: 249 downregulated and 139 upregulated in stems and 164 downregulated and 134 upregulated in leaves. The differentially expressed proteins in stems were mainly involved in amino acid biosynthesis, phenylpropanoid biosynthesis, carbon fixation, and phenylalanine metabolism. The differentially enriched proteins in leaves were mainly involved in porphyrin and chlorophyll metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and carbon fixation in photosynthetic organisms. Six differentially enriched proteins were mapped onto the porphyrin and chlorophyll metabolism pathway in leaves of the M genotype, including five upregulated proteins involved in chlorophyll biosynthesis and one downregulated protein involved in chlorophyll degradation. Eleven differentially enriched proteins were mapped onto the phenylpropanoid pathway in stems of the M genotype, including two upregulated proteins and nine downregulated proteins.Conclusion: Enhanced chlorophyll synthesis and decreased lignin synthesis provided a reasonable explanation for the larger leaves and lower levels of stem lignification in M genotype alfalfa. This proteomic study aimed to classify the functions of differentially enriched proteins and to provide information on the molecular regulatory networks involved in stem and leaf development.

Download Full-text

iTRAQ-Based Quantitative Proteomics Analysis Reveals the Mechanism of Golden-Yellow Leaf Mutant in Hybrid Paper Mulberry

International Journal of Molecular Sciences ◽

10.3390/ijms23010127 ◽

2021 ◽

Vol 23 (1) ◽

pp. 127

Author(s):

Fenfen Wang ◽

Naizhi Chen ◽

Shihua Shen

Keyword(s):

Chlorophyll Synthesis ◽

Carotenoid Content ◽

Yellow Leaf ◽

Mesophyll Cells ◽

Chlorophyll Metabolism ◽

Growth And Survival ◽

Leaf Phenotype ◽

Golden Yellow ◽

Leaf Mutant ◽

The Impact

Plant growth and development relies on the conversion of light energy into chemical energy, which takes place in the leaves. Chlorophyll mutant variations are important for studying certain physiological processes, including chlorophyll metabolism, chloroplast biogenesis, and photosynthesis. To uncover the mechanisms of the golden-yellow phenotype of the hybrid paper mulberry plant, this study used physiological, cytological, and iTRAQ-based proteomic analyses to compare the green and golden-yellow leaves of hybrid paper mulberry. Physiological results showed that the mutants of hybrid paper mulberry showed golden-yellow leaves, reduced chlorophyll, and carotenoid content, and increased flavonoid content compared with wild-type plants. Cytological observations revealed defective chloroplasts in the mesophyll cells of the mutants. Results demonstrated that 4766 proteins were identified from the hybrid paper mulberry leaves, of which 168 proteins displayed differential accumulations between the green and mutant leaves. The differentially accumulated proteins were primarily involved in chlorophyll synthesis, carotenoid metabolism, and photosynthesis. In addition, differentially accumulated proteins are associated with ribosome pathways and could enable plants to adapt to environmental conditions by regulating the proteome to reduce the impact of chlorophyll reduction on growth and survival. Altogether, this study provides a better understanding of the formation mechanism of the golden-yellow leaf phenotype by combining proteomic approaches.

Download Full-text

Albino seedling lethality 4 ; chloroplast 30S ribosomal protein S1 required for chloroplast ribosome biogenesis and early chloroplast development in rice

10.21203/rs.3.rs-367189/v1 ◽

2021 ◽

Author(s):

Kunneng Zhou ◽

Caijuan Zhang ◽

Jiafa Xia ◽

Peng Yun ◽

Yuanlei Wang ◽

...

Keyword(s):

Ribosomal Protein ◽

Ribosomal Proteins ◽

Ribosome Biogenesis ◽

Molecular Mechanisms ◽

Chloroplast Development ◽

Chlorophyll Biosynthesis ◽

Housekeeping Genes ◽

Chloroplast Biogenesis ◽

Ribosomal Protein S1 ◽

Photosynthesis Genes

Abstract Background : Ribosomes responsible for transcription and translation of plastid-encoded proteins in chloroplasts are essential for chloroplast development and plant growth. Although most ribosomal proteins in plastids have been identified, the molecular mechanisms regulating chloroplast biogenesis remain to be investigated. Results: Here, we identified albinic seedling mutant asl4 caused by disruption of 30S ribosomal protein S1 that is targeted to the chloroplast . The mutant was defective in early chloroplast development and chlorophyll biosynthesis . A 2,855-bp deletion in the ASL4 allele was verified as responsible for the mutant phenotype by complementation tests. Expression analysis revealed that the ASL4 allele was highly expressed in leaf 4 sections and newly expanded leaves during early leaf development. Expression levels were increased by exposure to light following darkness. Some genes involved in chloroplast biogenesis were up-regulated and others down-regulated in asl4 mutant tissues compared to wild type. PEP-dependent photosynthesis genes and NEP-dependent housekeeping genes were separately down-regulated and up-regulated, suggesting that plastid transcription was impaired in the mutant. Transcriptome and western blot analyses showed that levels of most plastid-encoded genes and proteins were reduced in the mutant. The decreased contents of chloroplast rRNAs and ribosomal proteins indicated that chloroplast ribosome biogenesis was impaired in the asl4 mutant. Conclusion: Rice ASL4 encodes 30S ribosomal protein S1, which is targeted to the chloroplast. ASL4 is essential for chloroplast ribosome biogenesis and early chloroplast development. These data will facilitate efforts to further elucidate the molecular mechanism of chloroplast biogenesis.

Download Full-text

CmNAC73 Mediates the Formation of Green Color in Chrysanthemum Flowers by Directly Activating the Expression of Chlorophyll Biosynthesis Genes HEMA1 and CRD1

Genes ◽

10.3390/genes12050704 ◽

2021 ◽

Vol 12 (5) ◽

pp. 704

Author(s):

Jing Luo ◽

Huan Wang ◽

Sijia Chen ◽

Shengjing Ren ◽

Hansen Fu ◽

...

Keyword(s):

Chlorophyll Biosynthesis ◽

Flower Color ◽

Chlorophyll Synthesis ◽

Chrysanthemum Morifolium ◽

Gene Encoding ◽

Chlorophyll Metabolism ◽

Chlorophyll Accumulation ◽

Transient Overexpression ◽

Highly Correlated ◽

Dark Green

Chrysanthemum is one of the most beautiful and popular flowers in the world, and the flower color is an important ornamental trait of chrysanthemum. Compared with other flower colors, green flowers are relatively rare. The formation of green flower color is attributed to the accumulation of chlorophyll; however, the regulatory mechanism of chlorophyll metabolism in chrysanthemum with green flowers remains largely unknown. In this study, we performed Illumina RNA sequencing on three chrysanthemum materials, Chrysanthemum vestitum and Chrysanthemum morifolium cultivars ‘Chunxiao’ and ‘Green anna,’ which produce white, light green and dark green flowers, respectively. Based on the results of comparative transcriptome analysis, a gene encoding a novel NAC family transcription factor, CmNAC73, was found to be highly correlated to chlorophyll accumulation in the outer whorl of ray florets in chrysanthemum. The results of transient overexpression in chrysanthemum leaves showed that CmNAC73 acts as a positive regulator of chlorophyll biosynthesis. Furthermore, transactivation and yeast one-hybrid assays indicated that CmNAC73 directly binds to the promoters of chlorophyll synthesis-related genes HEMA1 and CRD1. Thus, this study uncovers the transcriptional regulation of chlorophyll synthesis-related genes HEMA1 and CRD1 by CmNAC73 and provides new insights into the development of green flower color in chrysanthemum and chlorophyll metabolism in plants.

Download Full-text

Photosystem Disorder Could be the Key Cause for the Formation of Albino Leaf Phenotype in Pecan

International Journal of Molecular Sciences ◽

10.3390/ijms21176137 ◽

2020 ◽

Vol 21 (17) ◽

pp. 6137

Author(s):

Ji-Yu Zhang ◽

Tao Wang ◽

Zhan-Hui Jia ◽

Zhong-Ren Guo ◽

Yong-Zhi Liu ◽

...

Keyword(s):

Chlorophyll A ◽

Molecular Mechanisms ◽

Chlorophyll Biosynthesis ◽

Protoporphyrin Ix ◽

Photosynthetic Electron Transport ◽

Chlorophyll Degradation ◽

Pheophorbide A ◽

Leaf Phenotype ◽

Photosynthesis Pathway ◽

Almost All

Pecan is one of the most famous nut species in the world. The phenotype of mutants with albino leaves was found in the process of seeding pecan, providing ideal material for the study of the molecular mechanisms leading to the chlorina phenotype in plants. Both chlorophyll a and chlorophyll b contents in albino leaves (ALs) were significantly lower than those in green leaves (GLs). A total of 5171 differentially expression genes (DEGs) were identified in the comparison of ALs vs. GLs using high-throughput transcriptome sequencing; 2216 DEGs (42.85%) were upregulated and 2955 DEGs (57.15%) were downregulated. The expressions of genes related to chlorophyll biosynthesis (HEMA1, encoding glutamyl-tRNA reductase; ChlH, encoding Mg-protoporphyrin IX chelatase (Mg-chelatase) H subunit; CRD, encoding Mg-protoporphyrin IX monomethylester cyclase; POR, encoding protochlorophyllide reductase) in ALs were significantly lower than those in GLs. However, the expressions of genes related to chlorophyll degradation (PAO, encoding pheophorbide a oxygenase) in ALs were significantly higher than those in GLs, indicating that disturbance of chlorophyll a biosynthesis and intensification of chlorophyll degradation lead to the absence of chlorophyll in ALs of pecan. A total of 72 DEGs associated with photosynthesis pathway were identified in ALs compared to GLs, including photosystem I (15), photosystem II (19), cytochrome b6-f complex (3), photosynthetic electron transport (6), F-type ATPase (7), and photosynthesis-antenna proteins (22). Moreover, almost all the genes (68) mapped in the photosynthesis pathway showed decreased expression in ALs compared to GLs, declaring that the photosynthetic system embedded within the thylakoid membrane of chloroplast was disturbed in ALs of pecan. This study provides a theoretical basis for elucidating the molecular mechanism underlying the phenotype of chlorina seedlings of pecan.

Download Full-text

Regulation der Chlorophyllbiosynthese. Lidit- und entwicklungsbedingte Aktivitätsänderungen von vier aufeinander folgenden Enzymen der Porphyrin- und Chlorophyllbiosynthesekette / Regulation of Chlorophyll Biosynthesis. Changes in Activity of Four Consecutive Enzymes in the Porphyrin and Chlorophyll Biosynthesis Chain during Development and Illumination

Zeitschrift für Naturforschung C ◽

10.1515/znc-1973-1-208 ◽

1973 ◽

Vol 28 (1-2) ◽

pp. 45-58 ◽

Cited By ~ 12

Author(s):

Hansjörg A. W. Schneider

Keyword(s):

Nucleic Acid ◽

Chlorophyll Biosynthesis ◽

Acid Synthesis ◽

Chlorophyll Synthesis ◽

The Other ◽

Tissue Cultures ◽

Leaf Tissues ◽

Porphyrin Synthesis

The activities of enzymes related with chlorophyll and porphyrin synthesis have been examined during development and greening of young corn leaves. The enzymes succinyl-CoA-synthetase (SCoAS), δ-amino-levulinate synthetase (ALAS), δ-amino-levulinate dehydratase (ALAD) and the enzymes involved in porphobilinogenase (PBGA) were under investigaton. When leaves are illuminated and chlorophyll synthesis begins the activity of ALAD is not influenced. The activity of PBGA and SCoAS are slightly higher than in darkness, but the changes are below the range affecting chlorophyll biosynthesis. ALA, however, is only synthetized in the light. Synthesis ceases immediately when illuminiation ist stopped, indicating'that in darkness ALAS is not active. On the other hand ALAS is active in dark grown roots, tubers and other non-leaf tissues. Feeding the plant with succinate, glycine or α-keto-glutarate has no effect on chlorophyll synthesis, but the amount of ALA is reduced, whereas sucrose promotes its accumulation. The results are discussed with completely antitethaal results obtained with tissue cultures of tobacco and are integrated into a scheme which excludes the contrariety of hypotheses deduced from experi- ments with inhibitors of protein and nucleic acid synthesis. It is suggested that the varying results are caused by the action of light on different stages in differentiation of plastids and cells. In contrast to the enzymes SCoAS, ALAD and PBGA whose activities were determined in vitro, ALAS was assayed in vivo by means of the accumulation of (5-amino-levulinate (ALA) after blocking the enzyme ALAD by levulinate (LA). Optimum accumulation is observed when the concentration is about 2 · 10-2 м. LA is not converted to ALA in appreciable amounts. This could be proved by feeding the plants with 14C-LA which was prepared from uniformly labeled 14C-fructose.

Download Full-text