title: Plant degreening: evolution and expression of tomato (Solanum lycopersicum) dephytylation enzymes.
abstract: Chlorophyll is the most abundant pigment on earth and even though it is known that its high photo-excitability necessitates a tight regulation of its degradation pathway, to date there are still several steps in chlorophyll breakdown that remain obscure. In order to better understand the 'degreening' processes that accompany leaf senescence and fruit ripening, we characterized the enzyme-encoding genes involved in dephytylation from tomato (Solanum lycopersicum). A single pheophytinase (PPH) gene and four chlorophyllase (CLH) genes were identified in the tomato genome. A phenetic analysis revealed two groups of CLHs in eudicot species and further evolutionary analysis indicated that these enzymes are under diverse selection pressures. A comprehensive expression profile analysis also suggested functional specificity for these dephytylating enzymes. The integrated analysis allows us to propose three general roles for chlorophyll dephytylation: i) PPH, which is under high selective constraint, is responsible for chlorophyll degradation during developmentally programed physiological processes; ii) Group I CLHs, which are under relaxed selection constraint, respond to environmental and hormonal stimuli and play a role in plant adaptation plasticity; and iii) Group II CLHs, which are also under high selective constraint, are mostly involved in chlorophyll recycling.
authors.affiliation: Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. Electronic address: bslbsl@usp.br.
authors.forename: Bruno Silvestre
authors.initials: BS
authors.lastname: Lira
authors.affiliation: Centro de Ciências Naturais e Humanas, Universidade Federal do ABC, Santo André, SP, Brazil. Electronic address: setta@ufabc.edu.br.
authors.forename: Nathalia
authors.initials: N
authors.lastname: de Setta
authors.affiliation: Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. Electronic address: daniele.rosado@usp.br.
authors.forename: Daniele
authors.initials: D
authors.lastname: Rosado
authors.affiliation: Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. Electronic address: juliana.almeida.silva@usp.br.
authors.forename: Juliana
authors.initials: J
authors.lastname: Almeida
authors.affiliation: Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. Electronic address: freschi@usp.br.
authors.forename: Luciano
authors.initials: L
authors.lastname: Freschi
authors.affiliation: Departamento de Botânica, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil. Electronic address: mmrossi@usp.br.
authors.forename: Magdalena
authors.initials: M
authors.lastname: Rossi
mesh_terms: D002265:Carboxylic Ester Hydrolases / Q000096:biosynthesis* / Q000235:genetics; D002734:Chlorophyll / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D015971:Gene Expression Regulation, Enzymologic / Q000502:physiology*; D018506:Gene Expression Regulation, Plant / Q000502:physiology*; D018745:Genome, Plant / Q000502:physiology*; D018551:Solanum lycopersicum / Q000201:enzymology* / Q000235:genetics; D010940:Plant Proteins / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D010940:Plant Proteins; D002734:Chlorophyll; D002265:Carboxylic Ester Hydrolases; C019875:chlorophyllase
keywords: Chlorophyllase; Pheophytinase; Ripening; Senescence; Tomato