title: Correlation of leaf senescence and gene expression/activities of chlorophyll degradation enzymes in harvested Chinese flowering cabbage (Brassica rapa var. parachinensis).
abstract: Chinese flowering cabbage is one of the main leafy vegetables produced in China. They have a rapid leaf yellowing due to chlorophyll degradation after harvest that limits their marketing. In the present study, leaf senescence of the cabbages was manipulated by ethylene and 6-benzyl aminopurine (6-BA) treatment to investigate the correlation of leaf senescence and chlorophyll degradation related to gene expression/activities in the darkness. The patterns of several senescence associated markers, including a typical marker, the expression of senescence-associated gene SAG(12), demonstrated that ethylene accelerated leaf senescence of the cabbages, while 6-BA retarded this progress. Similar to the trends of BrSAG(12) gene expression, strong activation in the expression of three chlorophyll degradation related genes, pheophytinase (BrPPH), pheophorbide a oxygenase (BrPAO) and red chlorophyll catabolite reductase (BrRCCR), was detected in ethylene treated and control leaves during the incubation, while no evident increase was recorded in 6-BA treated leaves. The overall dynamics of Mg-dechelatase activities in all treatments displayed increasing trends during the senescence process, and a delayed increase in the activities was observed for 6-BA treated leaves. However, chlorophyllase activity as well as the expression of BrChlase1 and BrChlase2 decreased with the incubation in all treatments. Taken together, the expression of BrPPH, BrPAO and BrRCCR, and the activity of Mg-dechelatase was closely associated with the chlorophyll degradation during the leaf senescence process in harvested Chinese flowering cabbages under dark conditions.
authors.affiliation: College of Life Sciences, South China Agricultural University, Guangzhou 510642, China.
authors.forename: Xuelian
authors.initials: X
authors.lastname: Zhang
authors.forename: Zhaoqi
authors.initials: Z
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Li
authors.forename: Lajie
authors.initials: L
authors.lastname: Wu
authors.forename: Jiongye
authors.initials: J
authors.lastname: Guo
authors.forename: Lvqing
authors.initials: L
authors.lastname: Ouyang
authors.forename: Yinyin
authors.initials: Y
authors.lastname: Xia
authors.forename: Xuemei
authors.initials: X
authors.lastname: Huang
authors.forename: Xuequn
authors.initials: X
authors.lastname: Pang
mesh_terms: D001593:Benzyl Compounds; D015415:Biomarkers / Q000378:metabolism; D029741:Brassica rapa / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D002265:Carboxylic Ester Hydrolases / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism*; D004798:Enzymes / Q000378:metabolism; D005030:Ethylenes / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007701:Kinetin / Q000494:pharmacology*; D010088:Oxidoreductases / Q000378:metabolism; D010105:Oxygenases / Q000378:metabolism; D010937:Plant Growth Regulators / Q000494:pharmacology*; D018515:Plant Leaves / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D011687:Purines
chemical_list: D001593:Benzyl Compounds; D015415:Biomarkers; D004798:Enzymes; D005030:Ethylenes; D010937:Plant Growth Regulators; D011687:Purines; C421174:magnesium dechelatase; D002734:Chlorophyll; C036216:ethylene; D010088:Oxidoreductases; D010105:Oxygenases; C112915:pheide a oxygenase; D002265:Carboxylic Ester Hydrolases; C019875:chlorophyllase; C480551:benzylaminopurine; D007701:Kinetin