Biomaterial Database

Differential regulation of polygalacturonase and pectin methylesterase gene expression during and after heat stress in ripening tomato (Lycopersicon esculentum Mill.) fruits. 1995

V Kagan-Zur, and D M Tieman, and S J Marlow, and A K Handa

Institute for Applied Research, Ben-Gurion University of the Negev, Beer-Sheva, Israel.

The effects of extended heat stress on polygalacturonase (PG; EC 3.2.1.15) and pectin methylesterase (PME; EC 3.1.1.11) gene expression at mRNA, protein and activity levels in ripening tomato fruits were investigated. Steady state levels of PG mRNA declined at temperatures of 27 degrees C and above, and a marked reduction in PG protein and activity was observed at temperatures of 32 degrees C and above. Exogenous ethylene treatment did not reverse heat stress-induced inhibition of PG gene expression. Transfer of heat-stressed fruits to 20 degrees C partly restored PG mRNA accumulation, but the rate of PG mRNA accumulation declined exponentially with duration of heat stress. Heat stress-induced inhibition of PME mRNA accumulation was recoverable even after 14 days of heat stress. In fruits held at 34 degrees C, both PG and PME protein and activity continued to accumulate for about 4 days, but thereafter PG protein and activity declined while little change was observed in PME protein and activity. In spite of increases in mRNA levels of both PG and PME during the recovery of heat-stressed fruit at 20 degrees C, levels of PG protein and activity declined in fruits heat-stressed for four or more days while PME protein and activity levels remained unchanged. Collectively, these data suggest that PG gene expression is being gradually and irreversibly shut off during heat stress, while PME gene expression is much less sensitive to heat stress.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D011096	Polygalacturonase	A cell wall-degrading enzyme found in microorganisms and higher plants. It catalyzes the random hydrolysis of 1,4-alpha-D-galactosiduronic linkages in pectate and other galacturonans. EC 3.2.1.15.	Pectin Depolymerase,Pectinase,Endopolygalacturonase,Depolymerase, Pectin
D002265	Carboxylic Ester Hydrolases	Enzymes which catalyze the hydrolysis of carboxylic acid esters with the formation of an alcohol and a carboxylic acid anion.	Carboxylesterases,Ester Hydrolases, Carboxylic,Hydrolases, Carboxylic Ester
D005030	Ethylenes	Derivatives of ethylene, a simple organic gas of biological origin with many industrial and biological use.
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D013997	Time Factors	Elements of limited time intervals, contributing to particular results or situations.	Time Series,Factor, Time,Time Factor
D015971	Gene Expression Regulation, Enzymologic	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in enzyme synthesis.	Enzymologic Gene Expression Regulation,Regulation of Gene Expression, Enzymologic,Regulation, Gene Expression, Enzymologic
D018506	Gene Expression Regulation, Plant	Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action in plants.	Plant Gene Expression Regulation,Regulation of Gene Expression, Plant,Regulation, Gene Expression, Plant
D018551	Solanum lycopersicum	A plant species of the family SOLANACEAE, native of South America, widely cultivated for their edible, fleshy, usually red fruit.	Lycopersicon esculentum,Tomatoes,Tomato