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Plant Cell Environ

Title:		Competition between isoprene emission and pigment synthesis during leaf development in aspen
Author(s):		Rasulov B; Bichele I; Laisk A; Niinemets U;
Address:		"Institute of Molecular and Cell Biology, University of Tartu, Riia 23, Tartu, 51010, Estonia"
Journal Title:		Plant Cell Environ
Year:		2014
Volume:		20130917
Issue:		3
Page Number:		724 - 741
DOI:		10.1111/pce.12190
ISSN/ISBN:		1365-3040 (Electronic) 0140-7791 (Print) 0140-7791 (Linking)
Abstract:		"In growing leaves, lack of isoprene synthase (IspS) is considered responsible for delayed isoprene emission, but competition for dimethylallyl diphosphate (DMADP), the substrate for both isoprene synthesis and prenyltransferase reactions in photosynthetic pigment and phytohormone synthesis, can also play a role. We used a kinetic approach based on post-illumination isoprene decay and modelling DMADP consumption to estimate in vivo kinetic characteristics of IspS and prenyltransferase reactions, and to determine the share of DMADP use by different processes through leaf development in Populus tremula. Pigment synthesis rate was also estimated from pigment accumulation data and distribution of DMADP use from isoprene emission changes due to alendronate, a selective inhibitor of prenyltransferases. Development of photosynthetic activity and pigment synthesis occurred with the greatest rate in 1- to 5-day-old leaves when isoprene emission was absent. Isoprene emission commenced on days 5 and 6 and increased simultaneously with slowing down of pigment synthesis. In vivo Michaelis-Menten constant (Km ) values obtained were 265 nmol m(-2) (20 mum) for DMADP-consuming prenyltransferase reactions and 2560 nmol m(-2) (190 mum) for IspS. Thus, despite decelerating pigment synthesis reactions in maturing leaves, isoprene emission in young leaves was limited by both IspS activity and competition for DMADP by prenyltransferase reactions"
Keywords:		Alendronate/pharmacology Biomass Butadienes/*metabolism Carbon Dioxide/metabolism Cell Respiration/drug effects Computer Simulation Hemiterpenes/*metabolism Kinetics Organophosphorus Compounds/metabolism Pentanes/*metabolism Photosynthesis/drug effects Pi;
Notes:		"MedlineRasulov, Bahtijor Bichele, Irina Laisk, Agu Niinemets, Ulo eng 322603/ERC_/European Research Council/International Research Support, Non-U.S. Gov't 2013/09/17 Plant Cell Environ. 2014 Mar; 37(3):724-41. doi: 10.1111/pce.12190. Epub 2013 Sep 17"