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Competition between isoprene emission and pigment synthesis during leaf development in aspen
Author(s) -
RASULOV BAHTIJOR,
BICHELE IRINA,
LAISK AGU,
NIINEMETS ÜLO
Publication year - 2014
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12190
Subject(s) - isoprene , prenyltransferase , photosynthesis , pigment , chemistry , photosynthetic pigment , terpenoid , botany , biology , stereochemistry , biosynthesis , biochemistry , organic chemistry , enzyme , copolymer , polymer
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 P opulus 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 M ichaelis– M enten constant ( K m ) values obtained were 265 nmol m −2 (20 μ m ) for DMADP ‐consuming prenyltransferase reactions and 2560 nmol m −2 (190 μ m ) 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.