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Xylem‐transported glucose as an additional carbon source for leaf isoprene formation in Quercus robur
Author(s) -
Kreuzwieser Jürgen,
Graus Martin,
Wisthaler Armin,
Hansel Armin,
Rennenberg Heinz,
Schnitzler JörgPeter
Publication year - 2002
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1046/j.1469-8137.2002.00516.x
Subject(s) - isoprene , xylem , chemistry , photosynthesis , quercus robur , botany , carbon fibers , biochemistry , biology , organic chemistry , materials science , composite number , copolymer , composite material , polymer
Summary• In order to test whether xylem‐transported carbohydrates are a potential source for isoprene biosynthesis, [U‐ 13C]‐labelled α‐d‐glucose was fed via cut ends of stems into the xylem ofQuercus roburseedlings and the incorporation of13C into isoprene emitted was studied. Emission of13 C‐labelled isoprene was monitored in real time by proton‐transfer‐reaction mass spectrometry (PTR‐MS). • A rapid incorporation of 13C from xylem‐fed glucose into single (mass 70) and double (mass 71)13C‐labelled isoprene molecules was observed after a lag phase of approx. 5–10 min. This incorporation was temperature dependent and was highest (up to 13%13 C of total carbon emitted as isoprene) at the temperature optimum of isoprene emission (40–42°C), when net assimilation was strongly reduced. • Fast dark‐to‐light transitions led to a strong single or double 13C‐labelling of isoprene from xylem‐fed [U‐13C]glucose. During a period of 10–15 min up to 86% of all isoprene molecules became single or double13C‐labelled, resulting in a13 C‐portion of up to 27% of total carbon emitted as isoprene. • The results provide evidence that xylem‐transported glucose or its degradation products can potentially be used as additional precursors for isoprene biosynthesis and that this carbon source becomes more important under conditions of limited photosynthesis.