ABSTRACT
Volatile organic compounds (VOCs) are expected to have an important role in plant adaptation to high temperatures. The impacts of increasing night-time temperature on daytime terpenoid emissions and related gene expression in silver birch (Betula pendula) and European aspen (Populus tremula) clones were studied. The plants were grown under five different night-time temperatures (6, 10, 14, 18, and 22 degrees C) while daytime temperature was kept at a constant 22 degrees C. VOC emissions were collected during the daytime and analysed by gas chromatography-mass spectrometry (GC-MS). In birch, emissions per leaf area of the C11 homoterpene 4,8-dimethy1-nona-1,3,7-triene (DMNT) and several sesquiterpenes were consistently increased with increasing night-time temperature. Total sesquiterpene (SQT) emissions showed an increase at higher temperatures. In aspen, emissions of DMNT and beta-ocimene increased from 6 degrees C to 14 degrees C, while several other monoterpenes and the SQTs (Z,E)-alpha-farnesene and (E,E)-alpha-farnesene increased up to 18 degrees C. Total monoterpene and sesquiterpene emission peaked at 18 degrees C, whereas isoprene emissions decreased at 22 degrees C. Leaf area increased across the temperature range of 6-22 degrees C by 32% in birch and by 59% in aspen. Specific leaf area (SLA) was also increased in both species. The genetic regulation of VOC emissions seems to be very complex, as indicated by several inverse relationships between emission profiles and expression of several regulatory genes (DXR, DXS, and IPP). The study indicates that increasing night temperature may strongly affect the quantity and quality of daytime VOC emissions of northern deciduous trees.
Subject(s)
Betula/metabolism , Populus/metabolism , Temperature , Terpenes/metabolism , Alkenes/metabolism , Betula/genetics , Butadienes/metabolism , Gas Chromatography-Mass Spectrometry , Hemiterpenes/metabolism , Monoterpenes/metabolism , Pentanes/metabolism , Polymerase Chain Reaction , Populus/genetics , Sesquiterpenes/metabolism , Volatile Organic Compounds/metabolism , VolatilizationABSTRACT
⢠Expression of all known and newly found pathogenesis-related PR-10 proteins (PR-10a, b, c, d, e) was analysed from Cu-sensitive and -tolerant birch clones to find out whether they follow the same expression pattern. The relationship of PR-10 proteins, particularly PR-10c, to oxidative stress caused by metals or ozone was studied in tolerant and sensitive birch clones to find out possible linkages to tolerance. ⢠Antibody developed to PR-10c was used in Western blot analysis. Other PR-10 proteins were studied with two-dimensional electrophoresis and mass spectrometry. Metal-sensitive yeasts were transformed with PR-10c. ⢠Two new members of PR-10 family, PR-10d and PR-10e, were found. Various PR-10 proteins showed different expression patterns. The amount of PR-10c increased with increasing soil metal concentrations but was, in general, more prominent in Cu-sensitive than in Cu-tolerant clones. PR-10c did not alter metal tolerance in metal-sensitive yeasts. ⢠The PR-10c protein appears not to confer metal- or ozone-tolerance in birch. However, this does not exclude the possibility that it is involved in the tolerance or sensitivity mechanism in an indirect manner.
