A comprehensive analysis of the combined effects of high light and high temperature stresses on gene expression in sunflower.
OBJECTIVE
Although high light (HL) and high temperature (HT) stresses have been extensively investigated, a global analysis of their combined effects on the transcriptome of any plant species has not yet been described. Sunflower is an agronomically important oil crop frequently subjected to these stress factors. Because results in model plants may not always translate well to crop plants, responses of sunflower (Helianthus annuus) to HL, HT and a combination of both stresses were analysed by profiling gene expression in leaves and immature seeds.


METHODS
Plants were grown in HL (600 microE m(-2) s(-1)), HT (35 degrees C) and a combination of HL and HT (HL + HT), and gene expression in leaves and immature seeds was profiled using cDNA microarrays containing more than 8000 putative unigenes.


RESULTS
Using two-way analysis of variance, 105, 55 and 129 cDNA clones were identified showing significant changes in steady-state transcript levels, across the two tissues, in response to HL, HT and HL + HT, respectively. A significant number of these transcripts were found to be specific to each stress. Comparing gene expression profiles between leaves and immature seeds revealed that 89, 113 and 186 cDNA clones can be considered as differentially expressed in response to HL, HT and HL + HT, respectively. More than half of the cDNA clones showing significant differences between embryo and leaf tissues in response to HL + HT were specific to this stress. Significant differences between leaves and seeds shared by all three stress treatments were observed for only eight genes.


CONCLUSIONS
Taken together, these results indicate that vegetative and reproductive tissues employ different transcriptome responses to these stress treatments. Careful examination of the putative functions of these genes revealed novel and specific responses. The potential roles of many of the differentially expressed genes in stress tolerance are mentioned and discussed.
Hewezi
Tarek
T
Laboratoire de Biotechnologies et Amélioration des Plantes (BAP), INP-ENSAT, Pôle de Biotechnologies Végétales, IFR 40, 18 Chemin de Borde Rouge, BP107, Auzeville, 31326 Castanet Tolosan, France. hewezi@iastate.edu
Léger
Mathieu
M
Gentzbittel
Laurent
L
D020869:Gene Expression Profiling / Q000379:methods*; D018506:Gene Expression Regulation, Plant / Q000528:radiation effects; D006368:Helianthus / Q000235:genetics*; D008027:Light; D020411:Oligonucleotide Array Sequence Analysis; D010940:Plant Proteins / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012639:Seeds / Q000235:genetics; D013696:Temperature
D010940:Plant Proteins