Differential expression of acetohydroxyacid synthase genes in sunflower plantlets and its response to imazapyr herbicide

BRECCIA, G.; VEGA, T.; FELITTI, S.A.; PICARDI, L.; NESTARES, G.

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2013 vol. 208 p. 28 - 33

0168-9452

Acetohydroxyacid synthase (AHAS) catalyzes the first reaction in branch chain amino acidsbiosynthesis. This enzyme is of substantial importance because it is the target of severalherbicides, including all members of the sulfonylurea and imidazolinone families. Little is knownabout the expression of the three acetohydroxyacid synthase genes (ahas1, ahas2 and ahas3) insunflower (Helianthus annuus L.). The aim of this work was to evaluate ahas gene expression andAHAS activity in different tissues of sunflower plantlets. Three genotypes differing inimidazolinone resistance were evaluated. AHAS activity and transcript levels were higher inleaves than in roots. All three gene transcripts were detected with the highest expression of ahas1exhibited in leaf tissue. Similar transcript levels were found for ahas1 and ahas2 in roots. Theahas3 transcript was the less abundant in both tissues. Transcription of each ahas gene seemed tobe subjected to a different regulatory mechanism. Herbicide treatment triggered significantchanges in AHAS expression. A tissue-specific response was also observed. AHAS activity washighly inhibited in the susceptible genotype. Overall, steady-state levels of AHAS expression werenot significantly different among genotypes. This is the first report of quantitative measure of ahas transcripts in sunflower and of AHAS activity in leaf and root tissues of genotypes differing forherbicide resistance and its response to herbicide treatment. These findings enhance ourunderstanding of AHAS expression in sunflower and will serve as a base for further studies.