Acetohydroxyacid synthase activity and transcripts profiling reveal tissuespecific regulation of ahas genes in sunflower

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

PLANT SCIENCE

ELSEVIER IRELAND LTD

Lugar: Amsterdam; Año: 2014 vol. 224 p. 144 - 150

0168-9452

Acetohydroxyacid synthase (AHAS) is the target site of several herbicides andcatalyzes the first step in the biosynthesis of branched chain amino acid. Three genescoding for AHAS catalytic subunit (ahas1, ahas2 and ahas3) have been reported forsunflower. The aim of this work was to study the expression pattern of ahas genes familyand AHAS activity in sunflower. Different organs (leaves, shoots, roots, flowers andembryos) were evaluated at several developmental stages. The transcriptional profile wasstudied through RT-qPCR. In leaves the highest expression was ahas1, where all theinduced and natural gene mutations conferring herbicide resistance were found, whereas themaximal expression of ahas2 and ahas3 occurred in immature flowers and embryos. Apositive correlation was found between ahas2 and ahas3 transcript amounts in reproductivetissues. The highest AHAS activity was found in leaves and immature embryos, and apositive correlation between ahas genes and AHAS activity was detected in roots, flowers,and embryos but not in green tissues. Our results show that differences in ahas genesexpression are tissue-specific and temporally regulated. Moreover, the conservation ofmultiple AHAS isoforms in sunflower seems to result from different expressionrequirements controlled by tissue-specific regulatory mechanisms at differentdevelopmental stages.