engleski

Auxins in stress response of Brassicaceae plants

One of the major challenges in modern agriculture is overcoming the problem of reduced crop yield due the presence of abiotic stressors. Salinity stress combines two different stress stimuli: toxic effect of sodium and chloride ions and osmotic stress due the occurring dehydration. Plants respond to environmental triggers by complex hormonal crosstalk. In order to investigate the role of one of the major growth promoting substances, indole-3-acetic acid (IAA), different Brassica cultivars: Chinese cabbage (B. rapa ssp. pekinensis), white cabbage (B. oleracea var. capitata) and kale (B. oleracea var. acephala) were exposed to short term 24 h salinity stress (50-200 mM NaCl). Phytohormonal profiling revealed altered levels of stress hormones as well shift in auxins homeostasis which was the most prominent in the most sensitive Chinese cabbage. Presence of salt stressor resulted in higher biosynthetic rate of IAA via activation of indole-3-acetamide pathway. In parallel, the amount of IAA irreversible catabolic forms: 2- oxoindole-3-acetic acid (oxIAA) and indole-3- acetyl-L-glutamate (IAA-Glu) was increased upon salinity too. Higher gene expression levels of auxin-amidohydrolases showed contribution of reversible conjugation process of auxin homeostasis to salinity as well. Beside the perturbations in auxin metabolom, changes in IAA distribution in root were achieved using the A. thaliana DR5rev::GFP auxin reporter lines. Accumulation of GFP signal in vivo and consequently difference in IAA pattern upon 100 mM sodium chloride and 200 mM mannitol treatment was observed by confocal microscope.

abiotic stress ; Brassicaceae ; auxins ; A. thaliana DR5rev::GFP auxin reporter lines

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