engleski

PHYTOHORMONE AUXIN: A MEDIATOR OF PLANT STRESS RESPONSE

In the last decades the effect of environmental changes (abiotic stress) and diverse pathogens (biotic stress) on agricultural production challenges many scientists in the field of plant biology, agronomy, ecology, and biotechnology to investigate and understand mechanisms underlying plant stress responses and tolerance. Phytohormones are signalling molecules crucial for the ability of plants to adapt to unfavourable environmental changes by mediating wide range adaptive responses, such as growth, development, nutrient allocation, and source/sink transitions. In recent years emerging evidence suggests that phytohormone auxin (indole-acetic acid, IAA) acts as a common player in the majority of hormonal interactions in stress conditions, mostly interacting with the stress hormones: salicylic acid (SA), abscisic acid (ABA), and jasmonic acid (JA). Auxin levels and the regulation of auxin homeostasis as a mechanism of plant stress response have been investigated in cabbage (Brassica rapa L. ssp. pekinensis) upon biotic and abiotic stresses. It was shown that stress conditions caused perturbation of IAA levels with a tendency of increasing the IAA conjugate level in comparison to free IAA. Correlations of IAA and stress hormones were discussed. Gene expression experiments showed changes in transcript level of enzymes involved in auxin homeostasis upon stress conditions. Specifically, auxin amidohydrolases, enzymes involved in auxin homeostasis have been investigated at biochemical and structural level. The results implicated an important role of auxin and interactions with other stress hormones in the plant stress response.

auxin; abiotic stress; phytohormone homeostasis; Brassica rapa

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