ABSTRACT Rapid climate change greatly decreases global wheat yield, making further breeding of it a necessity to fulfil the also increasing dietary need of the population. For this, a wild relative of wheat, the goatgrass Aegilops biuncialis Vis. 382 ( Ae.b. 382) is a suitable candidate, in light of its better drought tolerance compared to wheat. Polyamines (PAs) are low molecular weight defensive molecules with a prominent role in abiotic stress reactions. This study investigated the role of polyamines in the adaptive response of Ae.b. 382 to PEG‐induced osmotic stress by investigating the effects of exogenous polyamines and their biosynthesis inhibitors on root architecture, polyamine levels and related gene expression profiles. The two‐day‐long 33 mM PEG treatment induced strong physiological changes, resulting in alterations in root robusticity. The simultaneous application of PA inhibitors strongly reduced root fresh weight (FW), length and surface, disrupting the process of adaptive thickening. However, additions of exogenous spermidine, spermine or a combined PA mix were able to counteract the negative effects of the inhibitors or activate defensive measures. The results on polyamine content and gene expressional profiling confirmed our hypothesis that polyamines are one of the key compounds in drought stress adaptation responses of Ae.b. 382. Also, the complex, bilateral regulation of polyamine metabolism and transport between root and shoot is important for fine‐tuning of balanced defence and signalling mechanisms.
Jobbágy et al. (Sun,) studied this question.