Changes in hormonal status of winter wheat (Triticum aestivum L.) and spelt wheat (Triticum spelta L.) after heat stress and in recovery period

The dynamics and distribution of endogenous cytokinins (CKs), gibberellic (GA3) and salicylic (SA) acids in wheat (Triticum aestivum L., ‘Podolyanka’) and spelt wheat (Triticum spelta L., ‘Frankenkorn’) plants was analyzed using HPLC–MS. Fourteen-day-old plants that had been exposed to short-term heat stress (+ 40 °C, 2 h) and 21-day-old plants after recovery were studied. Heat stress induced rapid changes, both specific and nonspecific, in hormone levels and distribution. The level of GA3 decreased in the shoots and roots of both winter and spelt wheat. A reduction in SA content was observed in wheat, while an increase was observed in spelt. The pool of CKs significantly increased in wheat, while in spelt—it decreased more than twofold. After recovery, an increase in GA3 content occurred in both species, but not to the levels measured in control plants. More active accumulation of GA3 was observed in the roots. The content of SA in the shoots of wheat continued to decrease, while in the roots it increased. In spelt, hormone concentration decreased, but it remained higher than in 21-day-old control plants. In shoots of both plants the pool of CKs decreased, while in wheat roots it did not change, and in spelt roots it decreased. The total CKs content in stressed wheat plants was twice as high as in spelt. In general, we established significant hormonal fluctuations, which indicate a direct involvement of endogenous cytokinins, gibberellic and salicylic acids in wheat and spelt response to heat stress. Screening of stress-resistant genotypes of cereals may benefit from quantitation of CKs, GA3, and SA.