Expression profiles of phytosulfokine signalling components in sorghum drought stress-adaptive response.

Phytosulfokine (PSK) signalling promotes drought adaptation in drought-sensitive plants. However, whether naturally drought-tolerant plants deploy PSK signalling in drought is unknown. We are using two sorghum varieties with different drought response phenotypes to investigate tolerance mechanisms. We show that PSK signalling components have high constitutive expression before stress in the drought-tolerant variety. In contrast, gene expression is low in the drought-sensitive variety and is induced after drought exposure. Ability of the drought-tolerant sorghum variety to maintain elevated PSK signalling under optimal water availability suggests that genetic and physiological factors driving drought tolerance may be linked to elevated constitutive PSK signalling.