The sucrose non-fermenting-1-related protein kinase 2 family (SnRK2s) is key molecules that unify different abiotic stress signals in plants. Therefore, research on the function of the SnRK2s is meaningful to fully understand the mechanisms of abiotic stress responses in plants. However, the functions of two rice SnRK2s, osmotic stress/ABA-activated protein kinase 1 (SAPK1) and SAPK2, have been unknown. No data on salt tolerance in SAPK gene knockouts in rice have been presented.
Researchers from Xishuangbanna Tropical Botanical Garden (XTBG) determined the functions of SnRK2s in response to salt stress using sapk1, sapk2 and sapk1/2 loss-of-function mutants (generated using the CRISPR/Cas9 system) and plants overexpressing these proteins (SAPK1-OE and SAPK2-OE).
The researchers analyzed the expression profiles of SAPK1 and SAPK2 and found that their expression levels were strongly induced by drought, NaCl, and polyethylene glycol (PEG) treatment, but not by abscisic acid (ABA).
The SAPK2 expression level was highest in the leaves, followed by the roots; whereas the SAPK1 expression level was highest in the roots, followed by the leaves.
The researchers localized both proteins to the nucleus and cytoplasm. They also analyzed the effects of SAPK1 and SAPK2 on osmotic stress, ROS detoxification and Na+, K+ accumulation.
The results suggest that SAPK1 and SAPK2 may function collaboratively as positive regulators of salt stress tolerance at the germination and seedling stages. Further study suggested that SAPK1 and SAPK2 affect osmotic stress and ROS detoxification in the salt stress response.
The study entitled “The sucrose non-fermenting-1-related protein kinases SAPK1 and SAPK2 function collaboratively as positive regulators of salt stress tolerance in rice” has been published in BMC Plant Biology.
YU Diqiu, Ph.D Principal Investigator
Key Laboratory of Tropical Plant Resources and Sustainable Use, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun 666303, Yunnan, China