Probable serine/threonine kinase that functions as a positive regulator of plant immunity. May be involved in the regulation of pattern-triggered immunity (PTI). Does not seem to be involved in responses to brassinosteroid (BR) signaling. ATP + L-seryl-[protein] = ADP + H(+) + O-phospho-L-seryl-[protein] ATP + L-threonyl-[protein] = ADP + H(+) + O-phospho-L-threonyl-[protein] Induced by treatment with the elicitors chitin or fagellin22 (flg22). Plants silencing BSK1-2 exhibit compromised responses to chitin- or flg22-triggered immunity and resistance to Magnaporthe oryzae. Belongs to the protein kinase superfamily. Ser/Thr protein kinase family.