Fig. 3

Diversity in the response to partial to complete submergence in rice. Submergence tolerant rice, possessing the SUB1 region from the landrace FR13A, limits underwater elongation growth via a quiescence strategy. SUB1A is the ethylene responsive factor (ERF) that controls this response. Submergence intolerant lowland rice lacks submergence-induced SUB1A and elongates when trapped underwater. The increase in growth to enable escape observed in these varieties resembles that of deepwater and floating rice. These types, however, have the capacity to dramatically extend internodes that are caught underwater as long as about 25% of the aerial tissue remains above water. The SNORKEL ERFs SK1 and SK2, present in deepwater and floating rice, contribute to the GA-mediated elongation growth that enables this remarkable extension of submerged shoots. The phytohormone ethylene triggers the expression of SUB1A and the SNORKEL ERFs, although they drive antithetical growth responses. SUB1 and SKs are members of the group VII ERF subfamily of transcription factors.