ANTAGONISTIC EFFECTS OF ABSCISIC-ACID AND JASMONATES ON SALT STRESS-INDUCIBLE TRANSCRIPTS IN RICE ROOTS

Abscisic acid (ABA) and jasmonates have been implicated in responses t o water deficit and wounding. We compared the molecular and physiologi cal effects of jasmonic acid (JA) (less than or equal to 10 mu M), ABA , and salt stress in roots of rice. JA markedly induced a cationic per oxidase, two novel 32- and 28-kD proteins, acidic PR-1 and PR-10 patho genesis-related proteins, and the salt stress-responsive SalT protein in roots. Most JA-responsive proteins (JIPs) from roots also accumulat ed when plants were subjected to salt stress. None of the JIPs accumul ated when plants were treated with ABA. JA did not induce an ABA-respo nsive group 3 late-embryogenesis abundant (LEA) protein. Salt stress a nd ABA but not JA induced oslea3 transcript accumulation. By contrast, JA, ABA, and salt stress induced transcript accumulation of salT and osdrr, which encodes a rice PR-10 protein. However, ABA also negativel y affected salT transcript accumulation, whereas JA negatively affecte d ABA-induced oslea3 transcript levels. Endogenous root ABA and methyl jasmonate levels showed a differential increase with the dose and the duration of salt stress. The results indicate that ABA and jasmonates antagonistically regulated the expression of salt stress-inducible pr oteins associated with water deficit or defense responses.