Poster: Oxidative Stress

Abs # 117: Isolation and analysis of an ozone-sensitive Arabidopsis mutant oji1

Presenter:	Kanna, Machi , kanna.machi@nies.go.jp
Authors	Kanna, Machi  (A)   Kubo, Akihiro  (B)   Tamaoki, Masanori  (B)   Nakajima, nobuyoshi  (B)   Saji, Hikaru  (B)   Aono, Mitsuko  (B)
Affiliations:	(A): Tokyo Institute of Technology (B): National Insitiute for Environmental Studies

Troposphelic ozone, which is the major component of photochemical oxidant, damages plants severely. However, molecular mechanisms underlying this damage are not understood thoroughly. To dissect these mechanisms, we screened ozone sensitive mutants from Arabidopsis T-DNA tagging lines by visible injury. Ethylene is one of the plant hormones and a trigger of cell death. One of these mutants showed higher ethylene emission during ozone exposure than wild type (Ws-2). Since jasmonate is known to be involved in plant defense responses, we examined methyl-jasmonate (MeJA) sensitivity of this mutant by the inhibition of root elongation. Sensitivity to MeJA of the mutant is lower than that of Ws-2. Therefore, this mutant was named oji1 (ozone-sensitive, jasmonate-insensitive 1). Low concentration of MeJA treatment decreased ethylene emission and ion leakage during ozone exposure in wild type, but not in oji1. However, high concentration MeJA decreased ethylene emission and ion leakage both in wild type and in oji1. We showed that MeJA suppressed ethylene emission and that jasmonate sensitivity of oji1 decreased but not completely lost.These results suggest that the ozone sensitivity of oji1 might be caused by ethylene overemission in consequence of decreased jasmonate insensitivity. Information of the location of oji1 on chromosome obtained by using SSLP and CAPS markers indicated that this mutation is different from jar1, which is known as a jasmonate insensitive and ozone sensitive mutant.