biologia plantarum

Biologia plantarum 61:385-388, 2017 | DOI: 10.1007/s10535-016-0676-5

Inhibition of putrescine biosynthesis enhanced salt stress sensitivity and decreased spermidine content in rice seedlings

A. Yamamoto^1,2,*, I.-S. Shim^1,3, S. Fujihara^1,4

¹ Institute of Applied Biochemistry, University of Tsukuba, Tsukuba, Ibaraki, Japan

² Faculty of Agriculture, University of Miyazaki, Miyazaki, Japan

³ Department of Environmental Horticulture, University of Seoul, Seoul, Korea

⁴ National Agriculture Research Center, Tsukuba, Ibaraki, Japan

The effect of polyamine biosynthesis inhibitors on the salt stress response of rice seedlings was investigated. For this, DL-α-difluoromethylarginine (DFMA) and DL-α-difluoromethylornithine (DFMO), two competitive inhibitors of arginine decarboxylase (ADC) and ornithine decarboxylase (ODC), were used. The ADC and ODC are rate-limiting enzymes involved in synthesis of putrescine. The effective quantum yield of photosynthetic energy conversion (Φ_PSII) decreased with the salt stress, and this decrease was highly significant in the treatments with DFMA and DFMO. Interestingly, addition of exogenous putrescine reduced the decline of Φ_PSII. Putrescine content strongly decreased after one day of the inhibitor treatment. Although the content of spermidine (converted from putrescine) also showed an initial decrease in response to the inhibitors, it recovered to a similar level to that in the control after 3 d of treatment. Under the salt stress, the effect of the inhibitors on the different compounds was similar. Moreover, the addition of exogenous putrescine partially suppressed the decrease in spermidine and spermine content. A positive correlation between the spermidine and spermine content and the Φ_PSII was observed. The results suggest that, under salt stress, a decrease in polyamine biosynthesis and/or polyamine content has a strong negative effect on leaves and increases salt stress sensitivity.

Keywords: arginine decarboxylase; chlorophyll fluorescence; ornithine decarboxylase; polyamines; spermine

Subjects: putrescine; spermidine; spermine; chlorophyll a fluorescence; salt stress; rice

Received: January 13, 2016; Revised: May 1, 2016; Accepted: May 30, 2016; Published: June 1, 2017  Show citation