Yamauchi Takaki, Shiono Katsuhiro, Nagano Minoru, Fukazawa Aya, Ando Miho, Takamure Itsuro, Mori Hitoshi, Nishizawa Naoko K, Kawai-Yamada Maki, Tsutsumi Nobuhiro, Kato Kiyoaki, Nakazono Mikio
Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan (T.Y., A.F., H.M., Mik.N.);Department of Bioscience, Fukui Prefectural University, Eiheiji-cho, Yoshida, Fukui 910-1195, Japan (K.S.);Graduate School of Science and Engineering, Saitama University, Sakura-ku, Saitama 338-8570, Japan (Min.N., M.K.-Y.);Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan (M.A., N.K.N., N.T.);Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8589, Japan (I.T.);Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Ishikawa 921-8836, Japan (N.K.N.); andDepartment of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan (K.K.).
Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8601, Japan (T.Y., A.F., H.M., Mik.N.);Department of Bioscience, Fukui Prefectural University, Eiheiji-cho, Yoshida, Fukui 910-1195, Japan (K.S.);Graduate School of Science and Engineering, Saitama University, Sakura-ku, Saitama 338-8570, Japan (Min.N., M.K.-Y.);Graduate School of Agricultural and Life Sciences, University of Tokyo, Bunkyo, Tokyo 113-8657, Japan (M.A., N.K.N., N.T.);Graduate School of Agriculture, Hokkaido University, Kita-ku, Sapporo, Hokkaido 060-8589, Japan (I.T.);Research Institute for Bioresources and Biotechnology, Ishikawa Prefectural University, Ishikawa 921-8836, Japan (N.K.N.); andDepartment of Crop Science, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan (K.K.)
Plant Physiol. 2015 Sep;169(1):180-93. doi: 10.1104/pp.15.00106. Epub 2015 Jun 2.
In rice (Oryza sativa) roots, lysigenous aerenchyma, which is created by programmed cell death and lysis of cortical cells, is constitutively formed under aerobic conditions, and its formation is further induced under oxygen-deficient conditions. Ethylene is involved in the induction of aerenchyma formation. reduced culm number1 (rcn1) is a rice mutant in which the gene encoding the ATP-binding cassette transporter RCN1/OsABCG5 is defective. Here, we report that the induction of aerenchyma formation was reduced in roots of rcn1 grown in stagnant deoxygenated nutrient solution (i.e. under stagnant conditions, which mimic oxygen-deficient conditions in waterlogged soils). 1-Aminocyclopropane-1-carboxylic acid synthase (ACS) is a key enzyme in ethylene biosynthesis. Stagnant conditions hardly induced the expression of ACS1 in rcn1 roots, resulting in low ethylene production in the roots. Accumulation of saturated very-long-chain fatty acids (VLCFAs) of 24, 26, and 28 carbons was reduced in rcn1 roots. Exogenously supplied VLCFA (26 carbons) increased the expression level of ACS1 and induced aerenchyma formation in rcn1 roots. Moreover, in rice lines in which the gene encoding a fatty acid elongase, CUT1-LIKE (CUT1L; a homolog of the gene encoding Arabidopsis CUT1, which is required for cuticular wax production), was silenced, both ACS1 expression and aerenchyma formation were reduced. Interestingly, the expression of ACS1, CUT1L, and RCN1/OsABCG5 was induced predominantly in the outer part of roots under stagnant conditions. These results suggest that, in rice under oxygen-deficient conditions, VLCFAs increase ethylene production by promoting 1-aminocyclopropane-1-carboxylic acid biosynthesis in the outer part of roots, which, in turn, induces aerenchyma formation in the root cortex.
在水稻（Oryza sativa）根系中，溶生性通气组织由皮层细胞的程序性细胞死亡和裂解形成，在有氧条件下组成性形成，在缺氧条件下其形成进一步被诱导。乙烯参与通气组织形成的诱导过程。reduced culm number1（rcn1）是一种水稻突变体，其中编码ATP结合盒转运蛋白RCN1/OsABCG5的基因存在缺陷。在此，我们报道，在停滞的脱氧营养液中生长的rcn1根系（即在停滞条件下，模拟淹水土壤中的缺氧条件），通气组织形成的诱导作用减弱。1-氨基环丙烷-1-羧酸合酶（ACS）是乙烯生物合成中的关键酶。停滞条件几乎不会诱导rcn1根系中ACS1的表达，导致根系中乙烯产量较低。rcn1根系中碳链长度为24、26和28的饱和超长链脂肪酸（VLCFAs）的积累减少。外源供应VLCFA（碳链长度为26）可提高rcn1根系中ACS1的表达水平并诱导通气组织形成。此外，在编码脂肪酸延长酶CUT1-LIKE（CUT1L；与拟南芥中参与表皮蜡质产生的CUT1基因同源）的基因被沉默的水稻品系中，ACS1表达和通气组织形成均减少。有趣的是，在停滞条件下，ACS1、CUT1L和RCN1/OsABCG5的表达主要在根系外部被诱导。这些结果表明，在缺氧条件下的水稻中，VLCFAs通过促进根系外部1-氨基环丙烷-1-羧酸的生物合成来增加乙烯产量，进而诱导根皮层通气组织的形成。
