Ethylene Biosynthesis Is Promoted by Very-Long-Chain Fatty Acids during Lysigenous Aerenchyma Formation in Rice Roots
Ethylene Biosynthesis Is Promoted by Very-Long-Chain Fatty Acids during Lysigenous Aerenchyma Formation in Rice Roots
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DOI：
10.1104/pp.15.00106
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发表时间：
2015-09-01
期刊：
影响因子：
7.4
通讯作者：
Nakazono, Mikio
中科院分区：
文献类型：
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作者：
Yamauchi, Takaki;Shiono, Katsuhiro;Nakazono, Mikio
在水稻（Oryza sativa）根系中，由细胞程序性死亡和皮层细胞裂解产生的溶解性通气组织在有氧条件下组成，在缺氧条件下进一步诱导其形成。乙烯参与了通气组织形成的诱导。减少茎数1 （rcn1）是一种水稻突变体，其编码atp结合盒转运体rcn1 /OsABCG5的基因存在缺陷。在这里，我们报道了在停滞的缺氧营养液中生长的rcn1根（即在停滞的条件下，模仿水淹土壤的缺氧条件），气孔形成的诱导减少。1-氨基环丙烷-1-羧酸合成酶（ACS）是乙烯生物合成的关键酶。停滞条件几乎不能诱导rcn1根中ACS1的表达，导致根中乙烯产量低。24,26和28个碳的饱和长链脂肪酸（VLCFAs）在rcn1根中的积累减少。外源供应的VLCFA（26个碳）增加了ACS1的表达水平，并诱导rcn1根中的通气组织形成。此外，在编码脂肪酸延长酶的基因CUT1- like （CUT1L，与拟南芥编码表皮蜡质所需的基因CUT1同源）基因被沉默的水稻品系中，ACS1的表达和气孔形成都减少了。有趣的是，在停滞条件下，ACS1、CUT1L和RCN1/OsABCG5的表达主要在根的外侧被诱导。这些结果表明，在缺氧条件下，VLCFAs通过促进根外部1-氨基环丙烷-1-羧酸的生物合成来增加乙烯产量，从而诱导根皮层形成通气组织。
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.