Lim Chae Woo, Han Sang-Wook, Hwang In Sun, Kim Dae Sung, Hwang Byung Kook, Lee Sung Chul
Department of Life Science (BK21 program), Chung-Ang University, Seoul 156-756, Republic of Korea These author contributed equally to this work.
Department of Integrative Plant Science, Chung-Ang University, Anseong 456-756, Republic of Korea These author contributed equally to this work.
Plant Cell Physiol. 2015 May;56(5):930-42. doi: 10.1093/pcp/pcv020. Epub 2015 Feb 4.
In plants, lipoxygenases (LOXs) are involved in various physiological processes, including defense responses to biotic and abiotic stresses. Our previous study had shown that the pepper 9-LOX gene, CaLOX1, plays a crucial role in cell death due to pathogen infection. Here, the function of CaLOX1 in response to osmotic, drought and high salinity stress was examined using CaLOX1-overexpressing (CaLOX1-OX) Arabidopsis plants. Changes in the temporal expression pattern of the CaLOX1 gene were observed when pepper leaves were treated with drought and high salinity, but not when treated with ABA, the primary hormone in response to drought stress. During seed germination and seedling development, CaLOX1-OX plants were more tolerant to ABA, mannitol and high salinity than wild-type plants. In contrast, expression of the ABA-responsive marker genes RAB18 and RD29B was higher in CaLOX1-OX Arabidopsis plants than in wild-type plants. In response to high salinity, CaLOX1-OX plants exhibited enhanced tolerance, compared with the wild type, which was accompanied by decreased accumulation of H2O2 and high levels of RD20, RD29A, RD29B and P5CS gene expression. Similarly, CaLOX1-OX plants were also more tolerant than wild-type plants to severe drought stress. H2O2 production and the relative increase in lipid peroxidation were lower, and the expression of COR15A, DREB2A, RD20, RD29A and RD29B was higher in CaLOX1-OX plants, relative to wild-type plants. Taken together, our results indicate that CaLOX1 plays a crucial role in plant stress responses by modulating the expression of ABA- and stress-responsive marker genes, lipid peroxidation and H2O2 production.
在植物中，脂氧合酶（LOXs）参与多种生理过程，包括对生物和非生物胁迫的防御反应。我们之前的研究表明，辣椒9-LOX基因CaLOX1在病原体感染导致的细胞死亡中起关键作用。在此，使用过表达CaLOX1（CaLOX1-OX）的拟南芥植株研究了CaLOX1在响应渗透、干旱和高盐胁迫中的功能。当辣椒叶片用干旱和高盐处理时，观察到CaLOX1基因的时间表达模式发生变化，但用脱落酸（ABA）处理时未观察到变化，ABA是响应干旱胁迫的主要激素。在种子萌发和幼苗发育过程中，CaLOX1-OX植株比野生型植株对ABA、甘露醇和高盐更具耐受性。相反，ABA响应标记基因RAB18和RD29B在CaLOX1-OX拟南芥植株中的表达高于野生型植株。在响应高盐胁迫时，与野生型相比，CaLOX1-OX植株表现出更强的耐受性，同时伴随着H2O2积累的减少以及RD20、RD29A、RD29B和P5CS基因的高水平表达。同样，CaLOX1-OX植株比野生型植株对严重干旱胁迫也更具耐受性。相对于野生型植株，CaLOX1-OX植株中H2O2的产生和脂质过氧化的相对增加较低，而COR15A、DREB2A、RD20、RD29A和RD29B的表达较高。综上所述，我们的结果表明，CaLOX1通过调节ABA和胁迫响应标记基因的表达、脂质过氧化和H2O2的产生，在植物胁迫反应中起关键作用。
