Jacob Blaustein Center for Scientific Cooperation, The Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Beer Sheva, 8499000, Israel.
Department of Biotechnology and Microbiology, L.N. Gumilyov Eurasian National University, Astana, Kazakhstan.
Plant J. 2024 Oct;120(1):272-288. doi: 10.1111/tpj.16985. Epub 2024 Aug 27.
Among the three active aldehyde oxidases in Arabidopsis thaliana leaves (AAO1-3), AAO3, which catalyzes the oxidation of abscisic-aldehyde to abscisic-acid, was shown recently to function as a reactive aldehyde detoxifier. Notably, aao2KO mutants exhibited less senescence symptoms and lower aldehyde accumulation, such as acrolein, benzaldehyde, and 4-hydroxyl-2-nonenal (HNE) than in wild-type leaves exposed to UV-C or Rose-Bengal. The effect of AAO2 expression absence on aldehyde detoxification by AAO3 and/or AAO1 was studied by comparing the response of wild-type plants to the response of single-functioning aao1 mutant (aao1S), aao2KO mutants, and single-functioning aao3 mutants (aao3Ss). Notably, aao3Ss exhibited similar aldehyde accumulation and chlorophyll content to aao2KO treated with UV-C or Rose-Bengal. In contrast, wild-type and aao1S exhibited higher aldehyde accumulation that resulted in lower remaining chlorophyll than in aao2KO leaves, indicating that the absence of active AAO2 enhanced AAO3 detoxification activity in aao2KO mutants. In support of this notion, employing abscisic-aldehyde as a specific substrate marker for AAO3 activity revealed enhanced AAO3 activity in aao2KO and aao3Ss leaves compared to wild-type treated with UV-C or Rose-Bengal. The similar abscisic-acid level accumulated in leaves of unstressed or stressed genotypes indicates that aldehyde detoxification by AAO3 is the cause for better stress resistance in aao2KO mutants. Employing the sulfuration process (known to activate aldehyde oxidases) in wild-type, aao2KO, and molybdenum-cofactor sulfurase (aba3-1) mutant plants revealed that the active AAO2 in WT employs sulfuration processes essential for AAO3 activity level, resulting in the lower AAO3 activity in WT than AAO3 activity in aao2KO.
在拟南芥叶片中的三种活性醛氧化酶（AAO1-3）中，AAO3 最近被证明是一种具有反应性醛解毒功能的酶，它能催化脱落酸醛氧化为脱落酸。值得注意的是，与暴露在 UV-C 或 Rose-Bengal 下的野生型叶片相比，aao2KO 突变体表现出较少的衰老症状和较低的醛积累，如丙烯醛、苯甲醛和 4-羟基-2-壬烯醛（HNE）。通过比较野生型植物对单功能 aao1 突变体（aao1S）、aao2KO 突变体和单功能 aao3 突变体（aao3Ss）的响应，研究了 AAO2 表达缺失对 AAO3 和/或 AAO1 醛解毒的影响。值得注意的是，aao3Ss 表现出与 aao2KO 用 UV-C 或 Rose-Bengal 处理相似的醛积累和叶绿素含量。相比之下，野生型和 aao1S 表现出更高的醛积累，导致剩余叶绿素含量低于 aao2KO 叶片，表明活性 AAO2 的缺失增强了 aao2KO 突变体中 AAO3 的解毒活性。支持这一观点，利用脱落酸醛作为 AAO3 活性的特异性底物标记物，发现与用 UV-C 或 Rose-Bengal 处理的野生型相比，aao2KO 和 aao3Ss 叶片中的 AAO3 活性增强。在未受胁迫或胁迫的基因型叶片中积累的类似脱落酸水平表明，AAO3 的醛解毒是 aao2KO 突变体更好的应激抗性的原因。在野生型、aao2KO 和钼辅因子硫代酶（aba3-1）突变体植物中利用硫化过程（已知能激活醛氧化酶），表明 WT 中的活性 AAO2 利用硫化过程对 AAO3 活性水平至关重要，导致 WT 中的 AAO3 活性低于 aao2KO 中的 AAO3 活性。
