Concentration-dependent impacts of exogenous methyl jasmonate (MeJA) on chlorophyll degradation of apple fruit during ripening
Concentration-dependent impacts of exogenous methyl jasmonate (MeJA) on chlorophyll degradation of apple fruit during ripening
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DOI：
10.1016/j.postharvbio.2023.112398
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发表时间：
2023-05-19
影响因子：
7
通讯作者：
Li, Jianrong
中科院分区：
文献类型：
--
作者：
Lv, Jingyi;Zhang, Yingzhi;Li, Jianrong
虽然茉莉酸类物质（JAs）已被证明对苹果果实的劣化有调节作用，但其分子机制尚不清楚。以往的研究表明，茉莉酸对收获的园艺作物的退化的影响可能取决于浓度的应用。苹果果实是否也能得到类似的结果还不清楚。研究了不同浓度茉莉酸甲酯（MeJA）处理对苹果采后叶绿素（Chl）降解的影响。苹果用10或1500 μ M MeJA处理商品成熟度为1000 μ M的葡萄酒，然后在20 ℃、0.5 ℃下储存.结果表明，外源10 μ M的MeJA处理延缓了苹果果实的衰老和成熟，而1500 μ M的MeJA处理则相反。处理10 μ M MeJA缓解叶绿素氧化通过降低叶绿素过氧化物酶（POX）活性和活性氧（ROS）水平在苹果果皮的叶绿体成熟过程中，而1500 μ M MeJA处理有相反的效果。在苹果成熟过程中，10 μ M MeJA处理对苹果果皮中镁脱螯合酶（MDcase）和脱镁叶绿素酶（PPH）活性有不同程度的抑制作用，而1500 μ M MeJA处理对苹果果皮中镁脱螯合酶和脱镁叶绿素酶活性有不同程度的促进作用。10 μ M MeJA处理延迟了苹果成熟过程中内源茉莉酸（JA）含量的高峰，降低了茉莉酸抗性1（JAR 1）含量和丙二烯氧化物合成酶（AOS）活性，并差异性下调了MdNYC 3、MdNYE 1a、MdPPH 1、MdPAO 6、MdPAO 8、MdRCCR 2和MdMYC 2a的表达。M MeJA处理的苹果果实。在苹果成熟后期，10 μ M MeJA处理促进了MdHCAR在苹果果皮中的表达，而1500 μ M MeJA处理则降低了MdHCAR在苹果果皮中的表达。MdNYC1和MdNOL2的转录水平普遍降低，在成熟后期的两个治疗。瞬时过表达MdMYC2a通过促进PPH和MDcase活性，提高上述Chl分解代谢基因（CCGs）的表达，加速了苹果果皮Chl降解，但MdHCAR在成熟过程中表达被其下调。瞬时过表达MdMYC2a后，苹果果皮中的AOS活性、JA和JAR1含量增加。这些数据表明，成熟过程中苹果果皮中PAO途径和Chl氧化受JA信号的调控，外源MeJA以浓度依赖的方式调控苹果果实Chl降解。
Although jasmonates (JAs) have been proved to regulate degreening of apple fruit, the relevant molecular mechanisms have not yet been clarified. Previous reports revealed that the effects of JAs on degreening of harvested horticultural crops might be dependent on concentration applied. Whether a similar result can be obtained from apple fruit is still unclear. This research explored the impacts of different concentrations of methyl jasmonate (MeJA) treatment on chlorophyll (Chl) degradation of postharvest apple fruit. Apples (Malus x domestica Borkh.) of commercial maturity were treated with 10 or 1500 & mu;M MeJA and then stored at 20 & PLUSMN; 0.5 degrees C. The results indicated that exogenous 10 & mu;M MeJA delayed degreening and ripening of apple fruit, whereas 1500 & mu;M MeJA treatment had the opposite effects. Treatment with 10 & mu;M MeJA alleviated Chl-oxidation by reducing Chl-peroxidase (POX) activity and reactive oxygen species (ROS) levels in chloroplast of apple peel during ripening, whereas 1500 & mu;M MeJA treatment had the opposite effects. Activities of Magnesium-dechelatase (MDcase) and pheophytinase (PPH) in apple peel were differentially suppressed by 10 & mu;M MeJA treatment while promoted by 1500 & mu;M MeJA treatment during ripening. Application of 10 & mu;M MeJA delayed the peak of endogenous jasmonic acid (JA) content, reduced jasmonate resistant 1 (JAR1) content and allene oxide synthase (AOS) activity, and differentially down-regulated expression of MdNYC3, MdNYE1a, MdPPH1, MdPAO6, MdPAO8, MdRCCR2 and MdMYC2a in apple peel during ripening, whereas opposite results were obtained from the 1500 & mu;M MeJA-treated apple fruit. At the late ripening stage, MdHCAR expression in apple peel was pro-moted by 10 & mu;M MeJA treatment while reduced by 1500 & mu;M MeJA treatment. Transcript levels of MdNYC1 and MdNOL2 were generally reduced by both treatments at the late ripening stage. Transient overexpression of MdMYC2a accelerated Chl degradation of apple peel by promoting PPH and MDcase activities and enhancing expression of the above Chl catabolic genes (CCGs), except MdHCAR whose expression was down-regulated by it during ripening. The AOS activity, JA and JAR1 contents in apple peel were increased after transient over-expression of MdMYC2a during ripening. These data indicated that the PAO pathway and Chl-oxidation were regulated by JA signal in apple peel during ripening, and exogenous MeJA regulated Chl degradation of apple fruit in a concentration-dependent manner.