Research Institute of Climate Change and Agriculture, National Institute of Horticultural and Herbal Science, Jeju, 63240, Republic of Korea.
Department of Horticulture and Landscape Architecture, National Taiwan University, Taipei, 10617, Taiwan.
Sci Rep. 2022 Jul 8;12(1):11593. doi: 10.1038/s41598-022-15821-3.
To investigate the effects of short-term low temperatures, three-year-old avocado (Persea americana cv. Hass) seedlings were treated with 1, - 2, or - 5 °C for 1 h and subsequently recovered in ambient condition for 24 h. Leaf color changes were investigated with chlorophyll, carotenoid, and phenolic contents. Photosynthetic responses were examined using gas exchange analysis. With HO contents as oxidative stresses, enzymatic (ascorbate peroxidase, APX; glutathione reductase, GR; catalase, CAT; peroxidase, POD) and non-enzymatic antioxidant activities were determined using spectrophotometry. Leaves in the avocado seedlings started to be discolored with changes in the contents of chlorophyll a, carotenoids, and phenolics when treated with - 5 °C. However, the HO content was not different in leaves treated with low temperatures. Photosynthetic activities decreased in leaves in the seedlings treated with - 5 °C. Of antioxidant enzymes, APX and GR have high activities in leaves in the seedlings treated with 1 and - 2 °C. In leaves in the seedlings treated with - 5 °C, the activities of all enzymes decreased. Non-enzymatic antioxidant activity was not different among leaves treated with low temperatures. These results indicated that APX and GR would play a critical role in withstanding chilling stress in 'Hass' avocado seedlings. However, under lethal temperature, even for a short time, the plants suffered irreversible damage with the breakdown of photosystem and antioxidant system.
为了研究短期低温的影响，将三年生鳄梨（Persea americana cv. Hass）幼苗在 1、-2 或-5°C 下处理 1 小时，然后在环境条件下恢复 24 小时。用叶绿素、类胡萝卜素和酚类含量来研究叶片颜色变化。通过气体交换分析来检查光合作用的响应。以 HO 含量作为氧化应激，用分光光度法测定酶（抗坏血酸过氧化物酶、APX；谷胱甘肽还原酶、GR；过氧化氢酶、CAT；过氧化物酶、POD）和非酶抗氧化剂的活性。当用-5°C 处理时，鳄梨幼苗的叶片开始变色，叶绿素 a、类胡萝卜素和酚类含量发生变化。然而，在低温处理的叶片中，HO 含量没有差异。在低温处理的幼苗叶片中，光合作用活性下降。在 1 和-2°C 处理的幼苗叶片中，APX 和 GR 等抗氧化酶具有高活性。在-5°C 处理的幼苗叶片中，所有酶的活性都下降。非酶抗氧化活性在低温处理的叶片中没有差异。这些结果表明，APX 和 GR 在‘Hass’鳄梨幼苗抵御冷胁迫中发挥关键作用。然而，在致死温度下，即使是很短的时间，植物也会遭受不可逆转的损害，光合作用系统和抗氧化系统崩溃。
