| Effect of drought stress on the photosynthesis, chloroplast ultrastructure and antioxidant system in leaves of three apple rootstocks |
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| DOI：10.7606/j.issn.1000-7601.2019.01.25 |
| Key Words: apple rootstocks drought stress photosynthesis chloroplast chloroplast ultrastructure antioxidant enzymes |
| Author Name | Affiliation | | GUO Ai-xia | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | SHI Xiao-yun | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | WANG Yan-xiu | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | HU Ya | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China | | ZHU Yan-fang | College of Horticulture, Gansu Agricultural University, Lanzhou, Gansu 730070, China |
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| Abstract: |
| One-year-old seedlings of three apple rootstocks, Malus sieversii Roem. (XJ), Malus halliana Koehne (CS), and Malus baccata Borkh. (SDZ), were used as test materials. The pot experiment with artificial water control was carried out with two water treatments including normal irrigation (75%~80% of the field moisture capacity) and drought stress (45%~50% of the field moisture capacity). Photosynthetic characteristics, chloroplast ultrastructure, malondialdehyde (MDA) content, superoxide anion (O-2) production rate, and antioxidant enzyme activities in leaves were determined under drought stress. These indices were analyzed by principal component analysis (PCA) to compare the drought tolerance of three apple rootstocks. The results showed that drought stress inhibited photosynthesis of three apple rootstocks. The decrease in net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), PSII maximum light conversion efficiency (Fv/Fm), potential photochemical activity (Fv/Fo), and photochemical quenching coefficient (qP) in CS was remarkably lower than those of the other two rootstocks, while the intercellular CO2 concentration (Ci) and non-photochemical quenching coefficient (NPQ) were enhanced to a greater extent in CS than that in the others. The chloroplast ultrastructure of three rootstocks were subjected to different degrees of damage when they were exposed to the same level of drought stress. The CS maintained integrity of cell structure better than did the other two rootstocks, and had less ultrastructure damage in leaves. The activities of SOD and CAT of three apple rootstocks increased firstly and then decreased, while POD activity increased gradually until the 21 day stress. In addition, MDA content and O-2 production rate of three apple rootstocks increased. Based on the PCA, the cumulative contribution rate of the 2 principal components totaled at 98.502%, and the PCA score of CS was the optimum under drought stress. Therefore, CS could maintain the integrity of chloroplast structure, activate the antioxidant enzyme system, and scavenge the oxidation products to maintain high photosynthetic capacity under drought stress. |
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