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Autophagy is a conserved degradation pathway in plants, which plays an important role in plant cellular homeostasis during abiotic stress. Although various abiotic stressors have been reported to induce autophagic activity in plants, the specific role of autophagy in plant cadmium (Cd) tolerance remains undiscovered. In this study, we treated three MdATG10 -overexpressing apple lines with hydroponic Cd stress and found the enhanced Cd tolerance in transgenic plants. Transgenic apple plants exhibited less growth limitation and reduced Cd damage on the photosynthetic system. That was accompanied by higher antioxidant enzymes activity and lower harmful ROS accumulation in apple leaves under Cd stress. The higher autophagic activity led to a more active metabolic system of Pro, His, and Arg in transgenic plants under Cd stress, which was closely related to the plant Cd tolerance. In addition, the transcriptional activities of several Cd transport and detoxification-related genes were regulated by MdATG10 -overexpression in response to Cd stress. This study is the first to demonstrate the protective role of autophagy in the Cd tolerance of plants. [Display omitted] • MdATG10 -OE plants showed higher autophagic activity and enhanced Cd tolerance. • MdATG10 -OE plants showed higher antioxidant enzymes activity and lower Cd damage. • MdATG10 -OE plants showed higher Pro, His, and Arg levels in both roots and leaves. • MdATG10 -OE plants showed reduced Cd accumulation. [ABSTRACT FROM AUTHOR]

Cadmium (Cd), a phytotoxic heavy metal accumulated in plants and fruits, has significant adverse effects on plant growth and development as well as human health. In particular, Cd pollution has become a serious agricultural issue in recent years. Apple is one of the most popular fruits consumed at the global scale. Improving apple Cd resistance via reductions in Cd absorption can benefit apple tree growth and ensure fruit safety. In this study, we determined that, under the 200 μM Cd treatment, 35S::MdIAA24 apple plants exhibited more biomass and less Cd accumulation in the tested tissues compared to wild type (WT). Furthermore, the 35S::MdIAA24 apple plants demonstrated more favorable photosynthesis characteristics, less reactive oxygen species (ROS) and a greater amount of active antioxidant enzymes under the Cd condition than WT. The expression levels of the Cd uptake genes were observed to be lower in the 35S::MdIAA24 apple plants compared with those of the WT under the Cd treatment. The results highlight the ability of the overexpression of MdIAA24 to enhance apple Cd resistance by improving antioxidant capacity and reducing Cd absorption. [Display omitted] ● Overexpression of MdIAA24 enhanced cadmium tolerance in apple. ● Photosynthetic activity, ROS scavengers and biomass of apple increased under Cd stress due to over expression of MdIAA24. ● Decreased uptake of Cd due to MdIAA24 ensures the quality produce of apple. [ABSTRACT FROM AUTHOR]

'Qinguan' apple is native to China with the outstanding qualities of disease resistance and long storage time. In this study, gas chromatography-mass spectrometry (GC-MS) was used to identify the volatile compounds in peel and flesh of post-harvest 'Qinguan' apples. Ninety-four and seventy volatile compounds were identified in 'Qinguan' peel and flesh, respectively. Esters and alcohols were predominant in 'Qinguan' peel, while alcohols were identified as the main volatiles in 'Qinguan' flesh. Odor-active compounds and the sensory profile of 'Qinguan' apples were investigated by aroma extract dilution analysis-gas chromatography-olfactometry (AEDA-GC-O) and sensory description analyses. The sensory profile of 'Qinguan' apples was mainly characterized by aroma descriptors of fruity and green categories. Among the 15 odor-active compounds with flavor dilution factor (FD) ranging from 3 to 81, hexyl acetate, α -farnesene, hexanol, and hexanal (with FD = 81) were shown to be the most potent odor-active compounds in 'Qinguan' apples. Based on the results obtained from GC-MS, AEDA-GC-O, and omission tests, hexyl acetate as the most abundant ester in peel was suggested to be one of the characteristic aroma compounds of 'Qinguan' apple, contributing to its strong fruity aroma note, while the other characteristic aroma compound, α -farnesene, was responsible for the green note. [Display omitted] • Post-harvest aroma profiles in the peel and flesh of 'Qinguan' were determined. • The main volatile compounds of 'Qinguan' peel were esters and alcohols. • The main volatile compounds of 'Qinguan' flesh were alcohols. • AEDA-GC-O, omission tests, and sensory description analysis were used in the study. • Hexyl acetate with a strong fruity note is the key aroma of 'Qinguan'. [ABSTRACT FROM AUTHOR]

Abstract: Marssonina apple blotch is one of the most severe diseases of apple. Using Malus sieversii and Malus prunifolia cv. Donghongguo, we investigated the levels of hydrogen peroxide, activities of both antioxidant and pathogenesis-related enzymes, and expression of marker genes for salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) in pathways for defense regulation during incompatible and compatible interactions. In incompatible interaction, as the key enzymes of antioxidant system coordinated work, a ROS burst and associated SA-signaling were activated within 10 days post inoculation. This was followed by activation of JA-mediated defense signaling. Levels of pathogenesis-related enzymes were induced more strongly by Diplocarpon mali than in compatible interaction. Suppression of the ET pathway was associated with the resistance response. Our findings provide important clues for designing strategies to curb the effects of this disease. [Copyright &y& Elsevier]