The skin protects a fruit from environmental stresses and supports the fruit’s structure.Failure of the skin leads to fruit splitting and may compromise commercial production for fruit growers.The mechanical properti...The skin protects a fruit from environmental stresses and supports the fruit’s structure.Failure of the skin leads to fruit splitting and may compromise commercial production for fruit growers.The mechanical properties of the cuticle and skin cell walls might influence the splitting susceptibility of fleshy fruits.Thin shell theory and fracture mechanics were utilized in this study to target the potential factors contributing to splitting susceptibility.The study analyzed the structure of the cuticle and epidermis in ripening grape berries and examined the temporal dynamics of berry splitting.Cuticular waxes were partially removed,and skin cell walls were manipulated using wall stiffening and loosening solutions that altered reactions involving hydrogen peroxide.A more than twofold difference in cuticle thickness among grape cultivars did not account for their differences in splitting resistance.However,while removing predominantly epicuticular wax did not alter the berries’splitting resistance,their surface appearance and increasing yield strength following partial wax removal support the notion that cuticular waxes contribute to berry mechanical properties.Immersing berries in H 2 O 2-based cell wall loosening solutions increased the splitting probability and accelerated berry splitting,whereas cell wall stiffening solutions decreased the splitting probability and delayed berry splitting.These results showed that both cuticle and skin cell walls contribute to the mechanical properties of grape berries and to their splitting resistance.The results also suggest that the two current explanations for fruit splitting,the critical turgor model and the zipper model,should be viewed as complementary rather than incompatible.展开更多
An understanding of physiological disorders associated with ripening of fruits triggered by abiotic stress relies on anatomical and physico-chemical analyses, as it provide insights into their origin and probable caus...An understanding of physiological disorders associated with ripening of fruits triggered by abiotic stress relies on anatomical and physico-chemical analyses, as it provide insights into their origin and probable causes. The objective of this study was to analyze different ripening disorders of grape (Vitis vinifera L.) berries by dissecting their morpho-anatomy, shriveling nature, and composition. Four well-defined disorders—sunburn, prolonged dehydration (PD), late-season bunch stem necrosis (LBSN), and berry shrivel (BS) were analyzed in field-grown grapevines of the cultivar Cabernet Sauvignon. Early bunch stem necrosis (EBSN) that occurred before ripening was also included in the study. Unlike healthy spherical berries, the pericarp of disordered berries except for sunburn shriveled causing concomitant reductions in fresh weight and volume. The exocarp of PD berries developed well-ordered indentations as distinct from the wrinkles in LBSN berries, whereas BS berries were flaccid with numerous skin folds. The epicuticular wax occurred as upright platelets in all shrivel forms excluding the sun-exposed hemisphere of sunburned berries. A chlorophyllous inflorescence framework persisted in all shrivel forms but in LBSN, wherein the necrotic regions developed tylosis. Unlike the translucent mesocarp of healthy, sunburned, and PD berries, the mesocarp was collapsed in BS and LBSN berries, nevertheless all had well-developed seeds. The composition of healthy berries was optimal, whereas the disordered berries were compositionally distinct from each other, which as a whole differed from the healthy berries. The BS berries had the lowest sugar content, and although sugar concentration was higher in LBSN, sunburned and PD berries, sugar amount per berry was highest in the healthy berries, the same was true for hexoses. Healthy and BS berries exhibited highest amounts of tartaric acid followed by sunburn and PD berries, whereas the LBSN berries had the lowest values. Conversely, healthy and PD berries had the highest amounts of malic acid followed by LBSN, sunburn and BS berries, which collectively displayed similar amounts. The PD berries exhibited the highest calcium content followed by LBSN, healthy, and finally BS and sunburned berries. A linear relationship existed between potassium (K) and pH of the berries. The PD berries had the highest amounts of K followed by healthy, sunburn, LBSN, and BS berries. Overall, the results reported here provided combined morpho-anatomical and compositional analyses of different shrivel types that occurred during a single growing season. Such analysis is needed to make a progress on understanding these ripening disorders culminating in the development of remedial measures.展开更多
基金This research was supported by the USDA National Institute of Food and Agriculture(Hatch project 1000186)the USDA Northwest Center for Small Fruits Research(59-2072-7-007)the Chateau Ste.Michelle Distinguished Professorship,and the Graduate School of Washington State University.
文摘The skin protects a fruit from environmental stresses and supports the fruit’s structure.Failure of the skin leads to fruit splitting and may compromise commercial production for fruit growers.The mechanical properties of the cuticle and skin cell walls might influence the splitting susceptibility of fleshy fruits.Thin shell theory and fracture mechanics were utilized in this study to target the potential factors contributing to splitting susceptibility.The study analyzed the structure of the cuticle and epidermis in ripening grape berries and examined the temporal dynamics of berry splitting.Cuticular waxes were partially removed,and skin cell walls were manipulated using wall stiffening and loosening solutions that altered reactions involving hydrogen peroxide.A more than twofold difference in cuticle thickness among grape cultivars did not account for their differences in splitting resistance.However,while removing predominantly epicuticular wax did not alter the berries’splitting resistance,their surface appearance and increasing yield strength following partial wax removal support the notion that cuticular waxes contribute to berry mechanical properties.Immersing berries in H 2 O 2-based cell wall loosening solutions increased the splitting probability and accelerated berry splitting,whereas cell wall stiffening solutions decreased the splitting probability and delayed berry splitting.These results showed that both cuticle and skin cell walls contribute to the mechanical properties of grape berries and to their splitting resistance.The results also suggest that the two current explanations for fruit splitting,the critical turgor model and the zipper model,should be viewed as complementary rather than incompatible.
文摘An understanding of physiological disorders associated with ripening of fruits triggered by abiotic stress relies on anatomical and physico-chemical analyses, as it provide insights into their origin and probable causes. The objective of this study was to analyze different ripening disorders of grape (Vitis vinifera L.) berries by dissecting their morpho-anatomy, shriveling nature, and composition. Four well-defined disorders—sunburn, prolonged dehydration (PD), late-season bunch stem necrosis (LBSN), and berry shrivel (BS) were analyzed in field-grown grapevines of the cultivar Cabernet Sauvignon. Early bunch stem necrosis (EBSN) that occurred before ripening was also included in the study. Unlike healthy spherical berries, the pericarp of disordered berries except for sunburn shriveled causing concomitant reductions in fresh weight and volume. The exocarp of PD berries developed well-ordered indentations as distinct from the wrinkles in LBSN berries, whereas BS berries were flaccid with numerous skin folds. The epicuticular wax occurred as upright platelets in all shrivel forms excluding the sun-exposed hemisphere of sunburned berries. A chlorophyllous inflorescence framework persisted in all shrivel forms but in LBSN, wherein the necrotic regions developed tylosis. Unlike the translucent mesocarp of healthy, sunburned, and PD berries, the mesocarp was collapsed in BS and LBSN berries, nevertheless all had well-developed seeds. The composition of healthy berries was optimal, whereas the disordered berries were compositionally distinct from each other, which as a whole differed from the healthy berries. The BS berries had the lowest sugar content, and although sugar concentration was higher in LBSN, sunburned and PD berries, sugar amount per berry was highest in the healthy berries, the same was true for hexoses. Healthy and BS berries exhibited highest amounts of tartaric acid followed by sunburn and PD berries, whereas the LBSN berries had the lowest values. Conversely, healthy and PD berries had the highest amounts of malic acid followed by LBSN, sunburn and BS berries, which collectively displayed similar amounts. The PD berries exhibited the highest calcium content followed by LBSN, healthy, and finally BS and sunburned berries. A linear relationship existed between potassium (K) and pH of the berries. The PD berries had the highest amounts of K followed by healthy, sunburn, LBSN, and BS berries. Overall, the results reported here provided combined morpho-anatomical and compositional analyses of different shrivel types that occurred during a single growing season. Such analysis is needed to make a progress on understanding these ripening disorders culminating in the development of remedial measures.
