Unlike the typical climacteric fruits, persimmons (Diospyros kaki Thunb.) produce higher levels of ethylene when they are detached from trees at a younger stage. In order to obtain detailed information on the role of ...Unlike the typical climacteric fruits, persimmons (Diospyros kaki Thunb.) produce higher levels of ethylene when they are detached from trees at a younger stage. In order to obtain detailed information on the role of abscisic acid (ABA) in ripening, we cloned the DKNCED1, DKACS2, and DKACO1 genes from the calyx. Water loss was first noted in the calyx lobe, and DKNCED1 was highly expressed 1 d after the fruits were detached, coinciding with an increase in the ABA content. Then, the DKACS2 and DKACO1 genes were expressed after some delay. In the calyx, the ABA peak was observed 2 d after the fruits were harvested, and this peak preceded the ethylene peak observed on day 3. The fruit firmness rapidly decreased on day 4, and the fruits softened completely 6 d after they were harvested. The increases in the expressions of ABA, ethylene, and the genes in the calyxes occurred earlier than the corresponding increases in the pulp, although the 3 increases occurred on different days. Exogenous ABA treatment increased ABA concentration, induced expression of both ACS and ACO, and promoted ethylene synthesis and young-fruit softening; by contrast, treatment with NDGA inhibited the gene expressions and ethylene synthesis and delayed young-fruit softening. These results indicate that ethylene biosynthesis in the detached young persimmon fruits is initially triggered by ABA, which is induced by water loss in the calyx, through the induction of DKACS2 and DKACO1 expressions. The ethylene produced in the calyx subsequently diffuses into the pulp tissue, where it induces autocatalytic ethylene biosynthesis, resulting in an abrupt increase in ethylene production.展开更多
With large-scale production and the need for high-quality tomatoes to meet consumer and market standards criteria,have led to the need for an inline,accurate,reliable grading system during the post-harvest process.Thi...With large-scale production and the need for high-quality tomatoes to meet consumer and market standards criteria,have led to the need for an inline,accurate,reliable grading system during the post-harvest process.This study introduced a tomato grading machine vision system based on RGB images.The proposed system performed calyx and stalk scar detection at an average accuracy of 0.9515 for both defected and healthy tomatoes by histogramthresholding based on themean g-r value of these regions of interest.Defected regionswere detected by an RBF-SVMclassifier using the LAB color-space pixel values.Themodel achieved an overall accuracy of 0.989 upon validation.Four grading categories recognitionmodelswere developed based on color and texture features.The RBF-SVMoutperformed all the explored modelswith the highest accuracy of 0.9709 for healthy and defected category.However,the grading accuracy decreased as the number of grading categories increased.A combination of color and texture features achieved the highest accuracy in all the grading categories in image features evaluation.This proposed system can be used as an inline tomato sorting tool to ensure that quality standards are adhered to and maintained.展开更多
基金Supported by the Beijing Natural Science Foundation (Grant No. 6052013)Beijing Municipal Science and Technology Commission (Grant No. D0706002000091)
文摘Unlike the typical climacteric fruits, persimmons (Diospyros kaki Thunb.) produce higher levels of ethylene when they are detached from trees at a younger stage. In order to obtain detailed information on the role of abscisic acid (ABA) in ripening, we cloned the DKNCED1, DKACS2, and DKACO1 genes from the calyx. Water loss was first noted in the calyx lobe, and DKNCED1 was highly expressed 1 d after the fruits were detached, coinciding with an increase in the ABA content. Then, the DKACS2 and DKACO1 genes were expressed after some delay. In the calyx, the ABA peak was observed 2 d after the fruits were harvested, and this peak preceded the ethylene peak observed on day 3. The fruit firmness rapidly decreased on day 4, and the fruits softened completely 6 d after they were harvested. The increases in the expressions of ABA, ethylene, and the genes in the calyxes occurred earlier than the corresponding increases in the pulp, although the 3 increases occurred on different days. Exogenous ABA treatment increased ABA concentration, induced expression of both ACS and ACO, and promoted ethylene synthesis and young-fruit softening; by contrast, treatment with NDGA inhibited the gene expressions and ethylene synthesis and delayed young-fruit softening. These results indicate that ethylene biosynthesis in the detached young persimmon fruits is initially triggered by ABA, which is induced by water loss in the calyx, through the induction of DKACS2 and DKACO1 expressions. The ethylene produced in the calyx subsequently diffuses into the pulp tissue, where it induces autocatalytic ethylene biosynthesis, resulting in an abrupt increase in ethylene production.
基金We thank the editor and the reviewers for assisting in improving the manuscript and acknowledge Fundamental Research Funds for the Central Universities,China(KYGX201701)for funding the research.
文摘With large-scale production and the need for high-quality tomatoes to meet consumer and market standards criteria,have led to the need for an inline,accurate,reliable grading system during the post-harvest process.This study introduced a tomato grading machine vision system based on RGB images.The proposed system performed calyx and stalk scar detection at an average accuracy of 0.9515 for both defected and healthy tomatoes by histogramthresholding based on themean g-r value of these regions of interest.Defected regionswere detected by an RBF-SVMclassifier using the LAB color-space pixel values.Themodel achieved an overall accuracy of 0.989 upon validation.Four grading categories recognitionmodelswere developed based on color and texture features.The RBF-SVMoutperformed all the explored modelswith the highest accuracy of 0.9709 for healthy and defected category.However,the grading accuracy decreased as the number of grading categories increased.A combination of color and texture features achieved the highest accuracy in all the grading categories in image features evaluation.This proposed system can be used as an inline tomato sorting tool to ensure that quality standards are adhered to and maintained.
