The developmental types of secretory cavities in Citrus remain controversial. The relationship between secretory cavity development and the accumulation of essential oil in fruits of Citrus species is also unknown. In...The developmental types of secretory cavities in Citrus remain controversial. The relationship between secretory cavity development and the accumulation of essential oil in fruits of Citrus species is also unknown. In order to develop better insights into these problems, histological, histochemical, and cytochemical methods were used to investigate secretory cavity development and the accumulation of essential oll at different developmental stages of fruits of Citrus medica L. var. sarcodactylis (Noot.) Swingle. The results indicate that the secretory cavity of the variety seemed to originate from an epidermal cell and a subepldermal cell. These two cells underwent successive divisions, resulting In the formation of two parts: (Ⅰ) a conical cap; and (Ⅱ) a globular gland. The formation of the lumen was schlzolysigenous. Regular changes in the size of vacuoles and the accumulation of essential oil were revealed during the process of secretory cavity development. In addition, when fruits were a light yellow or golden color, the structure of secretory cavities was well developed and the content of essential oil in a single fruit reached a maximum. It would be most appropriate to collect the fruit as a medicinal material at this time.展开更多
Hesperidin is a dihydroflavonoids, accounting for more than 50% of the total flavonoids in Citri Reticulatae Pericarpium(CRP) of traditional Chinese medicine. It is an effective antioxidant and free radical scavenger ...Hesperidin is a dihydroflavonoids, accounting for more than 50% of the total flavonoids in Citri Reticulatae Pericarpium(CRP) of traditional Chinese medicine. It is an effective antioxidant and free radical scavenger that has anti-inflammatory, antiviral and hypoglycemic properties.The latest studies reported that hesperidin has a potential for novel coronavirus resistance. However, little is known about the synthesis regulation and accumulation site of hesperidin in plants. In this study, hesperidin synthase gene Crc1,6RhaT was cloned, and the protein can be completely transformed flavanone-7-O-glucoside into hesperidin in vitro and in vivo. Studies on biological characteristics of ovary walls and exocarps showed that the relative expression levels of the Crc1,6RhaT gene and protein decreased gradually with the development of citrus fruits, and the relative content of hesperidin firstly increased, then sequentially decreased. In situ hybridization results further revealed that Crc1,6RhaT transcription was mainly concentrated in the secretory cavity cells, which are revealed to be the site of flavonoid synthesis.Immunocytochemistry localization results showed that the Crc1,6RhaT was mainly located in the endoplasmic reticulum, nucleus and vacuole of secretory cells. We inferred that the Crc1,6RhaT was synthesized in the endoplasmic reticulum, then was transported into the vacuoles through enlarged vesicles at the end of the endoplasmic reticulum. Our results not only revealed that Crc1,6RhaT may be involved in the synthesis of hesperidin of the main bioactive substance in the medicinal plant Citrus reticulata ‘Chachi' fruit, but also provided novel insights into the main subcellular sites of hesperidin biosynthesis in vacuoles.展开更多
基金Supported by the National Natural Science Foundation of China (30270083) and Science and Technology Key Program of Guangdong Province of China (2002C20147, C20605).
文摘The developmental types of secretory cavities in Citrus remain controversial. The relationship between secretory cavity development and the accumulation of essential oil in fruits of Citrus species is also unknown. In order to develop better insights into these problems, histological, histochemical, and cytochemical methods were used to investigate secretory cavity development and the accumulation of essential oll at different developmental stages of fruits of Citrus medica L. var. sarcodactylis (Noot.) Swingle. The results indicate that the secretory cavity of the variety seemed to originate from an epidermal cell and a subepldermal cell. These two cells underwent successive divisions, resulting In the formation of two parts: (Ⅰ) a conical cap; and (Ⅱ) a globular gland. The formation of the lumen was schlzolysigenous. Regular changes in the size of vacuoles and the accumulation of essential oil were revealed during the process of secretory cavity development. In addition, when fruits were a light yellow or golden color, the structure of secretory cavities was well developed and the content of essential oil in a single fruit reached a maximum. It would be most appropriate to collect the fruit as a medicinal material at this time.
基金supported by the National Natural Science Foundation of China (Grant No.32270381)Natural Science Foundation of Guangdong (Grant No.2022A1515011086)+2 种基金Key Realm R&D Program of Guangdong Province (Grant No.2020B020221001)Provincial Special Fund for Modern Agriculture Industry Technology Innovation Teams (Grant No.2019KJ125)Research Fund of Maoming Branch,Guangdong Laboratory for Lingnan Modern Agriculture (Grant No.2022KF009)。
文摘Hesperidin is a dihydroflavonoids, accounting for more than 50% of the total flavonoids in Citri Reticulatae Pericarpium(CRP) of traditional Chinese medicine. It is an effective antioxidant and free radical scavenger that has anti-inflammatory, antiviral and hypoglycemic properties.The latest studies reported that hesperidin has a potential for novel coronavirus resistance. However, little is known about the synthesis regulation and accumulation site of hesperidin in plants. In this study, hesperidin synthase gene Crc1,6RhaT was cloned, and the protein can be completely transformed flavanone-7-O-glucoside into hesperidin in vitro and in vivo. Studies on biological characteristics of ovary walls and exocarps showed that the relative expression levels of the Crc1,6RhaT gene and protein decreased gradually with the development of citrus fruits, and the relative content of hesperidin firstly increased, then sequentially decreased. In situ hybridization results further revealed that Crc1,6RhaT transcription was mainly concentrated in the secretory cavity cells, which are revealed to be the site of flavonoid synthesis.Immunocytochemistry localization results showed that the Crc1,6RhaT was mainly located in the endoplasmic reticulum, nucleus and vacuole of secretory cells. We inferred that the Crc1,6RhaT was synthesized in the endoplasmic reticulum, then was transported into the vacuoles through enlarged vesicles at the end of the endoplasmic reticulum. Our results not only revealed that Crc1,6RhaT may be involved in the synthesis of hesperidin of the main bioactive substance in the medicinal plant Citrus reticulata ‘Chachi' fruit, but also provided novel insights into the main subcellular sites of hesperidin biosynthesis in vacuoles.