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
以甜柿品种‘太秋’(Diospyros kaki Thunb.‘Taishuu’)和涩柿品种‘小方柿’(Diospyros kaki Thunb.‘Xiaofangshi’)为试材,探讨了内源多胺形态、种类和含量在柿果实和萼片发育中的变化。结果表明,花后10 d,甜柿果实游离态亚精胺(Spd...以甜柿品种‘太秋’(Diospyros kaki Thunb.‘Taishuu’)和涩柿品种‘小方柿’(Diospyros kaki Thunb.‘Xiaofangshi’)为试材,探讨了内源多胺形态、种类和含量在柿果实和萼片发育中的变化。结果表明,花后10 d,甜柿果实游离态亚精胺(Spd)和精胺(Spm)含量显著高于涩柿,游离态腐胺(Put)、束缚态Put、Spd和Spm含量显著低于涩柿;柿果实和萼片中能够检测出Put、Spd、Spm和己二胺(Hex)4种游离态多胺和Put、Spd、Spm、戊二胺(Cad)和Hex 5种束缚态多胺,未能检测出游离态Cad的存在;去除萼片能够显著降低甜柿果实中束缚态Put、Spd和Cad含量,抑制甜柿果实生长,表明萼片对果实多胺代谢具有调节作用,而束缚态Cad则可能是产生这种调节作用的关键多胺。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.
文摘以甜柿品种‘太秋’(Diospyros kaki Thunb.‘Taishuu’)和涩柿品种‘小方柿’(Diospyros kaki Thunb.‘Xiaofangshi’)为试材,探讨了内源多胺形态、种类和含量在柿果实和萼片发育中的变化。结果表明,花后10 d,甜柿果实游离态亚精胺(Spd)和精胺(Spm)含量显著高于涩柿,游离态腐胺(Put)、束缚态Put、Spd和Spm含量显著低于涩柿;柿果实和萼片中能够检测出Put、Spd、Spm和己二胺(Hex)4种游离态多胺和Put、Spd、Spm、戊二胺(Cad)和Hex 5种束缚态多胺,未能检测出游离态Cad的存在;去除萼片能够显著降低甜柿果实中束缚态Put、Spd和Cad含量,抑制甜柿果实生长,表明萼片对果实多胺代谢具有调节作用,而束缚态Cad则可能是产生这种调节作用的关键多胺。
