Flowers are the core reproductive organ of plants, and flowering is essential for cross-pollination. Diurnal flower-opening time is thus a key trait influencing reproductive isolation, hybrid breeding, and thermostabi...Flowers are the core reproductive organ of plants, and flowering is essential for cross-pollination. Diurnal flower-opening time is thus a key trait influencing reproductive isolation, hybrid breeding, and thermostability in plants. However, the molecular mechanisms controlling this trait remain unknown. Here, we report that rice Diurnal Flower Opening Time 1 (DFOT1) modulates pectin methylesterase (PME) activity to regulate pectin methylesterification levels of the lodicule cell walls, which affect lodicule swelling to control diurnal flower-opening time. DFOT1 is specifically expressed in the lodicules, and its expression gradually increases with the approach to flowering but decreases with flowering. Importantly, a knockout of DFOT1 showed earlier diurnal flower opening. We demonstrate that DFOT1 interacts directly with multiple PMEs to promote their activity. Knockout of PME40 also resulted in early diurnal flower opening, whereas overexpression of PME42 delayed diurnal flower opening. Lower PME activity was observed to be associated with higher levels of pectin methylesterification and the softening of cell walls in lodicules, which contribute to the absorption of water by lodicules and cause them to swell, thus promoting early diurnal flower opening. Higher PME activity had the opposite effect. Collectively, our work uncovers a molecular mechanism underlying the regulation of diurnal flower-opening time in rice, which would help reduce the costs of hybrid breeding and improve the heat tolerance of flowering plants by avoiding higher temperatures at anthesis.展开更多
Two-line hybrid breeding can fully utilize heterosis in crops.In thermo-sensitive genic male sterile(TGMS)lines,low critical sterility-inducing temperature(CSIT)is vital to safeguard the production of two-line hybrid ...Two-line hybrid breeding can fully utilize heterosis in crops.In thermo-sensitive genic male sterile(TGMS)lines,low critical sterility-inducing temperature(CSIT)is vital to safeguard the production of two-line hybrid seeds in rice(Oryza sativa),but the molecular mechanism determining CSIT is unclear.Here,we report the cloning of CSIT1,which encodes an E3 ubiquitin ligase,and show that CSIT1 modulates the CSIT of thermo-sensitive genic male sterility 5(tms5)-based TGMS lines through ribosome-associated quality control(RQC).Biochemical assays demonstrated that CSIT1 binds to the 80S ribosomes and ubiquitinates abnormal nascent polypeptides for degradation in the RQC process.Loss of CSIT1 function inhibits the possible damage of tms5 to the ubiquitination system and protein translation,resulting in enhanced accumulation of anther-related proteins such as catalase to suppress abnormal accumulation of reactive oxygen species and premature programmed cell death in the tapetum,thereby leading to a much higher CSIT in the tms5-based TGMS lines.Taken together,our findings reveal a regulatory mechanism of CSIT,providing new insights into RQC and potential targets for future two-line hybrid breeding.展开更多
基金supported by the Major Program of Guangdong Basicand Applied Research(2019B030302006)the National Natural Science Foundation of China(31921004,32172017 and 31871700)the Laboratory of Lingnan Modern Agriculture Project(NZ2021002 and NT2021002)。
文摘Flowers are the core reproductive organ of plants, and flowering is essential for cross-pollination. Diurnal flower-opening time is thus a key trait influencing reproductive isolation, hybrid breeding, and thermostability in plants. However, the molecular mechanisms controlling this trait remain unknown. Here, we report that rice Diurnal Flower Opening Time 1 (DFOT1) modulates pectin methylesterase (PME) activity to regulate pectin methylesterification levels of the lodicule cell walls, which affect lodicule swelling to control diurnal flower-opening time. DFOT1 is specifically expressed in the lodicules, and its expression gradually increases with the approach to flowering but decreases with flowering. Importantly, a knockout of DFOT1 showed earlier diurnal flower opening. We demonstrate that DFOT1 interacts directly with multiple PMEs to promote their activity. Knockout of PME40 also resulted in early diurnal flower opening, whereas overexpression of PME42 delayed diurnal flower opening. Lower PME activity was observed to be associated with higher levels of pectin methylesterification and the softening of cell walls in lodicules, which contribute to the absorption of water by lodicules and cause them to swell, thus promoting early diurnal flower opening. Higher PME activity had the opposite effect. Collectively, our work uncovers a molecular mechanism underlying the regulation of diurnal flower-opening time in rice, which would help reduce the costs of hybrid breeding and improve the heat tolerance of flowering plants by avoiding higher temperatures at anthesis.
基金supported by the Open Competition Program of Top Ten Critical Priorities of Agricultural Science and Technology Innovation for the 14th Five-Year Plan of Guangdong Province(2022SDZG05)the National Natural Science Foundation of China(31921004,32172017,32101775,and 32172097)+4 种基金the Guangdong Basic and Applied Research Foundation(2019B030302006 and 2022B1515120036)the Laboratory of Lingnan Modern Agriculture Project(NZ2021002 and NT2021002)the China Postdoctoral Science Foundation(2021M691086)the Natural Science Foundation of Guangdong Province(2022A1515012496)the Double First-Class Discipline Promotion Project(2021B10564001 and 2023B10564004).
文摘Two-line hybrid breeding can fully utilize heterosis in crops.In thermo-sensitive genic male sterile(TGMS)lines,low critical sterility-inducing temperature(CSIT)is vital to safeguard the production of two-line hybrid seeds in rice(Oryza sativa),but the molecular mechanism determining CSIT is unclear.Here,we report the cloning of CSIT1,which encodes an E3 ubiquitin ligase,and show that CSIT1 modulates the CSIT of thermo-sensitive genic male sterility 5(tms5)-based TGMS lines through ribosome-associated quality control(RQC).Biochemical assays demonstrated that CSIT1 binds to the 80S ribosomes and ubiquitinates abnormal nascent polypeptides for degradation in the RQC process.Loss of CSIT1 function inhibits the possible damage of tms5 to the ubiquitination system and protein translation,resulting in enhanced accumulation of anther-related proteins such as catalase to suppress abnormal accumulation of reactive oxygen species and premature programmed cell death in the tapetum,thereby leading to a much higher CSIT in the tms5-based TGMS lines.Taken together,our findings reveal a regulatory mechanism of CSIT,providing new insights into RQC and potential targets for future two-line hybrid breeding.
