Plant root system morphology is dramatically influenced by various environmental cues. The adaptation of root system architecture to environmental constraints, which mostly depends on the formation and growth of later...Plant root system morphology is dramatically influenced by various environmental cues. The adaptation of root system architecture to environmental constraints, which mostly depends on the formation and growth of lateral roots, is an important agronomic trait. Lateral root development is regulated by the external signals coordinating closely with intrinsic signaling pathways. MADS-box transcription factors are known key regulators of the transition to flowering and flower development. However, their functions in root development are still poorly understood. Here we report that AGL21, an AGL17-clade MADS-box gene, plays a crucial role in lateral root development. AGL21 was highly expressed in root, particularly in the root central cylinder and lateral root primordia. AGL21 overexpression plants produced more and longer lateral roots while ag121 mutants showed impaired lateral root development, especially under nitrogen-deficient conditions. AGL21 was induced by many plant hormones and environmental stresses, suggesting a function of this gene in root system plasticity in response to various signals. Furthermore, AGL21 was found positively regulating auxin accumulation in lateral root primordia and lateral roots by enhancing local auxin biosynthesis, thus stimulating lateral root initiation and growth. We propose that AGL21 may be involved in various environmental and physiological signals-mediated lateral root development and growth.展开更多
Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to regulate seed ge...Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to regulate seed germination. It has been well known that MCMI/AGAMOUS/DEFICIENS/SRF （MADS）-box transcription factors are key regulators of seed and flower development in Arabidopsis. However, little is known about their functions in seed germination. Here we report that MADS-box transcription factor AGL21 is a negative regulator of seed germination and post-germination growth by controlling the expression of ABA-INSENSITIVE 5 （ABIb＇） in Arabidopsis. The AGL21-overexpressing plants were hypersensitive to ABA, salt, and osmotic stresses during seed germination and early post-germination growth, whereas ag121 mutants were less sensitive. We found that AGL21 positively regulated ABI5 expression in seeds. Consistently, genetic analyses showed that AGL21 is epistatic to ABI5 in controlling seed germination. Chromatin immunoprecipitation assays further demonstrated that AGL21 could directly bind to the ABI5 promoter in plant cells. Moreover, we found that AGL21 responded to multiple environmental stresses and plant hormones during seed germination. Taken together, our results suggest that AGL21 acts as a surveillance integrator that incorporates environmental cues and endogenous hormonal signals into ABA signaling to regulate seed germination and early post-germination growth.展开更多
基金This work was supported by the Chinese Academy of Science （grant no. KSCX3-YW-N-007）, the Ministry of Science and Technology of China （grant no. 2012CBl14304）, and the National Nature Science Foundation of China （grant no. 30830075）.
文摘Plant root system morphology is dramatically influenced by various environmental cues. The adaptation of root system architecture to environmental constraints, which mostly depends on the formation and growth of lateral roots, is an important agronomic trait. Lateral root development is regulated by the external signals coordinating closely with intrinsic signaling pathways. MADS-box transcription factors are known key regulators of the transition to flowering and flower development. However, their functions in root development are still poorly understood. Here we report that AGL21, an AGL17-clade MADS-box gene, plays a crucial role in lateral root development. AGL21 was highly expressed in root, particularly in the root central cylinder and lateral root primordia. AGL21 overexpression plants produced more and longer lateral roots while ag121 mutants showed impaired lateral root development, especially under nitrogen-deficient conditions. AGL21 was induced by many plant hormones and environmental stresses, suggesting a function of this gene in root system plasticity in response to various signals. Furthermore, AGL21 was found positively regulating auxin accumulation in lateral root primordia and lateral roots by enhancing local auxin biosynthesis, thus stimulating lateral root initiation and growth. We propose that AGL21 may be involved in various environmental and physiological signals-mediated lateral root development and growth.
基金This work was supported by the China National Natural Science Funds for Distinguished Young Scholar （grant no. 31500231 to L.-H.Yo）, China Postdoctoral Science Foundation, No.9 Special Fund （grant no. 2016T90577 to L.-H.Y.）, and Chinese Academy of Sciences （grant no. KSCX3-EW-N- 07 to C.-B.X.）.
文摘Seed germination is a crucial checkpoint for plant survival under unfavorable environmental conditions. Ab- scisic acid （ABA） signaling plays a vital role in integrating environmental information to regulate seed germination. It has been well known that MCMI/AGAMOUS/DEFICIENS/SRF （MADS）-box transcription factors are key regulators of seed and flower development in Arabidopsis. However, little is known about their functions in seed germination. Here we report that MADS-box transcription factor AGL21 is a negative regulator of seed germination and post-germination growth by controlling the expression of ABA-INSENSITIVE 5 （ABIb＇） in Arabidopsis. The AGL21-overexpressing plants were hypersensitive to ABA, salt, and osmotic stresses during seed germination and early post-germination growth, whereas ag121 mutants were less sensitive. We found that AGL21 positively regulated ABI5 expression in seeds. Consistently, genetic analyses showed that AGL21 is epistatic to ABI5 in controlling seed germination. Chromatin immunoprecipitation assays further demonstrated that AGL21 could directly bind to the ABI5 promoter in plant cells. Moreover, we found that AGL21 responded to multiple environmental stresses and plant hormones during seed germination. Taken together, our results suggest that AGL21 acts as a surveillance integrator that incorporates environmental cues and endogenous hormonal signals into ABA signaling to regulate seed germination and early post-germination growth.
