1
|
Gao Q, Zeng Z, Hao T, Zhang Z, Liang D, Xia C, Gao H, Liu L. Transcriptional and post-transcriptional regulation of chloroplast development by nuclear-localized XAP5 CIRCADIAN TIMEKEEPER. PLANT SCIENCE : AN INTERNATIONAL JOURNAL OF EXPERIMENTAL PLANT BIOLOGY 2024; 343:112081. [PMID: 38579979 DOI: 10.1016/j.plantsci.2024.112081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 03/08/2024] [Accepted: 04/01/2024] [Indexed: 04/07/2024]
Abstract
Chlorophyll biosynthesis and breakdown, important cellular processes for photosynthesis, occur in the chloroplast. As a semi-autonomous organelle, chloroplast development is mainly regulated by nuclear-encoded chloroplast proteins and proteins encoded by itself. However, the knowledge of chloroplast development regulated by other organelles is limited. Here, we report that the nuclear-localized XAP5 CIRCADIAN TIMEKEEPER (XCT) is essential for chloroplast development in Arabidopsis. In this study, significantly decreased chlorophyll content phenotypes of cotyledons and subsequently emerging organs from shoot apical meristem were observed in xct-2. XCT is constitutively expressed in various tissues and localized in the nuclear with speckle patterns. RNA-seq analysis identified 207 differently spliced genes and 1511 differently expressed genes, in which chloroplast development-, chlorophyll metabolism- and photosynthesis-related genes were enriched. Further biochemical assays suggested that XCT was co-purified with the well-known splicing factors and transcription machinery, suggesting dual functions of XCT in gene transcription and splicing. Interestingly, we also found that the chlorophyll contents in xct-2 significantly decreased under high temperature and high light condition, indicating XCT integrates temperature and light signals to fine-tune the chlorophyll metabolism in Arabidopsis. Therefore, our results provide new insights into chloroplast development regulation by XCT, a nuclear-localized protein, at the transcriptional and post-transcriptional level.
Collapse
Affiliation(s)
- Qian Gao
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China
| | - Ziyang Zeng
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China
| | - Tianqi Hao
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China
| | - Ziru Zhang
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China
| | - Daan Liang
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China
| | - Congcong Xia
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China
| | - Hui Gao
- College of Marine Resources and Environment, Hebei Normal University of Science and Technology, Qinhuangdao 066600, China.
| | - Lei Liu
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huaian 223300, China.
| |
Collapse
|
2
|
Liu L, Li X, Yuan L, Zhang G, Gao H, Xu X, Zhao H. XAP5 CIRCADIAN TIMEKEEPER specifically modulates 3' splice site recognition and is important for circadian clock regulation partly by alternative splicing of LHY and TIC. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2022; 172:151-157. [PMID: 35065375 DOI: 10.1016/j.plaphy.2022.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 01/14/2022] [Accepted: 01/16/2022] [Indexed: 06/14/2023]
Abstract
Pre-mRNA splicing is an essential step during gene expression, which takes place in the spliceosome, a large dynamic ribonucleoprotein complex assembled in a stepwise manner. During the last decade, several spliceosomal mutants were functionally identified to cause a lengthened circadian period by introducing intron retention defects into circadian clock genes in Arabidopsis. However, the spliceosomal components that play opposite roles in the circadian period via alternative 3' splice site (Alt 3'ss) are largely unknown. Here, we demonstrated that XCT (XAP5 CIRCADIAN TIMEKEEPER) is a key spliceosomal component associated with multiple splicing factors. Moreover, genome-wide analysis revealed that inactivation of XCT particularly results in defects in Alt 3'ss recognition by RNA sequencing. Further analysis indicated that a strong alteration in the 3' splice sites of LHY and TIC partly accounts for the shortened circadian period of the xct mutant. Therefore, our results demonstrated that mutations in XCT shortened the circadian period partly by alternative splicing of LHY and TIC particularly in 3' splice site recognition, which provides new insight into the link between alternative splicing and the circadian clock.
Collapse
Affiliation(s)
- Lei Liu
- Jiangsu Key Laboratory for Eco-agriculture Biotechnology Around Hongze Lake, Jiangsu Collaborative Innovation Center of Regional Modern Agriculture and Environment Protection, Huaiyin Normal University, Huai'an, 223300, China.
| | - Xiaoyun Li
- College of Life Science, Hebei Normal University, Hebei, 050024, China
| | - Li Yuan
- Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Guofang Zhang
- College of Life Science, Hebei Normal University, Hebei, 050024, China
| | - Hui Gao
- College of Marine Resources and Environment, Hebei Normal University of Science and Technology, Qinhuangdao, 066600, China
| | - Xiaodong Xu
- Key Laboratory of Plant Stress Biology, School of Life Sciences, Henan University, Kaifeng, 475004, China
| | - Hongtao Zhao
- College of Life Science, Hebei Normal University, Hebei, 050024, China.
| |
Collapse
|
3
|
Kumimoto RW, Ellison CT, Toruño TY, Bak A, Zhang H, Casteel CL, Coaker G, Harmer SL. XAP5 CIRCADIAN TIMEKEEPER Affects Both DNA Damage Responses and Immune Signaling in Arabidopsis. FRONTIERS IN PLANT SCIENCE 2021; 12:707923. [PMID: 34659282 PMCID: PMC8517334 DOI: 10.3389/fpls.2021.707923] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 08/30/2021] [Indexed: 06/02/2023]
Abstract
Numerous links have been reported between immune response and DNA damage repair pathways in both plants and animals but the precise nature of the relationship between these fundamental processes is not entirely clear. Here, we report that XAP5 CIRCADIAN TIMEKEEPER (XCT), a protein highly conserved across eukaryotes, acts as a negative regulator of immunity in Arabidopsis thaliana and plays a positive role in responses to DNA damaging radiation. We find xct mutants have enhanced resistance to infection by a virulent bacterial pathogen, Pseudomonas syringae pv. tomato DC3000, and are hyper-responsive to the defense-activating hormone salicylic acid (SA) when compared to wild-type. Unlike most mutants with constitutive effector-triggered immunity (ETI), xct plants do not have increased levels of SA and retain enhanced immunity at elevated temperatures. Genetic analysis indicates XCT acts independently of NONEXPRESSOR OF PATHOGENESIS RELATED GENES1 (NPR1), which encodes a known SA receptor. Since DNA damage has been reported to potentiate immune responses, we next investigated the DNA damage response in our mutants. We found xct seedlings to be hypersensitive to UV-C and γ radiation and deficient in phosphorylation of the histone variant H2A.X, one of the earliest known responses to DNA damage. These data demonstrate that loss of XCT causes a defect in an early step of the DNA damage response pathway. Together, our data suggest that alterations in DNA damage response pathways may underlie the enhanced immunity seen in xct mutants.
Collapse
Affiliation(s)
- Roderick W. Kumimoto
- Department of Plant Biology, University of California, Davis, Davis, CA, United States
| | - Cory T. Ellison
- Department of Plant Biology, University of California, Davis, Davis, CA, United States
| | - Tania Y. Toruño
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Aurélie Bak
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Hongtao Zhang
- Department of Plant Biology, University of California, Davis, Davis, CA, United States
| | - Clare L. Casteel
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, NY, United States
| | - Gitta Coaker
- Department of Plant Pathology, University of California, Davis, Davis, CA, United States
| | - Stacey L. Harmer
- Department of Plant Biology, University of California, Davis, Davis, CA, United States
| |
Collapse
|
4
|
Singh M, Mas P. A Functional Connection between the Circadian Clock and Hormonal Timing in Arabidopsis. Genes (Basel) 2018; 9:E567. [PMID: 30477118 PMCID: PMC6315462 DOI: 10.3390/genes9120567] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2018] [Revised: 11/20/2018] [Accepted: 11/20/2018] [Indexed: 02/04/2023] Open
Abstract
The rotation of the Earth entails changes in environmental conditions that pervasively influence an organism's physiology and metabolism. An internal cellular mechanism known as the circadian clock acts as an internal timekeeper that is able to perceive the changes in environmental cues to generate 24-h rhythms in synchronization with daily and seasonal fluctuations. In plants, the circadian clock function is particularly important and regulates nearly every aspect of plant growth and development as well as proper responses to stresses. The circadian clock does not function in isolation but rather interconnects with an intricate network of different pathways, including those of phytohormones. Here, we describe the interplay of the circadian clock with a subset of hormones in Arabidopsis. The molecular components directly connecting the circadian and hormone pathways are described, highlighting the biological significance of such connections in the control of growth, development, fitness, and survival. We focus on the overlapping as well as contrasting circadian and hormonal functions that together provide a glimpse on how the Arabidopsis circadian system regulates hormone function in response to endogenous and exogenous cues. Examples of feedback regulation from hormone signaling to the clock are also discussed.
Collapse
Affiliation(s)
- Manjul Singh
- Center for Research in Agricultural Genomics (CRAG), Consortium CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, 08193 Barcelona, Spain.
| | - Paloma Mas
- Center for Research in Agricultural Genomics (CRAG), Consortium CSIC-IRTA-UAB-UB, Campus UAB, Bellaterra, 08193 Barcelona, Spain.
- Consejo Superior de Investigaciones Científicas, 08028 Barcelona, Spain.
| |
Collapse
|