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Mallikarjuna MG, Tomar R, Lohithaswa HC, Sahu S, Mishra DC, Rao AR, Chinnusamy V. Genome-wide identification of potassium channels in maize showed evolutionary patterns and variable functional responses to abiotic stresses. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2024; 206:108235. [PMID: 38039585 DOI: 10.1016/j.plaphy.2023.108235] [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: 07/20/2023] [Revised: 11/08/2023] [Accepted: 11/22/2023] [Indexed: 12/03/2023]
Abstract
Potassium (K) channels are essential components of plant biology, mediating not only K ion (K+) homeostasis but also regulating several physiological processes and stress tolerance. In the current investigation, we identified 27 K+ channels in maize and deciphered the evolution and divergence pattern with four monocots and five dicot species. Chromosomal localization and expansion of K+ channel genes showed uneven distribution and were independent of genome size. The dispersed duplication is the major force in expanding K+ channels in the target genomes. The mean Ka/Ks ratio of <0.5 in paralogs and orthologs indicates horizontal and vertical expansions of K+ channel genes under strong purifying selection. The one-to-one K+ channel orthologs were prominent among the closely related species, with higher synteny between maize and the rest of the monocots. Comprehensive K+ channels promoter analysis revealed various cis-regulatory elements mediating stress tolerance with the predominance of MYB and STRE binding sites. The regulatory network showed AP2-EREBP TFs, miR164 and miR399 are prominent regulatory elements of K+ channels. The qRT-PCR analysis of K+ channels and regulatory miRNAs showed significant expressions in response to drought and waterlogging stresses. The present study expanded the knowledge on K+ channels in maize and will serve as a basis for an in-depth functional analysis.
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Affiliation(s)
| | - Rakhi Tomar
- Division of Genetics, ICAR- Indian Agricultural Research Institute, New Delhi, 110012, India
| | | | - Sarika Sahu
- Division of Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, New Delhi, 110012, India
| | - Dwijesh Chandra Mishra
- Division of Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, New Delhi, 110012, India
| | - Atmakuri Ramakrishna Rao
- Division of Agricultural Bioinformatics, ICAR-Indian Agricultural Statistics Research Institute, New Delhi, 110012, India
| | - Viswanathan Chinnusamy
- Division of Plant Physiology, ICAR- Indian Agricultural Research Institute, New Delhi, 110012, India
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Dougherty L, Borejsza-Wysocka E, Miaule A, Wang P, Zheng D, Jansen M, Brown S, Piñeros M, Dardick C, Xu K. A single amino acid substitution in MdLAZY1A dominantly impairs shoot gravitropism in Malus. PLANT PHYSIOLOGY 2023; 193:1142-1160. [PMID: 37394917 DOI: 10.1093/plphys/kiad373] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/15/2023] [Accepted: 06/16/2023] [Indexed: 07/04/2023]
Abstract
Plant architecture is 1 of the most important factors that determines crop yield potential and productivity. In apple (Malus domestica), genetic improvement of tree architecture has been challenging due to a long juvenile phase and growth as complex trees composed of a distinct scion and a rootstock. To better understand the genetic control of apple tree architecture, the dominant weeping growth phenotype was investigated. We report the identification of MdLAZY1A (MD13G1122400) as the genetic determinant underpinning the Weeping (W) locus that largely controls weeping growth in Malus. MdLAZY1A is 1 of the 4 paralogs in apple that are most closely related to AtLAZY1 involved in gravitropism in Arabidopsis (Arabidopsis thaliana). The weeping allele (MdLAZY1A-W) contains a single nucleotide mutation c.584T>C that leads to a leucine to proline (L195P) substitution within a predicted transmembrane domain that colocalizes with Region III, 1 of the 5 conserved regions in LAZY1-like proteins. Subcellular localization revealed that MdLAZY1A localizes to the plasma membrane and nucleus in plant cells. Overexpressing the weeping allele in apple cultivar Royal Gala (RG) with standard growth habit impaired its gravitropic response and altered the growth to weeping-like. Suppressing the standard allele (MdLAZY1A-S) by RNA interference (RNAi) in RG similarly changed the branch growth direction to downward. Overall, the L195P mutation in MdLAZY1A is genetically causal for weeping growth, underscoring not only the crucial roles of residue L195 and Region III in MdLAZY1A-mediated gravitropic response but also a potential DNA base editing target for tree architecture improvement in Malus and other crops.
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Affiliation(s)
- Laura Dougherty
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell Agritech, Geneva, NY 14456, USA
| | - Ewa Borejsza-Wysocka
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell Agritech, Geneva, NY 14456, USA
| | - Alexandre Miaule
- School of Integrative Plant Sciences, Plant Biology Section, Cornell University, Ithaca, NY 14853, USA
| | - Ping Wang
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell Agritech, Geneva, NY 14456, USA
| | - Desen Zheng
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell Agritech, Geneva, NY 14456, USA
| | - Michael Jansen
- United States Department of Agriculture-Agricultural Research Service, Systematic Entomology Laboratory, Electron and Confocal Microscopy Unit, Beltsville, MD 20705, USA
| | - Susan Brown
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell Agritech, Geneva, NY 14456, USA
| | - Miguel Piñeros
- School of Integrative Plant Sciences, Plant Biology Section, Cornell University, Ithaca, NY 14853, USA
- Robert W. Holley Center for Agriculture and Health, USDA-ARS, Ithaca, NY 14853, USA
| | - Christopher Dardick
- United States Department of Agriculture-Agricultural Research Service, Appalachian Fruit Research Station, Kearneysville, WV 25430, USA
| | - Kenong Xu
- Horticulture Section, School of Integrative Plant Science, Cornell University, Cornell Agritech, Geneva, NY 14456, USA
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Musavizadeh Z, Najafi-Zarrini H, Kazemitabar SK, Hashemi SH, Faraji S, Barcaccia G, Heidari P. Genome-Wide Analysis of Potassium Channel Genes in Rice: Expression of the OsAKT and OsKAT Genes under Salt Stress. Genes (Basel) 2021; 12:784. [PMID: 34065373 PMCID: PMC8160896 DOI: 10.3390/genes12050784] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Revised: 05/09/2021] [Accepted: 05/18/2021] [Indexed: 12/21/2022] Open
Abstract
Potassium (K+), as a vital element, is involved in regulating important cellular processes such as enzyme activity, cell turgor, and nutrient movement in plant cells, which affects plant growth and production. Potassium channels are involved in the transport and release of potassium in plant cells. In the current study, three OsKAT genes and two OsAKT genes, along with 11 nonredundant putative potassium channel genes in the rice genome, were characterized based on their physiochemical properties, protein structure, evolution, duplication, in silico gene expression, and protein-protein interactions. In addition, the expression patterns of OsAKTs and OsKATs were studied in root and shoot tissues under salt stress using real-time PCR in three rice cultivars. K+ channel genes were found to have diverse functions and structures, and OsKATs showed high genetic divergence from other K+ channel genes. Furthermore, the Ka/Ks ratios of duplicated gene pairs from the K+ channel gene family in rice suggested that these genes underwent purifying selection. Among the studied K+ channel proteins, OsKAT1 and OsAKT1 were identified as proteins with high potential N-glycosylation and phosphorylation sites, and LEU, VAL, SER, PRO, HIS, GLY, LYS, TYR, CYC, and ARG amino acids were predicted as the binding residues in the ligand-binding sites of K+ channel proteins. Regarding the coexpression network and KEGG ontology results, several metabolic pathways, including sugar metabolism, purine metabolism, carbon metabolism, glycerophospholipid metabolism, monoterpenoid biosynthesis, and folate biosynthesis, were recognized in the coexpression network of K+ channel proteins. Based on the available RNA-seq data, the K+ channel genes showed differential expression levels in rice tissues in response to biotic and abiotic stresses. In addition, the real-time PCR results revealed that OsAKTs and OsKATs are induced by salt stress in root and shoot tissues of rice cultivars, and OsKAT1 was identified as a key gene involved in the rice response to salt stress. In the present study, we found that the repression of OsAKTs, OsKAT2, and OsKAT2 in roots was related to salinity tolerance in rice. Our findings provide valuable insights for further structural and functional assays of K+ channel genes in rice.
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Affiliation(s)
- Zahra Musavizadeh
- Department of Biochemical Sciences, Sapienza University of Rome, 00185 Rome, Italy;
| | - Hamid Najafi-Zarrini
- Department of Plant Breeding, Sari Agricultural Sciences and Natural Resources University (SANRU), Sari 4818166996, Iran; (H.N.-Z.); (S.K.K.); (S.F.)
| | - Seyed Kamal Kazemitabar
- Department of Plant Breeding, Sari Agricultural Sciences and Natural Resources University (SANRU), Sari 4818166996, Iran; (H.N.-Z.); (S.K.K.); (S.F.)
| | - Seyed Hamidreza Hashemi
- Genetics and Agricultural Biotechnology Institute of Tabarestan, Sari Agricultural Sciences and Natural Resources University, Sari 4818166996, Iran;
| | - Sahar Faraji
- Department of Plant Breeding, Sari Agricultural Sciences and Natural Resources University (SANRU), Sari 4818166996, Iran; (H.N.-Z.); (S.K.K.); (S.F.)
| | - Gianni Barcaccia
- Laboratory of Genomics for Breeding, DAFNAE, Campus of Agripolis, University of Padova, Legnaro, 35020 Padova, Italy;
| | - Parviz Heidari
- Faculty of Agriculture, Shahrood University of Technology, Shahrood 3619995161, Iran
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Jin R, Zhang A, Sun J, Chen X, Liu M, Zhao P, Jiang W, Tang Z. Identification of Shaker K + channel family members in sweetpotato and functional exploration of IbAKT1. Gene 2020; 768:145311. [PMID: 33220344 DOI: 10.1016/j.gene.2020.145311] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 10/10/2020] [Accepted: 11/13/2020] [Indexed: 01/27/2023]
Abstract
The Shaker K+ channel family plays a vital role in potassium absorption and stress resistance in plants. However little information on the genes family is available about sweetpotato. In the present study, eleven sweetpotato Shaker K+ channel genes were identified and classified into five groups based on phylogenetic relationships, conserved motifs, and gene structure analyses. Based on synteny analysis, four duplicated gene pairs were identified, derived from both ancient and recent duplication, whereas only one resulted from tandem duplication events. Different expression pattern of Shaker K+ channel genes in roots of Xu32 and NZ1 resulted in different K+ deficiency tolerances, suggesting there is different mechanism of K+ uptake in sweetpotato cultivars with different K+-tolerance levels. Quantitative real-time PCR analysis revealed that the shaker K+ channel genes responded to drought and high salt stresses. Higher K+ influx under normal condition and lower K+ efflux under K+ deficiency stress were observed in IbAKT1 overexpressing transgenic roots than in adventitious roots, which indicated that IbAKT1 may play an important role in the regulation of K+ deficiency tolerance in sweetpotato. This is the first genome-wide analysis of Shaker K+ channel genes and the first functional analysis of IbAKT1 in sweetpotato. Our results provide valuable information on the gene structure, evolution, expression and functions of the Shaker K+ channel gene family in sweetpotato.
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Affiliation(s)
- Rong Jin
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China
| | - Aijun Zhang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China
| | - Jian Sun
- Jiangsu Key Laboratory of Phylogenomics and Comparative Genomics, School of Life Sciences, Jiangsu Normal University, Xuzhou 221116, Jiangsu, China
| | - Xiaoguang Chen
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China
| | - Ming Liu
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China
| | - Peng Zhao
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China
| | - Wei Jiang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China
| | - Zhonghou Tang
- Xuzhou Sweetpotato Research Center, Xuzhou Institute of Agricultural Sciences, Jiangsu, China; Key Laboratory of Sweetpotato Biology and Genetic Breeding, Ministry of Agriculture, Xuzhou, China.
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Min MK, Choi EH, Kim JA, Yoon IS, Han S, Lee Y, Lee S, Kim BG. Two Clade A Phosphatase 2Cs Expressed in Guard Cells Physically Interact With Abscisic Acid Signaling Components to Induce Stomatal Closure in Rice. RICE (NEW YORK, N.Y.) 2019; 12:37. [PMID: 31134357 PMCID: PMC6536566 DOI: 10.1186/s12284-019-0297-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2018] [Accepted: 05/14/2019] [Indexed: 05/13/2023]
Abstract
BACKGROUND The core ABA signaling components functioning in stomatal closure/opening, namely ABA receptors, phosphatases, SnRK2s and SLAC1, are well characterized in Arabidopsis, but their functions in guard cells of rice have not been extensively studied. RESULTS In this study, we confirmed that OsSLAC1, the rice homolog of AtSLAC1, is specifically expressed in rice guard cells. Among the rice SAPKs, SAPK10 was specifically expressed in guard cells. In addition, SAPK10 phosphorylated OsSLAC1 in vitro and transgenic rice overexpressing SAPK10 or OsSLAC1 showed significantly less water loss than control. Thus, those might be major positive signaling components to close stomata in rice. We identified that only OsPP2C50 and OsPP2C53 among 9 OsPP2CAs might be related with stomatal closure/opening signaling based on guard cell specific expression and subcellular localization. Transgenic rice overexpressing OsPP2C50 and OsPP2C53 showed significantly higher water loss than control. We also characterized the interaction networks between OsPP2C50 and OsPP2C53, SAPK10 and OsSLAC1 and found two interaction pathways among those signaling components: a hierarchical interaction pathway that consisted of OsPP2C50 and OsPP2C53, SAPK10 and OsSLAC1; and a branched interaction pathway wherein OsPP2C50 and OsPP2C53 interacted directly with OsSLAC1. CONCLUSION OsPP2C50 and OsPP2C53 is major negative regulators of ABA signaling regarding stomata closing in rice. Those can regulate the OsSLAC1 directly or indirectly thorough SAPK10.
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Affiliation(s)
- Myung Ki Min
- Metabolic Engineering Division, Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, 54875, Republic of Korea
| | - Eun-Hye Choi
- Metabolic Engineering Division, Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, 54875, Republic of Korea
| | - Jin-Ae Kim
- Metabolic Engineering Division, Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, 54875, Republic of Korea
| | - In Sun Yoon
- Gene Engineering Division, Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, 54875, Republic of Korea
| | - Seungsu Han
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Yeongmok Lee
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Sangho Lee
- Department of Biological Sciences, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Beom-Gi Kim
- Metabolic Engineering Division, Department of Agricultural Biotechnology, National Institute of Agricultural Sciences, Rural Development Administration, Jeonju, 54875, Republic of Korea.
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Gao YQ, Wu WH, Wang Y. Electrophysiological Identification and Activity Analyses of Plasma Membrane K+ Channels in Maize Guard Cells. PLANT & CELL PHYSIOLOGY 2019; 60:765-777. [PMID: 30590755 DOI: 10.1093/pcp/pcy242] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Accepted: 12/19/2018] [Indexed: 05/11/2023]
Abstract
Stomatal movement, which plays an essential role in plant transpiration and photosynthesis, is controlled by ion channels that mediate K+ and anion fluxes across the plasma membrane (PM) of guard cells. These channels in dicots are accurately regulated by various physiological factors, such as pH, abscisic acid (ABA) and Ca2+; however, the data in monocots are limited. Here the whole-cell patch-clamping technique was applied to analyze the properties and regulations of PM K+ channels in maize guard cells. The results indicated that the hyperpolarization-activated inward-rectifying channels were highly K+-selective. These inward K+ (Kin) channels were sensitive to extracellular K+. Their slope factor (S) decreased when the apoplastic K+ concentration decline, causing a positive shift of the half-activation potential (V1/2). Their activities were promoted by apoplastic acidification but inhibited by apoplastic and cytosolic alkalization. Nevertheless, the outward K+ (Kout) channel activities were uniquely promoted by cytosolic alkalization. Both apoplastic and cytosolic ABA inhibited Kin channels independent of cytosolic Ca2+ ([Ca2+]cyt). And two Ca2+-dependent mechanisms with different Ca2+ affinities may mediate resting- and high-[Ca2+]cyt-induced inhibition on Kin channels, respectively. However, resting [Ca2+]cyt impaired the inhibition of Kin channels induced by apoplastic ABA, not cytosolic ABA. Furthermore, the result that high [Ca2+]cyt attenuated ABA-induced inhibition highlighted the importance of [Ca2+]cyt for Kin channel regulation. There may exist a Ca2+-dependent regulation of the Ca2+-independent ABA signaling pathways for Kin channel inhibition. These results provided an electrophysiological view of the multiple level regulations of PM K+ channel activities and kinetics in maize guard cells.
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Affiliation(s)
- Yong-Qiang Gao
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing, China
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing, China
- Center for Crop Functional Genomics and Molecular Breeding, China Agricultural University, Beijing, China
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Dwivedi SL, Siddique KHM, Farooq M, Thornton PK, Ortiz R. Using Biotechnology-Led Approaches to Uplift Cereal and Food Legume Yields in Dryland Environments. FRONTIERS IN PLANT SCIENCE 2018; 9:1249. [PMID: 30210519 PMCID: PMC6120061 DOI: 10.3389/fpls.2018.01249] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 08/06/2018] [Indexed: 05/29/2023]
Abstract
Drought and heat in dryland agriculture challenge the enhancement of crop productivity and threaten global food security. This review is centered on harnessing genetic variation through biotechnology-led approaches to select for increased productivity and stress tolerance that will enhance crop adaptation in dryland environments. Peer-reviewed literature, mostly from the last decade and involving experiments with at least two seasons' data, form the basis of this review. It begins by highlighting the adverse impact of the increasing intensity and duration of drought and heat stress due to global warming on crop productivity and its impact on food and nutritional security in dryland environments. This is followed by (1) an overview of the physiological and molecular basis of plant adaptation to elevated CO2 (eCO2), drought, and heat stress; (2) the critical role of high-throughput phenotyping platforms to study phenomes and genomes to increase breeding efficiency; (3) opportunities to enhance stress tolerance and productivity in food crops (cereals and grain legumes) by deploying biotechnology-led approaches [pyramiding quantitative trait loci (QTL), genomic selection, marker-assisted recurrent selection, epigenetic variation, genome editing, and transgene) and inducing flowering independent of environmental clues to match the length of growing season; (4) opportunities to increase productivity in C3 crops by harnessing novel variations (genes and network) in crops' (C3, C4) germplasm pools associated with increased photosynthesis; and (5) the adoption, impact, risk assessment, and enabling policy environments to scale up the adoption of seed-technology to enhance food and nutritional security. This synthesis of technological innovations and insights in seed-based technology offers crop genetic enhancers further opportunities to increase crop productivity in dryland environments.
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Affiliation(s)
| | | | - Muhammad Farooq
- The UWA Institute of Agriculture, The University of Western Australia, Perth, WA, Australia
- Department of Crop Sciences, College of Agricultural and Marine Sciences, Sultan Qaboos University, Al Khoud, Oman
- University of Agriculture, Faisalabad, Pakistan
| | - Philip K. Thornton
- CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), International Livestock Research Institute (ILRI), Nairobi, Kenya
| | - Rodomiro Ortiz
- Department of Plant Breeding, Swedish University of Agricultural Sciences, Alnarp, Sweden
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Gao YQ, Wu WH, Wang Y. The K + channel KZM2 is involved in stomatal movement by modulating inward K + currents in maize guard cells. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2017; 92:662-675. [PMID: 28891257 DOI: 10.1111/tpj.13712] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 08/28/2017] [Accepted: 09/01/2017] [Indexed: 06/07/2023]
Abstract
Stomata are the major gates in plant leaf that allow water and gas exchange, which is essential for plant transpiration and photosynthesis. Stomatal movement is mainly controlled by the ion channels and transporters in guard cells. In Arabidopsis, the inward Shaker K+ channels, such as KAT1 and KAT2, are responsible for stomatal opening. However, the characterization of inward K+ channels in maize guard cells is limited. In the present study, we identified two KAT1-like Shaker K+ channels, KZM2 and KZM3, which were highly expressed in maize guard cells. Subcellular analysis indicated that KZM2 and KZM3 can localize at the plasma membrane. Electrophysiological characterization in HEK293 cells revealed that both KZM2 and KZM3 were inward K+ (Kin ) channels, but showing distinct channel kinetics. When expressed in Xenopus oocytes, only KZM3, but not KZM2, can mediate inward K+ currents. However, KZM2 can interact with KZM3 forming heteromeric Kin channel. In oocytes, KZM2 inhibited KZM3 channel conductance and negatively shifted the voltage dependence of KZM3. The activation of KZM2-KZM3 heteromeric channel became slower than the KZM3 channel. Patch-clamping results showed that the inward K+ currents of maize guard cells were significantly increased in the KZM2 RNAi lines. In addition, the RNAi lines exhibited faster stomatal opening after light exposure. In conclusion, the presented results demonstrate that KZM2 functions as a negative regulator to modulate the Kin channels in maize guard cells. KZM2 and KZM3 may form heteromeric Kin channel and control stomatal opening in maize.
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Affiliation(s)
- Yong-Qiang Gao
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Wei-Hua Wu
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yi Wang
- State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB), College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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