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Meng Y, Zhan J, Liu H, Liu J, Wang Y, Guo Z, He S, Nie L, Kohli A, Ye G. Natural variation of OsML1, a mitochondrial transcription termination factor, contributes to mesocotyl length variation in rice. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 115:910-925. [PMID: 37133286 DOI: 10.1111/tpj.16267] [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: 12/24/2022] [Revised: 04/04/2023] [Accepted: 04/27/2023] [Indexed: 05/04/2023]
Abstract
Mesocotyl length (ML) is a crucial factor in determining the establishment and yield of rice planted through dry direct seeding, a practice that is increasingly popular in rice production worldwide. ML is determined by the endogenous and external environments, and inherits as a complex trait. To date, only a few genes have been cloned, and the mechanisms underlying mesocotyl elongation remain largely unknown. Here, through a genome-wide association study using sequenced germplasm, we reveal that natural allelic variations in a mitochondrial transcription termination factor, OsML1, predominantly determined the natural variation of ML in rice. Natural variants in the coding regions of OsML1 resulted in five major haplotypes with a clear differentiation between subspecies and subpopulations in cultivated rice. The much-reduced genetic diversity of cultivated rice compared to the common wild rice suggested that OsML1 underwent selection during domestication. Transgenic experiments and molecular analysis demonstrated that OsML1 contributes to ML by influencing cell elongation primarily determined by H2 O2 homeostasis. Overexpression of OsML1 promoted mesocotyl elongation and thus improved the emergence rate under deep direct seeding. Taken together, our results suggested that OsML1 is a key positive regulator of ML, and is useful in developing varieties for deep direct seeding by conventional and transgenic approaches.
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Affiliation(s)
- Yun Meng
- Sanya Nanfan Research Institute of Hainan University, Hainan University, Sanya, 572025, China
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Junhui Zhan
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Hongyan Liu
- Sanya Nanfan Research Institute of Hainan University, Hainan University, Sanya, 572025, China
| | - Jindong Liu
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Yamei Wang
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Zhan Guo
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Sang He
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Lixiao Nie
- Sanya Nanfan Research Institute of Hainan University, Hainan University, Sanya, 572025, China
| | - Ajay Kohli
- Rice Breeding Innovations Platform, International Rice Research Institute (IRRI), Metro Manila, 1301, Philippines
| | - Guoyou Ye
- CAAS-IRRI Joint Laboratory for Genomics-Assisted Germplasm Enhancement, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
- Rice Breeding Innovations Platform, International Rice Research Institute (IRRI), Metro Manila, 1301, Philippines
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Zhao X, Niu Y, Hossain Z, Shi J, Mao T, Bai X. Integrated QTL Mapping, Meta-Analysis, and RNA-Sequencing Reveal Candidate Genes for Maize Deep-Sowing Tolerance. Int J Mol Sci 2023; 24:ijms24076770. [PMID: 37047743 PMCID: PMC10094843 DOI: 10.3390/ijms24076770] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2023] [Revised: 03/24/2023] [Accepted: 03/30/2023] [Indexed: 04/08/2023] Open
Abstract
Synergetic elongation of mesocotyl and coleoptile are crucial in governing maize seedlings emergence, especially for the maize sown in deep soil. Studying the genomic regions controlling maize deep-sowing tolerance would aid the development of new varieties that are resistant to harsh conditions, such as drought and low temperature during seed germination. Using 346 F2:3 maize population families from W64A × K12 cross at three sowing depths, we identified 33 quantitative trait loci (QTLs) for the emergence rate, mesocotyl, coleoptile, and seedling lengths via composite interval mapping (CIM). These loci explained 2.89% to 14.17% of phenotypic variation in a single environment, while 12 of 13 major QTLs were identified at two or more sowing environments. Among those, four major QTLs in Bin 1.09, Bin 4.08, Bin 6.01, and Bin 7.02 supported pleiotropy for multiple deep-sowing tolerant traits. Meta-analysis identified 17 meta-QTLs (MQTLs) based on 130 original QTLs from present and previous studies. RNA-Sequencing of mesocotyl and coleoptile in both parents (W64A and K12) at 3 cm and 20 cm sowing environments identified 50 candidate genes expressed differentially in all major QTLs and MQTLs regions: six involved in the circadian clock, 27 associated with phytohormones biosynthesis and signal transduction, seven controlled lignin biosynthesis, five regulated cell wall organization formation and stabilization, three were responsible for sucrose and starch metabolism, and two in the antioxidant enzyme system. These genes with highly interconnected networks may form a complex molecular mechanism of maize deep-sowing tolerance. Findings of this study will facilitate the construction of molecular modules for deep-sowing tolerance in maize. The major QTLs and MQTLs identified could be used in marker-assisted breeding to develop elite maize varieties.
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Affiliation(s)
- Xiaoqiang Zhao
- State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China
| | - Yining Niu
- State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China
| | - Zakir Hossain
- Swift Current Research and Development Centre, Agriculture and Agri-Food Canada, Swift Current, SK S9H 3X2, Canada
| | - Jing Shi
- State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China
| | - Taotao Mao
- State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China
| | - Xiaodong Bai
- State Key Laboratory of Aridland Crop Science, College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China
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Molecular Mechanism of Gibberellins in Mesocotyl Elongation Response to Deep-Sowing Stress in Sweet Maize. Curr Issues Mol Biol 2022; 45:197-211. [PMID: 36661501 PMCID: PMC9856927 DOI: 10.3390/cimb45010015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2022] [Revised: 12/15/2022] [Accepted: 12/20/2022] [Indexed: 12/31/2022] Open
Abstract
Uneven germination is still a common problem in sweet maize planting. The mesocotyl is a key driver for ground-breaking sweet maize, and deep-sowing has a longer mesocotyl. However, the physiological and molecular mechanisms of sweet maize mesocotyl elongation in response to deep-sowing remain unknown. Here we found that sweet maize inbred line Ltx05 could obtain longer mesocotyls in deep soil of 10 cm depth, and that 20 mg/L GA3 was the optimal concentration to promote mesocotyl elongation and seedling emergence. Microstructure observation showed that the longitudinal cell length of mesocotyl at 10 cm sowing depth was significantly longer than that of 1 cm. Transcriptome analysis showed that microtubule process related differentially expressed genes may contribute to the longitudinal cell elongation. The content of GAs in the mesocotyl at 10 cm sowing depth was markedly higher than that of 1 cm. Combining transcriptome data and qRT-PCR at different developmental stages, ZmGA20ox1, ZmGA20ox4 and ZmGA20ox5 were identified as three positive regulation candidate genes during mesocotyl elongation under deep-sowing conditions, and this was further confirmed by the significant elongation of the hypocotyl in heterologous transformation of Arabidopsis thaliana. These results lay a foundation for improving the ability of sweet maize to tolerate deep-sowing stress and improving the breeding of excellent deep-sowing-tolerant germplasms.
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