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Shi CY, Hussain SB, Guo LX, Yang H, Ning DY, Liu YZ. Genome-wide identification and transcript analysis of vacuolar-ATPase genes in citrus reveal their possible involvement in citrate accumulation. PHYTOCHEMISTRY 2018; 155:147-154. [PMID: 30121429 DOI: 10.1016/j.phytochem.2018.08.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 07/26/2018] [Accepted: 08/12/2018] [Indexed: 06/08/2023]
Abstract
The vacuolar H+-ATPase (V-ATPase) proton pump plays an important role in the acidification of vacuoles; however, genes encoding V-ATPase in the citrus genome and their roles in citric acid accumulation remain unclear in citrus fruit. In this study, we found at least one gene encoding subunit A, B, C, D, G, c'', d or e; two genes encoding the subunit E, F, H or a; and four genes encoding subunit c in the citrus genome. Spatial expression analysis showed that most genes were predominantly expressed in the mature leaves and/or flowers but were less expressed in root and juice cells. Two sweet orange (Citrus sinensis) cultivars, 'Anliu' (AL) and 'Hong Anliu' (HAL), which differ in terms of fruit acidity, were used in this study. The citric acid content was significantly higher in 'AL' fruits than in 'HAL' fruits over the entire experimental period (82 days-236 days after full blossom, DAFB). Transcript analysis showed that the transcript levels of most subunit genes, including V1-A, V1-B, V1-C, V1-E1, V1-G, V1-H2 and V0-a2, V0-c", V0-c4, and V0-d, were significantly lower in 'HAL' than in 'AL' fruits during fruit development and ripening. Moreover, ABA injection significantly increased the citric acid content, simultaneously accompanied by the obvious induction of V1-A, V1-C, V1-E1, V1-F1, V1-H2, V0-a1, V0-a2, V0-c1, V0-c2, V0-c4, and V0-d transcription levels. In conclusion, the results demonstrated that V1-A, V1-C, V1-E1, V1-H2, V0-a2, V0-c4, and V0-d may play more roles than other subunit genes in the vacuole acidification of citrus fruits. The lower activity of V-ATPase caused by the transcript reduction of some subunit genes may be one reason for the low citrate accumulation in 'HAL' juice sacs.
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Affiliation(s)
- Cai-Yun Shi
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, PR China; College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Syed Bilal Hussain
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, PR China; College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Ling-Xia Guo
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, PR China; College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Huan Yang
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, PR China; College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Dong-Yuan Ning
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, PR China; College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, PR China
| | - Yong-Zhong Liu
- Key Laboratory of Horticultural Plant Biology (Ministry of Education), Huazhong Agricultural University, Wuhan, 430070, PR China; College of Horticulture & Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, PR China.
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Shi CY, Song RQ, Hu XM, Liu X, Jin LF, Liu YZ. Citrus PH5-like H(+)-ATPase genes: identification and transcript analysis to investigate their possible relationship with citrate accumulation in fruits. FRONTIERS IN PLANT SCIENCE 2015; 6:135. [PMID: 25806039 PMCID: PMC4353184 DOI: 10.3389/fpls.2015.00135] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 02/19/2015] [Indexed: 05/18/2023]
Abstract
PH5 is a petunia gene that encodes a plasma membrane H(+)-ATPase and determines the vacuolar pH. The citrate content of fruit cell vacuoles influences citrus organoleptic qualities. Although citrus could have PH5-like homologs that are involved in citrate accumulation, the details are still unknown. In this study, extensive data-mining with the PH5 sequence and PCR amplification confirmed that there are at least eight PH5-like genes (CsPH1-8) in the citrus genome. CsPHs have a molecular mass of approximately 100 kDa, and they have high similarity to PhPH5, AtAHA10 or AtAHA2 (from 64.6 to 80.9%). They contain 13-21 exons and 12-20 introns and were evenly distributed into four subgroups of the P3A-subfamily (CsPH1, CsPH2, and CsPH3 in Group I, CsPH4 and CsPH5 in Group II, CsPH6 in Group IV, and CsPH7 and CsPH8 in Group III together with PhPH5). A transcript analysis showed that CsPH1, 3, and 4 were predominantly expressed in mature leaves, whereas CsPH2 and 7 were predominantly expressed in roots, CsPH5 and 6 were predominantly expressed in flowers, and CsPH8 was predominantly expressed in fruit juice sacs (JS). Moreover, the CsPH transcript profiles differed between orange and pummelo, as well as between high-acid and low-acid cultivars. The low-acid orange "Honganliu" exhibits low transcript levels of CsPH3, CsPH4, CsPH5, and CsPH8, whereas the acid-free pummelo (AFP) has only a low transcript level of CsPH8. In addition, ABA injection increased the citrate content significantly, which was accompanied by the obvious induction of CsPH2, 6, 7, and 8 transcript levels. Taken together, we suggest that CsPH8 seems likely to regulate citrate accumulation in the citrus fruit vacuole.
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Affiliation(s)
- Cai-Yun Shi
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural UniversityWuhan, China
- Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), Ministry of EducationWuhan, China
| | - Rui-Qin Song
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural UniversityWuhan, China
- Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), Ministry of EducationWuhan, China
| | - Xiao-Mei Hu
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural UniversityWuhan, China
- Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), Ministry of EducationWuhan, China
| | - Xiao Liu
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural UniversityWuhan, China
- Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), Ministry of EducationWuhan, China
| | - Long-Fei Jin
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural UniversityWuhan, China
- Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), Ministry of EducationWuhan, China
| | - Yong-Zhong Liu
- Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural UniversityWuhan, China
- Key Laboratory of Horticultural Crop Biology and Genetic Improvement (Central Region), Ministry of EducationWuhan, China
- *Correspondence: Yong-Zhong Liu, Key Laboratory of Horticultural Plant Biology, Ministry of Education, Huazhong Agricultural University, Shizishan Road 1#, Wuhan 430070, China
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