Current Biotechnology ›› 2024, Vol. 14 ›› Issue (2): 173-181.DOI: 10.19586/j.2095-2341.2023.0157
• Reviews • Next Articles
Jiaqi SUN1,2(
), Jia GUO2, Chuang ZHANG2, Qing LIU2, Ziyu WANG2, Hanchao XIA2, Buxuan QIAN2, Fangfang ZHAO2, Qi WANG2, Jianfeng LIU1(
), Xiangguo LIU2(
)
Received:2023-12-07
Accepted:2024-01-04
Online:2024-03-25
Published:2024-04-17
Contact:
Jianfeng LIU,Xiangguo LIU
孙佳琪1,2(
), 郭嘉2, 张闯2, 柳青2, 王梓钰2, 夏涵超2, 钱步轩2, 赵方方2, 王棋2, 刘剑锋1(
), 刘相国2(
)
通讯作者:
刘剑锋,刘相国
作者简介:孙佳琪E-mail: 1094233375@qq.com
基金资助:CLC Number:
Jiaqi SUN, Jia GUO, Chuang ZHANG, Qing LIU, Ziyu WANG, Hanchao XIA, Buxuan QIAN, Fangfang ZHAO, Qi WANG, Jianfeng LIU, Xiangguo LIU. Research Progress of Phosphite Dehydrogenase in Genetically Engineered Microorganisms and Plants[J]. Current Biotechnology, 2024, 14(2): 173-181.
孙佳琪, 郭嘉, 张闯, 柳青, 王梓钰, 夏涵超, 钱步轩, 赵方方, 王棋, 刘剑锋, 刘相国. 亚磷酸脱氢酶在基因工程改造微生物和植物中的研究进展[J]. 生物技术进展, 2024, 14(2): 173-181.
| 基因来源 | 微生物种类 | 目标性状及产业化效果 | 参考文献 |
|---|---|---|---|
施氏假单胞菌 (Pseudomonas stutzeri) | 枯草芽孢杆菌 (Bacillus subtilis) | 建立抗菌污染体系,提高产物生产效率 | [ |
施氏假单胞菌 (Pseudomonas stutzeri) | 谷氨酸棒状杆菌 (Corynebacterium glutamicum) | 缩短发酵周期、简化发酵过程,降低生产成本,但目前连续发酵的赖氨酸产量不是很理想 | [ |
施氏假单胞菌WM88 (Pseudomonas sp. WM88) | 莱恩衣藻 (Chlamydomonas reinhardtii) | 作为选择标记基因,建立转质体系使其成为鉴定转化菌株的有效工具 | [ |
Table 1 Application of phosphite dehydrogenase genes in microorganisms
| 基因来源 | 微生物种类 | 目标性状及产业化效果 | 参考文献 |
|---|---|---|---|
施氏假单胞菌 (Pseudomonas stutzeri) | 枯草芽孢杆菌 (Bacillus subtilis) | 建立抗菌污染体系,提高产物生产效率 | [ |
施氏假单胞菌 (Pseudomonas stutzeri) | 谷氨酸棒状杆菌 (Corynebacterium glutamicum) | 缩短发酵周期、简化发酵过程,降低生产成本,但目前连续发酵的赖氨酸产量不是很理想 | [ |
施氏假单胞菌WM88 (Pseudomonas sp. WM88) | 莱恩衣藻 (Chlamydomonas reinhardtii) | 作为选择标记基因,建立转质体系使其成为鉴定转化菌株的有效工具 | [ |
| 基因来源 | 植物种类 | 目标性状及意义 | 参考文献 |
|---|---|---|---|
施氏假单胞菌WM88 (Pseudomonas sp. WM88) | 拟南芥 (Arabidopsis thaliana) | 转基因模式植物能代谢亚磷酸盐,为后续开发亚磷酸盐作为除草剂提供基础 | [ |
| 施氏假单胞菌WM88 | 烟草 (Nicotiana tabacum) | 转基因模式植物代谢亚磷酸盐,将亚磷酸盐作为新的磷源 | [ |
| 施氏假单胞菌WM88 | 棉花 (Gossypium spp.) | 建立ptxD/Phi筛选体系,作为除草剂 | [ |
| 施氏假单胞菌WM88 | 油菜 (Brassica napus) | 使其代谢亚磷酸盐,为后续油菜利用亚磷酸盐作为磷肥奠定基础 | [ |
罗尔斯通菌 4506 (Ralstonia 4506) | 水稻 (Oryza sativa) | 作为筛选标记基因,增加了筛选效率,而且降低了对自然的安全隐患 | [ |
| 施氏假单胞菌WM88 | 玉米 (Zea mays) | 建立ptxD/Phi选择标记系统,虽然转基因玉米能代谢亚磷酸盐,但愈伤组织的转化频率不高,后续需要对例如亚磷酸盐浓度等进行改进 | [ |
Table 2 Application of phosphite dehydrogenase genes in plants
| 基因来源 | 植物种类 | 目标性状及意义 | 参考文献 |
|---|---|---|---|
施氏假单胞菌WM88 (Pseudomonas sp. WM88) | 拟南芥 (Arabidopsis thaliana) | 转基因模式植物能代谢亚磷酸盐,为后续开发亚磷酸盐作为除草剂提供基础 | [ |
| 施氏假单胞菌WM88 | 烟草 (Nicotiana tabacum) | 转基因模式植物代谢亚磷酸盐,将亚磷酸盐作为新的磷源 | [ |
| 施氏假单胞菌WM88 | 棉花 (Gossypium spp.) | 建立ptxD/Phi筛选体系,作为除草剂 | [ |
| 施氏假单胞菌WM88 | 油菜 (Brassica napus) | 使其代谢亚磷酸盐,为后续油菜利用亚磷酸盐作为磷肥奠定基础 | [ |
罗尔斯通菌 4506 (Ralstonia 4506) | 水稻 (Oryza sativa) | 作为筛选标记基因,增加了筛选效率,而且降低了对自然的安全隐患 | [ |
| 施氏假单胞菌WM88 | 玉米 (Zea mays) | 建立ptxD/Phi选择标记系统,虽然转基因玉米能代谢亚磷酸盐,但愈伤组织的转化频率不高,后续需要对例如亚磷酸盐浓度等进行改进 | [ |
| 1 | LÓPEZ-ARREDONDO D L, HERRERA-ESTRELLA L. Engineering phosphorus metabolism in plants to produce a dual fertilization and weed control system[J]. Nat. Biotechnol., 2012, 30: 889-893. |
| 2 | 刘同同,刘诗琦,袁丽丽,等.亚磷酸脱氢酶作为筛选标记基因在水稻遗传转化中的应用[J].华中农业大学学报,2022,41(2):98-104. |
| LIU T T, LIU S Q, YUAN L L, et al.. Using phosphite dehydrogenase as a screening marker gene in rice genetic transformation[J]. J. Huazhong Agric. Univ., 2022, 41(2): 98-104. | |
| 3 | GUO Z W, OU X Y, LIANG S, et al.. Recruiting a phosphite dehydrogenase/formamidase-driven antimicrobial contamination system in Bacillus subtilis for nonsterilized fermentation of acetoin[J]. ACS Synth. Biol., 2020, 9(9): 2537-2545. |
| 4 | FOSTER T L, WINANS L, HELMS S J. Anaerobic utilization of phosphite and hypophosphite by Bacillus sp.[J]. Appl. Environ. Microbiol., 1978, 35(5): 937-944. |
| 5 | COSTAS A M, WHITE A K, METCALF W W. Purification and characterization of a novel phosphorus-oxidizing enzyme from Pseudomonas stutzeri WM88[J]. J. Biol. Chem., 2001, 276(20): 17429-17436. |
| 6 | METCALF W W, WOLFE R S. Molecular genetic analysis of phosphite and hypophosphite oxidation by Pseudomonas stutzeri WM88[J]. J. Bacteriol., 1998, 180(21): 5547-5558. |
| 7 | BARD A J P. Standard potentials in aqueous solutions[M]. New York: Marcel Dekker, 1985. |
| 8 | HIROTA R, YAMANE S T, FUJIBUCHI T, et al.. Isolation and characterization of a soluble and thermostable phosphite dehydrogenase from Ralstonia sp. strain 4506[J]. J. Biosci. Bioeng., 2012, 113(4): 445-450. |
| 9 | ZOU Y, ZHANG H, BRUNZELLE J S, et al.. Crystal structures of phosphite dehydrogenase provide insights into nicotinamide cofactor regeneration[J]. Biochemistry, 2012, 51(21): 4263-4270. |
| 10 | RELYEA H A, VAN DER DONK W A. Mechanism and applications of phosphite dehydrogenase[J]. Bioorg. Chem., 2005, 33(3): 171-189. |
| 11 | 张向楠.亚磷酸脱氢酶的体外定向进化及其固定化研究[D].武汉:华中农业大学,2016. |
| 12 | VRTIS J M, WHITE A K, METCALF W W, et al.. Phosphite dehydrogenase: an unusual phosphoryl transfer reaction[J]. J. Am. Chem. Soc., 2001, 123(11): 2672-2673. |
| 13 | MORTON S C, GLINDEMANN D, WANG X, et al.. Analysis of reduced phosphorus in samples of environmental interest[J]. Environ. Sci. Technol., 2005, 39(12): 4369-4376. |
| 14 | PASEK M A. Rethinking early earth phosphorus geochemistry[J]. Proc. Natl. Acad. Sci. USA, 2008, 105(3): 853-858. |
| 15 | WHITE A K, METCALF W W. Microbial metabolism of reduced phosphorus compounds[J]. Annu. Rev. Microbiol., 2007, 61: 379-400. |
| 16 | STONE B L, WHITE A K. Most probable number quantification of hypophosphite and phosphite oxidizing bacteria in natural aquatic and terrestrial environments[J]. Arch. Microbiol., 2012, 194(3): 223-228. |
| 17 | ADAMS F, CONRAD J P. Transition of phosphite to phosphate in soils[J]. Soil Sci., 1953, 75(5): 361-371. |
| 18 | CASIDA L E. Microbial oxidation and utilization of orthophosphite during growth[J]. J. Bacteriol., 1960, 80: 237-241. |
| 19 | MALACINSKI G, KONETZKA W A. Bacterial oxidation of orthophosphate[J]. J. Bacteriol., 1966, 91(2): 578-582. |
| 20 | YANG K, METCALF W W. A new activity for an old enzyme: Escherichia coli bacterial alkaline phosphatase is a phosphite-dependent hydrogenase[J]. Proc. Natl. Acad. Sci. USA, 2004, 101(21): 7919-7924. |
| 21 | MCDONALD A, GRANT B, PLAXTON W. Phosphite (phosphorous acid): its relevance in the environment and agriculture and influence on plant phosphate starvation response[J]. J. Plant Nutr., 2001, 24(10): 1505-1519. |
| 22 | LEI M, PENG X, SUN W, et al.. Nonsterile L-lysine fermentation using engineered phosphite-grown Corynebacterium glutamicum [J]. ACS Omega, 2021, 6(15): 10160-10167. |
| 23 | SANDOVAL-VARGAS J M, JIMÉNEZ-CLEMENTE L A, MACEDO-OSORIO K S, et al.. Use of the ptxD gene as a portable selectable marker for chloroplast transformation in Chlamydomonas reinhardtii [J]. Mol. Biotechnol., 2019, 61(6): 461-468. |
| 24 | CUTOLO E, TOSONI M, BARERA S, et al.. A phosphite dehydrogenase variant with promiscuous access to nicotinamide cofactor pools sustains fast phosphite-dependent growth of transplastomic Chlamydomonas reinhardtii [J/OL]. Plants, 2020, 9(4): 473[2024-01-04]. . |
| 25 | JIANG X R, YAO Z H, CHEN G Q. Controlling cell volume for efficient PHB production by Halomonas [J]. Metab. Eng., 2017, 44: 30-37. |
| 26 | XIAO Z, GU R, HOU X, et al.. Non-sterilized fermentative production of acetoin with 2, 3-butanediol as a main byproduct from maize hydrolysate by a newly isolated thermophilic Bacillus strain[J]. J. Chem. Technol. Biotechnol., 2017, 92(11): 2845-2852. |
| 27 | YE J, HU D, CHE X, et al.. Engineering of Halomonas bluephagenesis for low cost production of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) from glucose[J]. Metab. Eng., 2018, 47: 143-152. |
| 28 | CJOO Y, KO Y J, YOU S K, et al.. Creating a new pathway in Corynebacterium glutamicum for the production of taurine as a food additive[J]. J. Agric. Food Chem., 2018, 66(51): 13454-13463. |
| 29 | WENDISCH V F, JORGE J M P, PÉREZ-GARCÍA F, et al.. Updates on industrial production of amino acids using Corynebacterium glutamicum [J/OL]. World J. Microbiol. Biotechnol., 2016, 32(6): 105[2024-01-22]. . |
| 30 | BECKER J, WITTMANN C. Systems and synthetic metabolic engineering for amino acid production-the heartbeat of industrial strain development[J]. Curr. Opin. Biotechnol., 2012, 23(5): 718-726. |
| 31 | BECKER J, WITTMANN C. Bio-based production of chemicals, materials and fuels-Corynebacterium glutamicum as versatile cell factory[J]. Curr. Opin. Biotechnol., 2012, 23(4): 631-640. |
| 32 | HARRIS E H. Chlamydomonas as a model organism[J]. Annu. Rev. Plant Biol., 2001, 52: 363-406. |
| 33 | RASALA B A, MAYFIELD S P. Photosynthetic biomanufacturing in green algae; production of recombinant proteins for industrial, nutritional, and medical uses[J]. Photosynth. Res., 2015, 123(3): 227-239. |
| 34 | SCRANTON M A, OSTRAND J T, FIELDS F J, et al.. Chlamydomonas as a model for biofuels and bio-products production[J]. Plant J., 2015, 82(3): 523-531. |
| 35 | ALMARAZ-DELGADO A L, FLORES-URIBE J, PÉREZ-ESPAÑA V H, et al.. Production of therapeutic proteins in the chloroplast of Chlamydomonas reinhardtii [J/OL]. AMB Express, 2014, 4: 57[2024-01-22]. . |
| 36 | DYO Y M, PURTON S. The algal chloroplast as a synthetic biology platform for production of therapeutic proteins[J]. Microbiol. Read., 2018, 164(2): 113-121. |
| 37 | SCAIFE M A, NGUYEN G T D T, RICO J, et al.. Establishing Chlamydomonas reinhardtii as an industrial biotechnology host[J]. Plant J., 2015, 82(3): 532-546. |
| 38 | DOMINGUES S J, MELO F R, AGUIAR J M, et al. Resistance of Vigna unguiculata (cowpea) seeds to Callosobruchus maculatus is restricted to cotyledonary tissues[J]. J. Sci. Food Agric., 2006, 86(12): 1977-1985. |
| 39 | OUIMETTE D. Phosphonate levels in avocado (Persea americana) seedlings and soil following treatment with fosetyl-Al or potassium phosphonate[J/OL]. Plant Dis., 1989, 73(3): 212-215. |
| 40 | CARSWELL C, GRANT B R, THEODOROU M E, et al.. The fungicide phosphonate disrupts the phosphate-starvation response in Brassica nigra seedlings[J]. Plant Physiol., 1996, 110(1): 105-110. |
| 41 | CARSWELL M C, GRANT B R, PLAXTON W C. Disruption of the phosphate-starvation response of oilseed rape suspension cells by the fungicide phosphonate[J]. Planta, 1997, 203(1): 67-74. |
| 42 | FÖRSTER H, ADASKAVEG J E, KIM D H, et al.. Effect of phosphite on tomato and pepper plants and on susceptibility of pepper to Phytophthora root and crown rot in hydroponic culture[J]. Plant Dis., 1998, 82(10): 1165-1170. |
| 43 | TICCONI C, DELATORRE C, ABEL S. Attenuation of phosphate starvation responses by phosphite in Arabidopsis [J]. Plant Physiol., 2001, 127(3): 963-972. |
| 44 | VARADARAJAN D K, KARTHIKEYAN A S, MATILDA P D, et al.. Phosphite, an analog of phosphate, suppresses the coordinated expression of genes under phosphate starvation[J]. Plant Physiol., 2002, 129(3): 1232-1240. |
| 45 | HEAP I, HEAP I, HEAP J T, et al.. The international survey of herbicide resistant weeds[J]. Weed Technol., 2006, 4: 220-220. |
| 46 | BLOCK M D, BOTTERMAN J, VANDEWIELE M, et al.. Engineering herbicide resistance in plants by expression of a detoxifying enzyme[J]. EMBO J., 1987, 6(9): 2513-2518. |
| 47 | VAN DEN ELZEN P J M, TOWNSEND J, LEE K Y, et al.. A chimaeric hygromycin resistance gene as a selectable marker in plant cells[J]. Plant Mol. Biol., 1985, 5(5): 299-302. |
| 48 | ACHARY V M M, RAM B, MANNA M, et al.. Phosphite: a novel P fertilizer for weed management and pathogen control[J]. Plant Biotechnol. J., 2017, 15(12): 1493-1508. |
| 49 | GORDON-KAMM W J, SPENCER T M, MANGANO M L, et al.. Transformation of maize cells and regeneration of fertile transgenic plants[J]. Plant Cell, 1990, 2(7): 603-618. |
| 50 | PRICE J A, BALKCOM S K, CULPEPPER A S, et al.. Glyphosate-resistant Palmer amaranth: a threat to conservation tillage[J]. J. Soil Water Conserv., 2011, 66(4): 265-275. |
| 51 | DILLON A, VARANASI V K, DANILOVA T V, et al.. Physical mapping of amplified copies of the 5-enolpyruvylshikimate-3-phosphate synthase gene in glyphosate-resistant Amaranthus tuberculatus [J]. Plant Physiol., 2017, 173(2): 1226-1234. |
| 52 | LÓPEZ-ARREDONDO D L, HERRERA-ESTRELLA L. A novel dominant selectable system for the selection of transgenic plants under in vitro and greenhouse conditions based on phosphite metabolism[J]. Plant Biotechnol. J., 2013, 11(4): 516-525. |
| 53 | LIU L, GALLAGHER J, AREVALO E D, et al.. Enhancing grain-yield-related traits by CRISPR-Cas9 promoter editing of maize CLE genes[J]. Nat. Plants, 2021, 7: 287-294. |
| 54 | PANDEYA D, LÓPEZ-ARREDONDO D L, JANGA M R, et al.. Selective fertilization with phosphite allows unhindered growth of cotton plants expressing the ptxD gene while suppressing weeds[J]. Proc. Natl. Acad. Sci. USA, 2018, 115(29): 6946-6955. |
| 55 | 熊腾. 亚磷酸盐脱氢酶基因ptxD转化甘蓝型油菜的研究[D]. 长沙: 湖南农业大学, 2020. |
| XIONG T. Transformation of Brassica napus by phosphite dehydrogenase gene ptxD[D]. Changsha: Hunan Agricultural University, 2020. | |
| 56 | NAHAMPUN H N, LÓPEZ-ARREDONDO D, XU X, et al.. Assessment of ptxD gene as an alternative selectable marker for Agrobacterium-mediated maize transformation[J]. Plant Cell Rep., 2016, 35(5): 1121-1132. |
| 57 | 陆红臣,仵汉飞,文静,等.甘蓝型油菜多主花序性状的表型特点与遗传分析[J].中国油料作物学报,2019,41(6):850-857. |
| LU H C, WU H F, WEN J, et al.. Phenotypic characteristics and genetic analysis of multi-inflorescence trait in Brassica napus [J]. Chin. J. Oil Crop Sci., 2019, 41(6): 850-857. | |
| 58 | 徐文晖.水稻生长的生育特点与病虫害防治分析[J].智慧农业导刊,2022,2(5):67-69. |
| 59 | FRAME B R, SHOU H, CHIKWAMBA R K, et al.. Agrobacterium tumefaciens-mediated transformation of maize embryos using a standard binary vector system[J]. Plant Physiol., 2002, 129(1): 13-22. |
| 60 | FRAME B R, MCMURRAY J M, FONGER T M, et al.. Improved Agrobacterium-mediated transformation of three maize inbred lines using MS salts[J]. Plant Cell Rep., 2006, 25(10): 1024-1034. |
| 61 | ZHAO Z Y, GU W, CAI T, et al.. High throughput genetic transformation mediated by Agrobacterium tumefaciens in maize[J]. Mol. Breed., 2002, 8(4): 323-333. |
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