| 引用本文: | 杜雨欣,郑保海,李佳欣,李玉鑫,黄立成,施军琼,吴忠兴.微囊藻CO2-浓缩机制基因型的动态变化及其对CO2的竞争效应.湖泊科学,2023,35(5):1584-1593. DOI:10.18307/2023.0517 |
| Du Yuxin,Zheng Baohai,Li Jiaxin,Li Yuxin,Huang Licheng,Shi Junqiong,Wu Zhongxing.Dynamic changes of genotypes of Microcystis CO2-concentration mechanism and their competitive effects on CO2. J. Lake Sci.2023,35(5):1584-1593. DOI:10.18307/2023.0517 |
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| 微囊藻CO2-浓缩机制基因型的动态变化及其对CO2的竞争效应 |
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杜雨欣1, 郑保海1, 李佳欣1, 李玉鑫1, 黄立成2, 施军琼1, 吴忠兴1
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1.西南大学三峡库区生态环境教育部重点实验室, 重庆市三峡库区植物生态与资源重点实验室, 重庆 400715;2.昆明市滇池高原湖泊研究院, 昆明 650228
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| 摘要: |
| 由于具有高效的CO2-浓缩机制,蓝藻在低CO2浓度条件下具有竞争优势。然而,随着大气中CO2浓度急剧增加,蓝藻CO2-浓缩机制如何响应的研究较少。因此,本文以常见水华蓝藻——微囊藻为研究对象,通过对滇池微囊藻水华动态及不同CO2-浓缩机制基因型进行监测,探讨蓝藻CO2-浓缩机制基因的微进化特征及其动态变化。同时,设置高(0.08%)、中(0.04%)、低(0.02%)CO2浓度(V/V)进一步揭示微囊藻不同CO2-浓缩机制基因微进化对CO2的竞争效应。结果表明:滇池无机碳浓度在4个采样点存在空间差异性,均呈现先降低后升高的趋势,并以HCO-3为主要无机碳存在形式。调查期间,东大河、观音山、洛龙河和生态所4个采样点的微囊藻均以sbtA基因型占绝对优势,相对丰度远高于bicA基因型。在不同水华时期,bicA基因型和sbtA基因型呈现相反的变化趋势,即从水华前期到水华中期,sbtA基因型的相对丰度逐渐升高,而到水华后期,出现bicA基因型增多的现象。室内竞争实验同样表明高浓度CO2培养环境下,bicA基因型具有明显竞争优势,随CO2浓度的降低,呈现bicA基因型向sbtA基因型转变的趋势。这些结果表明水华中期无机碳浓度相对较低,能适应碳限制环境的sbtA基因型的微囊藻表现出竞争优势,而对CO2浓度变化敏感的bicA基因型的微囊藻随无机碳浓度的升高逐渐增多;同时,在总碱度,pH和Chl.a影响下,微囊藻基因型在滇池不同微囊藻水华期呈现bicA→sbtA→bicA转变。这些结果说明微囊藻能通过调节不同CO2-浓缩机制基因藻株响应水体无机碳浓度,保持种群竞争优势,并维持水华的形成。 |
| 关键词: 微囊藻 CO2-浓缩机制 微进化 无机碳 演替 滇池 |
| DOI：10.18307/2023.0517 |
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| 基金项目:国家自然科学基金项目(41877410,42177055)联合资助。 |
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| Dynamic changes of genotypes of Microcystis CO2-concentration mechanism and their competitive effects on CO2 |
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Du Yuxin1, Zheng Baohai1, Li Jiaxin1, Li Yuxin1, Huang Licheng2, Shi Junqiong1, Wu Zhongxing1
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1.Key Laboratory of Eco-environments in Three Gorges Reservoir Region, Ministry of Education, Chongqing Key Laboratory of Plant Ecology and Resources in Three Gorges Reservoir Region, Southwest University, Chongqing 400715, P.R. China;2.Kunming Dianchi and Plateau Lakes Institute, Kunming 650228, P.R. China
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| Abstract: |
| The highly efficient CO2 concentration mechanism (CCM) gives cyanobacteria a competitive advantage under low CO2 conditions. However, with the rapid increase in atmospheric CO2 concentration, little information has been presented on how the CO2 concentration mechanism of cyanobacteria responds. Therefore, this study takes a common blooming cyanobacterium, Microcystis, to investigate in the present by monitoring the dynamic changes and different CCM genotypes of Microcystis in Lake Dianchi. At the same time, the microevolutionary characteristics and dynamic changes of CCM genotypes in Microcystis were also discussed. Furthermore, the competing effects of different CCM genotypes in Microcystis at high (0.08%), medium (0.04%) and low (0.02%) CO2 concentrations (V/V) were compared. The results showed that the concentration of inorganic carbon (IC) in Lake Dianchi was spatially variable at four sampling sites, but all sites showed a trend of first decreasing and then increasing IC concentrations, and HCO-3 was the major form of IC. At the four sampling sites of DDH, GYS, LLH and STS, the sbtA genotype Microcystis was dominant and its relative abundance was much higher than that of the bicA genotype Microcystis. In different bloom periods, the bicA and sbtA genotypes of Microcystis showed opposite trends, i.e. the relative abundance of the sbtA genotype Microcystis gradually increased from early to mid- bloom, while the bicA genotype Microcystis increased only in late bloom. The competition experiments showed that the bicA genotype had an apparent competitive advantage in a high CO2 environment and showed a trend of transition from the bicA genotype to the sbtA genotype with decreasing CO2 concentration. These indicate that the IC concentration was relatively low in the middle of the bloom period, resulting in the sbtA genotype showing a competitive advantage in a carbon-limited environment, while the bicA genotype, a sensitive type to changing CO2 concentration, gradually increased with increasing IC concentration. In addition, the genotypes of Microcystis showed a bicA→sbtA→bicA transition during different Microcystis bloom periods in Lake Dianchi due to the effects of total alkalinity, pH and Chl.a. These results suggest that Microcystis can maintain its competitive advantage and sustain the bloom by regulating the algal strains with different CCM genotypes in response to the IC concentration in the water. |
| Key words: Microcystis CO2-concentration mechanism micro-evolution inorganic carbon succession Lake Dianchi |
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