Journal of Tropical Oceanography >
Effects of ammonium enrichment on the photosynthesis, glutamine synthetase and amino acid composition of seagrass Halophila beccarii Asch
Copy editor: LIN Qiang
Received date: 2022-05-26
Revised date: 2022-07-16
Online published: 2022-07-21
Supported by
Hainan Province Science and Technology Special Fund(ZDYF2021SHFZ254)
National Natural Science Foundation of China(41735029)
National Natural Science Foundation of China(41976144)
National Natural Science Foundation of China(U1901221)
National Natural Science Foundation of China(42176158)
Youth Innovation Promotion Association CAS(2023359)
Science and Technology Planning Project of Guangdong Province, China(2020B1212060058)
Seagrass Halophila beccarii Asch has long been neglected due to its small size, and the coastal nitrogen loading accelerates its degradation. The physiological response of H. beccarii to ammonium toxicity is not clear. Based on the lab cultivation experiment, the effects of ammonium enrichment in four gradients (Control, 25 μmol·L-1, 50 μmol·L-1 and 100 μmol·L-1) on the photosynthesis, chlorophyll, ammonium ion flux in mesophyll cell, glutamine synthetase activity and nutrients of H. beccarii are studied using chlorophyll fluorescence, non-invasive micro measurement technology and targeted metabolomics. The results showed that the maximum relative electron transport rate exhibits a trend of low ammonium enrichment>moderate ammonium enrichment>control>high ammonium enrichment. High ammonium enrichment significantly reduces the maximum relative electron transport rate and light utilization efficiency, while decreasing the carbon pool for ammonium assimilation. Meanwhile, ammonium enrichment significantly enhances the ammonium ion flux and glutamine synthetase activity, assimilating excess ammonium into amino acids. However, ammonium enrichment reduces the amino acid contents, which might be caused by that the amino acids are used to synthesize organic substances such as key secondary metabolites to further regulate and adapt to ammonium toxicity. Therefore, moderate ammonium enrichment is beneficial for the photosynthesis and growth of H. beccarii, while high ammonium enrichment has toxic effect on H. beccarii.
Key words: ammonium; Halophila beccarii Asch; photosynthesis; glutamine synthetase; amino acid
JIANG Zhijian , Chanaka Isuranga PREMARATHNE , FANG Yang , LIN Jizhen , WU Yunchao , LIU Songlin , HUANG Xiaoping . Effects of ammonium enrichment on the photosynthesis, glutamine synthetase and amino acid composition of seagrass Halophila beccarii Asch[J]. Journal of Tropical Oceanography, 2023 , 42(3) : 116 -125 . DOI: 10.11978/2022121
Chl a (μg·mL-1) = 12.7OD663 - 2.69OD645
Chl b (μg·mL-1) = 22.9OD645 - 4.86OD663
图1 铵态氮加富对贝克喜盐草最大相对电子传递速率和α(光能利用效率)的影响CK代表对照, LE代表低铵态氮加富, ME代表中铵态氮加富, HE代表高铵态氮加富。图中不同的小写字母表示差异显著(P<0.05) Fig. 1 The effect of ammonium enrichment on the relative maximum electron transport rates of Halophila beccarii. CK represents the control, LE represents low ammonium enrichment (25 μmol·L-1 NH+ 4), ME represents medium ammonium enrichment (50 μmol·L-1 NH+ 4), HE represents high ammonium enrichment (100 μmol·L-1 NH+ 4). Different small letters in the columns indicate significant differences (P<0.05) |
图2 铵态氮加富对贝克喜盐草叶绿素含量的影响CK代表对照, LE代表低铵态氮加富, ME代表中铵态氮加富, HE代表高铵态氮加富 Fig. 2 The effect of ammonium enrichment on the chlorophyll contents of Halophila beccarii. CK represents the control, LE represents low ammonium enrichment (25 μmol·L-1 NH+ 4), ME represents medium ammonium enrichment (50 μmol·L-1 NH+ 4), HE represents high ammonium enrichment (100 μmol·L-1 NH+ 4) |
表1 铵态氮加富对贝克喜盐草叶片氨基酸成分的影响Tab. 1 Effect of ammonium enrichment on the amino acid compositions in the leaf of Halophila beccarii |
氨基酸 | 对照 | 25μmol·L-1 NH+ 4 | 50μmol·L-1 NH+ 4 | 100μmol·L-1 NH+ 4 | ||||
---|---|---|---|---|---|---|---|---|
含量/(μg·g-1) | 占比/% | 含量/(μg·g-1) | 占比/% | 含量/(μg·g-1) | 占比/% | 含量/(μg·g-1) | 占比/% | |
甘氨酸 | ND | ND | ND | ND | ND | ND | ND | ND |
丙氨酸 | 2101.7±710.2A | 10.35 | 1538.0±524.9AB | 9.88 | 1537.1±412.8AB | 9.54 | 1062.9±272.8B | 9.48 |
γ-氨基丁酸 | 148.5±85.5A | 0.73 | 92.8±34.9AB | 0.60 | 100.2±53.1AB | 0.62 | 61.1±42.2B | 0.54 |
丝氨酸 | 254.7±70.4 | 1.25 | 218.1±62.1 | 1.40 | 218.9±55.3 | 1.36 | 154.8±46.2 | 1.38 |
脯氨酸 | 44.4±12.4 | 0.22 | 37.5±20.4 | 0.24 | 36.0±7.5 | 0.22 | 25.9±13.7 | 0.23 |
缬氨酸 | 299.0±93.9 | 1.47 | 203.2±49.6 | 1.31 | 224.7±107.4 | 1.39 | 154.8±72.7 | 1.38 |
苏氨酸 | ND | ND | ND | ND | ND | ND | ND | ND |
异亮氨酸 | 347.7±112.2 | 1.71 | 271.5±93.0 | 1.74 | 293.7±134.6 | 1.82 | 204.6±85.0 | 1.82 |
亮氨酸 | 75.1±20.8 | 0.37 | 49.2±9.5 | 0.32 | 61.4±40.3 | 0.38 | 36.3±19.7 | 0.32 |
天冬酰胺 | 14022.5±3810.7 | 69.04 | 11103.8±2500.6 | 71.34 | 11339.8±5312.9 | 70.38 | 7923.3±4034.9 | 70.64 |
鸟氨酸 | 2.3±1.0 | 0.01 | 3.3±1.7 | 0.02 | 2.8±1.5 | 0.02 | 1.8±0.9 | 0.02 |
天冬氨酸 | 506.9±114.1A | 2.50 | 392.8±65.9AB | 2.52 | 370.1±147.3AB | 2.30 | 285.4±124.3B | 2.54 |
高半胱氨酸 | ND | ND | ND | ND | ND | ND | ND | ND |
谷氨酰胺 | 2233.8±787.1A | 11.00 | 1429.1±570.5A | 9.18 | 1685.2±970.4AB | 10.46 | 1114.8±671.0B | 9.94 |
赖氨酸 | 11.1±2.4 | 0.05 | 14.6±8.9 | 0.09 | 10.2±6.3 | 0.06 | 6.4±4.5 | 0.06 |
谷氨酸 | 156.4±12.5 | 0.77 | 133.9±18.2 | 0.86 | 154.2±44.0 | 0.96 | 124.1±44.6 | 1.11 |
甲硫氨酸 | ND | ND | ND | ND | ND | ND | ND | ND |
组氨酸 | 16.9±3.0 | 0.08 | 13.3±2.8 | 0.09 | 12.4±9.8 | 0.08 | 11.0±6.7 | 0.10 |
苯丙氨酸 | 46.5±11.9A | 0.23 | 38.6±4.8AB | 0.25 | 39.1±19.3AB | 0.24 | 28.7±11.0B | 0.26 |
精氨酸 | 1.9±0.4 | 0.01 | 2.4±0.9 | 0.02 | 2.0±0.8 | 0.01 | 2.0±1.1 | 0.02 |
酪氨酸 | ND | ND | ND | ND | ND | ND | ND | ND |
色氨酸 | 41.6±14.9A | 0.20 | 23.1±7.7AB | 0.15 | 24.5±19.1B | 0.15 | 18.1±12.9B | 0.16 |
总氨基酸 | 20311.0±5768.9 | 100.00 | 15565.3±3627.4 | 100.00 | 16112.4±7267.6 | 100.00 | 11216.1±5384.5 | 100.00 |
注: 上标不同的大写字母表示差异显著(P<0.05) |
图3 铵态氮加富对贝克喜盐草叶片谷氨酰胺合成酶活性的影响CK代表对照, LE代表低铵态氮加富, ME代表中铵态氮加富, HE代表高铵态氮加富。图中不同的小写字母表示差异显著(P<0.05) Fig. 3 The effect of ammonium enrichment on the glutamine synthetase activity of the leaf of Halophila beccarii. CK represents the control, LE represents low ammonium enrichment (25 μmol·L-1 NH+ 4), ME represents medium ammonium enrichment (50 μmol·L-1 NH+ 4), HE represents high ammonium enrichment (100 μmol·L-1 NH+ 4). Different small letters in the columns indicate significant differences (P<0.05) |
图4 铵态氮加富对贝克喜盐草叶片稳定碳、氮同位素的影响CK代表对照, LE代表低铵态氮加富, ME代表中铵态氮加富, HE代表高铵态氮加富。图中不同的小写字母表示差异显著(P<0.05) Fig. 4 The effect of ammonium enrichment on the stable isotope carbon and nitrogen of the leaf of Halophila beccarii. CK represents the control, LE represents low ammonium enrichment (25 μmol·L-1 NH+ 4), ME represents medium ammonium enrichment (50 μmol·L-1 NH+ 4), HE represents high ammonium enrichment (100 μmol·L-1 NH+ 4). Different small letters in the columns indicate significant differences (P<0.05) |
图5 铵态氮加富对贝克喜盐草叶片铵根离子流速的影响CK代表对照, LE代表低铵态氮加富, ME代表中铵态氮加富, HE代表高铵态氮加富。图中不同的小写字母表示差异显著(P<0.05) Fig. 5 The effect of ammonium enrichment on the ammonium ion flux of the leaf of Halophila beccarii. CK represents the control, LE represents low ammonium enrichment (25 μmol·L-1 NH+ 4), ME represents medium ammonium enrichment (50 μmol·L-1 NH+ 4), HE represents high ammonium enrichment (100 μmol·L-1 NH+ 4). Different small letters in the columns indicate significant differences (P<0.05) |
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