More nitrogen partition in structural proteins and decreased photosynthetic nitrogen-use efficiency of <Emphasis Type="Italic">Pinus massoniana</Emphasis> under in situ polluted stress |
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Authors: | Lan-Lan Guan Da-Zhi Wen |
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Institution: | (1) Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, 510650, China;(2) Graduate University of the Chinese Academy of Sciences, Beijing, 100049, China;(3) Pearl River Delta Research Centre of Environmental Pollution and Control, Chinese Academy of Sciences, Guangzhou, 510640, China |
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Abstract: | Masson pine (Pinus massoniana L.) trees in the Pearl River Delta have shown growth decline since late 1980s, particularly those around industrially polluted
regions. As nitrogen is an important nutritional element composing functional proteins, structural proteins and photosynthetic
machinery, investigation on nitrogen allocation is helpful to understand nutrient alteration and its regulation mechanism
in response to pollution stress. Current year (C) and 1-year old needles (C + 1) of five mature trees were sampled in industrially
polluted site and unpolluted natural reserve for bioassay. Needles of declining trees had significantly higher leaf nitrogen
per unit area (NL) but lower photosynthetic capacity (P
max), which resulted in lower photosynthetic nitrogen use efficiency (PNUE) than those of healthy trees. Nitrogen fraction to
the photosynthetic apparatus in the C and C + 1 needles at polluted site was 27 and 22%, significantly lower than the corresponding
healthy needles (48 and 32%). The content of structural proteins was positively correlated with NL in C and C + 1 needles. Moreover, the C and C + 1 needles of declining trees had about 1.8 times structural protein as those
of healthy trees, suggesting that more nitrogen allocation to structural protein are needed for stronger structural defenses
under polluted stress. Decreases in PNUE of declining pine trees could be partially explained by increases in structural protein
nitrogen. |
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Keywords: | |
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