More nitrogen partition in structural proteins and decreased photosynthetic nitrogen-use efficiency of Pinus massoniana under in situ polluted stress

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 (N(L)) 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 N(L) 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.

A global trait‐based approach to estimate leaf nitrogen functional allocation from observations

“…Takashima et al (2004) estimated 55% and 65% nitrogen partitioning (assuming 5% nitrogen partitioning to respiratory mitochondrial enzymes) to FIG. The large percentage of total leaf nitrogen in the residual pool is hypothesized to be used in structural (cell wall) proteins (6-14%; Takashima et al 2004, Guan andWen 2011), other nitrogen proteins (i.e., proteins not invested in photosynthesis, respiration, and structure; 15-25% after subtracting 5% mitochondrial proteins; Chapin et al 1987, Takashima et al 2004, free amino acids (2.5%; Chapin et al 1987), lipids (3-4%;Chapin et al 1986), nucleic acids (8.5-15%;Chapin et al 1986, Chapin 1989, Evans and Seemann 1989, and CO 2 fixation proteins (other than Rubisco; 4%; Chapin et al 1987). The correlations between fractional leaf nitrogen allocation pools, photosynthesis parameters, and leaf nitrogen for all plant functional types combined.…”

“…Leaf nitrogen varies with environmental conditions, leaf traits, and geographic location (Reich et al 1992, Reich and Oleksyn 2004, Wright et al 2004, and is correlated with photosynthetic parameters (Wullschleger 1993, Xu and Baldocchi 2003, Coste et al 2005, Grassi et al 2005. However these studies relied on a few measurements (i.e., data at only three sites) for evaluating the behavior of their optimal nitrogen allocation model (e.g., Xu et al 2012), considered limited PFTs (mostly short-lived non-woody plants or woody juveniles) that lacked explicit representation of interspecies difference in nitrogen allocation (e.g., Chapin et al 1986, Evans 1989, Makino and Osmond 1991, Onoda et al 2004, Takashima et al 2004, Guan and Wen 2011, or did not consider nitrogen allocation for a complete range of processes including carboxylation, light harvesting, bioenergetics, maintenance respiration, and growth respiration (e.g., Coste et al 2005, Delagrange 2011. However these studies relied on a few measurements (i.e., data at only three sites) for evaluating the behavior of their optimal nitrogen allocation model (e.g., Xu et al 2012), considered limited PFTs (mostly short-lived non-woody plants or woody juveniles) that lacked explicit representation of interspecies difference in nitrogen allocation (e.g., Chapin et al 1986, Evans 1989, Makino and Osmond 1991, Onoda et al 2004, Takashima et al 2004, Guan and Wen 2011, or did not consider nitrogen allocation for a complete range of processes including carboxylation, light harvesting, bioenergetics, maintenance respiration, and growth respiration (e.g., Coste et al 2005, Delagrange 2011.…”

“…However these studies relied on a few measurements (i.e., data at only three sites) for evaluating the behavior of their optimal nitrogen allocation model (e.g., Xu et al 2012), considered limited PFTs (mostly short-lived non-woody plants or woody juveniles) that lacked explicit representation of interspecies difference in nitrogen allocation (e.g., Chapin et al 1986, Evans 1989, Makino and Osmond 1991, Onoda et al 2004, Takashima et al 2004, Guan and Wen 2011, or did not consider nitrogen allocation for a complete range of processes including carboxylation, light harvesting, bioenergetics, maintenance respiration, and growth respiration (e.g., Coste et al 2005, Delagrange 2011. Plants invest the largest proportion of nitrogen for photosynthesis to Rubisco, followed by light absorption and electron transport with allocation sensitive to environmental conditions (Evans and Seemann 1989, Takashima et al 2004, Guan and Wen 2011. Plants invest the largest proportion of nitrogen for photosynthesis to Rubisco, followed by light absorption and electron transport with allocation sensitive to environmental conditions (Evans and Seemann 1989, Takashima et al 2004, Guan and Wen 2011.…”

“…Studies have determined the fractional allocation of leaf nitrogen among proteins and the associated influence on individual process rates (e.g., Evans 1989, Niinemets and Tenhunen 1997, Onoda et al 2004, Takashima et al 2004. However these studies relied on a few measurements (i.e., data at only three sites) for evaluating the behavior of their optimal nitrogen allocation model (e.g., Xu et al 2012), considered limited PFTs (mostly short-lived non-woody plants or woody juveniles) that lacked explicit representation of interspecies difference in nitrogen allocation (e.g., Chapin et al 1986, Evans 1989, Makino and Osmond 1991, Onoda et al 2004, Takashima et al 2004, Guan and Wen 2011, or did not consider nitrogen allocation for a complete range of processes including carboxylation, light harvesting, bioenergetics, maintenance respiration, and growth respiration (e.g., Coste et al 2005, Delagrange 2011. Higher nitrogen investments in photosynthesis and respiration are expected for crops followed by herbaceous plants and then longer-lived woody PFTs (Chapin et al 1986, Evans 1989, Takashima et al 2004 but the relative magnitudes of the nitrogen partitioning to different functions (especially for tropical and temperate trees) at a global scale is currently lacking.…”

Pollutant-induced cell death and reactive oxygen species accumulation in the aerial roots of Chinese banyan (Ficus microcarpa)

“…The deposition of atmospheric sulfur, nitrogen, and industrial dust containing metals has caused the decline of indigenous tree species in South China, but the mechanisms are incompletely understood5625. Our previous studies indicated that different forms of pollutants, alone or in combinations, are involved in accelerating oxidative process, causing decreased rates of electron transport and damaged membrane systems in leaf cells256.…”