Plants (Oct 2022)

Nitrogen Allocation Tradeoffs Within-Leaf between Photosynthesis and High-Temperature Adaptation among Different Varieties of Pecan (<i>Carya illinoinensis</i> [Wangenh.] K. Koch)

  • Qiwen Xu,
  • Huichuan He,
  • Binghui He,
  • Tianyang Li,
  • Yumin Liu,
  • Shunyao Zhu,
  • Gaoning Zhang

DOI
https://doi.org/10.3390/plants11212828
Journal volume & issue
Vol. 11, no. 21
p. 2828

Abstract

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Interpreting leaf nitrogen (N) allocation is essential to understanding leaf N cycling and the economy of plant adaptation to environmental fluctuations, yet the way these mechanisms shift in various varieties under high temperatures remains unclear. Here, eight varieties of pecan (Carya illinoinensis [Wangenh.] K. Koch), Mahan, YLC10, YLC12, YLC13, YLC29, YLC35, YLJ042, and YLJ5, were compared to investigate the effects of high temperatures on leaf N, photosynthesis, N allocation, osmolytes, and lipid peroxidation and their interrelations. Results showed that YLC35 had a higher maximum net photosynthetic rate (Pmax) and photosynthetic N-use efficiency (PNUE), while YLC29 had higher N content per area (Na) and lower PNUE. YLC35, with lower malondialdehyde (MDA), had the highest proportions of N allocation in rubisco (Pr), bioenergetics (Pb), and photosynthetic apparatus (Pp), while YLC29, with the highest MDA, had the lowest Pr, Pb, and Pp, implying more leaf N allocated to the photosynthetic apparatus for boosting PNUE or to non-photosynthetic apparatus for alleviating damage. Structural equation modeling (SEM) demonstrated that N allocation was affected negatively by leaf N and positively by photosynthesis, and their combination indirectly affected lipid peroxidation through the reverse regulation of N allocation. Our results indicate that different varieties of pecan employ different resource-utilization strategies and growth–defense tradeoffs for homeostatic balance under high temperatures.

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