image: Schematic diagram of Lonicera japonica leaf anatomical traits (left side) and CO2 diffusion pathway under NH4+ alone supply (right side). In the left side, Sc/S was outlined with red lines and Smes/S was marked with yellow lines. The accurate Sc/S estimations overlapped Smes/S lines, whereas they are displayed independently here for clarity. Chloroplasts were highlighted with blue. Decreased chloroplast numbers resulted in the reductions in Sc/S. The intercellular spaces were pointed out with pink discontinuous lines. The tight arrangement of mesophyll cells under sole NH4+ supplies led to increased intercellular spaces, which exacerbated the reductions in Sc/S and Smes/S. In the right side, the black folded lines represent the strength of CO2 diffusion resistance into the cell from cell wall (rcw), plasma (rpl), cytoplasm (rcyt), envelope (renv), and stroma (rst), while the rcw and rcyt which are marked with red indicated the values of this component differed among the treatments (P < 0.05). Black discontinuous lines indicated the hypothesized pathways that could partially influence the CO2 diffusion and thereby gm.
Credit: Horticulture Research
Delving into the nuances of plant nutrition, researchers have discovered that the form of nitrogen intake profoundly affects the efficiency of photosynthesis in plants. This pivotal finding sheds light on how plants process and utilize nitrogen, offering critical insights for enhancing crop productivity and optimizing nitrogen use in agriculture.
Photosynthesis efficiency in plants is influenced by the type of nitrogen absorbed. Ammonium (NH4+) and nitrate (NO3-) are the primary nitrogen sources, each affecting plant physiology differently. Variations in leaf anatomy, such as cell wall thickness and chloroplast number, play a crucial role in these processes. Due to these challenges, there is a need to conduct in-depth research on the impact of nitrogen forms on leaf anatomical traits and photosynthesis.
The research conducted by a team from Nanjing Agricultural University and Huazhong Agricultural University, published (DOI: 10.1093/hr/uhae112) on February 22, 2024, in Horticulture Research, explores the physiological mechanisms by which different nitrogen forms affect photosynthesis in Lonicera japonica. The study aims to quantify the limitations on photosynthesis imposed by various leaf anatomical traits under different nitrogen nutrition conditions.
The study reveals that NH4+ nutrition leads to significantly lower photosynthesis compared to NO3- or mixed nitrogen sources. This reduction is primarily due to a decrease in mesophyll conductance (gm), which is associated with thicker cell walls and fewer chloroplasts. Pathway analysis indicates that increased lignin and hemicellulose content under NH4+ nutrition negatively impacts gm. Additionally, NH4+ nutrition reduces the volume of intercellular air space and increases cell wall thickness, further restricting CO2 diffusion. These findings highlight the crucial role of leaf anatomical variations in regulating photosynthesis. Understanding these interactions provides valuable insights for improving nitrogen use efficiency in agriculture, emphasizing the need to optimize nitrogen form applications to enhance photosynthesis and plant growth.
Dr. Yong Li from Huazhong Agricultural University notes, "This study highlights the complex interactions between nitrogen forms and leaf anatomy, shedding light on how specific nitrogen sources can optimize photosynthesis. These insights are crucial for developing more efficient fertilization strategies in crop production."
The findings suggest that optimizing nitrogen form applications can enhance photosynthesis and plant growth, particularly in crops like Lonicera japonica. By understanding the specific impacts of NH4+ and NO3- on leaf anatomy, farmers and agronomists can tailor fertilization practices to improve nitrogen use efficiency, reduce environmental impact, and increase crop yields. This research paves the way for future studies on the interplay between nitrogen forms and plant physiology, potentially leading to more sustainable agricultural practices.
###
References
DOI
Original Source URL
https://doi.org/10.1093/hr/uhae112
Funding information
This work was financially supported by the National Natural Science Foundation of China (32072673), the Fundamental Research Funds for the Central Universities (KYGD202007), the Young Elite Scientists Sponsorship Program by CAST (2018QNRC001), and the Innovative Research Team Development Plan of the Ministry of Education of China (IRT_17R56).
About Horticulture Research
Horticulture Research is an open access journal of Nanjing Agricultural University and ranked number one in the Horticulture category of the Journal Citation Reports ™ from Clarivate, 2022. The journal is committed to publishing original research articles, reviews, perspectives, comments, correspondence articles and letters to the editor related to all major horticultural plants and disciplines, including biotechnology, breeding, cellular and molecular biology, evolution, genetics, inter-species interactions, physiology, and the origination and domestication of crops.
Journal
Horticulture Research
Subject of Research
Not applicable
Article Title
Variation of mesophyll conductance mediated by nitrogen form is related to changes in cell wall property and chloroplast number
Article Publication Date
22-Feb-2024
COI Statement
The authors declare that they have no competing interests.