Ammonium and nitrate affect sexually different responses to salt stress in Populus cathayana

Abstract Synergistic regulation in leaf architecture and photosynthesis is essential for salt tolerance. However, how plant sex and inorganic nitrogen sources alter salt stress-dependent photosynthesis remains unknown. Leaf anatomical characteristics and photosynthesis of Populus cathayana Rehder females and males were investigated under salt stress conditions combined with NO3− and NH4+ supplies to clarify the underlying mechanisms. In salt-stressed females, we observed an increased mesophyll spongy cell density, a reduced chloroplast density, a decreased surface area of chloroplasts adjacent to the intercellular air space (Sc/S) and an increased mesophyll cell area per transverse section width (S/W), consequently causing mesophyll conductance (gm) and photosynthesis inhibition, especially under NH4+ supply. Conversely, males with a greater mesophyll palisade tissue thickness and chloroplast density, but a lower spongy cell density had lower S/W and higher Sc/S, and higher gm and photosynthesis. NH4+-fed females had a lower CO2 conductance through cell wall and stromal conductance perpendicular to the cell wall, but a higher chloroplast conductance from the cell wall (gcyt1) than females supplied with NO3−, while males had a higher chloroplast conductance and lower CO2 conductance through cell wall when supplied with NO3− instead of NH4+ under salt stress. These findings indicate sex-specific strategies in coping with salt stress related to leaf anatomy and gm under both types of N supplies, which may contribute to sex-specific CO2 capture and niche segregation.

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Growth, photosynthesis, and reactive oxygen system responses of allotriploid Populus cathayana to salt stress

Photosynthetica ◽

10.32615/ps.2020.043 ◽

2020 ◽

Vol 58 (4) ◽

pp. 944-950

Author(s):

T. QIU ◽

Y. WANG ◽

X.N. GENG ◽

Y. ZHANG ◽

Y. LI ◽

...

Keyword(s):

Salt Stress ◽

Reactive Oxygen ◽

Oxygen System ◽

Populus Cathayana

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Impact of salt and exogenous AM inoculation on indigenous microbial community structure in the rhizosphere of dioecious plant, Populus cathayana

Scientific Reports ◽

10.1038/s41598-021-97674-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Na Wu ◽

Zhen Li ◽

Ming Tang

Keyword(s):

Salt Stress ◽

Community Structure ◽

Microbial Community ◽

Microbial Community Structure ◽

Rhizosphere Soil ◽

Chemical Properties ◽

Biomass Accumulation ◽

Physical Chemical ◽

Populus Cathayana ◽

Inoculation Treatment

AbstractThe sex-specific physical and biochemical responses in dioecious plants to abiotic stresses could result in gender imbalance, and how to ease the current situation by microorganisms is still unclear. Using native soil where poplars were grown, growth parameters, soil physicochemical properties in the rhizosphere soil of different sexes of Populus cathayana exposed to salt stress and exogenous arbuscular mycorrhizal (AM) inoculation were tested. Besides, the sex-specific microbial community structures in the rhizosphere soil of different sexes of Populus cathayana were compared under salt stress. To identify the sex-specific microbial community characteristics related to salinity and AM symbiosis, a combined qPCR and DGGE method was used to monitor microbial community diversity. Seedlings suffered severe pressure by salt stress, reflected in limited growth, biomass, and nutrient element accumulation, especially on females. Exogenous AM inoculation treatment alleviated these negative effects, especially under salt treatment of 75 mM. Compared with salt effect, exogenous AM inoculation treatment showed a greater effect on soil physical–chemical properties of both sexes. Based on DGGE results, salt stress negatively affected fungal richness but positively affected fungal Simpson diversity index, while exogenous AM inoculation treatment showed the opposite effect. Structural equation modeling (SEM) was performed to show the causal relationships between salt and exogenous AM inoculation treatments with biomass accumulation and microbial community: salt and exogenous AM inoculation treatment showed complicated effects on elementary concentrations, soil properties, which resulted in different relationship with biomass accumulation and microbial community. Salt stress had a negative effect on soil properties and microbial community structure in the rhizosphere soil of P. cathayana, whereas exogenous AM inoculation showed positive impacts on most of the soil physical–chemical properties and microbial community status.

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