Ginkgo biloba is a dioecious heterophyllous tree species with two leaf types. Short shoots always bear many leaves, which are undivided or slightly bilobed, but long-shoot leaves are smaller and are deeply divided into two or more lobes. To clarify the functional difference between the two leaf types, we investigated the morphology, anatomy, gas exchange, and hydraulic traits of the two leaf types in male and female trees. Our results showed that long-shoot leaves possessed a lower specific leaf area (SLA), higher leaf thickness, gas exchange rates, and average tracheid number than short-shoot leaves. When compared to short-shoot leaves, long-shoot leaves in male trees had higher leaf hydraulic conductance (K_leaf) and leaf water potential of 50% loss in K_leaf (leaf P50), while female trees exhibited relatively higher K_leaf. When comparing sexual differences, male trees possessed higher leaf thickness, leaf dissection index, vein density (VD), and predawn leaf water potential and lower SLA, tracheid number, and midday leaf water potential, while no significant difference in leaf P50 was observed between the two sexes. Male trees exhibited greater leaf gas exchange rates, which were tightly associated with other functional traits, such as VD and K_leaf. We found strong shoot-based and sex-related heterogeneities in the leaf hydrology, anatomy, and economy of Ginkgo biloba. Moreover, male ginkgoes may perform better due to their greater leaf hydraulic efficiency and gas exchange rates.

Plants play a key role in the ecological restoration of urban wetlands. Previous studies have shown that heavy-metal accumulation capacities and adaptation strategies of wetland plants may be related to their life forms. In this study, pot experiments were conducted to investigate the effects of nitrogen (N) on the adaptation strategies of two evergreen and deciduous aquatic iris life forms under cadmium (Cd) stress. Our results showed that Cd stress decreased the gas exchange parameters and biomass in both evergreen and deciduous irises. However, the interactions between N and Cd reversed this effect. Specifically, for deciduous irises, the shoot mass (SM) and root-to-shoot ratio (S/R) increased with higher N concentrations, whereas in evergreen irises, these parameters initially increased and then decreased as N levels increased, suggesting that the two life forms have different efficiencies in utilizing N. Additionally, under the combined stress of N and Cd, evergreen irises exhibited higher malondialdehyde (MDA) content and antioxidant enzyme activity than deciduous irises, whereas deciduous irises had higher chlorophyll content and aboveground biomass. These findings suggest that evergreen and deciduous irises employ distinct adaptive strategies to Cd toxicity; evergreen irises mitigate oxidative stress through enhanced reactive oxygen species (ROS) scavenging, whereas deciduous irises dilute Cd toxicity by increasing biomass. These results provide valuable insight into the use of different aquatic iris life forms for heavy-metal pollution remediation in wetlands.

Salinity stress severely limits crop productivity worldwide. While plant growth-promoting rhizobacteria (PGPR) are known to alleviate abiotic stress, the specific mechanisms mediated by their volatile organic compounds (VOCs) remain largely elusive. In this study, an in vitro split-plate system was used to investigate the effects of VOCs emitted by Bacillus velezensis SQR9 on Arabidopsis thaliana seedlings under salt stress. Exposure to SQR9 VOCs significantly enhanced Arabidopsis salt tolerance, evidenced by increased biomass and root growth. Mechanistically, SQR9 VOCs mitigated salt-induced damage by increasing chlorophyll content, modulating osmolytes, and reducing malondialdehyde (MDA) levels. SQR9 VOCs alleviated oxidative stress by decreasing ROS (H₂O₂, O₂⁻) accumulation and enhancing antioxidant enzyme (SOD, CAT, POD) activities. Furthermore, SQR9 VOCs maintained ion homeostasis by significantly reducing leaf Na⁺ accumulation, maintaining a high K⁺/Na⁺ ratio, and upregulating key ion transporter genes. Analysis of the headspace from SQR9 cultured on MSgg medium identified 2,3-butanediol (2,3-BD) as a major active VOC. Exogenous application of 2,3-BD successfully mimicked the growth-promoting and salt-tolerance-enhancing effects of SQR9. Our findings demonstrate that SQR9 VOCs, particularly 2,3-BD, systemically prime Arabidopsis for salt tolerance by co-activating the antioxidant defense system and the SOS ion homeostasis pathway.