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[Objective] This study is aimed to explore the physiological and biochemical manifestations of Bougainvillea spectabilis Willd. to low temperature and the intrinsic adaptation mechanism to cold stress in the context of climate change. [Methods] Taking Bougainvillea Paederia Foetida, Bougainvillea Flaming Sumba and Bougainvillea Duranta with strong, medium, and weak cold tolerance as test materials, through indoor pot experiments, we conducted low temperature treatments for 7, 14 and 21 days and studied the responses of the photosynthetic and antioxidant systems of different cold tolerant Bougainvillea to cold stress during these different periods. [Results] (1) During the low-temperature treatment period, the initial fluorescence (F0) of all varieties increased, with the most significant change in B. Paederia Foetida, which increased by 60.2% compared to day 0. Maximum fluorescence (Fm), PSII effective photochemical electron production (Fv/Fm), and photosynthetic relative electron transfer rate (ETR) rapidly decreased and reached their lowest levels at day 21. As the intensification of low temperature stress, the photochemical quenching coefficient (qP) of the three Bougainvillea types decreased, while the non-photochemical quenching coefficient (qN) of B. Flaming Sumba and B. Paederia Foetida increased significantly. (2) After exposure to low temperature stress, the activities of SOD, POD and CAT enzymes in each variety decreased significantly and intensified with the extension of stress time, indicating that low temperature seriously inhibited the antioxidant enzyme activity of Bougainvillea. Among them, the SOD, POD and CAT enzyme activities of B. Paederia Foetida were higher than those of the other two varieties, indicating that B. Paederia Foetida had strong cold resistance. (3) In the AsA-GSH cycle system, the content of AsA and DHA of each Bougainvillea leaf significantly increased under low temperature. Compared to day 0, the GR activity of the three Bougainvillea types at day 21 increased by 180.91%, 175.97% and 112.37%, respectively. Additionally, the AsA/DHA ratio, APX activity and DHAR activity of B. Paederia Foetida significantly increased at day 21. [Conclusion] Low temperature inhibited plant growth through affecting the PSII photochemical reaction center. However, Bougainvillea could activate their photosynthetic system protection mechanism to reduce photoinhibition. Furthermore, it could accumulate osmoregulation substances, activate the antioxidant system, and exert stress regulatory effects to eliminate rapidly proliferating ROS in its own body and alleviate low-temperature damage.

Arbuscular mycorrhizal fungi (AMF) and Lactobacillus plantarum (LP) play pivotal roles in plant salinity resistance; however, difficulties are still exist in ascertaining their synergistic effects in counteracting legume soil salinity. Here, two peanut cultivars (salt‐tolerant and salt‐sensitive) were subjected to salinity stress, and the alleviation effects of combined microbial agent (CMA, inoculation with AMF + application with LP) on peanut salinity tolerance have been comprehensively characterized. CMA significantly enhanced the biomass production, leaf relative water content, increased the net photosynthetic rate, the maximal photochemical efficiency of photosystem II (PSII) and strengthened the antioxidant system, while dramatically decreased the reactive oxygen species (ROS) accumulation, lipid peroxidation and relative electrolyte conductivity under salinity conditions. Moreover, transcriptional and metabolomic evidence advocated that a subset of stress‐responsive pathways involved in plant growth (e.g. sucrose and starch), photosystem, antioxidant response, signal transduction (e.g. phytohormone and MAPK), osmotic homeostasis (e.g. total soluble sugar and amino acids) and root metabolism (e.g. asparagine and phenylpropanoid) have been regulated by CMA. Taken together, the physiological, transcriptional and metabolomic results indicate that CMA could induce peanut salinity tolerance through increasing plant growth performance, maintaining photosynthetic apparatus integrity, enhancing antioxidant system and regulating root metabolism. This study provides a promising CMA product and would be important for deepening the knowledge of the mechanisms regarding bacterial–fungal interactions. [ABSTRACT FROM AUTHOR]

Spiral waves in cardiac tissue have been identified as a significant factor leading to life-threatening arrhythmias and ventricular fibrillation. Consequently, understanding the mechanisms underlying the dynamics of such waves and exploring strategies for their elimination have garnered substantial interest and emerged as crucial research objectives. Spiral waves often become pinned (trapped) at anatomical obstacles in cardiac tissue, resulting in increased stability and posing challenges for their elimination. The unpinning of spiral waves can be achieved through the application of an external electric field and has been the subject of previous research. Recently, optogenetics has emerged as an alternative method to modulate electrical activity by illumination of cardiac tissue. In this paper, we employ mathematical modeling to investigate the potential of utilizing local illumination to unpin and eliminate spiral waves in cardiac tissue. We also extend this methodology to explore the effects of more complex turbulent excitation patterns. We conduct simulations using low-dimensional (Barkley) and ionic (Fenton-Karma) models of cardiac tissue, incorporating optogenetical channels. Our findings demonstrate that local suprathreshold illumination can successfully unpin spiral waves in 100% of cases. Notably, unlike unpinning by electrical field stimulation, this approach does not necessitate precise timing of stimulus application during a specific phase of rotation. Additionally, we demonstrate that periodic optogenetical stimulation can effectively eliminate both unpinned spiral waves and turbulence by moving them toward the boundary via an antitachycardia pacing mechanism.