Melatonin confers thermotolerance and antioxidant capacity in Chinese cabbage.

Due to the damaging effect of high temperatures on plant development, global warming is predicted to increase agricultural risks. Chinese cabbage holds considerable importance as a leafy vegetable that is extensively consumed and cultivated worldwide. Its year-round production also encounters severe challenges in the face of high temperatures. In this study, melatonin (MT), a pivotal multifunctional signaling molecule that coordinates responses to diverse environmental stressors was used to mitigate the harmful effects of high temperatures on Chinese cabbage. Through the utilization of growth indices, cytological morphology, physiological and biochemical responses, and RNA-Seq analysis, alongside an examination of the influence of crucial enzymes in the endogenous MT synthesis pathway on the thermotolerance of Chinese cabbage, we revealed that MT pretreatment enhanced photosynthetic activity, maintained signaling pathways associated with endoplasmic reticulum protein processing, and preserved circadian rhythm in Chinese cabbage under high temperatures. Furthermore, pretreatment with MT resulted in increased levels of soluble sugar, vitamin C, proteins, and antioxidant enzyme activity, along with decreased levels of malondialdehyde, nitrate, flavonoids, and bitter glucosinolates, ultimately enhancing the capacity of the organism to mitigate oxidative stress. The knockdown of the tryptophan decarboxylase gene, which encodes a key enzyme responsible for MT biosynthesis, resulted in a significant decline in the ability of transgenic Chinese cabbage to alleviate oxidative damage under high temperatures, further indicating an important role of MT in establishing the thermotolerance. Taken together, these results provide a mechanism for MT to improve the antioxidant capacity of Chinese cabbage under high temperatures and suggest beneficial implications for the management of other plants subjected to global warming.

Tetrad stage transient cold stress skews auxin-mediated energy metabolism balance in Chinese cabbage pollen.

Changing ambient temperature often impairs plant development and sexual reproduction, particularly pollen ontogenesis. However, mechanisms underlying cold stress-induced male sterility are not well understood. Here, we exposed Chinese cabbage (Brassica campestris) to different cold conditions during flowering and demonstrated that the tetrad stage was the most sensitive. After completion of pollen development at optimal conditions, transient cold stress at the tetrad stage still impacted auxin levels, starch and lipid accumulation, and pollen germination, ultimately resulting in partial male sterility. Transcriptome and metabolome analyses and histochemical staining indicated that the reduced pollen germination rate was due to the imbalance of energy metabolism during pollen maturation. The investigation of ß-glucuronidase (GUS)-overexpressing transgenic plants driven by the promoter of DR5 (DR5::GUS report system) combined with cell tissue staining and metabolome analysis further validated that cold stress during the tetrad stage reduced auxin levels in mature pollen grains. Low-concentration auxin treatment on floral buds at the tetrad stage before cold exposure improved the cold tolerance of mature pollen grains. Artificially changing the content of endogenous auxin during pollen maturation by spraying chemical reagents and loss-of-function investigation of the auxin biosynthesis gene YUCCA6 by artificial microRNA technology showed that starch overaccumulation severely reduced the pollen germination rate. In summary, we revealed that transient cold stress at the tetrad stage of pollen development in Chinese cabbage causes auxin-mediated starch-related energy metabolism imbalance that contributes to the decline in pollen germination rate and ultimately seed set.

Small and Micro-Water Quality Monitoring Based on the Integration of a Full-Space Real 3D Model and IoT.

In order to address the challenges of small and micro-water pollution in parks and the low level of 3D visualization of water quality monitoring systems, this research paper proposes a novel wireless remote water quality monitoring system that combines the Internet of Things (IoT) and a 3D model of reality. To begin with, the construction of a comprehensive 3D model relies on various technologies, including unmanned aerial vehicle (UAV) tilt photography, 3D laser scanning, unmanned ship measurement, and close-range photogrammetry. These techniques are utilized to capture the park's geographical terrain, natural resources, and ecological environment, which are then integrated into the three-dimensional model. Secondly, GNSS positioning, multi-source water quality sensors, NB-IoT wireless communication, and video surveillance are combined with IoT technologies to enable wireless remote real-time monitoring of small and micro-water bodies. Finally, a high-precision underwater, indoor, and outdoor full-space real-scene three-dimensional visual water quality monitoring system integrated with IoT is constructed. The integrated system significantly reduces water pollution in small and micro-water bodies and optimizes the water quality monitoring system.

MYB transcription factors and their roles in the male reproductive development of flowering plants.

As one of the largest transcription factor families with complex functional differentiation in plants, the MYB transcription factors (MYB TFs) play important roles in the physiological and biochemical processes of plant growth and development. Male reproductive development, an essential part of sexual reproduction in flowering plants, is undoubtedly regulated by MYB TFs. In this review, we summarize the roles of the MYB TFs involved in the three stages of male reproductive development: pollen grains formation and maturation, filament elongation and anther dehiscence, and fertilization. Also, the potential downstream target genes and upstream regulators of these MYB TFs are discussed. Furthermore, we propose the underlying regulatory mechanisms of these MYB TFs: (1) A complex network of MYB TFs regulates various aspects of male reproductive development; (2) MYB homologous genes in different species may be functionally conserved or differentiated; (3) MYB TFs often form regulatory complexes with bHLH TFs.

Identifying the trade-offs between climate change mitigation and adaptation in urban land use planning: An empirical study in a coastal city.

Cities play a significant role in climate change mitigation and adaptation. Urban land planning shapes the urban form and is considered to be an effective approach for climate change mitigation and adaptation. Yet, there is little knowledge about what urban forms can reduce both greenhouse gas (GHG) emissions and climate stresses while considering trade-offs between them. Here, we investigate the role of urban land use in both climate change mitigation and adaptation. In particular, we assess quantitatively the competition between strategies for mitigation and adaptation and identify potential win-win solutions in land use responses. Using a coastal city as a case study, we find that the land use strategies for unilateral mitigation or adaptation can cause contradicting consequences with respect to the reductions in GHG emissions and climate stresses, i.e. reductions in GHGs could increase climate stresses or vice versa. Poorly integrated strategies potentially may compromise international efforts to meet the Climate Action in the Sustainable Development Goals. Properly integrated mitigation and adaptation strategies, or climate-sensitive land use planning, however, can lead to win-win outcomes and eventually achieve co-benefits. Yet, any co-benefits will gradually diminish if there is a delay in climate-sensitive land use planning, implying growing GHGs and intensified climate stresses. Our analysis indicates that integrating climate change mitigation and adaptation in urban land use needs to be enacted as soon as possible: any delays in implementation reduce the window to act to maximize the co-benefits.