The WRKY transcription factors are a class of transcriptional regulators that are ubiquitous in plants, wherein they play key roles in various physiological activities, including responses to stress. Specifically, WRKY transcription factors mediate plant responses to biotic and abiotic stresses through the binding of their conserved domain to the W-box element of the target gene promoter and the subsequent activation or inhibition of transcription (self-regulation or cross-regulation). In this review, the progress in the research on the regulatory effects of WRKY transcription factors on plant responses to external stresses is summarized, with a particular focus on the structural characteristics, classifications, biological functions, effects on plant secondary metabolism, regulatory networks, and other aspects of WRKY transcription factors. Future research and prospects in this field are also proposed.

Houttuynia cordata is a medicinal and edible plant with a wide biological interest. Many parts were discarded due to various modes of consumption, resulting in resource waste. In this study, a comprehensive study was conducted on various edible indicators and medicinal components of Houttuynia cordata to understand its edible and medicinal value. The edible indexes of each root, stem, and leaf were determined, and the metabolites of different parts were investigated using the headspace solid-phase micro-extraction technique (HS-SPME-GC-MS). The differential metabolites were screened by orthogonal partial least squares discriminant analysis (OPLS-DA) and clustering analysis. The results of the study showed that the parts of Houttuynia cordata with high edibility values as a vegetable were mainly the roots and leaves, with the highest vitamin C content in the roots and the highest total flavonoids, soluble sugars, and total protein in the leaves. The nutrient content of all the stems of Houttuynia cordata was lower and significantly different from the roots and leaves (p < 0.05). In addition, 209 metabolites were isolated from Houttuynia cordata, 135 in the roots, 146 in the stems, 158 in the leaves, and 91 shared metabolites. The clustering analysis and OPLS-DA found that the parts of Houttuynia cordata can be mainly divided into above-ground parts (leaves and stems) and underground parts (roots). When comparing the differential metabolites between the above-ground parts and underground parts, it was found that the most important medicinal component of Houttuynia cordata, 2-undecanone, was mainly concentrated in the underground parts. The cluster analysis resulted in 28 metabolites with up-regulation and 17 metabolites with down-regulation in the underground parts. Most of the main components of the underground part have pharmacological effects such as anti-inflammatory, anti-bacterial and antiviral, which are more suitable for drug development. Furthermore, the above-ground part has more spice components and good antioxidant capacity, which is suitable for the extraction of edible flavors. Therefore, by comparing and analyzing the differences between the edible and medicinal uses of different parts of Houttuynia cordata as a medicinal and food plant, good insights can be obtained into food development, pharmaceutical applications, agricultural development, and the hygiene and cosmetic industries. This paper provides a scientific basis for quality control and clinical use.

Cinnamomum mairei H. Lév is a rare and valuable medicinal and timber species in China. It not only has a narrow distribution, but also has few resources, is an endangered species, and is a nationally protected plant. Climate change impacts the growth and development of plants; therefore, it is of great practical significance to predict the current and future distribution of C. mairei H. Lév in suitable areas of China and to protect these endangered plants. In this study, the MaxEnt model was used to predict the suitable growing areas for C. mairei H. Lév according to six environmental factors (the temperature seasonality, max. temperature in the warmest month, min. temperature in the coldest month, precipitation seasonality, precipitation in the coldest quarter and aspect), and three different climate models (SSP126, SSP245, and SSP585) were simulated for three periods (the 2030s, 2050s, and 2070s). In the present study, the suitable ecological environment for C. mairei H. Lév comprised the following: a min. temperature in the coldest month from −0.63 to 4.36 °C, temperature seasonality from 130.67 to 642.58, a max. temperature in the warmest month from 28.86 to 45.97 °C, and precipitation in the coldest quarter from 40.12 to 101.13 mm. Highly suitable habitats for C. mairei H. Lév are located in the Yunnan Province, Guizhou Province, Sichuan Province, and Chongqing City, China (southwestern part of China), and to a lesser extent in the Xizang Province and Shaanxi Province, China. The moderately suitable habitat district overlaps with the highly suitable habitat district, and a small number of suitable habitats are distributed in Guangxi Province, Hunan Province, Hubei Province, and Henan Province. In the future, the highly suitable areas for C. mairei H. Lév will increase slightly, and the gravity points will shift toward northeast China. Our simulations are helpful for understanding the geoecological characteristics of this species and provide a basis for regional projections of this species under current and future climate change scenarios in China. It is proposed to establish nature reserves for C. mairei H. Lév in the Chongqing, Yunnan, Sichuan and Guizhou provinces of China.

The effects of waterlogging on antioxidant enzyme activities responses in five different lines, i.e. ABA-deficient mutant (0673) and its control (0535), two ABA over-production transgenic rd29A:NCED1 lines (#2, #7) and Mill. L. cv. New Yorker (WT) were investigated. The waterlogging was mimicked by treating pot plants with flooding. The malondialdehyde (MDA) content, superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activity in the leaves were evaluated in all treatments. The results showed that after 7 days waterlogging treatment, the malondialdehyde (MDA) was increased in all plants, especially in LA0673. Compared with the LA0673, #2 and #7 significantly increase the activities of SOD, POD and CAT under waterlogging stress. Therefore, ABA could improve the waterlogging tolerance of tomato by increasing the activities of antioxidant enzymes under waterlogging stress.

Ethylene-responsive element binding factors (ERFs) are widely involved in the regulation of plant responses to different abiotic stresses. In petunia (Petunia × hybrida), PhERF2 belonging to the subfamily Ⅶ of ERF transcription factors participates in the response to waterlogging stress. In this study, we investigated waterlogging tolerance variation of WT and transgenic petunia plants with RNAi silencing and overexpression of PhERF2 through photosynthetic and physiological performance. Chlorophyll content and root vigor declined continuously in both WT and PhERF2 transgenic lines under waterlogging stress, but the extent of the fall in PhERF2-overexpressing lines was less than that in WT and PhERF2-RNAi lines. At the end of waterlogging treatment, soluble protein levels in PhERF2-overexpressing lines were significantly higher than those in WT and PhERF2-RNAi lines, while the latter showed a higher malondialdehyde content overall. Different degrees of reductions in Pn, Gs, and Tr levels occurred in both WT and PhERF2 transgenic lines upon exposure to waterlogging. The Ci levels of PhERF2-overexpressing lines decreased after 3 hours of waterlogging treatment, and the Ci levels of WT and PhERF2-RNAi lines gradually increased from 6 to 72 hours of waterlogging treatment. These data suggested that non-stomatal factors were the primary limiting factors for Pn in WT and PhERF2-RNAi lines under severe stress, while the stomatal opening was the main factor limiting Pn in PhERF2-overexpressing lines. Our results demonstrated that the contribution of PhERF2 to the waterlogging tolerance of petunia appears to depend on the regulation of physiological and photosynthetic responses. PhERF2 represents a hopeful candidate gene for enhancing waterlogging tolerance of ornamental plants.