Molecular Plant Breeding 2024, Vol.15, No.2, 42-51 http://genbreedpublisher.com/index.php/mpb 45 temperature (4 °C), while being inhibited by polyethylene glycol (PEG) and mechanical damage. It is worth noting that the hormonal signaling molecules GA3, 6-BA, ABA and SA strongly induce gene expression in GhWRKY25 (Liu, 2015). The interaction of WRKY transcription factors with other proteins is very important in regulating salt tolerance responses in plants. For instance, in Arabidopsis, the transcription factor WRKY8 interacts with VQ9, a member of the VQ protein family, to regulate salt tolerance responses in plants (Han et al., 2015). WRKY transcription factors can be induced by multiple stressors, including salt stress. For example, the overexpression of cotton GHWRKY39-1 in tobacco increased the tolerance of the transgenic plants to salt stress (Shi et al., 2014). The overexpression of the tomato SlWRKY39 gene in tomato plants also increased their proline content significantly, thereby improving their resistance to salt damage and drought caused by multiple stress factors such as PstDC3000, salt damage, and drought (Sun et al., 2015). WRKY transcription factors are also negatively regulated by salt stress. For example, overexpression of OsWRKY45-1 reduced rice tolerance to high salt (Tao et al., 2011); in transgenic Arabidopsis thaliana and chrysanthemum, chrysanthemumGmWRKY17 negatively regulated its salt tolerance (Li et al., 2015). 2.3 Temperature stress Temperature is a crucial factor that affects plant growth and development. High and low temperatures can cause stress on plants, which is referred to as abiotic stress. When plants are subjected to high or low temperatures, specific transcription factors known as WRKY transcription factors regulate the expression of related genes to reduce the damage caused by the temperature. For instance, the expression of transcription factors WRKY5 and WRKY24 in the highly cold-tolerant variety 'Dongnong Winter Wheat 1', varied significantly between different low-temperature treatments, indicating that this transcription factor plays a vital role in regulating the cold tolerance of plants. Furthermore, the chili CaWRKY13 gene plays a crucial role in coping with abiotic stresses, including low and high temperatures (Wei et al., 2017). The WRKY family of genes plays a crucial role in the response of plants to temperature-related stress by regulating the ABA signaling pathway. For instance, in the tea tree, 50 genes belonging to the WRKY family are identified, most of which are induced by cold stress. Among these genes, CsWRKY2 is responsible for enhancing plant cold resistance by regulating the ABA signaling pathway (Wu et al., 2016). Overexpression of VpWRKY1 and VpWRKY2 in Arabidopsis thaliana has been found to increase the plant's response to cold stress, salt stress, and frost, thus aiding in better cold resistance in transgenic plants. In addition to this, VpWRKY2 also enhances plant resistance to downy mildew (Li et al., 2010a). Similarly, in oilseed rape, the BcWRKY46 gene responds to strong induction of NaCl and drought and enhances cold resistance by regulating the ABA signaling pathway (Wang et al., 2012). The phytohormone JA, which is involved in the plant's response to various stressors, also reduces the damage caused by low temperatures in fruit. The MaWRKY26 gene found in bananas is activated by low-temperature stress and MeJA. This activation helps to improve the cold resistance of banana fruits. Additionally, when combined with its promoter, MaWRKY26 can also be reverse-activated to promote the synthesis of JA. This can reduce the damage caused by low temperatures on banana fruits. The transcription factors of the WRKY family, HbWRKY2, HbWRKY3, HbWRKY4, and HbWRKY9, respond to abiotic stresses such as PEG, high salinity, and low temperature. This response helps in improving the plant's resistance to these conditions (Xie, 2013; Zhao et al., 2015). Moreover, chili CaWRKY40 is involved in plant response to high-temperature stress (Dang et al., 2013). In Arabidopsis, high temperature inhibited the expression of the AtWRKY33 gene with a repressive effect, but induced the expression of the AtWRKY25 and AtWRKY26 genes. Among them, constitutive expression of AtWRKY25 andAtWRKY26 enhanced plant expression by activating Hsfs (Heat shock factors), Hsps (Heat shock proteins), Zat10 (Transcription factor), and MBF1c (Multiprotein bridging factor 1) enhance plant resistance to heat stress (Ohama et al., 2017); heat treatment induces the expression of AtWRKY39, which positively regulates the signalling pathways involved in SA (salicylic acid) and JA (jasmonic acid) through the activation of MBF1c, thereby increasing plant heat tolerance (Li et al., 2010b; Ohama et al., 2017).
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