Molecular Plant Breeding 2024, Vol.15, No.2, 42-51 http://genbreedpublisher.com/index.php/mpb 44 The expression of some WRKY family transcription factors in the tomato genome can be induced by drought stress, including SlWRKY1, SlWRKY25, SlWRKY31, SlWRKY32, and SlWRKY74.SlWRKY81 reduced proline synthesis and lowered drought tolerance in tomatoes, and the expression of SlWRKY81 was up-regulated under drought conditions. The silencing of SlWRKY81 accelerated the closure of tomato stomata under drought stress and significantly reduced drought-induced damage (Dong et al., 2023). It has been observed in a study that the overexpression of CmWRKY10 in chrysanthemum leads to a significant increase in the expression of drought-related genes (Jaffar et al., 2016). Additionally, CmWRKY1 has been reported to play a role in drought tolerance in chrysanthemums by down-regulating PP2C, ABI1, and ABI2, and up-regulating genes in the ABA signaling pathway such as PYL2, SnRK2.2, ABF4, MYB2, RAB18, andDREB1A(Fan et al., 2016). Plants can regulate the expression of drought-related genes by controlling the accumulation of ROS (reactive oxygen species). In cotton, the GhWRKY25 gene reduces drought tolerance by increasing MDA and ROS levels while decreasing the activities of SOD, POD, and CAT enzymes (Liu et al., 2016). On the other hand, overexpression of the MbWRKY5 gene from Zingiber officinale in tobacco plants increases their chlorophyll, proline, glutathione, and ascorbic acid contents, as well as the activities of POD, SOD, and CAT enzymes, resulting in improved drought tolerance (Han et al., 2019). After being subjected to drought stress, WRKY-like transcription factors may have a negative impact on the expression of related genes. Some transgenic plants exhibited less resistance to drought stress, with lower leaf water content and higher levels of transpiration water loss, resulting in lower survival rates than wild-type plants. For instance, transgenic plants that had overexpressed GhWRKY25 showed a decreased resistance to grey mould (Liu, 2015). In addition, a single WRKY transcription factor can correspond to multiple physiological processes. For instance, in land cotton, the expression of the WRKY4 gene is induced under both salt and drought stress, while WRKY5 is induced only under drought stress. 2.2 High salt stress In our country, plants not only suffer from drought stress, but also from high salt stress. This salt stress negatively affects the nutritional and reproductive growth of plants, causing primary and secondary salt damage. It destroys their normal morphological structure, and can even result in serious consequences such as plant death. Salt stress has become a major obstacle to the construction of a healthy ecological environment, as well as the sustainable development of agriculture in China, alongside drought stress. First, WRKY transcription factors may be directly involved in regulating salt stress response to alleviate damage caused by high salt. For example, overexpression of the SmWRKY28 gene in Arabidopsis thaliana enhances resistance to saline salts such as NaCl and NaHCO3 and reduces oxidative toxicity (Wang, 2016); overexpression of GsWRKY15 gene can significantly enhance alfalfa alkali tolerance (Zhu et al., 2017); Overexpression of GmWRKY34 in Arabidopsis thaliana (Zhou et al., 2015), as well as overexpression of GhWRKY41 (Chu et al., 2016) and GhWRKY25(Liu et al., 2016) in tobacco, can improve salt tolerance. Plants have the ability to respond to salt stress by producing signaling molecules like ABA and H2O2. For instance, when ZmWRKY17 is overexpressed, it can reduce the sensitivity of transgenic plants to ABA while increasing their sensitivity to salt stress. Additionally, with the addition of an ABA synthesis inhibitor, the seeds of transgenic lines can recover the phenotype of strongly inhibited germination under high salt stress (Cai, 2016). OsWRKY50 in rice contains a WRKY structural domain and acts as a transcriptional repressor in the nucleus. OsWRKY50 participates in the salt stress response of rice by regulating stress-responsive genes and decreasing the ABA sensitivity of the plant, and it plays a positive role in the regulation of salt stress in rice (Fan et al., 2023). WRKY transcription factors are known to play a role in various abiotic stress responses. For instance, TaWRKY44 expression in tobacco has been shown to enhance resistance to drought, salt stress, and osmotic stress (Han et al., 2015). In the case of ginseng, PgWRKYs transcript levels respond significantly to salt stress treatment (Xiu et al., 2016). Furthermore, the promoter sequence of GhWRKY25 contains cis-acting elements that are associated with low temperature, drought, endosperm, and gibberellin elements, and are induced by high salinity and low
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