Cotton Genomics and Genetics 2025, Vol.16, No.4, 184-191 http://cropscipublisher.com/index.php/cgg 188 6 Case Studies: Innate Immune Responses in Specific Cotton Varieties 6.1 Transcriptomic features of resistant hybrids Disease-resistant cotton hybrids exhibit rapid and robust induction of immune-related gene expression after pathogen infection. For example, in disease-resistant varieties, transcription factors such as WRKY41 are generally and rapidly upregulated after inoculation with Verticillium dahliae. Overexpression of GhWRKY41 enhances resistance by activating phenylpropanoid metabolism and upregulating genes involved in lignin and flavonoid biosynthesis, while knockdown increases susceptibility. Whole-genome analysis showed that a large proportion of WRKY41 target genes were upregulated during infection, including receptor kinases and other disease resistance proteins, which emphasizes the importance of transcriptional reprogramming in disease-resistant hybrids (Figure 2) (Xiao et al., 2023). Figure 2 GhWRKY41 is a positive regulator of cotton resistance toVerticillium dahliae. (a) Disease symptoms of cotton seedlings (G. barbadense cv. 7124) after inoculation for 20 days. Seedlings of TRV:00 and TRV:GhWRKY41 were inoculated with V. dahliae and re-planted in soil with at least 25 plants. (b) Reverse transcription PCR analysis to examine the expression of GbWRKY41 in TRV:00 and TRV:GhWRKY41plants. The GbUB7 gene was used as a control for expression. (c) V. dahliae hyphal accumulation of in TRV:00 and TRV:GhWRKY41 plant stems. (d) Disease index and rate of diseased plants of TRV:00 and TRV:GhWRKY41 plants after inoculation for 20 days. Values represent means ± SD; n=3. (e-f) Southern blotting (e) and reverse transcription-quantitative PCR (RT-qPCR) analysis (f) to examine the copy number and expression respectively of GhWRKY41 in GhWRKY41-transgenic cotton lines. The GhUB7 gene was used as the endogenous reference gene. Values represent means ± SD; n=3. (g) Disease symptoms in wild type (WT), overexpression (OE) and RNAi (Ri) cotton plants after inoculation for 11 days. Seedlings of WT and transgenic lines were inoculated with V. dahliae and re-planted in soil with at least 25 plants for each line. (h) Disease index of WT and transgenic plants at 5 days after the plants beginning to present disease symptoms. Values represent means ± SD; n=3. (i) RT-qPCR analysis of GhWRKY41 in WT and transgenic Arabidopsis lines. The AtACTINgene was used as the endogenous reference gene. The values are the means ± SD; n=3. (j) Disease symptoms in WT and overexpressing Arabidopsis lines at 3 weeks after inoculation with V. dahliae. (k) Disease index statistics in WT and transgenic Arabidopsis lines after inoculation with V. dahliae for 3 weeks. Values are the means ± SD; n=3. All statistical analyses were performed using Student's t test: **, P < 0.01. All assays were repeated three times with similar results (Adopted from Xiao et al., 2023)
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