A Phytochrome-Interacting Factor Gene <i>CaPIF7a</i> Positively Regulates the Defense Response against <i>Phytophthora capsici</i> Infection in Pepper (<i>Capsicum annuum</i> L.)
2024
Yu Li | Dan Wu | Ting Yu | Bing Liu | Xuchun Gao | Huibin Han | Jinyin Chen | Yong Zhou | Youxin Yang
Phytochrome-interacting factor (PIF) is a subfamily of the basic helix–loop–helix (bHLH) transcription factors (TFs) and plays key roles in plant responses to diverse biotic and abiotic stresses. In this work, a <i>PIF</i> gene named <i>CaPIF7a</i> was cloned and its role in the regulation of pepper’s resistance to <i>Phytophthora capsici</i> infection (PCI) was studied. The cloned <i>CaPIF7a</i> gene has a CDS length of 1383 bp, encodes a hydrophilic protein containing bHLH and APB characteristic domains, and subcellular localization results showed that CaPIF7a was located in the nucleus. Expression analysis showed that <i>CaPIF7a</i> gene has the highest expression level in leaf, and its expression was regulated under PCI and salicylic acid (SA) treatment. Silencing of <i>CaPIF7a</i> in pepper plants by virus-induced gene silencing (VIGS) reduces the resistance of pepper to PCI, with decreased expression of SA-responsive and SA-biosynthesis genes and obviously decreased SA content. DNA affinity purification sequencing (DAP-seq) was employed to identify the potential targets of CaPIF7a, and yeast one-hybrid (Y1H) verified that CaPIF7a could regulate the expression of <i>CaHY5</i> by binding its promoter. These findings indicated that CaPIF7a might be a key modulator in plant immune response and presented a possible regulatory network of CaPIF7a in PCI.
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