Functional and Promoter Analysis of ChiIV3, a Chitinase of Pepper Plant, in Response to Phytophthora capsici Infection

Abstract

Despite the involvement of many members of the chitinase family in plant immunity, the precise functions of the majority of the members remain poorly understood. Herein, the gene ChiIV3 in Capsicum annuum encoding a chitinase protein containing a chitin binding domain and targeting to the plasma membrane was found to be induced by Phytophthora capsici inoculation (PCI) and applied chitin treatment. Besides its direct inhibitory effect on growth of Phytophthora capsici (P. capsici), ChiIV3 was also found by virus-induced gene silencing (VIGS) and transient overexpression (TOE) in pepper plants to act as a positive regulator of plant cell death and in triggering defense signaling and upregulation of PR (pathogenesis related) genes against PCI. A 5′ deletion assay revealed that pChiIV3−712 to −459 bp was found to be sufficient for ChiIV3’ response to PCI. Furthermore, a mutation assay indicated that W-box−466 to −461 bp in pChiIV3−712 to −459 bp was noted to be the PCI-responsible element. These results collectively suggest that ChiIV3 acts as a likely antifungal protein and as a receptor for unidentified chitin in planta to trigger cell death and defense signaling against PCI.

The CaChiVI2 Gene of Capsicum annuum L. Confers Resistance Against Heat Stress and Infection of Phytophthora capsici

“…The subcellular localization of CBP members may show their associated functions. Some CBP genes in other plants such as ScChiI1 have been localized in the cytoplasm and the plasma membrane (Su et al, 2015) and ChiIV3 in the plasma membrane (Liu Z. et al, 2017). In Oryza sativa, CBP proteins are located in cytoplasm and mitochondria and are thought to be associated with the thylakoid membrane under heat stress (Xu et al, 2007).…”

“…Cis-regulatory elements (1500bp upstream region) were searched by PlantCARE online server 3 (Lescot et al, 2002). Publicly available transcriptomic data of root and leaf for pepper cultivar "Zunla" were obtained from the online server 4 , and the genomic database was generated by following Liu Z. et al (2017) and Yu et al (2017) method and the data were presented in line-graphs (CaChiVI2 sequence shown in Supplementary Table S1).…”

Challenges and Strategies for Breeding Resistance in Capsicum annuum to the Multifarious Pathogen, Phytophthora capsici

“…Furthermore, ChiIV3 is a positive regulator of plant cell death and triggers defense signaling and upregulation of pathogenesis related genes against P . capsici infection ( Liu et al, 2017 ). Interestingly, there appears to be several different types of R genes in Capsicum .…”

Plant Responses to Pathogen Attack: Small RNAs in Focus

“…Cumulatively, these are responsible for an approximately 30% loss in global crop production at pre- and post-harvest levels [ 2 ]. All plant pathogens continuously challenge the host immune system [ 3 ], so, to counteract multifarious infection types, plants have evolved an array of defense responses by activating or suppressing a number of genes [ 4 , 5 , 6 ]. In succeeding events of pathogen attack, plants recognize a cascade of PAMPs or DAMPs (host danger-associated molecular patterns) [ 3 , 7 , 8 , 9 ].…”

“…All plant pathogens continuously challenge the host immune system [ 3 ], so, to counteract multifarious infection types, plants have evolved an array of defense responses by activating or suppressing a number of genes [ 4 , 5 , 6 ]. In succeeding events of pathogen attack, plants recognize a cascade of PAMPs or DAMPs (host danger-associated molecular patterns) [ 3 , 7 , 8 , 9 ]. Cell-surface-based PRRs (pattern-recognition receptors), e.g., FLS2, EF-Tu, LYK5, and CERK1, perceive pathogens, i.e., bacteria- and fungi-triggered PAMPs or DAMPs [ 10 , 11 , 12 , 13 ].…”