Classification and Genome-Wide Analysis of Chitin-Binding Proteins Gene Family in Pepper (Capsicum annuum L.) and Transcriptional Regulation to Phytophthora capsici, Abiotic Stresses and Hormonal Applications

Abstract

Chitin-binding proteins are pathogenesis-related gene family, which play a key role in the defense response of plants. However, thus far, little is known about the chitin-binding family genes in pepper (Capsicum annuum L.). In current study, 16 putative chitin genes (CaChi) were retrieved from the latest pepper genome database, and were classified into four distinct classes (I, III, IV and VI) based on their sequence structure and domain architectures. Furthermore, the structure of gene, genome location, gene duplication and phylogenetic relationship were examined to clarify a comprehensive background of the CaChi genes in pepper. The tissue-specific expression analysis of the CaChi showed the highest transcript levels in seed followed by stem, flower, leaf and root, whereas the lowest transcript levels were noted in red-fruit. Phytophthora capsici post inoculation, most of the CaChi (CaChiI3, CaChiIII1, CaChiIII2, CaChiIII4, CaChiIII6, CaChiIII7, CaChiIV1, CaChiVI1 and CaChiVI2) were induced by both strains (PC and HX-9). Under abiotic and exogenous hormonal treatments, the CaChiIII2, CaChiIII7, CaChiVI1 and CaChiVI2 were upregulated by abiotic stress, while CaChiI1, CaChiIII7, CaChiIV1 and CaChiIV2 responded to hormonal treatments. Furthermore, CaChiIV1-silenced plants display weakened defense by reducing (60%) root activity and increase susceptibility to NaCl stress. Gene ontology (GO) enrichment analysis revealed that CaChi genes primarily contribute in response to biotic, abiotic stresses and metabolic/catabolic process within the biological process category. These results exposed that CaChi genes are involved in defense response and signal transduction, suggesting their vital roles in growth regulation as well as response to stresses in pepper plant. In conclusion, these finding provide basic insights for functional validation of the CaChi genes in different biotic and abiotic stresses.

Genome sequence and analysis of the eggplant (Solanum melongenaL.)

“…Annotation of these specific genes showed various functions (Tables S14, S15), but they were particularly overrepresented in the chitin-related Gene Ontology (GO) categories. Chitin-binding genes are known as a pathogenesis-related gene family, which plays a fundamental role in the defense response of plants [38, 39]. This finding suggests possible response roles, related to biotic stress, in eggplant.…”

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

“…As previously reported, the evolutionary relationship between CaChiVI2 and pepper CBP homologs in other species was based on phylogenetic analysis (Ali et al, 2018). The analysis revealed that pepper CBP could be classified into four main classes with potentially similar functions.…”

“…The total-RNA was extracted as explained in our recently published papers (Ali et al, 2018;Khan et al, 2018). The first chain was synthesized by the Primer Script TM Kit (TaKaRa, Dalian, China).…”

“…Sets of defense-related genes against heat shock and drought stress, i.e., HSP20, PR-2, and CBP gene families, are reported to have a role in effector-triggered immunity (ETI), relying on intensity and time of the interacting signaling components (Tsuda and Katagiri, 2010;Thomma et al, 2011). Among the defenserelated genes, chitin-binding protein genes family contributes significantly in plants adaptability and tolerance (Hejgaard et al, 1992;Ali et al, 2018). There are some CBP-encoded enzymes, which show high response during environmental stresses such as cold and high salt concentration.…”

“…The transcriptomic analysis revealed that CaChiVI2 gene had the most remarkable motif "AAAAAATTTC." It was heat stress responsive protein highly induced by ABA hormone (Ali et al, 2018).…”