Abstract
Chitinases, a subgroup of pathogenesis-related proteins, are responsible for catalyzing the hydrolysis of chitin. Accumulating reports indicate that chitinases play a key role in plant defense against chitin-containing pathogens and are therefore good targets for defense response studies. Here, we undertook an integrated bioinformatic and expression analysis of the cucumber chitinases gene family to identify its role in defense against Fusarium oxysporum f. sp. cucumerinum. A total of 28 putative chitinase genes were identified in the cucumber genome and classified into five classes based on their conserved catalytic and binding domains. The expansion of the chitinase gene family was due mainly to tandem duplication events. The expression pattern of chitinase genes was organ-specific and 14 genes were differentially expressed in response to F. oxysporum challenge of fusarium wilt-susceptible and resistant lines. Furthermore, a class I chitinase, CsChi23, was constitutively expressed at high levels in the resistant line and may play a crucial role in building a basal defense and activating a rapid immune response against F. oxysporum. Whole-genome re-sequencing of both lines provided clues for the diverse expression patterns observed. Collectively, these results provide useful genetic resource and offer insights into the role of chitinases in cucumber-F. oxysporum interaction.
Highlights
Chitinases (EC 3.2.1.14) are glycosyl hydrolases (GH) that catalytic mechanism involves the hydrolysis of the β-1-4-linkage in the N-acetyl-D-glucosamine polymer of chitin, a major structural component of chitin-containing pathogens [1,2,3]
A total of 28 putative chitinase genes were identified; each gene was annotated as CsChiXX, where Cs is the genus and species initials (Cucumis sativus) and XX is the sequential number of a gene in the genome
Most research on the identification and analysis of chitinase gene family have focused on A. thaliana, Nicotiana benthamiana, Oryza sativa and Zea mays, whereas studies are limited on non-model plants like C. sativus [46]
Summary
Chitinases (EC 3.2.1.14) are glycosyl hydrolases (GH) that catalytic mechanism involves the hydrolysis of the β-1-4-linkage in the N-acetyl-D-glucosamine polymer of chitin, a major structural component of chitin-containing pathogens [1,2,3]. Chitinases contains catalytic domains defining the two major GH families (GH18 and GH19) and are classified into seven classes (Class I–VII) [15,16]. GH18 chitinases (class III and V) are widely distributed in a variety of organisms, while GH19 chitinases (class I, II, IV, VI, VII) are found mainly in higher plants [17], and are responsible for the majority of chitinolytic activity within plants [4]. The two families are clearly distinguished by their sequences and three-dimensional structures, indicating they are derived from different ancestral genes [4,18]
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
