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Although, the C 2 H 2 zinc finger (ZF) family of plant transcription factors have been implicated in multiple biological processes, they are yet to be characterized in the economically important chilli pepper (Capsicum annuum). In this study, a total of 79 C 2 H 2 ZF genes were identified in the pepper genome. Phylogenetic analysis categorized the pepper C 2 H 2 ZF (CaZF) members into five subfamilies each with unique conserved domains and functions. Genomic organization revealed that CaZF genes have variable number of introns consistent with the characteristics defined by the evolutionary analysis. Segmental duplication-based purifying selection contributed to the expansion of CaZF genes in pepper. Additionally, 11 CaZF genes were identified as targets for 38 miRNAs indicating their role in post-transcriptional silencing-mediated genetic regulation. Gene expression analysis revealed that 18 CaZF genes were differentially expressed post-infection with the anthrocnose pathogen Colletotrichum truncatum, uncovering their potential function in pepper response to biotic stresses. Moreover, CaZFs were significantly induced post-treatment with methyl jasmonate and ethylene indicating their role in defense signaling. Notably, the MeJA responsive cis-elements were detected in the promoter regions of majority of CaZF genes, suggesting that CaZFs may be implicated in defense-responsive signal cross talking. Additionally, 18 CaZF genes were differentially expressed under drought and heat treatment, indicating their involvement in plant response to abiotic stresses. Overall, a comprehensive analysis of CaZF gene family in pepper provided significant insights into the understanding of C 2 H 2 ZFmediated stress regulation network, which would benefit the genetic improvement of pepper and other allied plants. KeywordsCapsicum annuum • C 2 H 2 zinc finger proteins • Genome wide analysis • Pepper anthracnose • Colletotrichum truncatum

MicroRNAs are small non-coding RNAs of 21-24 nucleotides in length that acts as important modulators of gene expression related to numerous biological processes including development and defense response in eukaryotes. However, only a limited report on onion (Allium cepa) miRNAs is available and their associated role in growth and development of onion is not yet clear. Therefore, it is of interest to identify miRNAs and their targets in Allium cepa using the genome survey sequences (GSSs) and expressed sequence tags (ESTs) and deduce the functions of the target genes using gene ontology (GO) terms. We report 14 potential miRNAs belonging to 13 different families (miR162, miR168, miR172c, miR172e, miR398, miR400, miR414, miR1134, miR1223, miR6219, miR7725, miR8570, miR8703 and miR8752). BLAST analysis using psRNATarget server predicted 39 potential targets for the identified miRNAs majority of which were transcription factors implicated in plant growth, development, hormone signaling and stress responses. These data forms the basis for further analysis and verification towards understanding the miRNA mediated regulatory mechanism in Allium cepa.

No abstract

Small RNAs (sRNAs) are short non-coding regulatory RNA sequences that silence the complementary expressive transcripts through an endogenous RNA mediated interference mechanism (RNAi). These sRNAs typically move through plasmodesmata and phloem in plants to support disease resistance, and also through septal pores and vesicles in fungi to act as effector of pathogenicity. Notably, recent reports have shown the occurrence of a bidirectional trafficking of these sRNAs between the host plants and the attacking fungal phytopathogen which have significant implication in the nature of the infection. While the trans-species sRNAs from the pathogen can silence the host mRNAs and inhibit the host immunity genes, the sRNA modules from the host plants can silence the mRNA in the pathogen by impeding the expression of the pathogenicity-related genes. In the present review, we discuss the current state of sRNA trafficking between the plant and the pathogen with special emphasis on the mechanism of cross-kingdom communication which could contribute to the development of pathogen and pest control in future agriculture.