The plant-specific TCP transcription factors (TFs) play important roles in multiple processes of plant development and environmental stress response. However, the characteristics of TCP TFs in peanut are still unclear. In this study, we characterized the peanut TCPs including the numbers, classification, structures, and expression patterns based on the information from the available database. We identified 28, 9, and 8 TCPs in A. hypogaea cv. Tifrunner (AhTCP1-28), A. duranensis (AdTCP1-9), and A. ipaensis (AiTCP1-8), respectively. These genes can be divided into three groups based on the phylogenetic tree: PCF, CIN, and CYC/TB1. A total of 10 paralogous gene pairs in A. hypogaea cv. Tifrunner, five orthologous gene pairs between A. duranensis and A. hypogaea cv. Tifrunner and five orthologous gene pairs between A. ipaensis and A. hypogaea cv. Tifrunner, were identified respectively. Most duplicated gene pairs underwent purifying selection except AdTCP2-AhTCP15 and AiTCP8-AhTCP28 were subjected to positive selection. Hormone-related and abiotic stress response elements were abundant in several TCP gene promoters in A. hypogaea cv. Tifrunner. AhTCP12 and AhTCP25 contained four EREs (ethylene-response elements), and AhTCP15 included four TCA elements. Most of TCPs were expressed lowly in 22 tissues, however, several genes such as AhTCP25 and a homologous gene pair, AhTCP13 and AhTCP28, were expressed highly in peg tip and perianth, respectively. AhTCP duplicated gene pairs did not show significant functional differentiation. This study provided insight into the evolution and expression of AhTCPs and might assist peanut molecular breeding.

Stem rot, caused by soilborne pathogen Sclerotium rolfsii, is one of the most destructive diseases of peanut (Arachis hypogaea L.) worldwide. Although microRNAs (miRNAs) are indispensable regulators for plant defense, the miRNA species have not been explored for peanut immunity against the soilborne pathogen Sclerotium rolfsii. Here, we report a miRNA comparative analysis of the durably resistant peanut variety Rizhaohua-1 (Rzh) and the susceptible peanut variety Jitian-1 (JT) in response to infection by Sclerotium rolfsii. We identified a group of known and novel miRNAs that were differentially expressed upon S. rolfsii infection. The predicted target genes included receptor kinases, transcription factors, and genes involved in the production and transport of metabolites. In this study, we have shown that miRNAs regulate a broad range of genes to respond to the pathogen, and eventually establish a systemic defense network to combat disease.