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To better understand the role of nitric oxide (NO) in mango fruit ripening, fruit that was pretreated with salicylic acid (SA) and NO was stored at 25 °C for 11 days. Fruit firmness, ethylene production, total soluble solids (TSS), titratable acidity (TA) and vitamin C content were monitored. The expression of six genes involved in ethylene biosynthesis and signalling, namely, MiACO, MiACS, MiETR1, MiERS1, MiEIN2 and MiERF, was investigated using real-time qPCR. The results showed that the treatment caused significant inhibition of the firmness decrease and ethylene output, maintained relatively high levels of TSS and vitamin C, and delayed the decrease in the TA. Furthermore, MiACO and MiERS1 were significantly downregulated, whereas MiETR1 and MiEIN2 were upregulated, and MiACS and MiERF exhibited fluctuating expression patterns. The findings of the study suggested that MiACO, MiACS, MiETR1, MiERS1, MiEIN2 and MiERF might participate in the SA and NO signal induction pathways during ripening.

The RIG-I-like receptors (RLRs)—RIG-I, MDA5, and LGP2—detect intracellular pathogenic RNA and elicit an antiviral immune response during viral infection. The protein architecture of the RLR family consists of multiple functional domains, including N-terminal Caspase Activation and Recruitment Domains (CARDs) for signaling initiation, a central RNA helicase core, and a C-terminal domain for RNA sensing. With these specialized sensing-and-responding modules, RLRs are able to selectively bind non-self RNA species and trigger downstream signaling events leading to interferon production. This article summarizes the recent progress toward defining the precise mechanisms of RNA recognition and subsequent signal induction by RLRs. Accepted version