MicroRNA1916 (miR1916) is one of the nonconserved miRNAs that respond to various stresses in plants, but little has been known at present about its mechanisms in biotic stresses. In this study, the expression of Solanum lycopersicum (sly)‐miR1916 in tomato was found to be down‐regulated after infection with Phytophthora infestans or Botrytis cinerea. Tomato plants that overexpressed sly‐miR1916 displayed significant enhancement in susceptibility to P. infestans and B. cinerea infection, as well as increased tendency to produce reactive oxygen species. Silencing of sly‐miR1916 by short tandem target mimic and artificial microRNA strategies caused the tomato plants to become more tolerant to adverse conditions. In addition, lower sly‐miR1916 expression could up‐regulate the expression of strictosidine synthase (STR‐2), UDP‐glycosyltransferases (UGTs), late blight resistance protein homolog R1B‐16, disease resistance protein RPP13‐like, and MYB transcription factor (MYB12), which ultimately resulted in the accumulation of α‐tomatine and anthocyanins via STR‐2, UGT, and MYB12. Furthermore, ectopic expression of sly‐miR1916/STR‐2 significantly changed the tolerance of tobacco to B. cinerea. Taken together, the results demonstrated that sly‐miR1916 might regulate the expression of STR‐2, UGT, and MYB12 in tomato plant, conferring sensitivity to biotic stress via modulating α‐tomatine and anthocyanins.
A Sweet potato-infecting sweet potato leaf curl virus (SPLCV) isolated in China was detected by Polymerase Chain Reaction (PCR). PCR products amplified from DNA-A were cloned and sequenced. The isolates of SPLCV from China(SPLCV-CN)has a genome organization similar to that of monopartite begomoviruses. The DNA-A had two ORFs (AV1 and AV2) in the virion sense and four ORFs (AC1, AC2, AC3, and AC4) in the complementary sense, separated by an intergenic region (IR) containing a conserved stem-loop motif. Three incomplete direct repeat iterons were also found within the IR. The presence of AV2 ORF supports the relationship of SPLCV-CN to the Old World gemimiviruses. Sequence comparisons showed that the DNA-A sequence of SPLCV-CN were closely related to those of sweet potato leaf curl Georgia virus-[16] (SPLCGV-[16]), Ipomoea yellow vein virus (IYVV-SI), and sweet potato leaf curl virus (SPLCV) with nucleotide sequence identity ranging from 88% to 91%. Comparison of individual encoded proteins between SPLCV-CN and that of three other SPLCV isolates showed the coat protein (AV1) shared the highest amino acid sequence identity (93%-96%), suggesting the coat protein of these viruses may have identical ancestor. The relationships between SPLCV-CN and other whitefly-transmitted geminiviruses were investigated by using phylogeny of derived AV1, AC1, and AV2 amino acid sequences. In all phylogenetic trees, SPLCV-CN clustered with three other isolates of SPLCV. The analyses revealed that the four isolates of SPLCV have coat proteins which are unique from its counterparts from both the Old World and New World. The present of AV2 and phylogenic analysis of AC1 suggest that SPLCV is more close to begomoviruses from the Old World but isolates of this virus seems to form a separate subset.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.