Alternative splicing coupled to nonsense-mediated mRNA decay contributes to the high-altitude adaptation of maca (Lepidium meyenii).

Alpine plants remain the least studied plant communities in terrestrial ecosystems. However, how they adapt to high-altitude environments is far from clear. Here, we used RNA-seq to investigate a typical alpine plant maca (Lepidium meyenii) to understand its high-altitude adaptation at transcriptional and post-transcriptional level. At transcriptional level, we found that maca root significantly up-regulated plant immunity genes in day-time comparing to night-time, and up-regulated abiotic (cold/osmotic) stress response genes in Nov and Dec comparing to Oct. In addition, 17 positively selected genes were identified, which could be involved in mitochondrion. At post-transcriptional level, we found that maca had species-specific characterized alternative splicing (AS) profile which could be influenced by stress environments. For example, the alternative 3' splice site events (A3SS, 39.62%) were predominate AS events in maca, rather than intron retention (IR, 23.17%). Interestingly, besides serine/arginine-rich (SR) proteins and long non-coding RNAs (lncRNAs), a lot of components in nonsense-mediated mRNA decay (NMD) were identified under differential alternative splicing (DAS), supporting AS coupled to NMD as essential mechanisms for maca's stress responses and high-altitude adaptation. Taken together, we first attempted to unveil maca's high-altitude adaptation mechanisms based on transcriptome and post-transcriptome evidence. Our data provided valuable insights to understand the high-altitude adaptation of alpine plants.

Antibacterial and antifungal potentials of the solvents extracts from Eryngium caeruleum, Notholirion thomsonianum and Allium consanguineum.

BACKGROUND: Herbal medicines have long been used for various ailments in various societies and natural bioactive compounds are gaining more and more importance due to various factors. In this context, three plant species i.e., Eryngium caeruleum, Notholirion thomsonianum and Allium consanguineum have been aimed for the scientific verification of their purported traditional uses against various infectious diseases. METHODS: In this study, three plants were assayed for antibacterial and antifungal potentials. The antibacterial investigations were performed via well diffusion method and nutrient broth dilution method. The bacterial strains used in the study were Enterococcus faecalis, Proteus mirabilis, Escherichia coli, Salmonella typhi, Klebsiella pneumonia and Pseudomonas aeruginosa. The antifungal potential was investigated by dilution method of Muller-Hinton agar media of the plants' samples. The fungal strains used were Aspergillis fumigatus, Aspergillis flavus and Aspergillis niger. Ceftriaxone and nystatin were used as standard drugs in antibacterial and antifungal assays respectively. RESULTS: Different fractions from N. thomsonianum were tested against five bacterial strains while the samples from A. consanguineum and E. caeruleum were tested against six bacterial strains. All the samples exhibited prominent antibacterial activity against the tested strains. Overall, chloroform and ethyl acetate fractions were found most potent among the three plants' samples. N. thomsonianum excelled among the three plants in antibacterial activity. Similarly, in antifungal assay, N. thomsonianum exhibited strong antifungal activity against the fungal strains. The chloroform fraction displayed MFCs of 175.67 ± 5.20***, 29.33 ± 5.48*** and 63.00 ± 4.93*** µg/ml against Aspergillus fumigatus, Aspergillus flavus and Aspergillus niger respectively. The whole study demonstrates that all the three plant species were active against tested bacterial and fungal strains. CONCLUSION: It can be concluded from our findings that N. thomsonianum, A. consanguineum and E. caeruleum have broad antibacterial and antifungal potentials. In all of the plants' samples, chloroform and ethyl acetate fractions were more active. Furthermore, being the potent samples, the chloroform and ethyl acetate fractions of these plants can be subjected to column chromatography for the isolation of more effective antimicrobial drugs.