Early diagnosis, monitoring, profiling, and management of bayberry twig blight disease by nitrogen metabolism

• The fingerprint of Pestalotiopsis versicolor was at 1454.46 cm −1 spectra. • MgONBs enhanced the recruitment of Bradyrhizobium to combat P.versicolor attack. • Urea, L-Methionine sulfone and 5-Aminosalicylic acid were enriched in MgONBs group. • MgONBs DEG mapped to KEGG pathway of amino acid metabolism and photosynthesis gene. Pestalotiopsis versicolor , pathogen of Bayberry Twig Blight Disease causes wilt and leaf spots thereby reducing the photosynthetic area which ultimately leads to production of small fruits with poor nutritional quality. Due to heavy dependence on chemicals with its detrimental effect, new biofriendly measures are sort. Surface-enhanced Raman scattering technology was used in early discovery and monitoring of the disease progression in bayberry seedlings. The spectra 1454.46 cm −1 was inferred as the fingerprint of the fungus. MgO nano-bioprotectant (MgONBs) antifungal mechanism of action was studied via transcriptomic and metabolomic profiling at 12 and 24 h post-inoculation (hpi) with P. versicolor and metagenomics profiling at 7 and 14 days post-inoculation (dpi) with P. versicolor. MgONBs enhanced the recruitment of Bradyrhizobium to overcome the attack of P. versicolor. Nitrogen fixation activities in the diseased leaves at 7 and 14 dpi were significantly reduced, while it was significantly increased from 17.74 % in the diseased leaves to 26.79 % in the diseased leaves treated with MgONBs at 14 dpi. Thus, activating bayberry defense by increasing its nitrogen metabolism. In addition, in MgONBs group compared to control, urea, L-Methionine sulfone, and 5-Aminosalicylic acid compounds were activated which enriched its defense and signaling pathways. Upregulated differentially expressed genes in MgONBs relative to the control at 12 and 24 hpi mapped to KEGG pathways involved in amino acid metabolism which was tightly linked to photosynthesis gene (CJ030_MR1G012863). Our results reveals the mechanism of action of MgONBs in combatting phytopathogens .