ABSTRACT
Monilinia laxa, a notorious fungal pathogen responsible for the devastating brown rot disease afflicting apples, wreaks havoc in both orchards and storage facilities, precipitating substantial economic losses. Currently, chemical methods represent the primary means of controlling this pathogen in warehouses. However, this study sought to explore an alternative approach by harnessing the biocontrol potential of bacterial isolates against brown rot in apple trees. A total of 72 bacterial isolates were successfully obtained from the apple tree rhizosphere and subjected to initial screening via co-cultivation with the pathogen. Notably, eight bacterial isolates demonstrated remarkable efficacy, reducing the mycelial growth of the pathogen from 68.75 to 9.25%. These isolates were subsequently characterized based on phenotypic traits, biochemical properties, and 16S rRNA gene amplification. Furthermore, we investigated these isolates' production capacity with respect to two enzymes, namely, protease and chitinase, and evaluated their efficacy in disease control. Through phenotypic, biochemical, and 16S rRNA gene-sequencing analyses, the bacterial isolates were identified as Serratia marcescens, Bacillus cereus, Bacillus sp., Staphylococcus succinus, and Pseudomonas baetica. In dual culture assays incorporating M. laxa, S. marcescens and S. succinus exhibited the most potent degree of mycelial growth inhibition, achieving 68.75 and 9.25% reductions, respectively. All the bacterial isolates displayed significant chitinase and protease activities. Quantitative assessment of chitinase activity revealed the highest levels in strains AP5 and AP13, with values of 1.47 and 1.36 U/mL, respectively. Similarly, AP13 and AP6 exhibited the highest protease activity, with maximal enzyme production levels reaching 1.3 and 1.2 U/mL, respectively. In apple disease control assays, S. marcescens and S. succinus strains exhibited disease severity values of 12.34% and 61.66% (DS), respectively, highlighting their contrasting efficacy in mitigating disease infecting apple fruits. These findings underscore the immense potential of the selected bacterial strains with regard to serving as biocontrol agents for combatting brown rot disease in apple trees, thus paving the way for sustainable and eco-friendly alternatives to chemical interventions.
ABSTRACT
Background: Since embryogenesis, plants deal with environmental changes, which might affect their growth and development. Plant autophagy has been shown to function in various stress responses, immunity, development, and senescence. Acquired thermotolerance or thermopriming is enhanced resistance to the elevated temperature following heat stress. Objectives: Potential contribution of autophagy mechanism after thermopriming was investigated in shoot apical meristem (SAM) of Arabidopsis thaliana. Materials and Methods: Transcriptic expression of Autophagy related Genes (ATGs) were analyzed by qRT-PCR data in 5-day old Arabidopsis thaliana (Col0) seedlings at 4 h and 24 h after thermopriming. Autophagy induction was confirmed by confocal microscopy. Results: Expression patterns of 39 ATGs and ATG-receptors were described and relevant thermopriming induced autophagy genes were identified according to their highest expression fold changes during the time after treatment. Significantly, ATG8A, ATG8B, ATG8G, ATG8H, ATI1, ATI2, NBR1, and TSPO genes were identified as the most relevant thermopriming-associated autophagy genes especially in SAM of young seedlings. This mainly implies the role of ATG8 core proteins and their receptor interactors in the regulation of autophagy in form of selective or non-selective during environmental stresses. Conclusions: Autophagy, a conserved mechanism for cell survival in plants will be activated in response to the thermopriming which is a promoted acquired resistance stimulus. Determined key genes and components of autophagy associated with thermal priming signaling pathway could be noteworthily employed to study transcriptional regulation of autophagy and integrated defense system against environmental stresses for the improvement of plant thermal tolerance and resistance to the pathogens.
