RESUMO
Microorganisms and their hosts communicate through an array of signals. Many physiological processes regulated in quorum sensing (QS) are dependent on auto-inducers, like N-acyl-homoserine lactones (AHLs) as in numerous groups of both gram-positive and gram-negative bacteria. In vitro grown seven-day old chickpea seedlings treated with plant growth promoting bacteria (PGPRs) were used to screen the AHL mimicking and for phytochemical substances like phytohormones and secondary metabolites such as phenolics and flavonoids. Potential anti-quorum sensing (anti-QS) activity surrounding the roots on semi-solid agar lawn of Chromobacterium violaceum (ATCC12742) was observed. Crude protein (4.46-8.30 µg/mL) and methanolic extracts (100 µg/mL) of seedling gave moderate anti-QS activity against CV12742 anti QS bioassay, respectively. Crude protein and methanolic extract of Bacillus amyloliquefaciens (34.00 ± 2.23; 34.00 ± 4.33 mm) and B. subtilis A (27.00 ± 2.10; 3.29 ± 2.16 mm) treated samples showed higher zone of inhibition due to anti-QS activity. Phytohormone analysis using LC-MS for zeatin, auxin and methyl jasmonate (MeJA) indicated that phytohormones were significantly upregulated by 1909.80 ng/g FW, 669.67 ng/g FW and 244.55 ng/g FW, respectively in Pseudomonas brassicacearum treated seedlings compared to control. UHPLC of PGPR treated seedlings showed overly expressed gallic acid, protocatechuic acid, catechin, p-hydroxybenzoic acid, caffeic acid, catechol, vanillin, and ferulic acid in B. amyloliquefaciens treated seedlings compared to others. Enrichment analysis identified significant pathways related to metabolism, biosynthesis of secondary metabolites. The present study indicates that chickpea neutralizes an extensive range of functional responses to AHLs that may play important role in legume host-microbe interactions. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12298-021-01034-x.
RESUMO
This study pertains to the effects of heavy metal salts viz., copper (Cu), manganese (Mn), lead (Pb) and zinc (Zn) on the chickpea accession ICC-4812. The salts were given as treatments to the chickpea seeds at various ascending levels of doses till proving toxic. The treatment of 24 h soaked and swollen seeds were then extended to 7 days duration from the date of treatment. Atomic absorption spectrophotometric analysis of bioassay tissue Cicer, showed maximum uptake of 9.41 mg/g and minimum of 1.65 mg/g tissue dry weight for Pb and Zn respectively. The study reveals that enhanced antioxidant responses are associated with substantial proline accumulation indicating induced stress. Ferric reducing antioxidant power assay measuring antioxidant activity was highest in the chickpea seedling treated with Zn, whereas, free radical scavenging activity was highest in the treatments with Mn. The total phenolic and flavonoid contents ranged between 0.24-0.97 and 0.27-1.00 mg/g of dry matter content respectively. Higher Pb and Zn doses seem to elicit higher proline levels therefore, suggesting an extreme condition of induced abiotic stress. Dose dependent protein oxidation coupled with DNA degradation was observed in all treatments, depicting genotoxicity. Unweighted pair-group method arithmetic average analysis presented similarity coefficients between the treatments.
