Biochemical and molecular insights of PGPR application for the augmentation of carotenoids, tocopherols, and folate in the foliage of Moringa oleifera.

Plant Growth Promoting Rhizobacteria (PGPR) were utilized to contemplate their impact on the foliage of
Moringa oleifera and examined for changes in tocopherols, chlorophyll, carotenoids, and folate in the sixth week.
Among the eight treatments, Bacillus subtilis GB03, B. pumilus SE34, B. pumilus T4, and Pseudomonas fluorescens
UOM14 improved α-tocopherol (10–14 fold) and β-carotene (1–1.40 fold) altogether significantly (P ≤ 0.05). The
most significant improvement in folate content was apparent for B. subtilis IN937B (5.47 fold) trailed by
B. pumilus SE34 (5.05 fold) and B. pumilus T4 (5.12 fold) treatments. P. fluorescens UOM14 indicated remarkable
improvement in Chl a (0.39 fold) and Chl b (0.44 fold) content. Organisms showing a significant increase for the
analyzed molecules in individual treatment were blended in different combinations and were used for the next
set of treatments. Of all the three combinations, Combination 2 (COM2-B. pumilus SE34 + B. pumilus T4 +
B. pumilus INR7) showed the maximum increase in α-tocopherol (8.46 fold) and γ-tocopherol (8.45 fold), followed by Combination 3 (COM3-B. pumilus SE34 + B. pumilus T4 + P. fluorescens UOM14) (5.93 and 3.65 fold).
On the whole COM2 containing different strains of B. pumilus was found to enhance the targeted metabolites in
foliage significantly. Real-time PCR studies were conducted for the biochemical pathway genes of the targeted
molecules, including, γ-tocopherol methyltransferase (γ-TMT), phytoene synthase (PSY), phytoene desaturase
(PDS), lycopene β cyclase (LBC) and dihydrofolate reductase thymidylate synthase (DHFR-TS). All the selected
genes exhibited an up-regulation compared to control, similar to the biochemical output. Our investigation
provides the strong evidence that PGPR can be viably utilized in combination to enhance the quality of the food
crops.