Impact of the Rhizosphere Bacterium Stenotrophomonas Pavanii on Curcuma Longa’s Growth, Yield, and Curcuminoid Biosynthesis Expression

Curcuma longa (Turmeric) is a spice and culinary ingredient that is high in antioxidants and utilized in medicine.It has been demonstrated that applying beneficial plant growth-promoting rhizobacteria (PGPR) may alter the composition of bioactive compounds in a variety of plant species and increase plant growth and production.Using a variety of plant measurements and gene expression studies, this study investigated the impact of Stenotrophomonas pavanii on the growth, yield, and chemical composition of C. longa.This bacterium was isolated from the rhizosphere of C. longa and described by means of 16S rRNA genomic sequencing.Real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) was used to focus on the transcription patterns of curcuminoid-related genes Curcumin synthase 1, -2, and -3 (CURS-1, -2, and -3) and diketide-CoA synthase (DCS).Compared to the control treatment, S. pavanii significantly increased the plant's height, the number and dry weight of C. longa leaves and roots, and the number of rhizomes and rhizome dry mass.Treatment with S. pavanii resulted in a significant rise in carotenoid and chlorophyll b levels, as well as a positive effect on the nitrogen (N) and potassium (K) contents in the leaves of C. longa.Moreover, the contents of curcumin, demethoxycurcumin, and bisdemethoxycurcumin in C. longa rhizome considerably increased by approximately 1.86-, 1.69-, and 1.77-fold, respectively, in comparison to the control treatment.Differential upregulation of curcuminoid-related genes upon application of S. pavanii led to an increase in the concentration of curcuminoid compounds, including bisdemethoxycurcumin, demethoxycurcumin, and curcumin.The aforementioned discoveries illuminate the possibility of S. pavanii functioning as a beneficial plant growth-promoting rhizobacterium to augment the development, yield, and bioactive composition of C. longa.Moreover, the results offer a substantial understanding of the molecular mechanisms underlying these advancements.This study determined the feasibility and advantages of employing biofertilizers based on microbial compost as a possible alternative to chemical fertilizers.