Burkholderia sp. AQ12-mediated Molecular Adjustments Assist Growth of Salt-stressed Cotton (Gossypium hirsutum L.) By Modulating Biochemical Status and Nutrient Acquisition Patterns

Purpose: Soil salinity negatively modulates plant growth and physio-biochemical attributes. The present study deciphered the Burkholderia sp. AQ12-mediated responses in cotton plants. Methods: Seeds of FH-941 (salt sensitive) and FH-326 (tolerant) genotypes were inoculated using AQ12 or water. Half of the both (inoculated and un-inoculated) received no salt while other received salt/NaCl stress. The raised plants were analyzed for various bio-chemical indicators. Results: In presence of salt stress, chlorophyll (chl) a content (24.68 mg g⁻¹ FW) in FH-941 was 11.3% and 8.6% less in comparison to its control group and chl a content in FH-326, respectively. FH-941 exhibited a higher oxidant response as indicated by 8.69 and 25.54 µmol g⁻¹ FW malondialdehyde (MDA) and hydrogen peroxide (H₂O₂), respectively. A balanced catalase (CAT) and peroxidase (POD) activity across all treatments particularly under salt stress (23.82 and 40.98 U mg⁻¹ protein, respectively) was recorded in FH-326 indicating its potential to cope NaCl induced oxidative injury. Further, FH-326 exhibited 17.58 mg g⁻¹ DW root K⁺ associated with balanced expression of NHX1 and HAK5. A higher expression of HKT1 but reduced expression of NHX1, SOS1 and HAK5 indicted poor salt tolerance by FH-941. However, AQ12 inoculation resulted in optimum chl a (28.66 mg g⁻¹ FW), chl b (13.93 mg g⁻¹ FW), MDA (6.89 µmol g⁻¹ FW), H₂O₂ (20.11 µmol g⁻¹ FW) content in FH-941 resulting in better growth in saline soil. Conclusions: The findings highlighted the biochemical and molecular basis of salt tolerance in cotton and signify the importance of AQ12 inoculation for cotton cultivation in saline soils.