Claroideoglomus claroideum inoculation improves bio-hardening of micropropagated G9 banana by modulating antioxidative response, nutrient uptake and photosynthetic efficiency

Bio-hardening is the application of microbial inoculum to micropropagated plants for acclimatization. Grand Naine or G9 banana is one of the popular dessert banana cultivars of the world. The current study investigated the impact of in vitro inoculation of arbuscular mycorrhizal fungi (AMF) Claroideoglomus claroideum on acclimatization and morpho-physiology of micropropagated banana plantlets. The experimental design is a randomized single-factor with AMF not inoculated non-mycorrhizal (NM) and AMF inoculated mycorrhizal (M) treatments. Morphological parameter such as shoot and root length, relative water content (RWC) of shoot and root, stem diameter and leaf area were measured. Biochemical parameters photosynthetic pigment, total sugar, protein, reducing sugar, free amino acid, proline and phenol content in the leaves were quantified. Anti-oxidative enzyme CAT, SOD, APX and GPX activity were estimated. The photosynthetic efficiency in terms of chlorophyll a fluorescence and the mineral content in root and shoots samples were analysed. The AMF inoculation improved the acclimatization rate by 17% and the mycorrhizal plantlets showed better morphology than the non-mycorrhizal. The photosynthetic pigments, total and reducing sugar, protein, free amino acids and phenol content increased with C. claroideum. Proline, the stress indicator content was decreased by 34% in mycorrhizal than non-mycorrhizal plants. Enhanced anti-oxidative enzyme activities of CAT (24%), SOD (20%), APX (17%), and GPX (26%) in mycorrhizal plants suggested better oxidative stress modulation than non-mycorrhizal plants. The macro and micro nutrient uptake in banana was improved with AMF inoculation as evident from mineral content analysis in shoot and root. Chlorophyll a fluorescence transient and derived parameters demonstrated improved photosynthetic efficiency in the mycorrhizal plants. The study underscores the significance of AMF C. claroideum inoculation for the bio-hardening and physiological performance of micropropagated banana suggesting practical implications in sustainable horticulture.