Plant growth promoting endophytic fungi of the wild halophytic rice Oryza coarctata

Abstract

Background Plant growth-promoting endophytic fungi (PGPEF) associated with halophytes have the potential to boost plant growth and salinity tolerance in crops enabling cultivation in the coastal lands. Methods Endophytic fungi from the wild halophytic rice Oryza coarctata were isolated, characterized, identified and studied for their effects on plant growth and yield both with and with without salt stress. Key results: In this study, three different fungal endophytes were isolated from the halophytic wild rice Oryza coarctata. Two isolates were identified as Talaromyces adpressus (OPCRE2) and Talaromyces argentinensis (OPCRh1) by ITS region sequencing, the remaining isolate NPCRE2 was identified as a novel strain named Aspergillus welwitschiae Ocstreb1 (AwOcstreb1) by whole genome sequencing. These endophytes showed various plant growth-promoting (PGP) abilities in vitro (e.g. IAA, ACC-deaminase and siderophore production, phosphate and zinc solubilization as well as nitrogen fixation), where AwOcstreb1 was significantly more efficient compared to the other two isolates at high salinity (900 mm). Independent treatment of these fungi in commercial rice (Oryza sativa) showed significant elevation in plant growth, especially in the case of the AwOcstreb1 inoculants, which had enhanced metabolite and chlorophyll content at the seedling stage in both no-salt control and 100 mm salt-stressed plants. At the same time, a significantly low level of H2O2, electrolyte leakage and Na+/K+ ratio was demonstrated under the saline condition. Higher expression (1.6 folds) of the SOS1 (Salt Overly Sensitive 1) gene was also observed in AwOcstreb1-treated plants under salinity stress. This strain also improved percent fertility, tillering, panicle number and filled grain number in both no-salt control and 45 mm salt-stressed inoculated plants at the reproductive stage. Consequently, their yield increased by 125.16% and 203.96% (p < 0.05) in colonized plants in normal and saline conditions, respectively, compared to uninoculated controls. Conclusions We propose that AwOcstreb1 is a potential candidate for an eco-friendly biofertilizer formula to improve cultivation and yield of rice or any crop in high saline coastal regions of Bangladesh.

Paired growth of cultivated and halophytic wild rice under salt stress induces bacterial endophytes and gene expression responses

“…Interestingly, the difference in 1000-grain weight between paired and unpaired was significant without salt, which indicates the positive impact of pairing but not enough to show differences in the yield under salt stress. The positive impact of the pairing with Oc may be due to the plant growth promoting bacteria (Sarker et al, 2023) and endophytic fungus associated with Oc (Airin et al, 2023).…”

“…Any possible mutualism between Oc and Os may be inclusive of any endophytic microbes growing within the halophyte and helping to defend the commercial but sensitive genotype against the stress. Our earlier work has identified a highly significant plant growth promoting endophytic fungus associated with Oc roots and rhizomes (Airin et al, 2023). Apart from that, previous studies showed plants communicate with neighboring plants and modify their physiological and morphological features, including alterations in root system architecture (RSA) (Zhang et al, 2022).…”