Indole 3-acetic acid producing bacteria from onion rhizosphere
| dc.contributor.author | Fernando, G.R. | |
| dc.contributor.author | Abeysinghe, S. | |
| dc.contributor.author | Widana Gamage, S.M.K. | |
| dc.contributor.author | Rajapakse, R.G.S.C. | |
| dc.date.accessioned | 2024-10-29T05:58:47Z | |
| dc.date.available | 2024-10-29T05:58:47Z | |
| dc.date.issued | 2024-11-01 | |
| dc.description.abstract | Onion (Allium cepa L.) is an important crop in Sri Lanka. It is important as a condiment, a leafy vegetable, and an ingredient in indigenous medicine. A recent study showed that the growth and quality of onion bulbs can be improved by exogenous application of Indole 3-acetic acid (IAA). Some phytohormones are known to improve human health. The current study aimed at isolating and identifying IAA-producing bacteria from the onion rhizosphere and incorporating them into plant-growth-promoting-rhizobacterial (PGPR) consortia. Rhizobacteria were isolated from the roots of onions grown in three main onion-growing areas in Sri Lanka, viz., Jaffna, Dambulla, and Angunakolapelessa. Both free-living and endophytic bacteria were isolated in nutrient agar. Hundred and twenty-six morphologically distinct strains were isolated and screened for their ability to synthesize IAA, with and without induction, by the externally added tryptophan (0.2% [w/v]), which is a precursor of IAA. Accumulated IAA in the culture broth was estimated spectrophotometrically at 535 nm following Salkowski’s method. Twenty-one strains, including two endophytic bacterial strains, were found to be IAA producers. More efficient IAA production was obtained in tryptophan-induced cultures. Two strains, i.e., R1OJ2 and OD20 produced > 200 mg/L of IAA while ROJ10, ROJ7, ROD12, ROJ5, ROJ50, ROD16, ROD15, ROA10, and ROJ8 produced >100 mg/L when induced. None of these strains could produce > 100 mg/L without tryptophan but ROJ7, ROJ11, ROJ2, ROJ50, ROJ38, and ROD16 produced IAA around 50 mg/L. The endophytic strains, EOA7 and EOJ1, also showed high IAA production, 73.4 mg/L and 83.6 mg/L, respectively. According to a previous study, IAA at 50 mg/L promotes onion growth, while IAA at 200 mg/L increases phenol content, thus increasing its medicinal value. Hence, ROJ7, ROJ11, ROJ2, ROJ50, ROJ38, and ROD16 strains are good candidates for PGPR-consortium development, while ROJ2, ROD20, and ROA10 are good candidates for enhancing the medicinal value of onion. | |
| dc.description.sponsorship | Financial assistance from the Indo-Sri Lanka Joint Research Programme 2019, funded by the State Ministry of Skill Development, Vocational Education, Research and Innovation, Sri Lanka (Grant No. MSVRI/RES/03/07-04/2021) is acknowledged. | |
| dc.identifier.citation | Proceedings of the Postgraduate Institute of Science Research Congress -2024, University of Peradeniya, Sri Lanka, P. 101 | |
| dc.identifier.issn | 3051-4622 | |
| dc.identifier.uri | https://ir.lib.pdn.ac.lk/handle/20.500.14444/2738 | |
| dc.language.iso | en | |
| dc.publisher | Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka | |
| dc.relation.ispartofseries | Volume 11 | |
| dc.subject | Indole 3-Acetic acid | |
| dc.subject | Onion | |
| dc.subject | PGPR | |
| dc.title | Indole 3-acetic acid producing bacteria from onion rhizosphere | |
| dc.type | Article |