Potential of mineral-solubilizing bacteria for physiology and growth promotion of Chenopodium quinoa Willd

Ejaz Rafique; Muhammad Zahid Mumtaz; Inam Ullah; Aneela Rehman; Kamal Ahmad Qureshi; Muhammad Kamran; Mujaddad Ur Rehman; Mariusz Jaremko; Muneefah Abdullah Alenezi

doi:10.3389/fpls.2022.1004833

Potential of mineral-solubilizing bacteria for physiology and growth promotion of Chenopodium quinoa Willd

Front Plant Sci. 2022 Oct 10:13:1004833. doi: 10.3389/fpls.2022.1004833. eCollection 2022.

Authors

Ejaz Rafique¹, Muhammad Zahid Mumtaz¹, Inam Ullah¹, Aneela Rehman², Kamal Ahmad Qureshi³, Muhammad Kamran⁴, Mujaddad Ur Rehman², Mariusz Jaremko⁵, Muneefah Abdullah Alenezi⁶

Affiliations

¹ Institute of Molecular Biology and Biotechnology, The University of Lahore, Lahore, Pakistan.
² Department of Microbiology, Abbottabad University of Science and Technology, Abbottabad, Pakistan.
³ Department of Pharmaceutics, Unaizah College of Pharmacy, Qassim University, Unaizah, Saudi Arabia.
⁴ School of Agriculture, Food and Wine, The University of Adelaide, Adelaide, SA, Australia.
⁵ Smart-Health Initiative (SHI) and Red Sea Research Center (RSRC), Division of Biological and Environmental Sciences and Engineering (BESE), King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia.
⁶ Department of Biology, Faculty of Science, University of Tabuk, Tabuk, Saudi Arabia.

Abstract

Nutrient deficiency in wild plant species, including quinoa (Chenopodium quinoa Willd), can be overcome by applying mineral-solubilizing bacteria. Quinoa is a gluten-free, nutritious food crop with unique protein content. The present study aimed to characterize mineral-solubilizing rhizobacterial strains and to evaluate their plant growth-promoting potential in quinoa seedlings. More than sixty rhizobacterial strains were isolated from the quinoa rhizosphere and found eighteen strains to be strong phosphate solubilizers. Most of these bacterial strains showed zinc solubilization, and more than 80% of strains could solubilize manganese. The selected strains were identified as Bacillus altitudinis Cq-3, Pseudomonas flexibilis Cq-32, Bacillus pumilus Cq-35, Pseudomonas furukawaii Cq-40, Pontibacter lucknowensis Cq-48, and Ensifer sp. Cq-51 through 16S rRNA partial gene sequencing. Mainly, these strains showed the production of organic acids, including malic, gluconic, tartaric, ascorbic, lactic, and oxalic acids in insoluble phosphorus amended broth. All strains showed production of gluconic acids, while half of the strains could produce malic, ascorbic, lactic, and oxalic acids. These strains demonstrated the production of indole-3-acetic acid in the presence as well as in the absence of L-tryptophan. The bacterial strains also demonstrated their ability to promote growth and yield attributes, including shoot length, root length, leave numbers, root and shoot dry biomass, spike length, and spikes numbers of quinoa in pots and field trials. Increased physiological attributes, including relative humidity, quantum flux, diffusive resistance, and transpiration rate, were observed due to inoculation with mineral solubilizing bacterial strains under field conditions. P. lucknowensis Cq-48, followed by P. flexibilis Cq-32, and P. furukawaii Cq-40 showed promising results to promote growth, yield, and physiological attributes. The multi-traits characteristics and plant growth-promoting ability in the tested bacterial strains could provide an opportunity for formulating biofertilizers that could promote wild quinoa growth and physiology.

Keywords: 16S rRNA sequencing; Chenopodium quinoa; Indole-3-acetic acid; Pontibacter spp.; Pseudomonas spp.; minerals solubilization; phosphate solubilization.