Zinc solubilizing Bacillus sp (SS9) and Enterobacter sp (SS7) promote mung bean (Vigna radiata L.) growth, nutrient uptake and physiological profiles

Abstract

Zinc (Zn) is a crucial micronutrient required for optimum plant growth. Zn-solubilizing bacteria (ZSB) are potential alternatives for Zn supplementation and convert applied inorganic Zn to available forms. In this study, ZSB were isolated from the root nodules of wild legumes. From a set of 17 bacteria, the isolates SS9 and SS7 were found to be efficient in tolerating 1 g (w/v) Zn. The isolates were identified as Bacillus sp (SS9, MW642183) and Enterobacter sp (SS7, MW624528) based on morphology and 16S rRNA gene sequencing. The screening of PGP bacterial properties revealed that both isolates possessed production of indole acetic acid (50.9 and 70.8 µgmL–1), siderophore (40.2% and 28.0%), and solubilization of phosphate and potassium. The pot study experiment in the presence and absence of Zn revealed that the Bacillus sp and Enterobacter sp inoculated plants showed enhanced mung bean plant growth (45.0% to 61.0% increment in shoot length and 26.9 to 30.9% in root length) and biomass compared to the control. The isolates also enhanced photosynthetic pigments such as total chlorophyll (1.5 to 6.0-fold) and carotenoids (0.5 to 3.0-fold) and 1–2-fold increase in Zn, phosphorous (P), and nitrogen (N) uptake compared to the Zn-stressed control. The present results indicated that the inoculation of Bacillus sp (SS9) and Enterobacter sp(SS7) reduced the toxicity of Zn and, in turn, enhanced the plant growth and mobilization of Zn, N, and P to the plant parts.

AMF Inoculation Alleviates Molybdenum Toxicity to Maize by Protecting Leaf Performance

“…Studies have shown that Zn is the specific activation ion of chloroplast carbonic anhydrase, which is a key point in controlling photosynthesis and provides the substrate for CO 2 fixation, thus promoting photosynthesis to a certain extent [62]. At the same time, Zn is a synthesis of chlorophyll precursor zinc porphyrin; thus, Zn is conducive to promoting chlorophyll synthesis, and chlorophyll plays a vital role in photosynthesis [63]. Therefore, it is speculated that the promotion of chlorophyll synthesis by Zn may also be one of the reasons for enhancing photosynthesis.…”