Exploration of the rhizosphere microbiome of native plant Ceanothus velutinus – an excellent resource of plant growth-promoting bacteria

Abstract

Continuous demand for an increase in food production due to climate change and a steady rise in world population requires stress-resilient, sustainable agriculture. Overuse of chemical fertilizers and monoculture farming to achieve this goal deteriorated soil health and negatively affected its microbiome. The rhizosphere microbiome of a plant plays a significant role in its growth and development and promotes the plant’s overall health through nutrient uptake/availability, stress tolerance, and biocontrol activity. The Intermountain West (IW) region of the US is rich in native plants recommended for low water use landscaping because of their drought tolerance. The rhizosphere microbiome of these native plants is an excellent resource for plant growth-promoting rhizobacteria (PGPR) to use these microbes as biofertilizers and biostimulants to enhance food production, mitigate environmental stresses and an alternative for chemical fertilizer, and improve soil health. Here, we isolated, purified, identified, and characterized 64 bacterial isolates from a native plant, Ceanothus velutinus, commonly known as snowbrush ceanothus, from the natural habitat and the greenhouse-grown native soil-treated snowbrush ceanothus plants. We also conducted a microbial diversity analysis of the rhizosphere of greenhouse-grown native soil-treated and untreated plants (control). Twenty-seven of the 64 isolates were from the rhizosphere of the native region, and 36 were from the greenhouse-grown native soil-treated plants. These isolates were also tested for plant growth-promoting (PGP) traits such as their ability to produce catalase, siderophore, and indole acetic acid, fix atmospheric nitrogen and solubilize phosphate. Thirteen bacterial isolates tested positive for all five plant growth-promoting abilities and belonged to the genera Pantoea, Pseudomonas, Bacillus, and Ancylobacter. Besides, there are isolates belonging to the genus Streptomyces, Bacillus, Peribacillus, Variovorax, Xenophilus, Brevundimonas, and Priestia, which exhibit at least one of the plant growth-promoting activities. This initial screen provided a list of potential PGPR to test for plant health improvement on model and crop plants. Most of the bacterial isolates in this study have a great potential to become biofertilizers and bio-stimulants.

IAA-producing plant growth promoting rhizobacteria from Ceanothus velutinus enhance cutting propagation efficiency and Arabidopsis biomass

“…We collected bulk soil samples of snowbrush ceanothus plants from the Tony Grove region of Logan Canyon, Utah – elevation 1950m AMSL (Above Mean Sea Level) (41°52’34” N 111°34’20” W, as described elsewhere ( Ganesh et al., 2022 ). The bulk soil samples from the top 30 cm layer around the plant were collected in one gallon Ziplock bags, kept on ice, transported to the lab, and stored at 4°C.…”

“…The bacterial isolation was done three times. The final isolates were stored as glycerol stocks at -80°C ( Ganesh et al., 2022 ).…”

“…Snowbrush ceanothus rhizosphere has a rich microbiome containing several plant-promoting bacteria that showed several plant growth-promoting characteristics such as IAA, catalase and siderophore production, phosphate solubilization, and the ability to fix nitrogen ( Ganesh et al., 2022 ). The majority of rhizobacteria belonged to Pseudomonas and Streptomyces .…”

“…The majority of rhizobacteria belonged to Pseudomonas and Streptomyces . However, there is a variety of PGPR belonging to Bacillus , Peribacillus , Variovorax , Xenophilus , Brevundimonas , Pantoea , Ancylobactor , and Priestia exhibiting various plant growth-promoting traits, including IAA, siderophore, and catalase production ( Ganesh et al., 2022 ). We hypothesize that the native soil of snowbrush ceanothus harbors many growth-promoting bacteria that produce IAA, which can help the propagation of snowbrush ceanothus in greenhouse conditions and colonize the rhizosphere.…”

Juvenile Plant–Microbe Interactions Modulate the Adaptation and Response of Forest Seedlings to Rapid Climate Change

“…Most of our knowledge about beneficial microorganisms during the early stages of plant development comes from studies conducted on crops [ 17 ]. However, in recent years, there has been an increasing focus on studying juvenile interactions between forest plants and microorganisms, driven by a growing awareness of the importance of preserving pristine forests [ 18 ]. Identifying and managing juvenile plant–microbe interactions is particularly important for sustainable forestry practices, as it provides an alternative for improving plant growth and adaptation rates.…”