Pichia kudriavzevii-a potential soil yeast candidate for improving soil physical, chemical and biological properties

Unlocking the plant growth-promoting potential of yeast spp.: exploring species from the Moroccan extremophilic environment for enhanced plant growth and sustainable farming

In this study, we successfully isolated two distinct yeasts from Moroccan extreme environments. These yeasts were subjected to molecular characterization by analyzing their Internal Transcribed spacer (ITS) regions. Our research thoroughly characterizes plant growth-promoting abilities and their drought and salt stress tolerance. In a greenhouse assay, we examined the impact of selected yeasts on Medicago sativa's growth. Four treatments were employed: (i) control without inoculation (NI), (ii) inoculation with L1, (iii) inoculation with L2, and (iv) inoculation with the mixture L1 + L2. L1 isolated from Toubkal Mountain shared 99.83% sequence similarity to Rhodotorula mucilaginosa. Meanwhile, L2, thriving in the arid Merzouga desert, displayed a similar identity to Naganishia albida (99.84%). Yeast strains were tolerant to NaCl (2 M) and 60% PEG (polyethylene glycol P6000) in case of drought. Both strains could solubilize phsphorus, with L2 additionally demonstrating potassium solubilization. In addition, both strains produce indole acetic acid (up to 135 µl ml-1), have siderophore ability, and produce aminocyclopropane-1-carboxylic acid deaminase. Isolates L1 and L2, and their consortium showed that the single or combined strain inoculation of M. sativa improved plant growth, development, and nutrient assimilation. These findings pave the way for harnessing yeast-based solutions in agricultural practices, contributing to enhanced crop productivity and environmental sustainability.

Comparative metataxonamic analyses of seeds and leaves of traditional varieties and hybrids of cucumber (Cucumis sativus L.) reveals distinct and core microbiome

Profiling the endophytic microbiome of different tissues and varieties of agricultural crops can help to understand i) the tissue specific and varietal specific microbes associated with the plants ii) their potential role in growth, stress tolerance, disease resistance, and yield of the plants. Comparative microbiome profiling across various varieties and hybrids will also be useful to identify the plant's core microbiome. The main objective of the work is to profile and study the microbiome of traditional varieties in comparison with hybrids of cucumber, which would help to understand the microbiome structure in developing consortia to engineer the microbiome of modern hybrids, for useful phenotypes. Metataxonomic sequencing of bacteria and fungi using 16S rRNA gene and ITS regions respectively were carried out in seed and leaf samples of cucumber traditional varieties and modern hybrids. Among bacteria, Prevotella, Bacteroides, Lactobacillus, Dialester, and Fecalibacterium, and among fungal genera, Pichia, Aspergillus, Phaeoisariopsis, Candida, and Malassezia belonged to the core microbiome of cucumber. Modern hybrids were rich in antibiotic producing and toxic pollutant degrading bacteria. Many of the fungi and bacteria observed in the study are well known plant growth promoting microorganisms and play role in offering disease resistance. Some of the bacteria and fungi have beneficial roles in human gut thus revealing the dietary importance of cucumber. The microbes identified in the current study will be useful starting point to develop a consortia to engineer the cucumber microbiome for growth, yield and stress tolerance traits.

Improved tolerance of apple plants to drought stress and nitrogen utilization by modulating the rhizosphere microbiome via melatonin and dopamine

This study explored the contributions of melatonin and dopamine to the uptake and utilization of nitrogen and the formation of rhizosphere microbial communities in ‘Tianhong 2’/M. hupehensis, with the goal improving plant resistance to drought stress. Drought stress was formed by artificially controlling soil moisture content. And melatonin or dopamine solutions were applied to the soil at regular intervals for experimental treatment. After 60 days of treatment, plant indices were determined and the structure of the rhizosphere microbial community was evaluated using high-throughput sequencing technology. The findings revealed two ways through which melatonin and dopamine alleviate the inhibition of growth and development caused by drought stress by promoting nitrogen uptake and utilization in plants. First, melatonin and dopamine promote the absorption and utilization of nitrogen under drought stress by directly activating nitrogen transporters and nitrogen metabolism-related enzymes in the plant. Second, they promote the absorption of nitrogen by regulating the abundances of specific microbial populations, thereby accelerating the transformation of the soil nitrogen pool to available nitrogen that can be absorbed directly by plant roots and utilized by plants. These findings provide a new framework for understanding how melatonin and dopamine regulate the uptake and utilization of nitrogen in plants and improve their ability to cope with environmental disturbances.

Effect of yeast application on soil health and root metabolic status of corn seedlings under drought stress

The soil enzymes are the heart of the biochemical reactions that occur in the soil saving the soil nutrients needed for plant growth. Recently yeast's importance as plant growth-promoting microorganisms has great attention. This study evaluated the effect of yeast application on the soil enzymes activity and root metabolic status in corn plants under drought stress. A pot experiment was performed. The pots were divided into two groups; the first group was used for yeast application, the other group was used as a non-treated group. Each group was subdivided into two groups according to water treatment. One is 75%; the other is 45% of field capacity. Soil and root samples were taken at 5, 10, and 15 days after drought application for analysis. Soil samples were subjected to NPK and soil enzymes activity analysis. The root samples were subjected to determination NPK content, the osmolytes, lipid peroxidation, and antioxidant enzymes. The present results showed that yeast application upregulated the soil enzymes under drought which protected the NPK content in the soil. Therefore NPK in the treated group was significantly higher than that in the non-treated group. Also, yeast application improved the roots' osmotic status, the treated group showed significant osmolytes accumulation. Besides that the antioxidant enzymes activity status in the treated group was significantly higher than that in the non-treated group which significantly decreased the lipid peroxidation in the treated group. Yeast application can be an effective promising tool for improving the corn plant tolerance against drought stress.