Aureobasidium pullulans Treatment Mitigates Drought Stress in Abies koreana via Rhizosphere Microbiome Modulation

Abstract

The Korean fir tree Abies koreana, an endangered species in Korea, faces threats primarily from climate change-induced stress and drought. This study proposed a sustainable method to enhance A. koreana drought tolerance using a black yeast-like fungus identified as Aureobasidium pullulans (AK10). The 16S/ITS metabarcoding analysis assessed the impact of drought and AK10 treatment on the seedlings’ rhizosphere microbiome. Results revealed a profound drought influence on the microbiome, particularly affecting fungal mycobiota. Drought-stressed seedlings exhibited elevated Agaricaceae levels, opportunistic fungi generally associated with decomposition. AK10 treatment significantly mitigated this proliferation and increased the relative abundance of beneficial fungi like Cystofilobasidium and Mortierella, known biocontrol agents and phosphate solubilizers. A notable reduction in the phytopathogenic Fusarium levels was observed with AK10, alongside an increase in beneficial bacteria, including Azospirillum and Nitrospirillum. Furthermore, the conducted correlation analysis shed light on microbial interrelationships within the rhizosphere, elucidating potential co-associations and antagonisms. Taken together, the isolated A. pullulans AK10 identified in this study serves as a potential biostimulant, enhancing the drought tolerance in A. koreana through beneficial alterations in the rhizosphere microbiome. This approach presents a promising strategy for the conservation of this endangered species.

Transcriptomic Insights into Abies koreana Drought Tolerance Conferred by Aureobasidium pullulans AK10

“…1B ). These findings are consistent with those of our previous study ( Mannaa et al, 2023 ), reinforcing the significant role of Au. Pullulans AK10 treatment in enhancing the drought tolerance of A. koreana .…”

“…To evaluate the effects of Au. pullulans AK10 on drought resistance in A. koreana , a seedling assay was conducted as described previously ( Mannaa et al, 2023 ). Briefly, three-year-old A. koreana seedlings were obtained from International Horticultural Seedlings, Seoul, and Republic of Korea.…”

“…Previous research revealed a correlation between environmental stress and gene expression linked to heat stress within these trees, suggesting an intricate relationship between the declining numbers of A. koreana and abiotic stress factors ( Kim et al, 2020 ). In our previous study ( Mannaa et al, 2023 ), we isolated the yeast-like fungus Aurobasidium pullulans AK10 and observed its potential as a foliar treatment to enhance drought-stress tolerance in A. koreana seedlings, correlating with beneficial shifts in rhizosphere microbiome composition . Au.…”

“…Au. pullulans is known for its adaptability across various environmental matrices and utility in biotechnological applications because it produces metabolites, such as pullulan, and a suite of hydrolytic enzymes, which could be beneficial for plant health and soil ecology ( Chi et al, 2009 ; Mannaa et al, 2023 ).…”