Microrhizal symbiosis associated with the phosphorus cycle and tolerance to water deficit in different bean cultivars

• Grant number: 24/19071-0
• Support Opportunities: Scholarships in Brazil - Doctorate (Direct)
• Start date: May 01, 2025
• End date: September 30, 2029
• Field of knowledge: Agronomical Sciences - Agronomy - Soil Science
• Principal Investigator: Lucas William Mendes
• Grantee: Maycon Cristiano Barbosa
• Host Institution: Centro de Energia Nuclear na Agricultura (CENA). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated research grant: 19/16043-7 - Rhizosphere microbiome of the drought tolerant common bean, AP.PFPMCG.JP

Abstract

Water stress is considered the primary challenge for global agricultural production, as the main agricultural regions of the world are affected by drought, resulting in negative impacts on the economy and society. The genetic improvement of crops for drought tolerance has received significant attention in recent years, and new research has elucidated the role of specific soil microorganisms in influencing water stress tolerance in plants, including arbuscular mycorrhizal fungi (AMF) and symbiotic rhizobacteria. Recent studies have shown that these rhizosphere microorganisms play a crucial role in plant functioning, affecting their physiology and development, as well as the cycling of essential elements such as phosphorus and nitrogen, which are influenced by water dynamics. Despite the widespread recognition of their importance for plant growth, the functional characteristics and mechanisms by which AMF assist in mitigating water stress are still poorly explored. In this context, the present project aims to evaluate the effects of manipulating AMF in the rhizosphere of beans, with the objective of taxonomically and functionally identifying these organisms, their interactions with symbiotic bacteria, and their influence on the phosphorus and nitrogen cycles. To achieve this, amplicon sequencing and metagenomic data of AMF communities in different bean cultivars subjected to drought will be analyzed. These cultivars will be inoculated with AMF and cultivated in a greenhouse under normal and water stress conditions to assess the effects of microbiome modulation on drought resistance induction and primarily on the phosphorus cycle. The experimental design will be organized in completely randomized blocks in a factorial arrangement, with five repetitions for each treatment, comprising two drought-tolerant bean genotypes, one control treatment without plants (bulk soil), two water regimes (<40% and >80% of field capacity, representing drought and normal irrigation, respectively), and two nutritional conditions (+P and -P) [(2 genotypes + 1 Bulk) x 2 inoculation conditions x 2 water regimes x 2 nutritional conditions x 5 repetitions each]. The evaluation of the AMF community will initially be conducted through sporulation and root colonization analysis, followed by amplicon sequencing of fungal (ITS) and bacterial (16S rRNA) communities in the hyphosphere, as well as functional profiling through metagenomics. Microbiome data will be integrated with the physicochemical properties of the soil, as well as the physiology and biometrics of the plants, with the aim of understanding the host plant's control over the assembly of the rhizosphere microbiome during water stress. Furthermore, data on phosphorus fractionation, acid phosphatase, and the abundance of the genes pqqC and phoC will be utilized to understand the influence of AMF on the phosphorus cycle under drought conditions. This project is linked to the JP FAPESP Project 2019/16043-7 "Microbiome of Drought-Tolerant Bean Rhizosphere," and its development will involve different laboratories at CENA-USP, encompassing microbiology, molecular biology, physiology, and plant nutrition. The results will significantly contribute to the understanding of plant-AMF interactions and their role in mitigating water stress, seeking to identify microbial groups and functions with potential biotechnological applications for sustainable agricultural development and ensuring food security in the current context of climate change.