Influence of irrigation water quality on the microbiome of apple trees and the quality of fruits - A "One Health" study (AppleHealth)

• Applicant: Professor Dr. Michael Schloter
• Subject Area: Ecology of Land Use
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 556427581

Apples (Malus × domestica Borkh.) are among the most consumed fruits worldwide and have long been associated with various health benefits. One of the most important producers for apples is the northern part of Italy. The quality of the apples as well as the yield has been considered as high, as a result of the mild climate and the highly fertile soils in that region. As a result of climate change and long-lasting drought periods, in the last decade more and more orchards started to use irrigation to compensate the missing water during drought periods. In the frame of this project, we want to investigate the role of irrigation water and its quality for the root associated microbiome of apple. We want to describe the consequences for apple tree growth, apple quality as well as the microbiome associated with apple fruits. As the use of irrigation water becomes more and more popular in Europe as a result of extended drought periods, we think this project is not only of importance for basic science to improve our understanding on the interaction of different environmental microbiomes with the microbiome of apple trees and consequences for the apple tree`s phenotype, but also for applied science and the development of regulations of water quality for irrigation. In this respect we think that antibiotic resistance genes and their spread, because of increased levels of pollutants in the irrigation water also in apple fruits is a matter of high relevance for consumers` safety. We will focus in our project on apple trees of two cultivars which is frequently used in South Tyrol (Golden Delicious and Stark Delicious) and include different ontogenetic ages of the trees into our analysis, as we think that the perception towards changes in the environmental microbiomes may differ depending on the tree`s age. Major aims of the project include: To characterize the water samples used for irrigation along a gradient of anthropogenic influence of the Adige River assessing abiotic and biotic properties; - To study the influence of irrigation water of different qualities on the structure and function of the microbiome at the plant soil interface. - To define and characterize the presence of metal and antibiotic resistance genes in the rhizosphere of Golden Delicious and Stark Delicious apple trees. - To define and characterize the presence of metal and antibiotic resistance genes in the fruits of these two cultivars, which are among the most produced in South Tyrol and widely commercialized in Germany, to determine their potential mobility and association with pathogenic organisms and to define the degree of similarity between any observed resistances and those of clinical interest. - To define consequences of irrigation water quality for the resilience of apple trees towards drought. Our study will focus on water taken from different parts of the Adige River, with different anthropogenic influence and quality.

• DFG Programme: Research Grants
• International Connection: Italy
• Partner Organisation: Autonome Provinz Bozen - Südtirol
• Cooperation Partner: Privatdozent Dr. Lorenzo Brusetti