Contrasting effects of genotype and root size on the fungal and bacterial communities associated with apple rootstocks

Abstract

The endophytic microbiome of plants is believed to have a significant impact on its physiology and disease resistance, however, the role of host genotype in determining the composition of the endophytic microbiome of apple root systems remains an open question that has important implications for defining breeding objectives. In the current study, the bacterial and fungal microbiota associated with four different apple rootstocks planted in April, 2018 in the same soil environment and harvested in May, 2019 were evaluated to determine the role of genotype on the composition of both the bacterial and fungal communities. Results demonstrated a clear impact of genotype and root size on microbial composition and diversity. The fungal community was more affected by plant genotype whereas the bacterial community was shaped by root size. Fungal and bacterial abundance was equal between different-sized roots however, significantly higher microbial counts were detected in rhizosphere samples compared to root endosphere samples. This study provides information that can be used to develop a comprehensive and readily applicable understanding of the impact of genotype and environmental factors on the establishment of plant microbiome, as well as its potential function and impact on host physiology.

Influence of Soil Type, Land Use, and Rootstock Genotype on Root-Associated Arbuscular Mycorrhizal Fungi Communities and Their Impact on Grapevine Growth and Nutrition

“…On the other hand, several works show that host genotypes affect root endophyte cooccurrence networks [70,[112][113][114]. In our study, we observed that the root-associated AMF network was less dense in 1103 P rootstock than in R 110.…”

Air-Pruning Containers Modify Root and Scion Growth and Alter Resource Allocation of Bench-Grafted Apple Plants

“…Though root order data were not collected in this study, the relationship between root diameter and root function of apple roots has been elucidated [20]. The relationship between root diameter and function provides a compelling argument that a 2 mm diameter cutoff for classifying absorptive roots in apple overestimates this population due to inclusion of structural roots, despite its common use in the literature [16][17][18]. Thus, in the present study, only roots with diameters ≤ 0.4 mm were classified as absorptive based on [20].…”

“…Fine roots of tree species are relatively short-lived (i.e., several months) and account for most of the total root length [12,13]. Fine, non-woody roots with diameters < 2 mm are generally associated with nutrient and water acquisition for a range of species [14,15], including apple [16][17][18]. More recently, studies on root function argue that a 2 mm cutoff is non-discriminative for segregating absorptive from structural or pioneer roots and, thus, highly overestimates the actual percentage of absorptive roots [19].…”

Evaluating the hologenome concept by analyzing the root-endosphere microbiota of chimeric plants

“…In grafted plants, root associated microbiota composition can be responsive to rootstock genotypes, 30 , 31 but the existence of interaction between scion and rootstock in the root microbiota recruitment is often neglected. Recent studies on grafted grapevine plants have however shown the effect of both scion and rootstock on the rhizosphere composition.…”