Microbial Turnover and Dispersal Events Occur in Synchrony with Plant Phenology in the Perennial Evergreen Tree CropCitrus sinensis

Abstract

Research at the forefront of plant microbiome studies indicates that plant-associated microbes can alter the timing of plant development (phenology). However, it is unclear if host phenological stage affects microbial community assembly.

Microbiome diversity, composition and assembly in a California citrus orchard

“…AMF can facilitate water and nutrient acquisition (phosphorus and nitrogen) and support host defenses against pathogen attack (Hohmann and Messmer, 2017;Chen et al, 2018;Xi et al, 2022). In contrast to rhizocompartments, above ground microorganisms associated with plants are under strong selective pressure because they are continually exposed to changing environmental conditions (rainfall, heat, and UV radiation) and agricultural practices (agrochemical sprays) but are also influenced by the host phenology (Vorholt, 2012;Burgess and Schaeffer, 2022;Ginnan et al, 2022). The strong year effect measured on bacteriome and mycobiome betadiversity for above ground tissues clearly support the evidence that microbiome composition in flower and flush is volatile and under environmental constraints.…”

“…The aim of this study was to characterize the citrus microbiome across five biocompartments (flush, flower, root, rhizosphere and bulk soil) during the floral development phase. At this stage, trees undergo drastic physiological shifts with respect to carbon reallocation, water dynamics and phytohormone production (Goldschmidt and Koch, 2017;Agustí et al, 2022) that are linked to significant shifts in microbial community assemblage (Ginnan et al, 2022). Both flower and flush are short-lived organs.…”

“…The root-associated microbiome of healthy plants is a relatively stable ecosystem because roots are immersed in a buffered environment (the soil) that is not in under the direct constraints of extreme weather conditions and agricultural practices that above ground plant compartments experience. Roots are also less affected by the host phenological changes unlike flower and flush tissues (Ginnan et al, 2022). Root microbial assembly has been described as a two-step process, involving acquisition of specific microbes from the soil to the rhizosphere and a host-driven sorting step mechanism that subsets specific microbes into the root (Bulgarelli et al, 2013).…”

“…It accounts for 16% of the total value of the United States fruit production (Li et al, 2020) with California representing 80% of the nation's fresh fruit market with an annual value of 2.3 billion dollars (CDFA, 2021). There has been tremendous interest in exploring the structure and function of the citrus phyllosphere and rhizosphere microbiomes and engineering its assembly to address current challenges in citriculture (Zhang et al, 2021;Ginnan et al, 2022). Root microbiome has emerged as a focal point of citrus health especially in the context of Huanglongbing (HLB) disease (Blaustein et al, 2017;Xu et al, 2018;Ginnan et al, 2020;Wu et al, 2020).…”

“…However, research indicated that rhizosphere microbiome can also drive changes in the host phenological traits including flowering period (Lau and Lennon, 2011;Lu et al, 2018). The host phenological stage appears to be a major driver of the leaf microbiome assemblage indicating that it could also influence flower microbiome composition (Ginnan et al, 2022). Flowering is the most important determinate of yield and quality of citrus fruit production (Stander, 2015).…”