Abstract
Tea gray blight disease and its existing control measures have had a negative impact on the sustainable development of tea gardens. However, our knowledge of safe and effective biological control measures is limited. It is critical to explore beneficial microbial communities in the tea rhizosphere for the control of tea gray blight. In this study, we prepared conditioned soil by inoculating Pseudopestalotiopsis camelliae-sinensis on tea seedling leaves. Thereafter, we examined the growth performance and disease resistance of fresh tea seedlings grown in conditioned and control soils. Next, the rhizosphere microbial community and root exudates of tea seedlings infected by the pathogen were analyzed. In addition, we also evaluated the effects of the rhizosphere microbial community and root exudates induced by pathogens on the performance of tea seedlings. The results showed that tea seedlings grown in conditioned soil had lower disease index values and higher growth vigor. Soil microbiome analysis revealed that the fungal and bacterial communities of the rhizosphere were altered upon infection with Ps. camelliae-sinensis. Genus-level analysis showed that the abundance of the fungi Trichoderma, Penicillium, and Gliocladiopsis and the bacteria Pseudomonas, Streptomyces, Bacillus, and Burkholderia were significantly (p < 0.05) increased in the conditioned soil. Through isolation, culture, and inoculation tests, we found that most isolates from the induced microbial genera could inhibit the infection of tea gray blight pathogen and promote tea seedling growth. The results of root exudate analysis showed that infected tea seedlings exhibited significantly higher exudate levels of phenolic acids and flavonoids and lower exudate levels of amino acids and organic acids. Exogenously applied phenolic acids and flavonoids suppressed gray blight disease by regulating the rhizosphere microbial community. In summary, our findings suggest that tea plants with gray blight can recruit beneficial rhizosphere microorganisms by altering their root exudates, thereby improving the disease resistance of tea plants growing in the same soil.
Highlights
The soil near plant roots, i.e., the rhizosphere, plays a key role in plant immunity and overall plant performance (Pineda et al, 2020) and in protecting above-ground plant tissues from pests and diseases (Edwards et al, 2019)
Arabidopsis thaliana plants infected with the downy mildew pathogen recruited beneficial microorganisms that induced disease resistance and promoted growth, improving the survival chances of offspring growing in the same soil (Berendsen et al, 2018)
We aimed to investigate whether tea plants with aboveground Pseudopestalotiopsis camelliae-sinensis infection can recruit beneficial rhizosphere microbes by altering their root exudates to resist subsequent pathogen infection
Summary
The soil near plant roots, i.e., the rhizosphere, plays a key role in plant immunity and overall plant performance (Pineda et al, 2020) and in protecting above-ground plant tissues from pests and diseases (Edwards et al, 2019). Some rhizosphere soils can inhibit the occurrence of plant diseases even in the presence of virulent pathogens or under climatic conditions conducive to disease development (Weller et al, 2002; Mazzola, 2004). In such disease-suppressive soils, disease inhibition is related to the abundance of beneficial microorganisms (Mendes et al, 2011; Cha et al, 2016). Arabidopsis thaliana plants infected with the downy mildew pathogen recruited beneficial microorganisms that induced disease resistance and promoted growth, improving the survival chances of offspring growing in the same soil (Berendsen et al, 2018). Aphid and whitefly infestations led to the recruitment of beneficial bacteria that helped pepper plants cope with subsequent pathogen attacks (Lee et al, 2012; Kong et al, 2016)
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