‘Candidatus Phytoplasma solani’ interferes with the distribution and uptake of iron in tomato

Abstract

Background ‘Candidatus Phytoplasma solani’ is endemic in Europe and infects a wide range of weeds and cultivated plants. Phytoplasmas are prokaryotic plant pathogens that colonize the sieve elements of their host plant, causing severe alterations in phloem function and impairment of assimilate translocation. Typical symptoms of infected plants include yellowing of leaves or shoots, leaf curling, and general stunting, but the molecular mechanisms underlying most of the reported changes remain largely enigmatic. To infer a possible involvement of Fe in the host-phytoplasma interaction, we investigated the effects of ‘Candidatus Phytoplasma solani’ infection on tomato plants (Solanum lycopersicum cv. Micro-Tom) grown under different Fe regimes. Results Both phytoplasma infection and Fe starvation led to the development of chlorotic leaves and altered thylakoid organization. In infected plants, Fe accumulated in phloem tissue, altering the local distribution of Fe. In infected plants, Fe starvation had additive effects on chlorophyll content and leaf chlorosis, suggesting that the two conditions affected the phenotypic readout via separate routes. To gain insights into the transcriptional response to phytoplasma infection, or Fe deficiency, transcriptome profiling was performed on midrib-enriched leaves. RNA-seq analysis revealed that both stress conditions altered the expression of a large (> 800) subset of common genes involved in photosynthetic light reactions, porphyrin / chlorophyll metabolism, and in flowering control. In Fe-deficient plants, phytoplasma infection perturbed the Fe deficiency response in roots, possibly by interference with the synthesis or transport of a promotive signal transmitted from the leaves to the roots. Conclusions ‘Candidatus Phytoplasma solani’ infection changes the Fe distribution in tomato leaves, affects the photosynthetic machinery and perturbs the orchestration of root-mediated transport processes by compromising shoot-to-root communication.

Modifying Anthocyanins Biosynthesis in Tomato Hairy Roots: A Test Bed for Plant Resistance to Ionizing Radiation and Antioxidant Properties in Space

“…Solyc01g010480 (Log 2 Fc = −2.2; tomato K+ channel KAT1) was demonstrated to be highly upregulated in low K tolerant tomato genotypes upon potassium deficiency ( Zhao et al, 2018 ). Solyc01g102610.3.1 (Log2Fc = −3.60; tomato FRO6) is involved in nutrient transport in phloem and was observed to be downregulated under Phytoplasma solani infection of tomato ( Buoso et al, 2019 ).…”

Effect of Phytoplasma Associated with Sesame Phyllody on Ultrastructural Modification, Physio-Biochemical Traits, Productivity and Oil Quality

“…As one of the first visible symptoms of disease progression, leaf chlorosis might be exacerbated by poor soil fertility. In this context, Buoso et al [70] reported that iron deficiency in phytoplasma-infected plants had negative impacts on chlorophyll pigment and young leaf chlorosis in tomato plants. The sesame's lower leaf greenness index (i.e., chlorophyll content) in our study related to the severe damage of the thylakoid stacks, structural and functional destruction of the grana and stroma lamellae of chloroplasts (Figure 9), and increased numbers of starch granules in the infected plant's leaves [23].…”

Phytoplasma-induced biochemical and genetic variations in Crassula argentea

“…There is no significant differences in Fe content of normal and abnormal plants. Buoso et al (2019) observed that phytoplasma infection accumulate Fe from the phloem, converting the phloem into a sink tissue for Fe causing Fe starvation of plant.…”