The Streptomyces scabiei Pathogenicity Factor Thaxtomin A Induces the Production of Phenolic Compounds in Potato Tubers

Abstract

The phytotoxin thaxtomin A (TA) is the key pathogenicity factor synthesized by the bacteria Streptomyces scabiei, the main causal agent of common scab of potato (Solanum tuberosum L.). TA treatment of potato tuber flesh produces a brown color that was attributed to necrosis. The intensity of TA-induced browning was generally thought to correlate with potato sensitivity to the disease. In this study, we found that TA-induced browning was much more intense in the potato tuber flesh of the common scab moderately resistant variety Russet Burbank (RB) than that observed in tubers of the disease-susceptible variety Yukon Gold (YG). However, there was no significant difference in the level of TA-induced cell death detected in both varieties, suggesting that tubers response to TA does not correlate with the level of sensitivity to common scab. TA-treated potato tuber tissues accumulated significantly higher levels of phenolic compounds than untreated controls, with a higher phenol content detected in RB TA-treated tissues than in those of YG. Browning was associated with a significant induction of the expression of genes of the phenylpropanoid pathway in RB tubers, indicating that TA activated this metabolic pathway. These results suggest that tuber flesh browning induced by TA is due to the accumulation of phenolic compounds. These phenolics may play a role in the protection of potato tubers against S. scabiei.

Assessment of genetic diversity of latent bacteria in coconut leaves associated with lethal yellowing disease symptoms in Kenya

“…While these bacteria form mutualistic relationships with coconut plants and plants in general, protecting them against pathogens through the production of secondary metabolites and activation of the plant's immune system, it is important to note that they can pose some environmental concerns. If not properly managed, the antimicrobial properties of these metabolites can disrupt natural microbial communities and potentially affect beneficial microorganisms (Isayenka & Beaudoin, 2022). Additionally, certain Streptomyces spp.…”

“…Additionally, certain Streptomyces spp. can cause potato scab and produce phytotoxins involved in plant diseases (Isayenka & Beaudoin, 2022; Pandey & Gupta, 2020). Despite reduced microbial diversity in healthy coconut samples, Streptomyces and Nonomuraea genera continued to dominate, suggesting their potential significance in either suppressing diseases or preserving plant health.…”

“…1E, 2E and 3E denote healthy samples from their respective counties. microbial communities and potentially affect beneficial microorganisms(Isayenka & Beaudoin, 2022). Additionally, certain Streptomyces spp.…”

Combined Transcriptome and Metabolome Analysis Reveals Adaptive Defense Responses to DON Induction in Potato

“…Notably, phenolic acids, alkaloids, and flavonoids accounted for the highest percentage of the differential metabolites in each comparison group. Similarly, Isayenka et al [62] found that the phytotoxin thaxtomin A (TA) induced browning of potato tuber flesh due to the accumulation of phenolic compounds, which may play a role in protecting potato tubers from Streptomyces scabiei. In addition, it is possible that because the family of tyrosinederived metabolites is flavonoids, DON induction caused significant downregulation of L-tyrosine, resulting in a reduction of 84% of all flavonoids in DAMs, suggesting that flavonoid levels may be negatively correlated with DON-induced plant defense.…”