Host infection selects for sRNA variants that drive bacterial social cheating.

Five recurrent single-nucleotide arcZ alleles in the plant pathogen Dickeya solani arise during potato tuber infection and form a graded impairment series linked to social cheating.

• Why it matters: sRNA mutations are an underexplored way bacteria may evolve cheating during infection, potentially undermining cooperative virulence and shaping disease progression.
• What they did: During potato tuber infection, the authors identified five arcZ alleles and tested fitness during coinfection; they also used transcriptomics and quantitative proteomics plus genetic dissection to pinpoint the cooperative public good.
• The result: Cheater alleles gain fitness only when rare in coinfection with wild-type arcZ1 cells, correlating with reduced total bacterial productivity and BudAB-dependent limitation of tissue acidification.

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