SOBIR1 Links Potato Responses to Potato Tuber Moth Attack and High Temperature Stress.

Herbivory and high temperature stress affect plant performance and frequently co-occur under natural conditions. The molecular mechanisms by which plants coordinate responses to these two stresses deserve more attention. Here, we explored how StSOBIR1, a leucine-rich repeat receptor-like kinase gene, modulates plant responses to herbivory and high temperature stress using genetic, molecular, biological, and chemical analysis approaches. StSOBIR1 encodes a plasma membrane-localized protein and its expression is rapidly induced upon herbivore attack. StSOBIR1 negatively regulates jasmonic acid (JA) signaling and JA-mediated defenses, thereby hindering herbivore resistance to potato tuber moth (Phthorimaea operculella) at a normal temperature (22°C). In contrast, the transcripts of StSOBIR1 were suppressed by high temperature (32°C). StSOBIR1 positively regulates plant responses to high temperature stress, including the accumulation of sucrose, proline and chlorophylls. Moreover, at high temperature, both the StSOBIR1-knock down and overexpression plants exhibited similar JA signaling and herbivore resistance to wild-type plants. Transcriptome analysis revealed that high temperature interferes with StSOBIR1-mediated defensive responses to herbivory by disrupting herbivory-associated gene co-expression networks and reprioritizing its functions. Taken together, these results show that StSOBIR1-mediated fine-tune plant responses to herbivory and high temperature, while under combined stresses, its negative regulatory function over herbivore defense is lost.