Whitefly hijacks host NtWRKY6 to activate NtRGL2 and suppress gibberellin signaling

BACKGROUND: Piercing-sucking insects severely impair crop productivity by suppressing the growth of host plants. Whitefly (Bemisia tabaci) infestation induces a pronounced dwarf phenotype associated with reduced gibberellin (GA) signaling; however, the underlying molecular mechanism remains largely unknown. Here, we investigated the role of the hormone-responsive transcription factor, NtWRKY6, in mediating whitefly-induced inhibition of host growth. RESULTS: Silencing of NtWRKY6 significantly restored bioactive GA₃ accumulation and alleviated whitefly-induced growth inhibition, whereas NtWRKY6 overexpression further aggravated GA deficiency and dwarfism. Using DNA affinity purification sequencing (DAP-seq) as a discovery screen, together with yeast one-hybrid and dual-luciferase assays, we identified NtRGL2, a DELLA-encoding negative regulator of GA signaling, as a direct transcriptional target of NtWRKY6. Intensive whitefly feeding induced NtRGL2 expression in wild-type plants, but this induction was largely abolished in NtWRKY6-silenced plants, demonstrating that NtWRKY6 is required for the whitefly-mediated activation of NtRGL2. Furthermore, silencing NtRGL2 substantially mitigated the inhibitory effects of whitefly infestation on GA₃ accumulation and plant growth, confirming its critical role downstream of NtWRKY6. CONCLUSION: Our findings reveal a previously unrecognized regulatory module in which whitefly infestation exploits the host transcription factor NtWRKY6 to promote NtRGL2 expression, a change consistent with enhanced DELLA-associated repression of GA signaling and suppression of host growth. This study reveals a molecular mechanism by which a piercing-sucking insect modulates host phytohormone homeostasis to alter plant development, providing new insights into plant-insect interactions and potential targets for sustainable pest management.