Rust effector delivered into infected tissues to modulate host functions and contribute to pathogen virulence (PubMed:30283062). Binds the TGA1a-binding DNA sequence to repress the expression of genes involved in immune responses such as the defense-related transcription factors WRKY18, WRKY27, WRKY33, MYB51, the defense-related proteins NHL3, RPP8, YLS9, AZI1, CRK11 and the jasmonate pathway and regulation genes JAZ1, ASA1, ASB1. Other genes involved in diverse mechanisms also down-regulated include the chitinase CHI, the brassinosteroid-related genes BAS1, BES1 PAR1, BEE1, the salicylic acid-related gene NPR3, the ethylene-related response genes ARGOS and ARGOS-like (ARL), EBF2, ERF6, ETR2, RTE1, the carbon metabolism-related gene EXO, as well as the red/far red light signalization-related genes FAR1, GA2OX2, PAR1, PIF3, PKS4 (PubMed:30283062). Expressed during host infection. The nucleolar localization signal (residues 29 to 38) is required for host nucleolar accumulation but not for the nuclear localization, nor for the augmented plant susceptibility to pathogens.