A more notable effect was observed in the progression of the infection events, with 58% of the infection events remaining at the microcolony stage and only 10% of the ITs reaching the dividing cortical cells in ARF2/3/4a/4b RNAi roots, whereas over 50% of the infection events reached the base of the epidermal cells or reached the cortex in GUS RNAi roots (Figure 4E). The gene discussed is ARF4; the disease is infection.