AGO2 and viral infectious disease: This feedback regulation has been reported in plant responses to both biotic and abiotic stresses, including repression of AGO1 by miR168 during virus infection in Nicotiana benthamiana [57], upregulation of miR168 for AGO1 degradation under drought in Arabidopsis [58], degradation of DCL1, AGO1 and AGO2 by miR162a, miR168a and miR403 respectively in Phaseolus vulgaris under different stresses [59], downregulation of AGO1, AGO2, DCL1 and DCL2 by miR168a, miR403a, miR162b and miR1515a respectively in soybean infected by soybean mosaic virus [60].