In the normal response of P. alba × P. grandidentata to infection by the biotroph M. aecidiodes, there is a decrease in galactinol levels; activation of SA, calcium and phosphatide signaling; increased expression of NPR1 and PR1; and increased ROS levels, which do not occur in the mutant line overexpressing Arabidopsis galactinol synthase 3 (AtGolS) and Cucumber sativa raffinose synthase (CsRFS) and, therefore, making it more susceptible to rust diseases [262]. This evidence concerns the gene TMEM37 and infection.