I am currently screening several potato materials for virus resistance genes using published molecular markers. However, even though those molecular markers have been shown to be efficient in several research articles, I have observed that certain materials, despite being susceptible in field trials and greenhouse resistance evaluations, exhibit bands indicative of resistance when screened with these markers. Additionally, many of the resistant materials display the presence of all known Ry genes (Rysto, Ryadg, and Rychc) and Rx genes (Rx1 and Rx2). This complicates the initial assessment of molecular markers as the definitive cause of resistance against a specific virus.

What would be the major factors behind these problems?

I am eager to find research articles addressing this issue, even if they focus on other crops.