In vitro Methodology to Assess Quantitative Resistance in Plant-fungus Pathosystems

Quantitative resistance (QR) to fungal pathogens remains a primary focus of all major host breeding programs. Field screenings for resistant plants, although accurate and effective, demand significant time and a sizable workforce to accomplish. Moreover, weather conditions in the field may not always be favorable for uniform disease spread, which eventually may lead to the failure of the overall experiment. The development of a more efficient and reliable bioassay to screen for resistance to fungal pathogens would be advantageous for any breeding program working on disease resistance; however, only if it correlates with field screening trials.

The objective of this review is to combine novel findings related to rapid screening methods to evaluate QR, which are needed to accelerate the progress in developing fungal disease resistance in cultivars. Insights into the in vitro quantitative components of the host-pathogen interaction, factors affecting in vitro evaluation in young plant materials, as well as molecular pathways for the association between the in vitro and adult plant responses to fungal infection are also reviewed.

An in vitro method was found to be efficient and successful in terms of inoculum volume, plant samples, and working space. The main advantage of this method is its predictive ability for adult plant disease. In addition, it provides reproducible results and is found to be a simple and reliable method. The in vitro assay allows rapid and early determination of resistance/susceptibility to fungal pathogens, which can be incorporated into a breeding program for identifying resistant plants.