Although my research program has always been rooted in studying the regulatory aspects of plant gene expression, I have broadened my focus since becoming faculty into the area of sustainable agriculture. In particular I am interested in evaluating and developing sustainable organic horticulture production systems. Over the last decade I have conducted a range of experiments looking at whole systems, such as optimizing diverse direct-marketed vegetable systems, to evaluating specific pest problems in cucurbits, peppers, tomatoes and apples. In the last five years I have been dedicating much of my research towards investigating the interactions between soil microbes and plants. In particular I have focused on characterizing the soil-derived microbiome inside of plants and investigating the impact at a molecular level of these associations. The long-term goal of this work is to correlate organic production practices with increased microbial migration into plants and elucidate how these microbes positively impact plant health. In addition to research I am fully committed to student learning, and have led an effort in our college to develop an undergraduate curriculum in sustainable agriculture, which I direct. As part of these efforts I developed the 25-acre Organic Farming Unit of the Horticulture Research Farm, which I manage.

Mark Williams was appointed interim chair of the Department of Horticulture in July 2018, and officially took over the role of chair on October 1, 2019.