Water scarcity threatens crop production in dry growing regions of the western US, and changing climatic conditions could aggravate this situation. Nevada farmers are interested in meeting increasing demands for fresh, local, specialty crops, but production is challenged by low soil nutrient availability, due to high soil pH and poor root system development, which compromises capacity for nutrient and water uptake.
Water and nutrient deficits decrease root hydraulic conductivity (i.e., increase resistance) and can affect water uptake, resulting in daily transient plant water deficits and reduced carbon assimilation capacity. These changes in root hydraulic conductivity result from earlier suberization (i.e., development of physical barriers impeding water and nutrient flow) closer to the root tip and lower activity of water channels (i.e., aquaporins) that facilitate water movement into roots.
To adapt and optimize production under these conditions, growers need to tightly manage their soils’ resources (water and nutrient) to maintain plant growth and improve yield. Among the root interactions with the soil microbial community, the symbiosis with arbuscular mycorrhizae can improve the plant nutritional status. Mycorrhizal plants increase their nutrient uptake capacity through an extended network of fungal hyphae, and changes in drought resistance have been reported although it is unclear if those changes result from the symbiosis or improved nutritional status.
Our primary project goal is to understand how the interaction of plant nutritional status and water availability affects young root development and physiology under drying soil and upon rewatering, and whether arbuscular mycorrhizae condition the plant drought response to maintain higher root water uptake capacity and leaf carbon assimilation. We will use a well-established tomato system for studying mycorrhizal symbiosis that consists of a commercial tomato and its counterpart genotype with reduced mycorrhizal colonization.