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GRP8 as a target for improving plant stress response to water and nutrient starvation

Genetically engineered plants for increased resistance to nutrient stress

Problem:

The plant root epidermis absorbs water and nutrients from the environment, using long hair-like projections from root hair cells to increase surface area. Plants regulate the ratio of root hair to nonhair cells based on environmental signals, with plants grown under nutrient-poor conditions developing higher density and longer hair cells. Roots can only absorb inorganic phosphates, present at very low concentrations in soil, making phosphate starvation one of the most common nutrient stresses in plants. Furthermore, the molecular mechanisms regulating root hair cell fate and phosphate starvation response are not well understood.

Solution:

The Gregory Lab has discovered that the overexpression of the GRP8 gene (glycine-rich RNA-binding protein) increases the number of root hairs on the surface of plant roots, increasing the surface area for water and nutrient absorption. This finding is the first identification of GRP8 as a promising target for crop plant trait improvement, with connections to stress response to water and nutrient deprivation.

GRP8 overexpression was also determined to improve plant tolerance to phosphate starvation, with acid phosphatase levels in Arabidopsis roots correlating with GRP8 abundance. By measuring the expression of phosphate starvation response genes under normal growth conditions, GRP8 was found to positively regulate the transcripts of phosphate transporters and their upstream activators.