Phenomic Evaluation of Drought Response and Impacts of Grafting

James Crabb

As populations around the world grow, demand for water will increase faster than for any other resource because it is in turn essential to other resources such as energy, food, public health and drinking water. Agricultural industries face the prospect of limited future water supplies and have financial incentives to operate efficiently. Growing plants that require less water fits this scenario. The technique of grafting is widely used to improve production efficiency for many crops, but currently is not widely used to improve drought tolerance and reduce water inputs. The goal of this project was to evaluate the role grafting may play in imparting drought tolerance in composite plants. Non-invasive phenomic measurements (chlorophyll fluorescence, leaf water potential, stomatal conductance) and leaf peroxisome proliferation assay were used to characterize drought response profiles of own-rooted, self-grafted and cross-grafted tomato plants, with some trials also performed using grapevines. Chlorophyll fluorescence was found to be a robust indicator of drought stress and it enabled detection of differences between graft treatments and varieties. Drought stress rapidly altered stomatal conductance, while leaf water potential changed only after reaching very low soil water levels. Leaf peroxisome content changed with drought stress but did not show consistent differences between graft treatments. Most graft combinations in tomato and grape showed higher photosynthetic efficiency in both cross- and self-grafted plants compared to own-rooted plants. This supports the hypothesis that grafting different genotypes can be used to maintain productivity under reduced water application, but with a novel finding: it appears that the process of grafting itself can result in higher efficiency under drought. Additional novel results were obtained from the peroxisome assays, showing differences in peroxisome proliferation between two varieties of tomato under drought stress and recovery. Research is underway to combine chlorophyll fluorescence measurements and peroxisome analysis under drought stress to determine whether peroxisome proliferation is associated with other measurable stress responses. The question of how grafting improves photosynthesis under drought stress is a subject of subsequent investigation using molecular methods targeting stress-related microRNAs.

Phenomic Evaluation of Drought Response and Impacts of Grafting

Files and links (1)

Abstract

Metrics

Details