Location: Crop Improvement and Protection Research
Project Number: 2038-21530-002-034-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Nov 1, 2020
End Date: Apr 30, 2023
Lettuce is produced under high irrigation requirements and is very sensitive to drought conditions. It is reported that drought conditions lead to metabolic reprogramming of plants resulting in the accumulation of antioxidant compounds, amino-acids, carbohydrates, alcohols and proline, which together have an osmo-protective role. We will perform comprehensive metabolome studies on drought sensitive and tolerant genotypes, to identify key metabolites accumulated in the plants due to water-stress. We will identify genomic loci controlling the concentration of metabolites (mQTL) using interspecific recombinant mapping population. We will screen lettuce germplasm collection to identify cultivars/lines with high levels of drought induced metabolites including antioxidant compounds, which are also important nutritional compounds. Successful completion of this project will produce nutritionally enriched, drought tolerant lettuce breeding lines along with publications and citations.
The ARS Project Manager (PM) will conduct all experiments unless otherwise noted. Protocol standardization, metabolite extraction from drought tolerant and susceptible cultivars grown in greenhouse under control and water stress conditions will start from November 2020 to May 2021. Extracted metabolites will be sent to Metabolomics Core Facility (MCF) at the University of California, Riverside. We expect that the analysis will be completed by July 2021. PM will write a manuscript to report these results from August 2021 to October 2021. Planting of a recombinant inbred line (RIL) population in greenhouse, application of drought treatment, phenotyping and metabolite extraction and targeted metabolome analysis will be done from June 2021 to December 2021. PM will analyze the results and write a manuscript from January 2022 to May 2022. Screening of lettuce germplasm for genome-wide association study for metabolites accumulated under drought stress will be done from January 2022 to August 2022. PM will analyze the results and write a manuscript from July 2022 to January 2023. Transfer drought tolerant gene(s) into elite cultivars will be done from August 2021 to January 2023. Crossing between tolerant and elite cultivar(s) will begin in June 2021, F1 seeds from each cross will be harvested separately, cleaned and planted in growth chamber. F2 progeny will be evaluated in greenhouse using molecular biomarkers. F3 progeny from selected F2 will be evaluated for drought tolerance between August 2022 and January 2023 in replicated trials. PM will write a manuscript to report these results from February 2023 to April 2023. Results from these studies will be reported in peer reviewed manuscripts. PM and ARS Project Director (PD) will present results from these studies at the American Society for Horticultural Science meetings in July 2021 and August 2022 and extension events in Salinas, Imperial, and Yuma Valleys.