Location: Forage Seed and Cereal Research Unit
Project Number: 2072-21000-051-005-R
Project Type: Reimbursable Cooperative Agreement
Start Date: Sep 30, 2017
End Date: Sep 29, 2021
Our objectives are to identify existing hop varieties with increased water use efficiency, to compare the physiological response of these varieties to drought/heat sensitive varieties, and to compare patterns in gene expression from the leaves and roots of these varieties to identify candidate genes for increased drought/heat tolerance. Our goal will be to identify candidate genes that can further be used for marker- assisted selection to eventually breed a more drought/heat tolerant hop variety. Objective 1: To describe the physiological response and the response of marketable traits of various hop cultivars commonly grown in Washington to drought and heat. Objective 2: To identify putative drought and heat tolerant cultivars, as well as drought and heat sensitive cultivars. Objective 3: To correlate physiological trait responses to gene expression patterns in the leaf and root in drought/heat tolerant cultivars and compare these responses and expression patterns to drought/heat sensitive cultivars. Objective 4: To identify candidate genes that impart greater stress tolerance in hops for use in future marker-assisted selection trials in an attempt to breed a more drought/heat tolerant variety.
Establish cuttings of 20-30 common U.S. grown hop varieties and experimental varieties from the germplasm collection in greenhouse or growth chambers where temperatures can be manipulated. Identify growers willing to collaborate by growing some of their plants at 50% irrigation during the coming field season so we can have yield data during year one while USDA-ARS fields are established. Plant cuttings of at least three putative drought/heat- tolerant varieties and three drought/heat-sensitive varieties in fields at USDA- ARS station. Equip experimental plants in collaborator’s fields with temperature and soil moisture dataloggers. Establish cuttings and repeat growth chamber/greenhouse experiment with emphasis on varieties that are putatively drought/heat-tolerant and very drought/heat-sensitive. Take physiological measurements for three months. In USDA-ARS fields planted in 2018, measure physiological traits monthly under 50% and control irrigation. At end of growing season, we will record yield, total biomass, and marketable traits. Take leaf and root tissue samples at the end of three months for qPCR confirmation of expression of candidate genes identified during previous year’s RNAseq study. In USDA-ARS fields, measure physiological traits monthly on mapping populations under 50% and control irrigation. At end of growing season, record yield, total biomass, and total acid content.