Location: Sunflower and Plant Biology Research
Project Number: 3060-21000-043-027-T
Project Type: Trust Fund Cooperative Agreement
Start Date: May 1, 2019
End Date: Apr 30, 2022
Objective:
(1) Phenotype nectar production for an inbred population, HA 434 × HA 456, segregating for nectar volume and other floral traits.
(2) Continue field observations to develop a model for how nectar access, nectar volume, and other traits influence bee visitation to sunflowers.
(3) Use phenotypic data to map gene(s) controlling nectar volume in cultivated sunflower.
Approach:
(Objective 1) Individual F6 plants from HA 434 × HA 456 population (between 196 and 224) will be grown out, along with the parental lines, in growth chambers at the USDA-ARS in Fargo. When bloom begins, nectar volume will be measured using small microcapillary tubes. Each plant will be sampled on multiple consecutive days (technical replications) to ensure high quality data for each plant (line). While this method is tedious and requires high (technical and biological) replication in the field, we have found that controlled lighting, temperature and humidity in growth chambers permits much more consistent results. If possible, additional data on sugar concentration in samples will also be collected using a hand-held refractometer.
(Objective 2) Using data from Objective 1, selected lines from HA 434 × HA 456 will be grown in the field for bee observations used to develop models of pollinator behavior. For each line, 2–4 rows will be needed to ensure enough pollinators are present for meaningful counts of bee activity. Methods will be similar to previous research, where floret samples are taken just prior to anthesis, nectar sampling during bloom, and bee observations on replicate rows several times per day during bloom. A sample of bees visiting lines will also be taken to determine whether different species have different responses to plant traits. All of the data will be incorporated into a statistical model to estimate the value of nectar access, nectar volume or other plant traits.
(Objective 3) Using data on nectar volumes from 196 to 224 F6 plants from the HA 434 × HA 456 population, we will conduct QTL mapping for this trait using the r/qtl function in R. To generate the genomic data, we will sample tissue from the same plants that are phenotyped in the growth chamber. The resulting DNA will be subjected to either a SNP assay or partial genome resequencing.
