2018 ASHS Annual Conference

Spinach (Spinacia oleracea L.) is an economically important leafy green crop widely grown in the US. Spinach production must thrive in a dynamic environment constantly challenged by abiotic and biotic stresses. Such stresses have a profound effect on plant growth and development, ultimately reducing yield. Selecting for resistance and tolerance to these stresses is one of the main focus of breeding programs. Growth rate has direct effect on yield and agronomical practices in the field such as irrigation, fertilization, and harvesting time. With the advancements in next-generation sequencing tools and the completion of the reference spinach genome, as well as the identification of a large panel of SNPs by high-throughput genotyping, it is now possible to identify markers associated to traits of interest to improve breeding efficiency. In order to determine plant growth parameters, a population of 315 spinach accessions from the USDA National Germplasm System and the Texas A&M AgriLife spinach breeding program was monitored from germination to plant senescence using a drone equipped with a RGB camera. Canopy cover, canopy volume, and plant height for each accession was measured once a week. Changes on those parameters between measurements were used to determine crop growth rates. Genotype by sequencing was performed (GBS) using ddRadSeq. Genome-wide association (GWAS) analysis was performed to develop molecular markers associated with plant growth variables using mixed linear model (MLM) from TASSEL and GAPIT. Identification of molecular markers associated with crop growth parameters will facilitate selection and development of cultivars with improved agronomic characteristics. Furthermore, changes in growth rates can be used to screen breeding populations for resistance and tolerance to biotic and abiotic stresses.