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USDA Sunflower Unit Looks to the Future

Thursday, August 24, 2023
filed under: Research and Development

Brent Hulke
Brent Hulke
Brent Hulke, USDA-ARS sunflower research geneticist, provided 2023 NSA Summer Seminar participants with a valuable overview of the staffing situation and projects of the ARS sunflower team based at the Edward T. Schafer Agricultural Research Center in Fargo, N.D.
        Seven scientists (including three weed scientists), plus support staff, constitute the current Sunflower & Plant Biology Research Unit.  Research encompasses two broad areas:  wholistic sunflower genetic research (which incorporates pathology, entomology and biotic stress issues), and agroecological impacts of cover crops and crop-weed interactions.
        The sunflower plant pathology program, headed by pathologist Bill Underwood, has delivered several important accomplishments in recent years, Hulke reported.  Among them are:
        •  Germplasm releases with good levels resistance to Sclerotinia basal stalk rot and head rot (in collaboration with Hulke and molecular geneticist Lili Qi).
        •  Mapping of basal stalk rot and head rot resistance QTL* introgressed from wild sunflower species (collaborating with Qi).
        •  Development of an improved greenhouse method for basal stalk rot disease evaluations.
        •  Identification of inbred lines with high levels of basal stalk rot resistance and development of mapping populations.
        •  Mapping of loci associated with aggressiveness in S. sclerotiorum, the fungus that causes Sclerotinia.
        •  Germplasm releases with resistance to Phomopsis and other diseases (in collaboration with Hulke).
        •  Mapping of Phomopsis resistance QTL from the inbred line HA-R3 (in collaboration with Qi).
        •  Identification of distinct forms of physiological resistance to Phomopsis stem canker and lines with distinct resistance mechanisms.
        Future research for the sunflower plant pathology team will zone in on genetic mapping, focusing on highly resistant sources and specific resistance traits.  Other work will examine the genetic and physiological characterization of Phomopsis resistance mechanisms – including insensitivity to a phytotoxin.  Underwood will also investigate the relationship between Sclerotinia resistance and time to plant flowering and maturity.
        Research entomologist Jarrad Prasifka has spearheaded ARS sunflower entomology work for the past decade.  Host plant insect resistance has been a key focus area, with significant progress made on the red sunflower seed weevil and banded sunflower moth in particular.  Prasifka also has conducted considerable work on pollinator value, including estimating yield benefits to confection sunflower hybrids.  Associated plant traits and bee preference have been examined as well.
        The red seed weevil – an especially serious problem in South Dakota in recent years – has been a primary research target.  Prasifka’s work has shown likely causes for those high populations and helped define improved management recommendations.
        Ongoing ARS entomology projects include studies of pollinator health and preference, as well as red seed weevil population genetics. Prasifka additionally is studying seed weevil pheromones and monitoring, as well as conducting early planting date trials in both Dakotas.
        Research molecular geneticist Lili Qi has utilized her knowledge and skills in several areas.  She has worked to identify and introgress new sources of disease resistance, studied genetic inheritance, developed molecular markers for genes/QTL controlling new traits in sunflower, and released improved germplasm to address emerging disease problems plaguing sunflower. 
        While she’ll soon be retiring, Qi continues working on mapping new resistance genes for rust and downy mildew.  She also is developing a population for QTL mapping of both Phomopsis and head rot resistance from a wild perennial species, H. nuttallii.
        Led by Brent Hulke and his predecessor, Jerry Miller, the USDA-ARS sunflower breeding program has generated impressive results over the past several decades.  More than 200 inbred lines and genetic stocks with new or improved traits have been developed through the ARS program and made available to commercial breeders.  Among those traits are Express® and Clearfield® tolerance, high-oleic acid, numerous disease resistances, the first pest-insect resistance traits – and, in recent years, increased adaptation (e.g., days-to-maturity range) and fitness for specific locations (“niche” germplasm diversity).  The team also has worked on detailed mapping of disease and pest/beneficial insect interaction genes on the sunflower genome as a means of deploying research more efficiently in the future.
        ARS chemist Jim Anderson has been investigating multi-cropping systems for colder climates.  His research encompasses the identification of the ecosystem services from growing sunflower or corn with forages and cover crops; characterizing genes associated with freezing tolerance, maturity and yield in canola and camelina; and determining the impact that temperatures have on fatty acid profiles in early maturing sunflower.
        Hulke also spoke to the future of the ARS unit — a future that very likely will include additional scientists and a significantly expanded scope of research projects.  “We expect major changes in scientist and support staffing in the next few years,” he noted, “providing opportunities to refocus that only come around every 15 to 30 years.”
        With Lili Qi retiring later this year, that leaves geneticist Hulke, plant pathologist Underwood and entomologist Prasifka on the primary ARS sunflower team.  There are two vacant scientist positions, with funding; three additional new vacant scientist positions (dependent upon funding from the Sunflower Breeding Initiative), and two other new positions (one in ag engineering, the second in bioinformatics/genetics) that would be funded from the Predictive Crop Performance domain.
        The “wish list” of new scientist positions includes placement of a research geneticist at Fort Collins, Colo.  This person would focus on line development and “pre-commercial” hybrid breeding.  His/her responsibilities would be similar to those of Hulke in Fargo, but with emphasis on the Central and Southern Great Plains.  Hulke foresees three main benefits to locating this work at Fort Collins:
        •  More attention to sunflower in a double-crop system with wheat —  of value given climate change and reduced irrigation resources in the Great Plains.
        •  “Full-season” materials for this zone would be developed, which cannot be done from Fargo.
        •  Entomology studies on the sunflower head moth would benefit from a dedicated presence in the region.
        The possible establishment of an ARS plant physiologist at the Fort Collins location would also carry substantial benefits, Hulke added, centered on establishing biotic stress (drought, salt, heat, etc.) as a part of the sunflower research portfolio.  That person would collaborate with other ARS scientists to find drivers of stress tolerance (i.e., genes), integrating sensors and computational tools into breeding workflows and establishing the nature of yield tradeoffs with stress tolerance.
          As he did when speaking at the 2022 NSA Summer Seminar, Hulke concluded this year’s presentation by welcoming his audience’s input and support as ARS constructs its sunflower future.  Along with helping prioritize future areas of research, NSA and its members can assist in helping ensure continuation of good research leadership — a critical component.
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