Location: Sunflower Research
Project Number: 5442-21000-039-03
Start Date: May 01, 2011
End Date: Apr 30, 2016
Kansas State University (KSU) and the USDA, Agricultural Research Service (ARS), corresponded regarding the 2005 Sunflower Status Report reference to discovery of triazine resistance in sunflower germplasm. This correspondence resulted in transfer of bulked seed of mutagen-treated HA 821, HA 382, RHA 274 and RHA 801 (Miller and Vick, 1999. Crop Sci. 39:364-367), from ARS to KSU. These seeds were produced for the purpose of gene discovery for reduced saturated fatty acid seed composition, but could also be used for other gene discovery purposes. KSU received the bulked population of fourth generation seed on April 29, 2005, and proceeded to conduct field and greenhouse screens for atrazine resistance. Following field exposure to atrazine, heads of surviving plants were bagged to ensure self pollination. Resulting seed was bulked within source population, and subjected to greenhouse trials to confirm atrazine resistance. Seed bulked within populations was subjected to field and greenhouse atrazine challenges again in 2006 and 2007, with greenhouse trials conducted at KSU in 2006 and 2007. At the suggestion of Croplan Genetics, seed collected from individual heads in 2007 were kept separate, subjected to greenhouse challenge, and planted as individual lines in 2008 and subsequent field and greenhouse trials. Under guidance of USDA-ARS, testcrosses were made with promising lines in 2008 to investigate transmissibility of the resistance trait; the resulting hybrid seed was subjected to controlled environment challenge in 2008. The traditional breeding with chemical mutagenesis, described above, was used to produce lines derived from HA 821, HA 382, RHA 274 and RHA 801 with point mutations scattered throughout the genome. The field and greenhouse screening trials described above resulted in discovery that one or more of these point mutants provide resistance to atrazine and possibly other herbicides of the triazine family. Research is ongoing to determine the mode of resistance of each of the potential sources, and also to determine transmittance of the resistance to hybrids. After the mode of resistance is determined, purification of resistant lines and or transfer of the resistance trait to alternative lines will continue until a pure line is available for joint release by USDA-ARS and Kansas State University.