| Species name: Silver-Leaf Sunflower (Helianthus argophyllus Torrey and Gray)|
Helianthus argophyllus is an herbaceous annual sunflower native to the gulf coast of Texas and inland to San Antonio (http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250066869). The species is highly drought tolerant, and unlike most other annual sunflowers, produces woody stems. As a consequence, H. argophyllus has attracted interest as a possible source of genes for breeding high cellulosic biomass cultivars. Recent classifications place the species in subfamily Asteroideae, tribe Heliantheae, and subtribe Helianthineae. Helianthus argophyllus is genetically diploid (n=17; http://www.tropicos.org/Project/IPCN), with a genome size of circa 4,238 Mbp (http://data.kew.org/cvalues/).
| Images of Helianthus argophyllus|
| Figure 1: Silver-leaf sunflower. Photograph by Brook Moyers.||
| Figure 2: Silver-leaf sunflower leaves. Photo by Nolan Kane. ||
| CGP Activities|
We generated the Sanger ESTs described above, which we have used to generate SSR markers, as well as to determine the distribution of whole genome duplications in the Compositae. A high resolution genetic map of the species based on SNP genotyping has recently been completed, and population genomic studies are underway to identify alleles involved in the differentiation of an early flowering coastal form of the species from a late flowering inland variety. In addition, genetic studies and introgression lines have been developed with the cultivated sunflower, H. annuus, to determine the genetic basis of drought tolerance and cellulosic biomass traits.
Barker MS, NC Kane, A Kozik, RW Michelmore, M Matvienko, SJ Knapp, and LH Rieseberg. 2008. Multiple paleopolyploidizations during the evolution of the Asteraceae reveal parallel patterns of duplicate gene retention after millions of years. Molecular Biology and Evolution 25:2445-2455.
Heesacker A, Kishore VK, Gao WX, Tang SX, Kolkman JM, Gingle A, Matvienko M, Kozik A, Michelmore RM, Lai Z, Rieseberg LH, Knapp SJ (2008) SSRs and INDELs mined from the sunflower EST database: abundance, polymorphisms, and cross-taxa utility. Theoretical and Applied Genetics 117:1021-1029.