|KANTAR, MICHAEL - University Of Minnesota|
|SOSA, CHRYSTIAN - International Center For Tropical Agriculture (CIAT)|
|KHOURY, COLIN - International Center For Tropical Agriculture (CIAT)|
|CASTANEDA-ALVAREZ, NORA - International Center For Tropical Agriculture (CIAT)|
|ACHICANOY, HAROLD - International Center For Tropical Agriculture (CIAT)|
|BERNAU, VIVIAN - International Center For Tropical Agriculture (CIAT)|
|KANE, NOLAN - University Of Colorado|
|MAREK, LAURA - Iowa State University|
|RIESEBERG, LOREN - University Of British Columbia|
Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/24/2015
Publication Date: 10/8/2015
Citation: Kantar, M.B., Sosa, C.C., Khoury, C.K., Castaneda-Alvarez, N.P., Achicanoy, H.A., Bernau, V., Kane, N.C., Marek, L., Seiler, G., Rieseberg, L.H. 2015. Ecogeography and utility to plant breeding of the crop wild relatives of sunflower (Helianthus annuus L.). Frontiers in Plant Science. doi: 10.3389/pls.2015.00841.
Interpretive Summary: With the world’s population projected to increase, the need to produce more food while using fewer natural resources and inputs under increasingly stochastic climatic conditions presents a major challenge. Plant genetic resources represent the biological foundation for maintaining and improving crop productivity, having played a central role in crop development since antiquity. Crop wild relatives (CWR) of sunflower are an important source of useful traits for plant breeding. Their conservation and utilization focusing on the use of improving technologies (high throughput phenotyping, genotyping, and geographical information systems) has been proposed as a way to acquire a greater knowledge of conservation needs and lead to more targeted use of the germplasm. Targeted collecting of sunflower CWR for genebank conservation has become a priority as rapid changes in both climate and land use patterns increasingly threaten their natural habitats. Despite their historical use, CWR of sunflower are considered to be relatively untapped, particularly in regard to adaptation to abiotic stresses. To contribute to an enhanced understanding of the sunflower wild relatives, geographic occurrence, bioclimatic and biophysical data were used to predict species distributions, range overlap, and niche occupancy in 36 taxa closely related to sunflower. Taxa lacking comprehensive genebank conservation were identified, as well as those occurring in extreme environments of potential interest to sunflower breeding. Using a combination of ecological niche and genetic relatedness analyses, taxa that are underrepresented in genebank collections were identified. Also, highlighted species and populations inhabiting environmental niches with extreme phenotypes may possess traits of value to crop improvement. Finally, much of the sunflower primary gene pool occurs in extreme environments indicating that utilization of this germplasm for the breeding of abiotic stress tolerance may produce quick gains with minimal effort.
Technical Abstract: Crop wild relatives (CWR) are a rich source of genetic diversity for crop improvement. Combining ecogeographic and phylogenetic techniques can inform both conservation and breeding. Geographic occurrence, bioclimatic, and biophysical data were used to predict species distributions, range overlap and niche occupancy in 36 taxa closely related to sunflower (Helianthus annuus L.). Taxa lacking comprehensive ex situ conservation were identified. The predicted distributions for 36 Helianthus taxa identified substantial range overlap and asymmetry and niche conservatism. Specific taxa (e.g., Helianthus debilis Nutt., Helianthus anomalus Blake, and Helianthus divaricatus L.) were identified as targets for traits of interest, particularly for abiotic stress tolerance and adaptation to extreme soil properties. The combination of techniques demonstrates the potential for publicly available ecogeographic and phylogenetic data to facilitate the identification of possible sources of abiotic stress traits for plant breeding programs. Much of the primary gene pool (wild H. annuus) occurs in extreme environments indicating that introgression of targeted traits may be relatively straightforward. Sister taxa in Helianthus have greater range overlap than more distantly related taxa within the genus. This adds to a growing body of literature suggesting that in plants (unlike some animal groups), geographic isolation may not be necessary for speciation.