Genomics of Regional Adaptation and Breeding Challenges in the Perennial Sunflower Species Helianthus maximiliani Schrad

Maximilian sunflower (Helianthus maximiliani Schrad.) is a perennial sunflower species widely distributed across the North American prairie and a candidate species for perennial oilseed development. Across its range Maximilian sunflower shows strong clinal variation in life history traits such as photoperiod sensitivity, disc diameter and plant height. Existing programs in Manitoba and Kansas are situated in substantially different growing regions and differences in photoperiod and heat unit sensitivity between breeding materials poses a challenge for synergistic breeding efforts.

To address these issues wild Maximilian sunflower sub-populations were surveyed across Southern Manitoba for the purposes of characterizing the extent of clinal variation in this species on a regional basis. Seventeen sub-populations across multiple soil, temperature and precipitation gradients were surveyed and sampled for phenotyping under controlled environment conditions. Populations are undergoing genotyping using genotype-by-sequencing (GBS) with the intent of mapping divergent family traits using a family-based association mapping approach. Select Manitoba wild-type individuals have been crossed with advanced breeding lines exhibiting a novel unbranched architecture developed by the Kansas based organization The Land Institute. Segregating F₂ mapping populations for photoperiod sensitivity, disc diameter and branching architecture are under development for QTL mapping also employing the GBS marker platform.

Initial results suggest there is enough regional diversity in Maximilian sunflower in Southern Manitoba for mapping traits of interest for breeding. These include a strong latitudinal gradient for days to flowering, plant height and node count, significant family differences in disc size and the presence of an unspecified male-sterility mechanism warranting further investigation.