Development and Evolution of an Intermediate Wheatgrass Domestication Program

Abstract

Ecological intensification of agriculture is a proposed strategy to enhance the production of food while expanding ecosystem services and reducing inputs. Perennial plants that are directly harvested for human food are a novel means of ecological intensification, by potentially providing unprecedented levels of ecological services, such as increased soil carbon and reduced nutrient leaching. However, existing herbaceous perennial plants produce low yields of harvestable seed. Therefore, we initiated a domestication program to improve the grain yield of the perennial intermediate wheatgrass (Thinopyrum intermedium [Host] Barkworth & D.R. Dewey). The breeding program has adapted to changing resources and to results from previous generations, with methods becoming more elaborate as the program has matured over six breeding cycles. Average predicted gains from selection accumulated over five cycles were 143, 181 and 60% respectively, for seed yield per head, percent naked seed and mass per seed. We did not detect negative correlations that would indicate simultaneously achieving increased grain yield and sustained perenniality would be particularly difficult. Heritability estimates based on genetic markers were the same or higher than those calculated from a pedigree, indicating that markers have potential to expedite breeding efforts.

Effects of defoliation and row spacing on intermediate wheatgrass I: Grain production

“…Both excessive intra‐stand competition and the steady decline in resource allocation to reproductive growth must be addressed in future research and germplasm improvement. First, ongoing breeding efforts (Bajgain et al, 2019; DeHaan et al., 2018; Zhang et al., 2016) should focus on developing IWG germplasm that maintains a high number of grains spike −1 after the first production year, without over‐producing culmed tillers. Reducing the rate of rhizomatous spread may also help avoid excessive intra‐stand competition.…”

“…However, the economic viability of this crop is limited by low initial grain yields that further decline over the life of the stand (Jungers, DeHaan, Betts, Sheaffer, & Wyse, 2017). Breeding and genomics efforts—aided by a recently released reference genome ( Thinopyrum intermedium v2.1, U.S. Department of Energy Joint Genome Institute, 2019)—are underway to improve many agronomic traits of IWG, including yield and yield persistence (Bajgain, Zhang, & Anderson, 2019; DeHaan, Christians, Crain, & Poland, 2018; Zhang et al., 2016).…”

Effects of defoliation and row spacing on intermediate wheatgrass II: Forage yield and economics

“…Dewey] (IWG; Bell, Byrne, Ewing, & Wade, 2008; Watt, 1989). Originally introduced to North America as a forage crop, IWG has been bred in recent years to produce higher yields of larger seeds, which have been marketed under the trade name Kernza (The Land Institute, Salina, KS; DeHaan, Christians, Crain, & Poland, 2018). Harvesting IWG for grain typically results in a straw harvest; in addition, vegetative biomass can be cut in spring, fall, or both for hay production.…”

Strategies, Advances, and Challenges in Breeding Perennial Grain Crops

“…In this special issue, reports on de novo domestication projects include intermediate wheatgrass (Thinopyrum intermedium), which produces a grain similar to wheat called Kernza ® [29,30], silflower (Silphium integrifolium), a member of the sunflower family under development as an oilseed crop [31,32], and perennial barley (Hordeum spp.) [33].…”