Ecotypes of Italian ryegrass from Swiss permanent grassland outperform current recommended cultivars

Abstract

Italian ryegrass (Lolium multiflorum Lam. ssp. italicum Volkart ex Schinz et Keller) thrives well in permanent grassland in mild and moist regions of Switzerland. Ecotypes of Italian ryegrass from Swiss permanent meadows have often been used successfully as the base material of breeding programmes. However, their agronomic performance per se has never been studied in detail. Therefore, field trials were conducted to assess the potential of this semi-natural genetic resource for use in breeding. Twenty ecotype populations were collected in different geographical regions in 2003 and seed was increased. Plot trials with 20 ecotype populations were conducted 2005-2007 at three locations, supplemented by row trials at two additional locations, and including four currently recommended cultivars as controls. Average performance in terms of yield, vigour and resistance to snow mould of ecotypes was superior to the cultivars. Depending on the characteristic, between three and 16 of the 20 ecotypes performed significantly better than the cultivars mean. However, resistance against crown rust of all ecotypes was significantly poorer than that of the cultivars. Correlation and regression analysis showed that more eastern and more northern collecting sites harboured better performing ecotypes. However, the most consistent site related factor favouring performance of the ecotypes in terms of yield, vigour, snow mould and Xanthomonas resistance was a low abundance of species which are typical of Arrhenatheretum type meadows. Data from the plot trials were related to results obtained with spaced plants at a single site, either in a seedling nursery or in the greenhouse. Resistance against crown rust was extremely well predicted by spaced plant observations. Xanthomonas resistance observed after artificial inoculation in the greenhouse was also significantly, but less closely correlated with field observations. An early date of ear emergence as observed on spaced plants was associated with high annual yield in the plot trials. It is concluded that in intensively managed habitats, natural selection has resulted in ecotype populations of Italian ryegrass which are highly promising for use in breeding. Individual plant selection for resistance can be expected to efficiently reduce their high susceptibility to crown rust.

Do Cultivated Varieties of Native Plants Have the Ability to Outperform Their Wild Relatives?

“…Therefore, cultivars may not be well adapted to harsh climatic conditions like frost [29]. Such trade-offs may also result in lower resistance to pest infestation [30]. Thus, cultivars may only be competitively superior as long as they are not subjected towards stressful environmental factors.…”

“…Moreover, further evolving hybrids might inherit more maladaptive life-history traits from parental cultivars or maladaptive trade-offs than 1 st -generation hybrids in our study [29], [30]. Such development may lead to a selection against hybrids over the long-term, assuming that natural selection is identifying over the long-term the most beneficial trade-offs and allows re-evolving towards the wild’s behavior [33].…”

Comparative genomics of host adaptive traits in Xanthomonas translucens pv. graminis

“…With view on the high yield losses observed across infected plants, Xtg resistance is of major concern for breeding of new Italian ryegrass cultivars. The currently applied approach is based on recurrent phenotypic selection; however, reoccurrence of susceptible individuals after several selection cycles indicates the need for a detailed understanding of underlying pathogenicity mechanisms, which can be exploited in targeted breeding for bacterial wilt resistance [6, 7]. …”

Quantitative Traits Breeding for Multifunctional Grasslands and Turf

“…They not only harbor a large number of different plant species, they also serve as important reservoirs of genetic diversity for many important forage species including ryegrasses, fescues and clovers (Kölliker et al 2003 ;Peter-Schmid et al 2008 ). In Italian ryegrass, certain local ecotypes have even been found to outperform today's cultivars for traits such as persistence, vigor or resistance to snow mold (Boller et al 2009 ). Although many of these ecotypes suffer from disadvantages such as reduced forage yield and quality when compared to advanced cultivars, they also often carry alleles for valued characteristics such as disease resistance or early fl owering.…”