Vernalisation requirement is an agriculturally important trait that postpones the development of cold-sensitive floral organs until the spring. The family Rosaceae includes many agriculturally important fruit and berry crops that suffer from crop losses caused by frost injury to overwintering flower buds. Recently, a vernalisation-requiring accession of the Rosaceae model woodland strawberry (Fragaria vesca) has been identified in northern Norway. Understanding the molecular basis of the vernalisation requirement in this accession would advance the development of strawberry cultivars better adapted to temperate climate. We use gene silencing, gene expression analysis, genetic mapping and population genomics to study the genetic basis of the vernalisation requirement in woodland strawberry. Our results indicate that the woodland strawberry vernalisation requirement is endemic to northern Norwegian population, and mapping data suggest the orthologue of TERMINAL FLOWER1 (FvTFL1) as the causal floral repressor. We demonstrate that exceptionally low temperatures are needed to downregulate FvTFL1 and to make these plants competent to induce flowering at low postvernalisation temperatures in the spring. We show that altered regulation of FvTFL1 in the northern Norwegian woodland strawberry accession postpones flower induction until the spring, allowing plants to avoid winter injuries of flower buds that commonly occur in temperate regions.
The woodland strawberry, Fragaria vesca, holds great promise as a model organism. It not only represents the important Rosaceae family that includes economically important species such as apples, pears, peaches and roses, but it also complements the well-known model organism Arabidopsis thaliana in key areas such as perennial life cycle and the development of fleshy fruit. Analysis of wild populations of A. thaliana has shed light on several important developmental pathways controlling, for example, flowering time and plant growth, suggesting that a similar approach using F. vesca might add to our understanding on the development of rosaceous species and perennials in general. As a first step, 298 F. vesca plants were analyzed using microsatellite markers with the primary aim of analyzing population structure and distribution of genetic diversity. Of the 68 markers tested, 56 were polymorphic, with an average of 4.46 alleles per locus. Our analysis partly confirms previous classification of F. vesca subspecies in North America and suggests two groups within the subsp. bracteata. In addition, F. vesca subsp. vesca forms a single global population with evidence that the Icelandic group is a separate cluster from the main Eurasian population.
Barley is of great importance in modern agriculture and is currently the fourth most important cereal after wheat, maize, and rice. It is well adapted to a range of climatic and day-length conditions, with a distribution from Ethiopia to northern Scandinavia. Despite this, Iceland, with its sub-arctic agriculture, is considered to be at the margin of barley cultivation. Still the importance of barley has steadily increased in Icelandic agriculture, most likely as the result of positive environmental change, continuous testing of new Nordic cultivars, and an Icelandic barley breeding project. Here we present a review of the results from barley cultivar trials from 40 locations over a 28-year period in Iceland in the years 1987-2014. The results showed that yields were rising and the time from sowing to harvest was getting shorter. Also, the Icelandic genotypes were heading earlier, while showing higher yields. The results also showed that test locations were getting fewer but at the same time the number of tested genotypes was increasing. The analysis presented here highlights both the strengths and weaknesses of the current breeding program and is therefore an important basis for future breeding projects for Icelandic agriculture and possibly for other small scale breeding projects aimed at peripheral areas. YFIRLIT Yfirlit um byggkynbaetur og yrkjatilraunir á Íslandi 1987-2014.Bygg er mikilvaeg nytjaplanta og er í fjórða saeti yfir mikilvaegustu korntegundir í heiminu á eftir hveiti, maís og hrísgrjónum. Þó bygg hafi aðlagast fjölbreytilegum umhverfisskilyrðum, baeði loftslagi og daglengd, þá er raektun á jaðri heimskautasvaeðanna enn á mörkum þess mögulega, sem endurspeglast meðal annars í stuttri raektunarsögu byggs á Íslandi og þeim erfiðleikum sem steðja að byggraektendum hérlendis. Þrátt fyrir það þá hefur mikilvaegi byggs fyrir íslenskan landbúnað aukist nokkuð stöðugt undanfarin ár, sem meðal annars hefur verið skýrt sem afleiðing batnandi umhverfisskilyrða, prófana á erlendum byggyrkjum og kynbóta sérstaklega fyrir íslenskar aðstaeður. Hér birtum við niðurstöður úr samanburðartilraunum á byggi sem fram hafa farið á 40 stöðum yfir 28 ára tímabili á árunum 1987-2014. Gögnin sýndu að tilraunastöðum faekkaði á meðan arfgerðum í tilraunum fjölgaði. Niðurstöðurnar sýndu að uppskera í tilraunum jókst á sama tíma og raektunartímabilið styttist. Íslensku kynbótalínurnar skiluðu ekki aðeins meiri uppskeru í tilraunum heldur skriðu þaer einnig fyrr. Niðurstöðurnar sem kynntar eru hér undirstrika baeði kosti og galla kynbótaverkefnisins og eru því mikilvaegar áframhaldandi byggyrkjatilraunum fyrir íslenskan landbúnað og geta ef til vill nýst öðrum sambaerilegum verkefnum á jaðarsvaeðum.
Spring barley (Hordeum vulgare L.) is the most important cereal in Iceland and its national breeding program aims to select barley genotypes adapted to its environment. A critical step to understand the adaptation of Nordic barley material to a cool maritime climate is to assess the genotype by environment interaction (GxE). In this study, we evaluated the yield and thousand-kernel weight (TKW) of 32 spring barley genotypes in seven Icelandic environments. We applied three methods to analyze GxE: the additive main effects and multiplicative interaction model, a factorial model, and a linear mixed model. For yield, GxE was mainly caused by a better response of six-row genotypes compared to two-row genotypes in high fertility soils. For TKW, GxE showed a pattern along a gradient of daily mean temperatures. This pattern translated into a divergent TKW response between the 2-row and 6-row genotypes, with substantial crossovers along the temperature gradient. This GxE pattern was disentangled using all three methods, illustrating the value of cross-analysis. As yield is the main trait of interest for barley cultivation in Iceland, and few crossovers of genotype performance have been observed between environments, the definition of one mega-environment was recommended for Icelandic cultivation and breeding. We identified promising genetic material for both traits and highlighted the superiority of six-row genotypes for yield.
Genome-Wide Association Studies (GWAS) of four Multi-parent Advanced Generation Inter-Cross (MAGIC) populations identified nine regions on chromosomes 1H, 3H, 4H, 5H, 6H and 7H associated with resistance against barley scald disease. Three of these regions are putatively novel resistance Quantitative Trait Loci (QTL). Barley scald is caused by Rhynchosporium commune, one of the most important barley leaf diseases that are prevalent in most barley-growing regions. Up to 40% yield losses can occur in susceptible barley cultivars. Four MAGIC populations were generated in a Nordic Public–Private Pre-breeding of spring barley project (PPP Barley) to introduce resistance to several important diseases. Here, these MAGIC populations consisting of six to eight founders each were tested for scald resistance in field trials in Finland and Iceland. Eight different model covariate combinations were compared for GWAS studies, and the models that deviated the least from the expected p-values were selected. For all QTL, candidate genes were identified that are predicted to be involved in pathogen defence. The MAGIC progenies contained new haplotypes of significant SNP-markers with high resistance levels. The lines with successfully pyramided resistance against scald and mildew and the significant markers are now distributed among Nordic plant breeders and will benefit development of disease-resistant cultivars.
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