Arne Stensvand
Seniorforsker
Sammendrag
The soil-borne oomycete Phytophthora cactorum causes crown rot, a major disease of the allo-octoploid strawberry (Fragaria × ananassa Duch., 2n = 8× = 56) that limits cultivation worldwide. Resistance to P. cactorum is a highly desirable trait but is typically quantitative and moderately heritable. A better understanding of the genetic basis of resistance to crown rot is essential for developing durable crown rot-resistant cultivars. We conducted a genome-wide association study (GWAS) using multi-locus models on 100 wild strawberry accessions from South and North America. The accessions were genotyped using the Axiom™ 50 K strawberry SNP array and mapped to the F. × ananassa cv. Royal Royce v. 1.0 reference genome. Testing for resistance to P. cactorum revealed a wide range of phenotypes. A single genetic marker, AX-184528282, located on chromosome 7B, was strongly associated with resistance to P. cactorum and explained 53% of the observed phenotypic variation. This marker was present in several highly resistant exotic Fragaria accessions that represent potential donors for introgression of favorable alleles into modern strawberry cultivars. In addition, several strong candidate resistance genes were identified within the 2 Mb genomic region surrounding the significant marker. This study advances understanding of resistance to P. cactorum in strawberry and identifies genetic resources that can accelerate the development of crown rot-resistant cultivars through marker-assisted breeding.
Sammendrag
Disease symptoms, sources of inoculum, and patterns of spore release of Mycosphaerella ribis, the cause of Mycosphaerella leaf spot, were studied over three years in an organic blackcurrant planting receiving no fungicide applications. In addition to typical foliar symptoms, also fruit lesions were observed on the cultivars included in the study. Ascospores from leaf litter on the ground were trapped from bud break in April to mid-to-late July, but 99% were released by one month before. Conidia formed in old fruit cluster stalks overwintering on the blackcurrant shrubs were present from bud break to early August, but 99% were trapped from late May to mid-July. Conidia were found in leaf litter but were never captured in the spore trap, and ascospores were observed in old fruit cluster stalks. Degree-day models (base = 0˚C) were used to estimate the proportion of mature spores. Extended periods of dry conditions slowed spore maturation in the field. Models halting degree-day accumulation after 4 or 7 days with no rain (< 0.2 mm) or leaf wetness of < 12 h per day, gave the best performance for release of conidia or ascospores, respectively, if validated by data from controlled conditions in the laboratory. Ascospore release was suppressed during night, and if rain and wetness started during night and continued the following day, very few spores were released before sunrise. The present investigation provides new information that may be used when planning sanitary measures to reduce primary inoculum and predict spore release patterns for Mycosphaerella leaf spot.
Sammendrag
The study presents the results of nine years of field observations of ascospore release of Venturia inaequalis in the Skierniewice area in central Poland. In total, spores were trapped 221 times during 2005–2008 and 2010– 2014. Of these, 142 episodes lasted for less than 8 hours, 69 lasted from 8 to 29 hours, and 10 episodes lasted from 30 to 93 hours. Spore releases started in spring from 25 March to 28 April and ended from 27 May to 17 June, and the season for ascospore release lasted from 43 to 76 days, with an average of 58 days. During 139 ascospore releases, less than 1 000 spores per cubic meter of air were collected and during 25 discharges more than 10 000 spores were trapped. Releases of ascospores were highly related to rainfall and daylight. Two-thirds (67%) of the spores were trapped during rain. Only 12% of the discharges occurred without any registered rain, accounting for 7% of all trapped spores. Nearly three fourth (73%) of all ascospore release hours occurred in daylight, and 91% of the spores were trapped in daytime. Rainy nights with constant leaf wetness were observed, during which no spore releases occurred despite the rainfall. Ascospore releases were also less prominent at the beginning and end of the season and after weak rains. Rain was most effective as the trigger of discharges at temperature between 5 and 13 °C and when global radiation coinciding with rainfall was below 700 W/m2. In conclusion, the study confirms the dominant role of daytime rainfall in the release of ascospores by Venturia inaequalis.
Divisjon for bioteknologi og plantehelse
IPM-Fruit: IPM strategier for framtidens fruktproduksjon
I IPM fruit skal undersøke hvordan man kan bruke preventive og alternative tiltak for å oppnå et mer bærekraftig plantevern i frukt. Prosjektet legger opp til å undersøke både naturlige fiender i og utenfor frukthager, fysiske tiltak som preventive tiltak, biologiske plantevernmidler og hvordan best kombinere ulike tiltak under norske forhold. Prosjektet vil bli utført i samarbeid med NMBU, NLR, NIAB East Malling (UK), IRTA (Spania) og i nært samarbeid med fruktnæringen.
Divisjon for matproduksjon og samfunn
Innovativ og bærekraftig produksjon av Ribes i hele Norge-RibesMax
Solbær, stikkelsbær og rips, som alle hører til slekten Ribes, har på tross av sine lange tradisjoner og påviste positive helseeffekter hatt en negativ trend i norsk produksjonsvolum. I dag dekker den norske Ribes-produksjonen bare en femtedel av markedets behov. Det er derfor et stort potensial for økt norsk produksjon av disse artene. De dyrkes i dag hovedsakelig til industri-formål (saft, syltetøy og gelé), men det er også en økt interesse for produksjon til friskkonsum (dyrking i hekk eller espalier). Nye mat- og helsetrender gir mulighet for nye produkter basert på Ribes. I RibesMax ønsker vi å bruke erfaringer fra sidereventyret i Hardanger til å teste Ribes som råvare for drikker med og uten alkohol. RibesMax vil sette søkelys på utfordringer og muligheter for økt produksjon og økt verdiskapning, og prosjektet vil gi næringen et løft, ved å involvere hele verdikjeden.
Divisjon for matproduksjon og samfunn
JordbærSmak: En optimalisert moderne produksjonsteknologi for mer smakfulle norske jordbær
Det er et mål å øke produksjonen i den norske grøntsektoren, inkludert jordbær, med inntil 50 prosent de kommende 15 årene. For å oppnå dette må dyrkingssesongen utvides, men da trengs en mye bedre kunnskap om hvordan man kan påvirke planteveksten og ta i bruk teknologi for å overvåke og beskytte plantene, uten at det går utover kvalitet og smak.
Divisjon for bioteknologi og plantehelse
IPM-fruit: IPM strategies for future fruit production
IPM fruit will investigate how preventive and alternative control measures can be used for sustainable fruit production. The project will study how natural enemies, physical control, and biologicals as well as combinations of these can be best applied under Norwegian conditions. The project will be carried out in collaboration with the Norwegian University of Life Sciences (NMBU), the Norwegian advisory service (NLR), NIAB East Malling (UK), IRTA (Sapin), and also in close collaboration with fruit growers.