Uncovering genetic and metabolite markers associated with resistance against anthracnose fruit rot in northern highbush blueberry

Anthracnose fruit rot(AFR),caused by the fungal pathogen Colletotrichum fioriniae,is among the most destructive and widespread fruit disease of blueberry,impacting both yield and overall fruit quality.Blueberry cultivars have highly variable resistance against AFR.To date,this pathogen is largely controlled by applying various fungicides;thus,a more cost-effective and environmentally conscious solution for AFR is needed.Here we report three quantitative trait loci associated with AFR resistance in northern highbush blueberry(Vaccinium corymbosum).Candidate genes within these genomic regions are associated with the biosynthesis of flavonoids(e.g.anthocyanins)and resistance against pathogens.Furthermore,we examined gene expression changes in fruits following inoculation with Colletotrichum in a resistant cultivar,which revealed an enrichment of significantly differentially expressed genes associated with certain specialized metabolic pathways(e.g.flavonol biosynthesis)and pathogen resistance.Using non-targeted metabolite profiling,we identified a flavonol glycoside with properties consistent with a quercetin rhamnoside as a compound exhibiting significant abundance differences among the most resistant and susceptible individuals from the genetic mapping population.Further analysis revealed that this compound exhibits significant abundance differences among the most resistant and susceptible individuals when analyzed as two groups.However,individuals within each group displayed considerable overlapping variation in this compound,suggesting that its abundance may only be partially associated with resistance against C.fioriniae.These findings should serve as a powerful resource that will enable breeding programs to more easily develop new cultivars with superior resistance to AFR and as the basis of future research studies.

A roadmap for research in octoploid strawberry

The cultivated strawberry(Fragaria×ananassa)is an allo-octoploid species,originating nearly 300 years ago from wild progenitors from the Americas.Since that time the strawberry has become the most widely cultivated fruit crop in the world,universally appealing due to its sensory qualities and health benefits.The recent publication of the first highquality chromosome-scale octoploid strawberry genome(cv.Camarosa)is enabling rapid advances in genetics,stimulating scientific debate and provoking new research questions.In this forward-looking review we propose avenues of research toward new biological insights and applications to agriculture.Among these are the origins of the genome,characterization of genetic variants,and big data approaches to breeding.Key areas of research in molecular biology will include the control of flowering,fruit development,fruit quality,and plant–pathogen interactions.In order to realize this potential as a global community,investments in genome resources must be continually augmented.