TY - ABST

T1 - Characterization of foliar diseases infecting quinoa (Chenopodium quinoa)

AU - Little, Carla Ximena

AU - Lund, Ole Søgaard

AU - Amby, Daniel Buchvaldt

AU - Andreasen, Christian

AU - Jacobsen, Sven-Erik

AU - Schmid, Karl J.

AU - Cristina, Ocana

PY - 2018

Y1 - 2018

N2 - Quinoa (Chenopodium quinoa) is an ancient crop from the Andes of Bolivia, Peru and Ecuador and isincreasingly cultivated outside its native range on all continents. Cultivation in new environments maylead to incidence of diseases previously not described for quinoa that may interfere with acommercially successful production of this crop. To test this hypothesis, we identified foliar pathogensat different stages of quinoa development to understand their epidemiology, host interactions andsources of resistance. We grew three cultivars (Vikinga, Titicaca and Puno) in an experimental plot inTåstrup, Eastern Denmark. A first set of symptomatic leaves was collected from cv. Puno at the end ofthe growing season in late September 2017 to identify pathogens. A diversity of symptoms wereobserved that included small yellowish anamorph blots on the upper leaf surface; a pale chlorotic halosurrounded the yellow lesion which occasionally had slight pink colouring in the centre; and lightbrown spots, concentric rings and apical necrosis on the lower leaf surface. The symptomatic sectionsof leaf tissue were surface sterilized and plated onto potato dextrose. After 10 days, three main fungalgroups could be differentiated by their morphological characteristics such us conidia shape, colour andnumber/occurrence of septae, colony diameter, reverse colour and formation of rings. Monoconidialisolations allowed to establish pure cultures of each fungus. For molecular identification we PCRamplified the intergenic transcribed spacer (ITS) and conducted BLAST searches for identification.Using this protocol we identified the following species: Didymella chenopodii, Alternariainfectoria/methacromatica, Alternaria tenuissima and Epicocum nigrum. To validate their identity, Kochpostulates and pathogenicity tests are in progress. To our knowledge this is the first demonstration ofAlternaria infectoria, Alternaria tenuissima, Didymella chenopodii and Epicocum nigrum causinglesions in quinoa foliage in Europe. Among the known fungal pathogens, downy mildew (Peronosporavariabilis) is a serious constraint to quinoa production worldwide. The pathogen is seed transmitted,which is one of the reasons for its increasing prevalence. If the infection occurs during initial growthstages, susceptible crops could fail completely. Even in resistant cultivars, the loss may be 20-40%.Our results indicated the development of quinoa varieties for cultivation outside its native range needto include resistance breeding. We therefore are currently conducting a genome-wide associationstudy of downy mildew-quinoa interactions with a large sample of Bolivian landraces with differentlevels of resistance against downy mildew.

AB - Quinoa (Chenopodium quinoa) is an ancient crop from the Andes of Bolivia, Peru and Ecuador and isincreasingly cultivated outside its native range on all continents. Cultivation in new environments maylead to incidence of diseases previously not described for quinoa that may interfere with acommercially successful production of this crop. To test this hypothesis, we identified foliar pathogensat different stages of quinoa development to understand their epidemiology, host interactions andsources of resistance. We grew three cultivars (Vikinga, Titicaca and Puno) in an experimental plot inTåstrup, Eastern Denmark. A first set of symptomatic leaves was collected from cv. Puno at the end ofthe growing season in late September 2017 to identify pathogens. A diversity of symptoms wereobserved that included small yellowish anamorph blots on the upper leaf surface; a pale chlorotic halosurrounded the yellow lesion which occasionally had slight pink colouring in the centre; and lightbrown spots, concentric rings and apical necrosis on the lower leaf surface. The symptomatic sectionsof leaf tissue were surface sterilized and plated onto potato dextrose. After 10 days, three main fungalgroups could be differentiated by their morphological characteristics such us conidia shape, colour andnumber/occurrence of septae, colony diameter, reverse colour and formation of rings. Monoconidialisolations allowed to establish pure cultures of each fungus. For molecular identification we PCRamplified the intergenic transcribed spacer (ITS) and conducted BLAST searches for identification.Using this protocol we identified the following species: Didymella chenopodii, Alternariainfectoria/methacromatica, Alternaria tenuissima and Epicocum nigrum. To validate their identity, Kochpostulates and pathogenicity tests are in progress. To our knowledge this is the first demonstration ofAlternaria infectoria, Alternaria tenuissima, Didymella chenopodii and Epicocum nigrum causinglesions in quinoa foliage in Europe. Among the known fungal pathogens, downy mildew (Peronosporavariabilis) is a serious constraint to quinoa production worldwide. The pathogen is seed transmitted,which is one of the reasons for its increasing prevalence. If the infection occurs during initial growthstages, susceptible crops could fail completely. Even in resistant cultivars, the loss may be 20-40%.Our results indicated the development of quinoa varieties for cultivation outside its native range needto include resistance breeding. We therefore are currently conducting a genome-wide associationstudy of downy mildew-quinoa interactions with a large sample of Bolivian landraces with differentlevels of resistance against downy mildew.

M3 - Conference abstract in proceedings

SN - 978-87-996274-1-7

SP - 124

EP - 125

BT - Plant Biology Europe 2018 Conference Abstract Book

PB - University of Copenhagen

ER -