Pathogenicity, vegetative compatibility and genetic diversity ofVerticillium dahliaeisolates from sugar beet

Abstract

Verticillium wilt of sugar beet is a disease that has received very little attention, but which has been reported to reduce sugar quality. A survey of sugar beet fields with wilt symptoms was conducted in 2007 (5 roots from each of 40 fields) and 2008 (5 roots from each of 45 fields) in Idaho. Verticillium dahliae was isolated from all root samples. From a collection of 106 V. dahliae sugar beet isolates, all were of the MAT1-2 mating type. The vegetative compatibility grouping (VCG) was evaluated for 93 of these isolates and 95, 3, 1 and 1% were VCG 4A, VCG 2B, VCG 4B and non-compatible, respectively. All the VCG 4A isolates had the same mitochondrial haplotype based on sequencing of cox3 to nad6 and cox1 to rnl loci, while the VCG 2B isolates had two haplotypes. Pathogenicity tests on sugar beet cultivar 'Monohikari' revealed that the VCG 4A isolates produced more foliar symptoms (P < 0.0001) than VCG 1, 1A, 2A, 2B, 3 and 4B isolates, but none of the VCGs consistently reduced root and foliage weight. Since V. dahliae VCG 4A isolates have also been reported as a pathogen of potato in North America, rotating sugar beet fields with potato could be a concern.Keywords: Beta vulgaris, mitochondrial haplotype, soilborne pathogens, Verticillium wilt Résumé: La flétrissure verticillienne de la betterave à sucre est une maladie dont on s'est peu préoccupé, mais qui est reconnue pour altérer la qualité du sucre. Une étude des champs de betterave à sucre affichant des symptômes de la flétrissure a été menée en Idaho en 2007 (5 racines dans chacun des 40 champs) et en 2008 (5 racines dans chacun des 45 champs). On a obtenu des isolats de Verticillium dahliae de tous les échantillons de racines. À partir d'une collection de 106 isolats de V. dahliae obtenus de la betterave à sucre, il a été possible de conclure que tous appartenaient au type sexuel MAT1-2. Le groupement de compatibilité végétative (GCV) a été évalué pour 93 de ces isolats et 95, 3 et 1 % appartenaient au GCV 4A, au GCV 2B et au GCV 4B, respectivement, et 1 % étaient incompatibles. En se basant sur le séquençage des locus cox3 à nad6 et cox1 à rnl, tous les isolats du GCV 4A avaient le même haplotype mitochondrial, tandis que les isolats du GCV 2B en avaient deux. Des tests de pathogénicité menés sur le cultivar de la betterave à sucre 'Monohikari' ont révélé que les isolats du GCV 4A produisaient plus de symptômes foliaires (P < 0.0001) que les isolats des GCV 1, 1A, 2A, 2B, 3 et 4B, mais qu'aucun ne réduisait substantiellement le poids du feuillage et de la racine. Étant donné qu'on a rapporté que les isolats du GCV 4A s'attaquent également à la pomme de terre en Amérique du Nord, le fait d'alterner, selon un plan de rotation, betterave à sucre et pomme de terre dans un même champ, devrait préoccuper les producteurs.

Efficient Discovery of Single-Nucleotide Variations in Cochliobolus sativus Vegetative Compatibility Groups by Ecotilling

“…SNPs were detected among isolates belonging to the same VCG typically, and twenty-six putative nucleotide polymorphisms were identified among the C. sativus VCGs ( Table 2: Vegetative compatibility (VCG A,B and C), nit mutants, and Ecotilling polymorphisms between the C. sativus isolates and refernce isolate. Mutant phyenotype generated as described by Puhalla [11].…”

“…VCGs characterization for these isolates has been described previously [9]. Five C. sativus isolates (Cs1, 11,15,16,22) belonging to the nit1/nit3 (colonies that grew with a thin mycelium on both CDA and as a wild type phyenotype on CDA amended with sodium nitrate) whereas, Cs23 characterized as Nit M (colonies that grew with a thin mycelium on both CDA and CDA media amended with sodium nitrate) according to Puhalla [10].…”

“…In previous work [9], we found that Syrian C. sativus population grouped into three major VCGs based on complementation tests with nitrate-nonutilizing (nit) mutants, which are impaired in their ability to utilize nitrate from the growing media [10,11]. However, a little is known about their genetic diversity, and this lack of a clear molecular distinction among these VCGs suggests that some gene flow might occur among them.…”

New insights into virus yellows distribution in Europe and effects of beet yellows virus, beet mild yellowing virus, and beet chlorosis virus on sugar beet yield following field inoculation

“…Insects like the capsid bugs from the Miridae family can also cause yellowing due to their sucking activity on the leaves (Draycott, 2008). Some fungal diseases caused by Fusarium or Verticillium species can also cause chlorotic tissue (Hanson & Jacobsen, 2009; Strausbaugh et al, 2016). Finally, herbicides can have toxic properties that can lead to leaf yellowing (Draycott, 2008).…”

Genetics, Host Range, and Molecular and Pathogenic Characterization of Verticillium dahliae From Sunflower Reveal Two Differentiated Groups in Europe

“…Vegetatively compatible isolates are placed in the same vegetative compatibility group (VCG). In spite of there being many studies on the genetic diversity of Vd from artichoke ( Jiménez-Díaz et al, 2006 ), cotton ( Dervis et al, 2008 ; Korolev et al, 2008 ), eggplant ( Dervis et al, 2009b ), olive tree ( Navas-Cortés et al, 2009 ; Dervis et al, 2010 ), potato and mint ( Dung et al, 2013 ) or sugarbeet ( Strausbaugh et al, 2016 ) among other crops, the genetic characterization of Vd isolates from sunflower has been scarcely addressed. Isolates of Vd affecting sunflowers in Canada showed weak reactions with testers from VCG4A and 4B; one isolate was identified as VCG3 and another one was compatible with all VCG groups except VCG2A ( El-Bebany et al, 2013 ).…”