Cotton production in Xinjiang, the largest cotton producing area in China, has an increasingly serious disease threat from Verticillium dahliae. Eighty-five V. dahliae isolates were obtained from wilted cotton plants collected from 8 counties in Xinjiang. The isolates were assessed for genotypic diversity by DNA sequence analysis and PCR molecular genotyping with specific markers for race 1, race 2, defoliating (D) pathotype, non-defoliating (ND) pathotype, and mating type idiomorph Mat1-2. Isolates belonged to lineages 1A or 2B with 3 sub-genotypes found in each lineage. All isolates tested positive for race 2 and Mat1-2 markers. All isolates in lineage 2B tested positive for the ND pathotype marker, but only isolates in the major sub-genotype in lineage 1A tested positive for the D pathotype marker. Pathogenicity assays on Gossypium hirsutum ‘Acala 44’ demonstrated no significant difference among sub-genotypes within each lineage. Isolates in lineage 1A caused greater shoot weight reductions, % leaf drop, and % diseased leaves than isolates in lineage 2B. One isolate in each lineage for 1A and 2B was avirulent. Isolates in lineage 1A caused greater than 50% leaf drop and a 17 gram shoot weight reduction compared to a 9% leaf drop and a 6 gram shoot weight reduction by isolates in lineage 2B. Overall, 42% of the V. dahliae isolates from Xinjiang were D pathotype, but the percentage varied widely among locations. Two plants had both pathotypes. Nineteen isolates of Fusarium oxysporum f. sp. vasinfectum VCG0114 also were recovered from wilted plants in Xinjiang. Two plants had both Verticillium and Fusarium wilt pathogens. Both pathogens should be considered when using or developing wilt resistant/tolerant materials for Xinjiang.
Cotton WATs Modulate SA Biosynthesis and Local Lignin Deposition Participating in Plant Resistance Against Verticillium dahliae
