Comparison of Media for Recovery of Verticillium dahliae from Soil

Abstract

Polygalacturonic acid (PGA) is an important constituent of Sorensen's NP-10 medium (NP-10) for estimating the population density of Verticillium dahliae in soil. Different types of PGA are available, but not all of them favor the growth of V. dahliae. Unavailability of PGA sodium salt from orange (P-1879) has created an unprecedented problem for the quantification of microsclerotia (MS) of V. dahliae in soil. The PGA from orange (P-3889) that is now available does not support the growth of V. dahliae. Therefore, experiments were conducted to optimize the use of NP-10 prepared with P-3889 and various concentrations of NaOH. NP-10 with P-3889 amended with eight concentrations of NaOH were compared with NP-10 prepared from PGA sodium salt from orange (P-1879, now discontinued) and citrus (P-3850) along with cellophane and Napectate media for recovery of MS from soil and growth of V. dahliae on the media. Seven soils were assayed for MS, and eight isolates of V. dahliae were evaluated for growth and production of MS. Concentrations of NaOH >0.035N and <0.02N in NP-10 with P-3889 reduced mycelial growth, microsclerotial production, and recovery of MS from soils. Similarly, NP-10 with P-3850 alone, cellophane, and Na-pectate media had significantly reduced growth on media and recovery of V. dahliae from soils. The NP-10 with P-3889 and 0.025N NaOH consistently yielded numbers of V. dahliae MS from soil samples and supported the growth and production of MS similar to the NP-10 with P-1879. The medium developed in this study can serve as a direct replacement for the original NP-10 that was developed nearly three decades ago, an important component of which is no longer available.

Seed transmission of verticillium wilt of cotton

“…Subsequently, each sample was passed through a 0.8-mm sieve to remove organic debris and large particles, followed by mixing by hand. The V. dahliae inoculum's density was estimated by wet sieving using 20 petri dishes containing modified NP-10 selective medium (Kabir et al 2004). Plates were incubated at 22-24°C in the dark for 14 days, after which soil residues were removed with tap water and V. dahliae colonies counted by using a dissecting microscope with transmitted light.…”

SNP association analysis of resistance to Verticillium wilt (Verticillium dahliae Kleb.) in spinach

“…Roots, crown, and lower stems were placed on NP-10 medium after surface sterilization (1% bleach solution for 1 min) and examined microscopically for development of conidiophores and/or microsclerotia of V. dahliae. To examine the seed transmission of the pathogen, mature seeds from each plant were harvested separately and assayed for V. dahliae by plating 20 seeds on NP-10 medium (Kabir et al, 2004;Short et al, 2014). The seeds were observed under a microscope for microsclerotia and/or conidiophores and conidial characteristics of V. dahliae.…”

Effects of arbuscular mycorrhizal fungus, humic acid, and whey on wilt diseasecaused by Verticillium dahliae Kleb. in three solanaceous crops

“…Soil samples were air-dried under ambient temperatures for 4 weeks and then passed through 2-mm and 250-µm sieves, respectively, after removal of plant residues. The number of microsclerotia per gram of soil was estimated by the method of Kabir et al (2004). 2.2.3.…”