Genetic diversity, aggressiveness and metalaxyl sensitivity of Pythium aphanidermatum populations infecting cucumber in Oman

Abstract

Seventy three isolates of Pythium aphanidermatum obtained from cucumber from four different regions of Oman and 16 isolates of muskmelon from the Batinah region in Oman were characterized for aggressiveness, sensitivity to metalaxyl and genetic diversity using AFLP fingerprinting. Twenty isolates of P. aphanidermatum from diverse hosts from different countries were also included in the study. Most isolates from Oman were found to be aggressive on cucumber seedlings and all were highly sensitive to metalaxyl (EC 50 < 0·80 µ g mL -1). Isolates from cucumber and muskmelon were as aggressive as each other on both hosts ( P > 0·05), which implies a lack of host specialization in P. aphanidermatum on these two hosts in Oman. AFLP analysis of all isolates using four primer-pair combinations resolved 152 bands, of which 61 (~40%) were polymorphic. Isolates of P. aphanidermatum from Oman and other countries exhibited high genetic similarity (mean = 94·1%) and produced 59 different AFLP profiles. Analysis of molecular variance indicated that most AFLP variation among populations of P. aphanidermatum in Oman was associated with geographical regions ( F ST = 0·118; P < 0·0001), not hosts ( F ST = -0·004; P = 0·4323). These data were supported by the high rate of recovery (24%) of identical phenotypes between cucumber and muskmelon fields in the same region as compared to the low recovery (10%) across regions in Oman, which suggests more frequent movement of Pythium inoculum among muskmelon and cucumber fields in the same region compared to movement across geographically separated regions. However, recovering clones among regions and different countries may imply circulation of Pythium inoculum via common sources in Oman and also intercontinental spread of isolates.

Aspergillus terreus Inhibits Growth and Induces Morphological Abnormalities in Pythium aphanidermatum and Suppresses Pythium-Induced Damping-Off of Cucumber

“…Chemical control of Pythium damping-off is practiced through the use of Mefenoxam, Hymexazol, Propamocarb, and other fungicides (Papavizas et al, 1978; Al-Sa’di et al, 2008, Al-Sadi et al, 2015a). Growers usually use solarization in summer to reduce Pythium propagules in soil (Deadman et al, 2007).…”

Population Structure and Development of Resistance to Hymexazol Among Fusarium solani Populations from Date Palm, Citrus and Cucumber

“…The PCR conditions were as described by Al‐Sa'di et al. (). Fragment analysis was conducted at Macrogen, Korea, using ABI 3130 (Applied Biosystems, Carlsbad, CA, USA).…”

Genetic analysis suggests a shared origin of Punica granatum cultivars in Oman with cultivars from the center of origin, Iran

“…AFLP fingerprinting AFLP fingerprinting was carried out for 88 pomegranate samples following a modified protocol of Vos et al (1995) as described by Al-Sa'di et al (2008) and Al-Sadi et al (2012a). The amplified products were subjected to fragment analysis at Macrogen, Korea using ABI 3730XL (Applied Biosystems, Carlsbad, CA).…”