Differential Colonization Patterns of Bananas (Musa spp.) by Physiological Race 1 and Race 4 Isolates of Fusarium oxysporum f.sp. cubense

Abstract

Fusarium oxysporum f.sp. cubense (Foc) is the causative agent of Fusarium wilt of bananas (Musa spp.). To clarify the colonization patterns of Foc in bananas, two green fluorescent protein-tagged isolates, NT320 (race 1) and B2-gfp (race 4), were used to follow infection of the banana varieties Pisang Awak and Brazil. Penetration and colonization of both isolates in roots of these two banana varieties were observed within 6 days, but sporulation in xylem vessels was not observed until day 30 postinoculation. Interestingly, B2-gfp penetrated into xylem vessels of Pisang Awak banana roots more quickly than NT320, implying that the race 4 isolate is more virulent than the race 1 isolate. This result was further confirmed by comparing the disease severity of plants inoculated with NT320 with that of plants inoculated with B2-gfp. Quantitative real-time PCR revealed that some pathogenicity-associated genes, including Fga1, Fhk1, Fow2 and Ste12, were upregulated by B2-gfp during exposure to Brazil bananas, while they were either downregulated by NT320 or not significantly changed. These data might partly explain why the race 4 isolate was more virulent than the race 1 isolate.

Functional analysis of the G-protein α subunits FGA1 and FGA3 in the banana pathogen Fusarium oxysporum f. sp. cubense

“…We previously identified three Ga subunit genes in the genome of the banana pathogen Foc [17], which were named fga1, fga2, and fga3. The number of the Foc Ga subunit genes is identical with that of most characterized filamentous fungi, except the fungi U. maydis, Rhizopus oryzae, and Schizophyllum commune, which have four or more Ga subunit genes [2].…”

“…The disease severity was evaluated at 30 d post inoculation. All plants were cut just above the roots, and the internal symptoms of the corms were rated on a 0e5 scale [17]. The disease index was calculated using the following formula: DI ¼ ð100  Sðn  sÞÞ=ðN  5Þ, where "n" means the number of banana plants with the corresponding scale (s) of the disease symptom and "N" means the total number of banana plants tested.…”

Marchitez por Fusarium raza tropical 4: Estado actual y presencia en el continente americano

“…cubense (Fusarium odoratissimum). Actualmente, según García-Bastidas et al (2019), con capacidad de producir estructuras de resistencia (clamidosporas), constantemente liberadas al invadir el huésped, que puede o no mostrar síntomas visibles (Bai et al, 2013;Guo et al, 2015;Dita et al, 2018;Warman y Aitken, 2018). Las clamidosporas le permiten al patógeno adaptarse a condiciones extremas y perpetuarse en el suelo en ausencia de hospederos por más de veinte años, lo que limita su control (Moore et al, 1995;Buddenhagen, 2009).…”

“…cubense inicia cuando las clamidosporas latentes en el suelo germinan ante el estímulo de exudados de raíces de plantas hospederas. El micelio y los conidios se originan de seis a ocho horas después, con formación de nuevas clamidosporas entre dos a tres días después (Guo et al, 2015;Li et al, 2017). Por lo general, la infección se produce a través de raíces secundarias, terciarias o a través de heridas (Moore et al, 1995;Pérez, 2004;Dita et al, 2010;SAGARPA, 2012;Li et al, 2017).…”

“…Al realizarse la penetración, una vez superadas las barreras del huésped, se producen microconidias e hifas gruesas, que se convertirán en nuevas clamidosporas en los espacios intra e intercelulares (Dita et al, 2018;Warman y Aitken, 2018). Diez días después, en los vasos del xilema, se pueden encontrar hifas que se desarrollaran en el xilema del rizoma, a lo largo de las uniones de las células epidérmicas de la raíz, e inclusive se pueden observar en la superficie de las raíces (Guo et al, 2015;Li et al, 2017).…”