The Genetic Structure, Virulence, and Fungicide Sensitivity of Fusarium fujikuroi in Taiwan

Abstract

The rice disease bakanae, caused by Fusarium fujikuroi Nirenberg, has been present in Taiwan for over a century. To better understand the genetic diversity and structure of F. fujikuroi, a set of 16 polymorphic simple sequence repeat (SSR) markers were newly developed and used to analyze 637 F. fujikuroi isolates collected in 14 cities or counties around Taiwan from 1996 to 2013. On the basis of Bayesian clustering, the isolates were classified into four highly differentiated clusters: cluster B likely derived from the more widespread and genetically diversified clusters A or C, and cluster D was restricted to four cities or counties and may have been introduced from unknown sources genetically distinct from clusters A, B, and C. The coexistence of both mating types (MAT1-1:MAT1-2 = 1:1.88) and the highly diversified vegetative compatibility groups (VCG) (16 VCG among the 21 assessed isolates) suggest the likelihood of sexual reproduction in the field. However, the biased mating type ratios and linkage disequilibrium in the population suggest nonrandom mating between individuals. A significant pattern of isolation by distance was also detected, which implies a geographical restricted gene flow and low dissemination ability of F. fujikuroi. Evaluation of 24 representative isolates on eight rice varieties revealed differential levels of virulence, however no clear pattern of specific variety x isolate interaction was observed. Investigations of the differences in virulence and fungicide sensitivity between 8 early isolates (1998 and 2002) and 52 recent isolates (2012) indicate the evolution of increased resistance to the fungicide prochloraz in F. fujikuroi in Taiwan.

The puzzle of bakanae disease through interactions between Fusarium fujikuroi and rice

“…Fusarium fujikuroi genetic structure is mainly clonal in Italy, but the 1:1 ratio of mating type alleles found in 6 out of 8 Italian fungal populations indicates that sexualreproduction of F. fujikuroi may occur in the field (29). Similar coexistence of both mating types was also observed within F. fujikuroi populations in Taiwan (7).…”

“…To this end, molecular techniques were initially developed using random amplified polymorphic DNA (RAPD), restriction fragment length polymorphism (RFLP) techniques, and electrophoretic karyotype analysis to separate Fusarium isolates with different degrees of virulence, and to distinguish among the different species of GFSC (32,33). Recently, a set of various polymorphic simple sequence repeat (SSR) marker have been developed as a sensitive molecular technique for characterization of the genetic variation among different F. fujikuroi populations (7,29).…”

“…It was first identified in 1828 in Japan (1), and is present in the all of the major rice cultivation areas throughout the world. Over the last few decades, disease incidence and yield losses have increased in several Asian countries: Pakistan (2), Malaysia and Indonesia (3), Bangladesh (4), India (5), South Korea (6) and Taiwan (7). Yield losses ranging from 5 to 15%, with an increasing trend, have also been found in Italy, the main European rice producer (219,500 ha and 1,386,100 t in 2014).…”

Multicenter Study of Azole-Resistant Aspergillus fumigatus Clinical Isolates, Taiwan1

“…The prevalence of TR 34 /L98H/S297T/F495I isolates in Taiwan might be attributed to widespread use of prochloraz over the past 3 decades. Studies have suggested an association between use of imidazole fungicides and emergence of azole-resistant A. fumigatus with TR 34 / L98H/S297T/F495I mutations (7,8).…”

Identification of bakanae disease resistance loci in japonica rice through genome wide association study

“…In various rice growing countries, significant yield losses caused by the disease can range from 50% to more than 70% (Ou 1985; Rood 2004). Increasing bakanae disease incidence has been reported in Italy (Amatulli et al 2012) and major growing areas of Asia such as Pakistan, South Korea, Bangladesh, Northern India, and Taiwan (Khan et al 2000; Park et al 2009; Haq et al 2011; Gupta et al 2014; Chen et al 2016). …”