Race 3, a new race of Fusarium oxysporum f. sp. lactucae determined by a differential system with commercial cultivars

Abstract

Race 3, a new race of Fusarium oxysporum f. sp. lactucae determined by a differential system with commercial cultivars Abstract Pathogenic variation among 26 Japanese isolates of Fusarium oxysporum f. sp. lactucae (FOL) was tested using 21 lettuce cultivars to select commercial lettuce cultivars as race differential indicators. Cultivar Costa Rica No. 4 was resistant to race 1 but susceptible to race 2, consistent with the conventional standard differential line VP1010. Cultivar Banchu Red Fire was susceptible to race 1 but resistant to race 2, which showed an opposite type of reaction as another differential line VP1013. Cultivar Patriot was susceptible to both races. The resistance reactions of the three cultivars under field conditions were identical with that observed in the seedlings. Thus cv. Costa Rica No. 4 and cv. Banchu Red Fire can be used as differential hosts to identify pathogenic races of FOL. This differential system showed that all FOL isolates obtained from diseased butterhead lettuce in Fukuoka, Japan were new races (i.e., pathogenic to three cultivars). We propose that the new race be designated race 3. Isolates of FOL, the pathogen of Fusarium wilt in lettuce, obtained from California showed the same reaction as that of race 1. Furthermore, the Japanese isolate SB1-1 (race 1) and California isolate HL-2 belonged to the same vegetative compatibility group. Our results suggest that both of the fungi are the same forma specialis.

Analysis of RAPD and AFLP markers linked to resistance to Fusarium oxysporum f. sp. lactucae race 2 in lettuce (Lactuca sativa L.)

“…The disease severities of VP1013 and Patriot were reported previously by Fujinaga et al (2001Fujinaga et al ( , 2003. Results shown in figure 1. suggested resistance to FOL race 2 might be determined by a single major dominant locus, but with minor loci that contribute some modifications.…”

“…Thus, this marker will provide efficient selection of candidates that are resistant to FOL race 2 in breeding programs. FOL is categorized into three races, namely 1, 2, and 3 (Fujinaga et al, 2001(Fujinaga et al, , 2003. To date, only single races of FOL have been found in infected areas, but it is possible that fields will be contaminated by multiple races in the near future.…”

“…Mild symptoms lead to failure of head formation but the plant remains alive, whereas severe symptoms kill infected plants. In Japan, FOL is classified into three races, namely 1, 2, and 3 (Fujinaga et al, 2001(Fujinaga et al, , 2003. Lettuce genetic resources were evaluated and selected using these races by Tsuchiya et al (2004a).…”

‘Chouya No. 37’, a Fusarium Root Rot (Race 2)-Resistant Lettuce

“…RRL also occured in Nagano prefecture, a major lettuce production area, in 1995 (Fujinaga and Wada, 1997). FOL is categorized to three races, 1, 2, and 3 (Fujinaga et al, 2003). In Nagano, race 1 and 2 were confirmed (Fujinaga et al, 2001;Tsuchiya et al, 2000).…”

Characterization of biotin-autotrophic isolates derived from naturally occurring auxotrophic race 2 isolates of Fusarium oxysporum f. sp. lactucae

“…Isolates were categorized into three physiological races (races 1, 2, or 3) based on their pathogenicity on race differential cultivars, i.e., Patriot (susceptible to all races), Banchu Red Fire (resistant to race 2), and Costa Rica No. 4 (resistant to race 1), which were commercially cultivated in Japan (Fujinaga et al 2003). In Japan, race 1 occurred in Nagano and Hokkaido, and race 3 in Fukuoka and Shizuoka, while race 2 was found only in Nagano Prefecture (Fujinaga et al 2001(Fujinaga et al , 2003Yamauchi et al 2004).…”