Stability of partial resistance in potato cultivars exposed to aggressive strains ofPhytophthora infestans

Abstract

Potato cultivars were evaluated for their resistance responses to aggressive strains of Phytophthora infestans in field and laboratory experiments. Analysis of variance revealed differential cultivar-by-isolate interactions for both foliar and tuber blight resistance. Differential responses occur as revealed by specific susceptibilities of cultivars to certain pathogen genotypes and changing rank order. In general, severity of late blight epidemics as observed in the haulms did not correlate well with foliar blight resistance ratings as presented in the National List of Recommended Potato Varieties. No significant correlation was found between tuber blight incidence under field conditions and the tuber blight rating in the National List. Also, there was no relation between the field and laboratory tuber blight resistance assessments. A significant association was demonstrated between late blight infection in the foliage and tuber blight incidence under field conditions. The presence of differential interaction, independent of R-gene-based resistance, indicates some adaptation of P. infestans to partial resistance and consequently adverse effects on the stability and durability of partial resistance to potato late blight.

Resistance to Phytophthora infestans in Solanum tuberosum landraces in Southern Chile

“…A similar trend was observed for accessions UCT-32Ci and UCT-33cab. Wide variation in response to this disease in potato have been reported by various authors (Micheletto et al, 2000;Flier et al, 2003;Jenkins & Jones, 2003;Barquero et al, 2005a;Lucca et al, 2008;Andreu et al, 2009;Mendoza, 2010). Barquero et al (2005b) reported the existence of important differences between genotypes resulting from crosses with different wild species.…”

“…Initially the search concentrated on specific resistance (Flier et al, 2003;Forbes et al, 2005). This type of resistance is characterized by a hypersensitive response in the form of small necrotic lesions, and is called race-specific, monogenic, qualitative, or complete resistance.…”

“…It is based on the recognition of avirulence genes (Avr) of the pathogen by major plant resistance genes (R-genes) (Flor, 1971). However, this type of resistance is not very longlasting, since P. infestans populations can quickly overcome it (Flier et al, 1998;Flier et al, 2003). More recently, the emphasis has been switched to non-specific resistance which is considered to be more stable over time and space (Goodwin et al, 1995;Micheletto et al, 1999;Micheletto et al, 2000;Parlevliet, 2002;Barquero et al, 2005b;Forbes et al, 2005;Naerstad et al, 2007).…”

Allele mining in Solanum: conserved homologues of Rpi-blb1 are identified in Solanum stoloniferum

“…For the late blight resistance test, detached leaf assays (DLAs) were performed as described by Vleeshouwers et al (1999). The P. infestans isolates IPO82001 (race structure: 1, 2, 3 ,4, 5, 6, 7, 10, 11) and IPO655-2A (race structure 1,2,3,4,5,6,7,8,10,11) (Flier et al 2003) were from the collection of PRI, isolate "Marknesse" (race structure: 1, 2, 3, 4, 6, 7, 10, 11) was from a diseased potato collected in 2005 near the Dutch village Marknesse.…”

Genetic linkage of QTLs for late blight resistance and foliage maturity type in six related potato progenies

“…The field tests for late blight resistance consisted of three randomised blocks with two plants per plot. Plants were inoculated approximately 8 weeks after emergence by spray application of a spore suspension of race 1.2.3.4.5.6.7.10.11 of P. infestans (IPO82001; Flier et al, 2003). Percentages of late blight-affected leaf tissue were assessed over a period of 6 weeks after inoculation at weekly intervals in the year 2000 and twice a week in 2001.…”