Evaluation of Lettuce Germplasm Resistance to Gray Mold Disease for Organic Cultivations

Abstract

This study was conducted to evaluate the resistance of 212 accessions of lettuce germplasm to gray mold disease caused by Botrytis cinerea. The lettuce germplasm were composed of five species: Lactuca sativa (193 accessions), L. sativa var. longifolia (2 accessions), L. sativa var. crispa (2 accessions), L. saligna (2 accessions), and L. serriola (1 accession); majority of these originated from Korea, Netherlands, USA, Russia, and Bulgaria. After 35 days of spray inoculation with conidial suspension (3×107 conidia/ml) of B. cinerea on the surface of lettuce leaves, tested lettuce germplasm showed severe symptoms of gray mold disease. There were 208 susceptible accessions to B. cinerea counted with 100% of disease incidence and four resistant accessions, IT908801, K000598, K000599, and K021055. Two moderately resistant accessions of L. sativa, K021055 and IT908801, showed 20% of disease incidence of gray mold disease at 45 days after inoculation; and two accessions of L. saligna, K000598 and K000599, which are wild relatives of lettuce germplasm with loose-leaf type, showed complete resistance to B. cinerea. These four accessions are candidates for breeding lettuce cultivars resistant to gray mold disease.

Effectiveness of Different Classes of Fungicides on Botrytis cinerea Causing Gray Mold on Fruit and Vegetables

“…However, owing to the improper application of fungicides and the high genetic variability of B. cinerea , strains resistant to fungicides have emerged and become threats to producers. For example, benzimidazole fungicides, which act by binding to fungal microtubules and inhibiting hyphal growth, were highly effective against gray mold in the late 1960s, but strains resistant to these fungicides started to emerge within a few years of their application, and the fungicides are less effective (Beever and Brien, 1983; Shim et al, 2014). In addition, strains resistant to aniline-pyrimidine, dicarboximide, hydroxyaniline, and phenylpyrrole have been reported (Fernández-Ortuño et al, 2012).…”

Silencing of the Slt2-Type MAP Kinase Bmp3 in Botrytis cinerea by Application of Exogenous dsRNA Affects Fungal Growth and Virulence on Lactuca sativa

“…Gray mold caused by the fungus B. cinerea has been considered as a major disease in greenhouse-grown lettuce. The romaine lettuce variety and some iceberg lettuces are susceptible to B. cinerea also in the field [34].…”

Inhibitory effect and possible mechanism of a Pseudomonas strain QBA5 against gray mold on tomato leaves and fruits caused by Botrytis cinerea

“…However, evidence demonstrates that isolates of B . cinerea have developed some specific resistances to several fungicides including dicarboximides, benzimidazole, phenylpyrrole and hydroxyanilide [ 6 , 7 , 8 , 9 , 10 ]. Worse still, misuse and excessive use of fungicides for years result in environmental pollution, disturbance of natural ecosystems, and pose a potential threat to human health because of the high level of toxic residues of fungicides in tomato fruit [ 1 , 3 , 11 , 12 ].…”