The genetics of resistance to lettuce drop (Sclerotinia spp.) in lettuce in a recombinant inbred line population from Batavia Reine des Glaces x Eruption

Authors: MAMO, BULLO - University Of California; Hayes, Ryan; TRUCO, MARIA-JOSE - University Of California; PURI, KRISHNA - University Of California; MICHELMORE, RICHARD - University Of California; SUBBARAO, KRISHNA - University Of California; Simko, Ivan

Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/14/2019
Publication Date: 7/15/2019
Citation: Mamo, B.E., Hayes, R.J., Truco, M., Puri, K.D., Michelmore, R.W., Subbarao, K.V., Simko, I. 2019. The genetics of resistance to lettuce drop (Sclerotinia spp.) in lettuce in a recombinant inbred line population from Batavia Reine des Glaces x Eruption. Theoretical and Applied Genetics. 132(8):2439-2460. https://doi.org/10.1007/s00122-019-03365-6.
DOI: https://doi.org/10.1007/s00122-019-03365-6

Interpretive Summary: Lettuce drop, caused by Sclerotinia minor and S. sclerotiorum, is an economically important disease of lettuce (Lactuca sativa L.). The association of resistance to lettuce drop with the commercially undesirable trait of fast-bolting has previously hampered the integration of host resistance in control of this disease. Eruption is a slow-bolting cultivar (cv.) that exhibits a high level of resistance to lettuce drop. Eruption also is completely resistant to Verticillium wilt caused by race 1 of Verticillium dahliae. A recombinant inbred line population from the cross Batavia Reine des Glaces × Eruption was genotyped by sequencing and evaluated for lettuce drop and bolting in a field infested with S. minor in three experiments and for incidence of Verticillium wilt. Two quantitative trait loci (QTL) for lettuce drop resistance were consistently detected at least in two experiments and two more QTL in another experiment; the alleles for resistance at all four QTL originated from Eruption. Three out of four resistance QTL are distinct from QTL for bolting. QTL for lettuce drop resistance in Eruption also is distinct from QTL for red pigmentation due to anthocyanin accumulation. Resistance to Verticillium wilt in Eruption is conferred by the Verticillium resistance 1 (Vr1) locus previously described from cv. La Brillante. The SNP markers linked with these QTL will be useful in breeding for resistance through marker-assisted selection.

Technical Abstract: Lettuce drop, caused by Sclerotinia minor and S. sclerotiorum, is an economically important disease of lettuce (Lactuca sativa L.). The association of resistance to lettuce drop with the commercially undesirable trait of fast-bolting has previously hampered the integration of host resistance in control of this disease. Eruption is a slow-bolting cultivar (cv.) that exhibits a high level of resistance to lettuce drop. Eruption also is completely resistant to Verticillium wilt caused by race 1 of Verticillium dahliae. A recombinant inbred line population from the cross Batavia Reine des Glaces × Eruption was genotyped by sequencing and evaluated for lettuce drop and bolting in a field infested with S. minor in three experiments and for incidence of Verticillium wilt. Two quantitative trait loci (QTL) for lettuce drop resistance were consistently detected at least in two experiments and two more QTL in another experiment; the alleles for resistance at all four QTL originated from Eruption. A QTL on linkage group (LG) 5, qLDR5.1, was consistently detected in all experiments and explained 11 to 25% of phenotypic variation. On LG1, qLDR1.1 was detected in two experiments explaining 9 to 12% of the phenotypic variation. Three out of four resistance QTL are distinct from QTL for bolting. The qLDR5.1 is pleiotropic or closely linked with QTL for early bolting that is associated with only a small variance in resistance observed at this locus. QTL for lettuce drop resistance in Eruption also is distinct from QTL for red pigmentation due to anthocyanin accumulation. Resistance to Verticillium wilt in Eruption is conferred by the Verticillium resistance 1 (Vr1) locus on LG9 previously described from cv. La Brillante. The SNP markers linked with these QTL will be useful in breeding for resistance through marker-assisted selection.