Verticillium wilt in Lettuce

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(Contributed by  Li Bo)

       Verticillium wilt caused by thesoil borne fungus Verticillium dahliae Kleb. is a serious diseaseaffecting a broad range of economically important crops[1]. Lettuce(Lactuca sativa L.) was not considered a host until the mid-1990s, when it wasdiscovered in coastal lettuce production districts of California[2].The disease has subsequently spread many areas[3,4,5]. Verticilliumdahliae is seed transmitted in lettuce and other vegetable crops grown inrotation with lettuce[3,6]. Within V. dahliae isolates fromlettuce, two pathogenic races (race 1 and race 2) are known. The L. sativaBatavian type cultivar La Brillante and several other heirloom cultivars areresistant to race 1 isolates[7,8].

       Hayeset al.[9] reported a single dominant gene of major effect Verticilliumwilt which named Verticillium resistance 1 (Vr1). The genedescribed large portions of the phenotypic variance (R2 =0.49–0.68) and was mapped to linkage group 9 coincident with an expressedsequence tag marker (QGD8I16.yg.ab1) that has sequence similarity with the Vegene that confers resistance to V. dahliae race 1 in tomato.

       Becausethe Vr1 locus in lettuce contains a cluster of several genes withsequence similarity to the tomato Ve genes. Inderbitzin et al.[10] usedgenome sequencing and/or PCR screening along with pathogenicity assays of 152accessions of lettuce to investigate allelic diversity and its relationship torace 1 resistance in lettuce. This study identified a total of four Vegenes: LsVe1, LsVe2, LsVe3, and LsVe4. The majorityof accessions, however, contained a combination of only three of these LsVegenes clustered on chromosomal linkage group 9. A single allele, LsVe1L,was present in all resistant accessions and absent in all susceptibleaccessions. This allele can be used as a molecular marker for V. dahliaerace 1 resistance in lettuce, allows identification of resistant genotypes in earlystages of plant development or at seed-level without time- and laborintensivetesting in the field.

Sandoya et al.[11] screened germplasm forresistance and investigated the genetics of partial resistance against race 2using three mapping populations derived from crosses involving L.sativa × L. sativa and L. serriola × L.sativa. The inheritance of resistance in              Lactuca speciesagainst race 2 is complex but a common quantitative trait locus (QTL) onlinkage group 6, designated qVERT6.1 (quantitativeVerticillium dahliae resistance on LG 6, first QTL), was detected inmultiple populations. Additional race 2 resistance QTLs located in severallinkage groups were detected in individual populations and environments.

Reference:

[1] Pegg GF, Brady BL.Verticillium wilts. CABI Publishing, New York, 2002.

[2] Subbarao KV, HubbardJC, Greathead AS, Spencer GA. Verticillium wilt. In: Davis RM, Subbarao KV,Raid RN, Kurtz EA (eds) Compendium of lettuce diseases. The AmericanPhytopathological Society, St. Paul. 1997,pp 26–27.

[3] Atallah ZK,Maruthachalam K, du Toit L, Koike ST, Davis RM, Klosterman SJ, Hayes RJ,Subbarao KV (2010) Population analyses of the vascular plant pathogenVerticillium dahliae detect recombination and transcontinental gene flow.Fungal Genet Biol. 2010, 47:416–422.

[4] Garibaldi A, GilardiG, Gullino ML (2007) First report of Verticillium wilt caused by Verticilliumdahliae on lettuce in Italy. Plant Dis. 2007, 91:770.

[5] Ligoxigakis EK,Vakalounakis DJ, Thanassoulopoulos CC (2002) Weed hosts of Verticillium dahliaein Crete: susceptibility, symptomatology and significance. Phytoparasitica.2002, 30:511–518.

[6] Vallad GE, Bhat RG,Koike ST, Ryder EJ, Subbarao KV. Weedborne reservoirs and seed transmission ofVerticillium dahliae in lettuce. Plant Dis.2005, 89:317–324.

[7] Hayes RJ, Vallad GE,Qin Q-M, Grube RC, Subbarao KV. Variation for resistance to Verticillium wiltin lettuce (Lactuca sativa L.). Plant Dis. 2007, 91:439–445.

[8] Vallad GE, Qin Q-M,Grube RC, Hayes RJ, Subbarao KV (2006) Characterization of race-specificinteraction among isolates of Verticillium dahliae pathogenic on lettuce.Phytopathology. 2006, 96:1380–1387.

[9] Hayes RJ, etal. The inheritance of resistance to Verticillium wilt caused by race 1isolates of Verticillium dahliae in the lettuce cultivar La Brillante. TheorAppl Genet. 2011, 123(4):509-517.

[10] Inderbitzin P,Christopoulou M, Lavelle D, Reyes-Chin-Wo S, Michelmore RW, Subbarao KV, SimkoI. The LsVe1L allele provides a molecular marker for resistance to Verticillium dahliae race 1 in lettuce.BMC Plant Biol. 2019, 19(1):305.

[11]Sandoya GV, Truco MJ, Bertier LD, Subbarao KV, Simko I, Hayes RJ,Michelmore RW. Genetics of Partial ResistanceAgainst Verticillium dahliae Race 2 in Wild andCultivated Lettuce. Phytopathology. 2021, 111(5):842-849.