This study was a field trial of tomato varieties' resistance to tomato yellow leaf curl virus. Growers were able to assess characteristics of tolerant hybrids and then assess the plants' sustainability in localized field operations

Fukuda, Steve

Melzer, Michael

Migita, Susan

Pant, Archana

Radovich, Ted

Sugano, Jari

Uyeda, Jensen

ScholarSpace at University of Hawai'i at Manoa

Plant DiseaseNovember 2011PD-78Leaf curl and interveinal chlorosis. All photos by Michael Melzer and Jari Sugano.Published by the College of Tropical Agriculture and Human Resources (CTAHR) and issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in co-operation with the U.S. Department of Agriculture, under the Director/Dean, Cooperative Extension Service/CTAHR, University of Hawai‘i at Mānoa, Honolulu, Hawai‘i 96822. Copyright 2011, University of Hawai‘i. For reproduction and use permission, contact the CTAHR Office of Communication Services, ocs@ctahr.hawaii.edu, 808-956-7036. The university is an equal opportunity/affirmative action institution providing programs and services to the people of Hawai‘i without regard to race, sex, gender identity and expression, age, religion, color, national origin, ancestry, disability, marital status, arrest and court record, sexual orientation, or status as a covered veteran. Find CTAHR publications at www.ctahr.hawaii.edu/freepubs.Field Evaluations of Tomato Yellow Leaf Curl Virus-Resistant Varieties for Commercial ProductionJari Sugano,1 Michael Melzer,1 Archana Pant,2 Ted Radovich,2 Steve Fukuda,2 Susan Migita,3 and Jensen Uyeda21Department of Plant and Environmental Protection Sciences; 2Department of Tropical Plant and Soil Sciences; 3Poamoho Research StationTomato is an economically important crop for many small- and large-scale produc-ers in Hawai‘i. Tomato yellow leaf curl, caused by Tomato yellow leaf curl virus (TY-LCV), is a devastating disease of tomato worldwide and was first detected and identified in commercial tomato plant-ings around O‘ahu and Maui in 2009 (Melzer et al. 2009). It has since been identified in the Kona area of Hawai‘i. Susceptible varieties become chlorotic, with interveinal dis-coloring; they are stunted due to shortened internodes; leaflets curl or cup upwards at the leaf margins; and the plants suffer from reduced fruit set due to premature flower abortion. TYLCV is transmitted by sweetpotato (Bemisia tabaci) and silverleaf (Bemisia argentifolii) whiteflies but is not transmitted by the greenhouse whitefly (Trial-eurodes vaporariorum). TYLCV is not spread through mechanical means. Alternate hosts for the virus include solanaceous crops such as potato, pepper, tobacco, etc. Common beans and weeds are also known to harbor the virus. Alternate hosts do not typically exhibit virus-like symptoms.TYLCV can completely devastate commercial toma-to operations without proper control strategies statewide. It is important to screen and identify resistant varieties that can tolerate this virus. In 2010, a replicated field trial was installed at the Poamoho Research station with 11 com-mercial varieties with putative resistance to TYLCV (Table 1). Kewalo was selected as a susceptible control. Four rep-lications were installed, with twelve plants of each variety per replication. The varieties were evaluated based on total marketable yield, total mar-ketable count, grade-A yield, grade-A count, and tolerance to TYLCV. Plants were seeded in April and transplanted in May 2010. Harvest period was from June through September 2010. Varieties selected for this evaluation included determinate and indeterminate plant types and beefsteak, Roma, and cherry fruit types. Harvest data were collected weekly. Fruits were sorted and graded based on the Hawaii Department of Agriculture’s market standards for tomato. Data were analyzed with the computer software SigmaPlot. A tissue blot hybridization assay was used to identify the presence of TYLCV. Results Overall, data indicated varieties VT-62940 and VT-62966 had the highest marketable yields, followed by Adonis, Tygress, PIK Ripe 461, and Tovi Star (Figure 1). Indeterminate varieties such as Adonis, Tygress, and PIK Ripe 461 had the highest yield of grade-A fruit in UH–CTAHR Tomato Yellow Leaf Curl Virus-Resistant Varieties for Commercial Production PD-78 — Nov. 20112comparison to other varieties. A single VT-62940 plant developed symptoms of tomato yellow leaf curl and tested positive for the virus. A mix-up in seed may account for this result, although it is possible that this high-yielding variety is not entirely resistant to the virus. Further field evaluations may be needed to assess VT-62940 resistance to TYLCV. Screening Process for TYLCVFor each variety, two plants were sampled from each of the four replications (2 x 4 = 8). These samples were evaluated for the presence of TYLCV using a tissue blot immunoassay. The dark spots indicate the presence of the virus (Figure 2). All Sunchaser, Sunsugar, and Kewalo (susceptible control) plants evaluated were strongly posi-tive for TYLCV. A single VT-62940 plant was also found to be strongly positive for TYLCV. Plants that tested strongly positive for TYLCV also had severe disease symptoms. The remaining varieties (Adonis, Tovi Star, Tovi Roca, VT-62966, Yaqui, PIK Ripe 461, Xaman, and Tygress) tested negative or weakly positive for TYLCV and had no observable disease symptoms.A field day was conducted to showcase the different varieties to interested stakeholders. Growers evaluated Close-up of leaf discolorationStunting effect due to shortened internodes. Susceptible local variety with upward-cupping leaf marginsVariety Name Type Seed SourceAdonis Determinate SeminisTygress Determinate SeminisPIK Ripe 461 Determinate SeminisSunchaser Determinate SeminisSunsugar (yellow cherry) Indeterminate SeminisYaqui Determinate SeminisTovi Roca Indeterminate Zeraim GederaVT-62966 Indeterminate Zeraim GederaVT-62940 Indeterminate Zeraim GederaXaman (Roma type) Determinate SeminisKewalo Determinate UH CTAHRTovi Star Indeterminate Zeraim GederaTable 1. Tomato varieties used in TYLCV-resistance field trial3UH–CTAHR Tomato Yellow Leaf Curl Virus-Resistant Varieties for Commercial Production PD-78 — Nov. 2011the horticultural characteristics of tolerant hybrids and are in the process of assessing their suitability to their localized field operations via seeds obtained through various seed companies. A further consideration is to-mato spotted wilt virus (TSWV), another important virus that can severely hinder tomato production in Hawai‘i. The varieties evaluated in this study were putatively resistant to TYLCV but were susceptible to TSWV. As such, many plants were lost to TSWV infection. Cur-rently there are only a few commercial tomato varieties that have putative resistance to both TYLCV and TSWV. We have obtained seeds of these varieties, and they are currently under evaluation. The results of this study will Figure 1. Total marketable and grade-A yield of different varieties. Means followed by the same letter are not statisti-cally significant (p<0.05). Capital letters separate the means of total marketable yield, and small letters separate the means of grade-A yield. X DataVT-62940VT-62966AdonisTygressPIK Ripe 461Tovi StarToquiTovi RocaSunchaserXaman (Roma Type)Sunsugar (Yellow Cherry)KewaloYield (lb)01 0 02 0 03 0 04 0 05 0 0T o t a l  m a r k e ta b l e  y i e l dG r a d e  A  y i e l dAA BBBBB CD CD ED E FD E FE FFbb caaacb c b ccc dcdbe released in a subsequent CTAHR publication. Applied field testing by CTAHR and adoption of tolerant variet-ies by producers may lead to increased productivity and long-term sustainability of Hawai‘i’s tomato industry.  AcknowledgementsThanks are due to the Seminis Seed Company, Zeraim Gedera, and CTAHR’s Agricultural Diagnostic Service Center Seed Lab for donation of seeds; Poamoho Ex-periment Station for field and harvest support; Radovich laboratory for field and harvest support; Melzer/Hu lab for field support and tissue blot tabulations; and CTAHR’s OCS for publication editing and design. VT-62940KewaloSunchaserYaquiTovi RocaXamanSunsugarTovi StarTygressPIK Ripe 461AdonisVT-62966Grade-A Yieldotal Marketable Yieldc dE F  D Eab cb   B  A B  B B aac b cb D  D E FUH–CTAHR Tomato Yellow Leaf Curl Virus-Resistant Varieties for Commercial Production PD-78 — Nov. 20114ReferencesMelzer, M. et al. 2009. Tomato Leaf Curl. University of Hawai‘i at Mänoa, College of Tropical Agriculture and Human Resources, Plant Disease publication PD-70.DisclaimerMention of company names does not imply endorsementby UH CTAHR.Figure 2: Tissue blot immunoassay results for the 12 different tomato varieties. A black dot indicates the presence of TYLCV.Tygress Xaman1. TygressAdonisSunsugarSunchaserKewaloTovi StarTovi RocaVT-62940VT-62966YaquiPIK Ripe 4619. Kewalo7. Tovi Roca6. VT-629405. VT-629664. Yaqui3. PIK Ripe 4612. Xaman12. Adonis11. Sunsugar10. Sunchaser8. Tovi Star

Tomato Yellow Leaf Curl Virus-Resistant Varieties for Commercial Production

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Tomato Yellow Leaf Curl Virus-Resistant Varieties for Commercial Production

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