Screening tomato genotypes for resistance and tolerance to Tomato chlorosis virus

Abstract

Tomato chlorosis virus (ToCV) is an emerging crinivirus in Brazil that causes an economically important disease in tomato (Solanum lycopersicum) and other solanaceous species. ToCV is transmitted predominantly by the whitefly Bemisia tabaci Middle East‐Asia Minor 1 (MEAM1, formerly biotype B), in a semipersistent manner. As all cultivated tomato varieties and hybrids are susceptible to this crinivirus, the main alternatives for the control of the disease are the use of healthy seedlings for transplanting and the chemical control of the insect vector. The objective of this work was to evaluate the responses of tomato genotypes to infection with this crinivirus and their tolerance to the disease in order to support the development of other alternatives for disease control. Resistance to infection was evaluated by ToCV inoculation with viruliferous B. tabaciMEAM1 followed by virus detection by RT‐PCR and RT‐qPCR. To measure tolerance to the disease, plant development and fruit yield of ToCV‐infected and healthy plants were compared. Among 56 genotypes, only the lineage IAC‐CN‐RT (S. lycopersicum ‘Angela Gigante’ × S. peruvianum ‘LA 444‐1’) was highly resistant to infection with ToCV. Tolerance to the disease over two trials with different genotypes showed variable results. The effect of ToCV on plant development varied from 2.9% to 71.9% reduction, while yield loss varied from 0.2% to 51.8%. The highly ToCV‐resistant lineage IAC‐CN‐RT, which is also resistant to a Spanish isolate of ToCV, might be useful for tomato breeding programmes.

Temporal and spatial progress of the diseases caused by the crinivirus tomato chlorosis virus and the begomovirus tomato severe rugose virus in tomatoes in Brazil

“…Virus-and whitefly-free tomato transplants of cultivars resistant to begomovirus infection were used in all fields: Dominador (TopSeed) in Goian apolis, An apolis and Taquara, as well as Predador (Top-Seed) in Boa Esperanc ßa. By carrying the Ty-1 resistance gene, both Dominador and Predador are moderately resistant to begomovirus infection; however, Dominador is moderately resistant, and Predador is highly susceptible to ToCV infection (Mansilla-C ordova et al, 2018). In these plants, the infection rate to Brazilian begomoviruses (e.g.…”

“…The control of golden mosaic disease usually relies on the use of resistant tomato cultivars and frequent applications of insecticides for vector control , while chemical spraying is the major control method used for the yellowing disease, due to the absence of resistant cultivars (Mansilla-C ordova et al, 2018). Even though tomato growers in Brazil usually spray insecticides to combat whiteflies two or three times per week to prevent the spread of both viruses, the high incidence of the diseases caused by ToSRV and ToCV demonstrates that this strategy has low efficacy .…”

Tomato chlorosis virus, an emergent plant virus still expanding its geographical and host ranges

“…To date, there is no commercial tomato cultivar reported to be resistant or tolerant to ToCV. However, experiments carried out in Spain, Brazil and Uruguay have identified several wild tomato species ( Solanum section Lycopersicon ) that contain genotypes reacting with mild symptoms and/or low viral titres to the natural or experimental inoculation with ToCV (García‐Cano et al , ; González‐Arcos et al , ; Mansilla‐Córdova et al , ). The most promising materials include genotypes of S. chmielewskii , S. habrochaites and S. lycopersicum × S. peruvianum .…”

Lack of synergistic effects in tomato plants co‐infected with tomato severe rugose virus and tomato chlorosis virus

“…For plants inoculated 75 days after transplanting, a yield reduction of about 6.3% was observed in only one experiment. Mansilla-C ordova et al (2018), analysing the tolerance of 18 tomato genotypes to the yellowing disease caused by ToCV, reported that the reduction in plant development, based on the dry weight of the aerial part and on fruit yield ranged from 1.4% to 67.6% and 0.1% to 51.8%, respectively, compared to healthy plants of each genotype.…”