Resistance of Solanum species to Cucumber mosaic virus subgroup IA and its vector Myzus persicae

Abstract

Sixty-nine tomato genotypes representing nine Solanum species were evaluated for resistance to Cucumber mosaic virus (CMV) subgroup IA and its aphid vector Myzus persicae. Resistance was assessed by visual scoring of symptoms in the field under natural conditions, and in the greenhouse by artificial inoculations through aphid M. persicae and mechanical transmissions in the year 2007 and 2009. Considerable variation in responses was observed among the evaluation methods used. Field evaluations were found liable to errors as different levels were observed for the same genotypes in the different years, however mechanical inoculation was found to be the most useful in identifying CMV subgroup IA resistance, in contrast aphid transmission was most useful in identifying insect transmission resistance. All genotypes observed as highly resistant to CMV subgroup IA in the field or through vector transmission became systemically infected through mechanical inoculations. Using mechanical inoculation, six genotypes (TMS-1 of S. lycopersicum, LA1963 and L06049 of S. chilense, LA1353, L06145 and L06223 of S. habrochaites)were found resistant and another six (L06188 and L06238 of S. neorickii, L06219 of S. habrochaites, L05763, L05776 and L06240 of S. pennellii) were found tolerant showing mild symptoms with severity index (SI) ranging 1-2 and with delayed disease development after a latent period (LP) of 18-30 days. However, these genotypes were found to be resistant to highly resistant in the field and through inoculation by M. persicae; and they also supported low population levels of M. persicae except TMS-1. Another nine genotypes (LA2184 of S. pimpinellifolium L., LA2727 of S. neorickii, LA0111, L06221, L06127 and L06231 of S. peruvianum L., LA1306, L06057 and L06208 of S. chmielewskii) showing a susceptible response after mechanical inoculation were highly resistant, resistant and tolerant after M. persicae transmission. The resistant genotypes, identified in the present study can be exploited in the breeding programmes aimed at developing tomato varieties resistant to CMV subgroup IA and broadening the genetic base of CMV-resistant germplasm. The differences observed between mechanical and aphid transmission suggests that one should consider both evaluation methods for tomato germplasm screening against CMV subgroup IA.

Effect of cucumber mosaic virus infection on morphology, yield and phenolic contents of tomato

“…Tomato (Solanum lycopersicum, 2n ¼ 24) belongs to family Solanaceae and is the most important vegetable crop worldwide in terms of production and consumption (Jones et al 1997;Akhtar et al 2010). Its fruit is a rich source of nutrition, such as carotenoids (lycopene), ascorbic acid (vitamin C), vitamin A, vitamin E, folate, flavonoids and potassium (Beecher 1998;Leonardi et al 2000).…”

“…It is one of the best characterised tripartite positivesence single-stranded RNA viruses (Takahashi 2008). CMV-infected plants can show a broad spectrum of symptoms from mild to severe mosaic, stunting, filiformity, chlorosis and necrosis depending on viral strain and host (Carrere et al 1999;Sulistyowati et al 2004;Akhtar et al 2010).…”

“…Disease management is focused mainly on vector control, since its control is thought to be complicated by the broad host range of the virus and its vector, development of resistance in M. persicae against most of the pesticides used and the environment due to the excessive use of insecticides (Stamova and Chetelat 2000;Akhtar et al 2010). The most reliable and safe methods of disease control is breeding of cultivars resistant to CMV and its vector M. persicae (Akhtar et al 2010). A good deal of research work has been directed by Akhtar et al (2010) towards screening of tomato genotypes against CMV to identify sources of resistance, and a number of virus and vector resistant lines were selected.…”

Assessing the genetic diversity and resistance to Cucumber mosaic virus and Tobacco etch virus of tobacco cultivars in China

“…In order to assess symptom severity, data from 15 plants of each tobacco cultivar were recorded for CMV and TEV symptoms in late July or early August, according to the following five grades (0-4) (Figs. 1 and 2): 0 = no visible disease symptoms; 1 = mild mosaic or mottling; 2 = moderate mosaic or mottling, leaf deformity (moderate mottling and etching or yellow for TEV); 3 = severe mosaic or mottling or leaf deformity, minor to medium stunting (severe mottling, etching and necrotic lines for TEV) and 4 = severe mosaic or mottling, leaf deformity, stunting (severe mottling, etching, necrotic lines and stunting for TEV) (Legnani et al 1996;Zhu et al 1996;Akhtar et al 2010).…”

“…Based on the recorded data, disease index (DI) values were calculated using the formula below (Zhu et al 1996;Akhtar et al 2010), and statistical analyses were performed with SPSS software (IBM SPSS Statistics 19.0, New York, USA).…”