Resistance to Tobacco Mosaic Virus in Tomato: Effects of the Tm-1 Gene on Virus Multiplication

Abstract

SUMMARYThe gene Tin-1 in tomato plants is dominant for suppression of mosaic symptoms caused by tobacco mosaic virus isolates designated as tomato strain o. Virus multiplication (measured either by virus RNA content or by virus coat protein content) was inhibited in plants containing Tm-l. Inhibition was greater in hosts homozygous for Tin-1 (90 to 95 %) than in hosts heterozygous for Tin-1 (65 to 75 %). Thus, inhibition of tobacco mosaic virus multiplication is Tin-1 gene dosagedependent; suppression of visible symptoms is not.Inhibition of TMV RNA accumulation occurred in both directly inoculated and systemically-infected leaves of Tin-l-containing hosts, and was consistent from experiment to experiment. Tin-1 inhibited accumulation of RNA of different isolates of strain o to different extents: two isolates causing yellow mosaic symptoms on susceptible plants were especially strongly inhibited.In Tm-I hosts, there was a delay between inoculation and the first detection of virus multiplication, measured either as increase in virus RNA content or recoverable infectivity. The delay was about 8 days in heterozygous Tm-1 hosts and about t 6 days in homozygous Tin-1 hosts. The implications of these results for the mode of action of the Tin-1 gene resistance are discussed.

Induced ER Chaperones Regulate a Receptor-like Kinase to Mediate Antiviral Innate Immune Response in Plants

“…One difficulty of studying defense responses in whole organisms is that during a normal infection only a small number of cells are infected, which results in a mixed population of uninfected and infected cells. To overcome this, we exploited the temperature sensitive nature of N-mediated resistance (Fraser and Loughlin, 1980) to coordinate a defense response in every cell (Figure 1A). Plants were shifted to 32°C to fully inactivate N and to allow TMV to spread without inducing a defense response.…”

Plant growth regulators and virus infection: A critical review

“…For example, tobacco mosaic virus (TMV) can multiply in tobacco or tomato until it forms 1% of the leaf fresh weight (38,44) . In the synthesis of this vast amount of `foreign' nucleoprotein, some 75% of the host capacity for synthesis of RNA and protein is diverted to production of viral products (39,43) .…”

The Genetics of Resistance to Plant Viruses

“…The gene-dosage dependent resistance mech anism to TMV controlled by the Tm-J gene in tomato, which allows systemic spread but inhibits multiplication (44,110), does appear to be constitutive (44). The latter mechanism es pecially would be consistent with a quantitative interaction between a con stitutive inhibitor and a viral function, rather than an all-or-nothing reaction causing induction of resistance.…”