Differential expression of cytochrome oxidase and ALY-family genes in resistant and susceptible tomato cultivars (Solanum lycopersicum) inoculated with Tomato bushy stunt virus

Abstract

Tomato cultivars (TY20, TY70/84 and TY70/70) were mechanically inoculated with purified virus preparations of Tomato bushy stunt virus (TBSV). Inoculated plant tissues were collected after one day, one week and two weeks post-inoculation, respectively. The P19 gene was amplified using specific RT-PCR from the three examined tomato cultivars. Our main result is that the expression of the P19 gene was high in both TY70/84 and TY70/70, but it was very low in case of TY20 tomato cultivars. Messenger RNA of the inoculated and healthy plants was scanned using the differential display technique to discover the up- and down-regulated genes induced or suppressed in the infected plants. Three down-regulated and four up-regulated genes were observed. Sequence analysis revealed that the 400 bp up-regulated genes amplified from cultivars TY70/84 and TY70/70 were cytochrome oxidase genes. Expression of these genes was highest in cultivar TY70/84, followed by cultivar TY70/70; it was considerably low in cultivar TY20 and the control plants. The other four up-regulated genes belonged to the ALY gene family. We conclude that the expression of P19, cytochrome oxidase, and ALY family genes were highly expressed in inoculated plants with TBSV compared to the control plants, which suggest that these genes are members of the plant innate immune system. Keywords Differential expression; Tomato (Solanum lycopersicum); Tomato bushy stunt virus (TBSV); P19 gene; Cytochrome oxidase; Aly-family genes