Understanding Sweet Pepper Disease Caused by Tomato Virus

Jenn Hoskins
1st May, 2024

Understanding Sweet Pepper Disease Caused by Tomato Virus

Image Source: Natural Science News, 2024

Key Findings

  • In Japan, ToMMV can infect tomatoes thought to be virus-resistant
  • ToMMV shows genetic consistency worldwide, challenging global tomato production
  • Some resistance genes in tomatoes and peppers only partially block ToMMV
Tomato mottle mosaic virus (ToMMV) has emerged as a significant concern for tomato producers globally. Scientists from Akita Prefectural University have recently advanced our understanding of this plant pathogen[1]. ToMMV, known for causing economic losses in tomato crops, has shown the ability to bypass some of the plants' defense mechanisms, leading to the infection of resistant tomato cultivars. The Japanese researchers constructed infectious clones from ToMMV isolated from sweet pepper seeds within Japan. These clones are nearly identical to those found elsewhere, such as the Mauritius isolate, underscoring the virus's widespread genetic consistency. This finding aligns with previous studies that have sequenced the ToMMV genome from different regions, confirming the virus's high genetic similarity across various geographic locations[2]. A significant finding of the Akita Prefectural University study is that ToMMV can infect tomato plants carrying resistance genes previously believed to confer protection. Specifically, tomato plants with the Tm-1 resistance gene showed typical symptoms of infection. While cultivars with Tm-2 or Tm-22 genes exhibited symptoms only on inoculated leaves, suggesting that these genes provide a stronger, yet not complete, defense against the virus. The study also tested the virus on commercial tomato and sweet pepper cultivars with known resistance to tobamoviruses. Alarmingly, all tested tomato cultivars showed systemic infections, with infection rates varying from 25 to 100%. This suggests that ToMMV has the potential to overcome even the heterozygous forms of resistance present in these cultivars. Sweet pepper cultivars with resistance genes L1, L3, and L4 were about 70% susceptible to ToMMV, although many did not show symptoms, indicating a silent spread of the virus could occur in pepper crops. Earlier studies have provided a foundation for this research by identifying the genetic makeup of ToMMV and its close relation to other tobamoviruses[3][4]. The Akita Prefectural University study builds on this by demonstrating the virus's ability to infect plants that were presumed resistant. This is particularly concerning as it parallels findings from other regions where ToMMV broke resistance in tomato cultivars[4]. The study also assessed the potential for cross-protection using Tomato mosaic virus strain L11A, an attenuated virus. However, this strain failed to protect against ToMMV, leading to systemic infections with typical symptoms. This finding is significant as it suggests that existing strategies for managing tobamoviruses may not be effective against ToMMV. Furthermore, the research contributes to our understanding of the Tm-2(2) gene, previously identified as a source of durable resistance against Tomato mosaic virus[5]. The current study indicates that while Tm-2(2) may offer some level of protection against ToMMV, it is not entirely effective, as systemic infections were observed in Tm-22 heterozygous tomato cultivars. In conclusion, the Akita Prefectural University study provides crucial insights into the challenge ToMMV presents to tomato and sweet pepper production. The ability of ToMMV to infect resistant cultivars underscores the need for continued research and the development of new strategies to protect crops from this tenacious virus. As ToMMV continues to spread globally, understanding its behavior and interactions with host plants will be vital for safeguarding the agricultural industry from this and other emerging plant pathogens.

AgricultureGeneticsPlant Science

References

Main Study

1) Molecular characterization and host reaction to tomato mottle mosaic virus isolated from sweet pepper seeds in Japan.

Published 30th April, 2024

https://doi.org/10.1007/s00705-024-06035-1

Related Studies

2) Synthesis and Characterization of a Full-Length Infectious cDNA Clone of Tomato Mottle Mosaic Virus.

https://doi.org/10.3390/v13061050

3) The complete genome sequence, occurrence and host range of Tomato mottle mosaic virus Chinese isolate.

https://doi.org/10.1186/s12985-016-0676-2

4) Molecular and Biological Characterization of Tomato mottle mosaic virus and Development of RT-PCR Detection.

https://doi.org/10.1094/PDIS-10-16-1504-RE

5) Cloning and characterization of the durable tomato mosaic virus resistance gene Tm-2(2) from Lycopersicon esculentum.

Journal: Plant molecular biology, Issue: Vol 52, Issue 5, Jul 2003


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