**11. Conclusions**

The contribution of seed transmission to viral spread may be significant even under conditions of low seed-to-seedling transmission rate. The rapid spread of tobamoviruses by any mechanical contacts is reflected in the spread of the disease especially in plants that are grown trellised in protected structures. This mechanical virus spread may occur when handling seeds and transplanting seedlings. Furthermore, the modern monoculture agriculture contributes to virus buildup, preservation, and spread to new susceptible host plants which increase viral copy number leading to higher viral load in the growing area. Tobamoviruses contaminate both the seed coat and the PEE or the endosperm. The mechanism of *Tobamovirus* transmission in the seed is not quite clear, but it may follow the path suggested for the *Potyvirus* PSbMV in pea seeds. Seeds have regulatory mechanisms that may limit virus transmission, and dominant resistance genes block virus transmission. However, *Tm-22* and L<sup>4</sup> resistance-breaking tobamoviruses have recently been spread, and new approaches for conferring resistance to cultivars against tobamoviruses are in demand. The CRISPR-Cas9 methodology offers exciting prospects and provides an alternative approach to conventional breeding for the acquisition of resistance to viruses. Hopefully, in the near future, it will be applied to *Tobamovirus* species in imported crops.
