Faced with the effectiveness and the absence of environmental damage from genetic control, major breeding programs have been and are being carried out throughout the world. They should make it possible to control a growing number of pests.

The molecular biology techniques used to mark genes of interest to breeders allow the selection of resistance that is difficult to demonstrate by early biotests. They thus facilitate the selection of partial, oligogenic or polygenic resistance and the accumulation of a greater number of resistance genes.

There are serious hopes of resistance for practically all types of phytopathogenic microorganisms. Several of them relate to the control of certain races adapted to the resistance currently available in cultivated varieties. By way of example, the microorganisms likely to be controlled by resistance from wild species Solanum (ex Lycopersicon ) are presented below.

- A new pathotype of Fusarium oxysporum f. sp. lycopersici which overcomes the " genes I " and " I-2 " is now present in different regions. This new race, generally designated “race 3”, is controlled by the dominant “ gene I-3 ” from S. pennellii (ex L. pennellii ) . It was introduced in tomato lines; commercial F1 hybrids resistant to the 3 races are starting to appear.

- Numerous studies report partial resistance to Alternaria tomatophila , originating from various wild species including S. habrochaites (ex L. hirsutum ) and present in various commercial varieties. This resistance should not, however, be confused with that effective against A. alternata f. sp. lycopersici which is controlled by the dominant gene " Asc ". This resistance, present in almost all ancient and modern cultivated varieties, is referred to as “resistance to Alternaria ” in certain seed catalogs. This indication is misleading: it is in no way a resistance to alternaria blight caused by leaf A. tomatophila .

- The “ gene Ph-1 ” for resistance to Phytophthora infestans was overcome even before having been used in selection, and the “ gene Ph-2 ” , which was incompletely dominant and controlling partial resistance, suffered the same setbacks. Breeders then looked for more effective resistance. Hopes are now on the “ gene Ph-3 ” from S. pimpinellifolium (ex L. pimpinellifolium ).

- With regard to Oidium neolycopersici , the breeders aim to combine resistance genes from wild species in order to ensure a high level of resistance to different breeds recently revealed.

- Sources of resistance to Clavibacter michiganensis subsp. michiganensis have been known for a long time. These are partial resistances, with expression levels very influenced by the environmental conditions. Derived from wild species, they are the basis of breeding programs conducted all over the world, of which the varietal types intended for industrial processing seem to be the most advanced.

- Different sources of resistance to Xanthomonas spp. have been highlighted. Selection work aims to accumulate resistance to different races and to obtain resistance that is expressed both for the foliage and for the fruits. A resistance from S. pimpinellifolium is particularly worked.

- With regard to Potato virus Y (PVY), the work mainly focuses on resistance from S. habrochaites controlled by two genes: “ pot-1 ”, recessive, and “ Pot-2 ”, dominant. This resistance is effective both against strains causing mosaic disease and necrotic strains.

- A dominant gene, stable at high temperature and making it possible to control Alfalfa mosaic virus (AMV), has been demonstrated in an origin of S. habrochaites . This gene, called “ Am ”, is of interest to breeders in Mediterranean countries where AMV is sometimes severe.

- For the Tomato yellow leaf curl virus (TYLCV), selection tends to increase the level of resistance of hybrids by combining genes from different wild species. Selection programs are also carried out to control the other Begomoviruses , the diversity of which is important.

- The “ gene Mi ” , used for a long time in various cultural contexts to combat root-knot nematodes belonging to the genus Meloidogyne , has been overcome in many regions. Two other genes from S. peruvianum (ex L. peruvianum ) were introduced into tomato lines. The “ gene Mi-2 ” controls the strains overcoming “ Mi ” but, like the latter, is ineffective at high temperature. On the other hand, " Mi-3 " makes it possible to control the strains adapted to " Mi " and is shown to be stable at high temperature. Breeders are interested in this gene, especially for tomato crops in hot areas and sandy soils, where the temperature rises more at the roots.

Breeding programs, aided by molecular labeling, are now seeking to combine these new resistances with those already available and having proved their worth in the material on the market.

In the longer term, resistance to other pests will be introduced into breeding programs. Hopes exist, for example, to control Verticillium albo-atrum , a race overcoming the “ gene Ve ” , Phytophthora nicotianae, Colletotrichum coccodes, Botrytis cinerea, Pseudomonas syringae pv. tomato (race overcoming the " gene Pto " ) and the Pepino mosaic virus (PepMV). Research is also being conducted to genetically control various insects, but it is too early to predict practical results.