Complex patterns in tolerance and resistance to pests and diseases underpin the domestication of tomato

Abstract

Summary A frequent hypothesis explaining the high susceptibility of many crops to pests and diseases is that, in the process of domestication, crops have lost defensive genes and traits against pests and diseases. Ecological theory predicts trade‐offs whereby resistance and tolerance go at the cost of each other. We used wild relatives, early domesticated varieties, traditional local landraces and cultivars of tomato (Solanum lycopersicum) to test whether resistance and tolerance trade‐offs were phylogenetically structured or varied according to degree of domestication. We exposed tomato genotypes to the aphid Macrosiphum euphorbiae, the cotton leafworm Spodoptera littoralis, the root knot nematode Meloidogyne incognita and two common insect‐transmitted plant viruses, and reconstructed their phylogenetic relationships using Genotyping‐by‐Sequencing. We found differences in the performance and effect of pest and diseases but such differences were not related with domestication degree nor genetic relatedness, which probably underlie a complex genetic basis for resistance and indicate that resistance traits appeared at different stages and in unrelated genetic lineages. Still, wild and early domesticated accessions showed greater resistance to aphids and tolerance to caterpillars, nematodes and diseases than modern cultivars. Our findings help to understand how domestication affects plant–pest interactions and underline the importance of tolerance in crop breeding.

Tomato Domestication Attenuated Responsiveness to a Beneficial Soil Microbe for Plant Growth Promotion and Induction of Systemic Resistance to Foliar Pathogens

“…In addition, wild relatives and landraces were more susceptible to P. infestans than modern tomato genotypes. These results contrast with the general 'domestication theory, ' which presumes that domesticated cultivars should be highly sensitive while also exhibiting reduced genetic diversity (Yamasaki et al, 2005;Gaillard et al, 2018;Ferrero et al, 2020). In the case of P. infestans, greater resistance in modern germplasm is likely due to targeted breeding efforts that have introgressed specific resistance genes (Ph-1, Ph-2, Ph-3, and Ph-5) (Foolad et al, 2008;Gardner and Panthee, 2010;Panthee and Gardner, 2010).…”

Tomato Domestication Affects Potential Functional Molecular Pathways of Root-Associated Soil Bacteria

“…Just after transplanting, plants were watered with 15:15:15 solution (15% nitrogen, 15% phosphorus and 15% potassium) during 30 min adding-up a volume of 4 l per plant. During the course of the experiment, watering consisted of 30 min of water twice in a week (Mondays and Fridays) [ 41 ]. At harvest, the soil attached to the main and secondary roots was taken by shaking, placed in separate plastic bags, and kept at 4 °C.…”

Characterization of the detrimental effects of type IV glandular trichomes on the aphid Macrosiphum euphorbiae in tomato

“…‘Moneymaker’ (MM). The clonal population was established from an individual gravid female coming from an infested tomato field (in Aranjuez, Spain); aphids were reared on tomato plants inside insect‐proof cages (46.5 × 46.5 × 46.5 cm) in a climatic chamber at 22–25 °C 65% of relative humidity (HR) and a L16:D8 photoperiod 25 . Plants were watered twice a week.…”

“…Cultivated tomato shows in general low levels of anti‐herbivore substances (acylsugars among others) compared with wild relatives, making them more susceptible to a wide range of pests 12,25 . However, traditional breeding techniques allow the introgression of defensive traits from wild relatives into cultivated tomato.…”