Potential of wild Solanum stramonifolium accesses as rootstock resistant to soilborne pathogens in tomato crops

<div><p>ABSTRACT Resistant rootstocks is one of the most effective method to control soilborne pathogens in tomato crops. Thus, this study was installed to evaluate the reaction of Solanum stramonifolium accesses to Fusarium oxysporum f. sp. lycopersici (Fol) races 2 and 3 and to Meloidogyne enterolobii (Me). The seedlings were grown in trays and inoculated separately with Fol races 2 and 3 at 50 days after planting by immersing the roots in the spore suspension (1×106 microconidia mL-1). Then, seedlings were transplanted in pots containing sterilized soil and kept in greenhouse conditions. To study the reaction of S. stramonifolium accesses to nematodes, we used 27-day old seedlings that were also planted in pots and inoculated with 6,000 eggs and second-stage juveniles in greenhouse conditions. The experiments were evaluated in the 34th day (Fol) and in the 64th day (Me) after inoculation. The experiment consisted of a randomized block design with five replications, where each plot consisted of one pot with three plants (Fol) and one pot with one plant (Me). We observed that the plants used as controls, susceptible to Fol races 2 and 3 and Me, presented 100% of incidence. All accesses were resistant to Fol race 2 and the accesses CNPH-19, CNPH-22, CNPH-23, CNPH-25, CNPH-120, CNPH-122 and CNPH-349 presented multiple resistance to pathogens, indicating great potential for using as resistant rootstock. The CNPH-24, CNPH-119, CNPH-121 and CNPH-336 accesses also presented resistance to nematode. However, they presented slight browning symptoms of vascular tissues when they were inoculated with Fol race 3. This symptom was also observed in the CNPH-21, CNPH-107 and CNPH-117 accesses. All other accesses were resistance to Fol race 3 and susceptible to Me.</p></div

Reaction of squash and butternut squash genotypes to Phytophthora capsici

<p></p><p>ABSTRACT Phytophthora capsici causes significant losses in squash (Cucurbita moschata) and butternut squash (Cucurbita maxima), including root and crown rot, leaf blight and fruit rot, which can result in up to 100% loss in production. The objective of this study was to evaluate the reaction of squash and butternut squash genotypes to P. capsici. Initially an experiment was conducted to evaluate the aggressiveness of isolates of P. capsici from different regions. Later two experiments were carried out in a greenhouse with 16 genotypes of C. moschata and seven of C. maxima in different years, using the most aggressive isolates, PCA 40 and PCA 43 identified as the most aggressive in a preliminary test. As control we used the hybrid cultivar Jabras and the pepper cultivar Cascadura Ikeda (susceptibility patterns to the pathogen). The genotypes were sown in pots of four liters containing autoclaved soil. Fourteen days later, plants were inoculated by depositing 3.0 mL of the suspension of 2.0x104 zoospores/mL in the soil, near to plant stem. The disease incidence was evaluated 8 days after inoculation. The experiments were conducted in a randomized block design with five replicates of four plants. The genotypes showed different levels of disease resistance, TX 10350, PHYT-043, CNPH-3001-1 and MAM-2523-1 stood out because they showed greater degree of resistance to P. capsici in both trials. However, none of the genotypes showed complete resistance. The results indicate the promising use of these genotypes to obtain resistant lines, aiming to obtain hybrid cultivars resistant to Phytophthora root rot.</p><p></p