Cucumis metuliferus is resistant to root‐knot nematode Mi1.2 gene (a)virulent isolates and a promising melon rootstock

Abstract

Pot experiments were carried out to characterize the response of two Cucumis metuliferus accessions (BGV11135 and BGV10762) against Mi1.2 gene (a)virulent Meloidogyne arenaria, M. incognita and M. javanica isolates and to determine the compatibility and the effect on physicochemical properties of fruit melons. In addition, histopathological studies were conducted. One week after transplanting, plants were inoculated with one J2 cm−3 of sterilized sand (200 cm3 pots) and maintained in a growth chamber at 25 °C for 40 days. The susceptible cucumber cv. Dasher II or melon cv. Paloma were included for comparison. The number of egg masses and number of eggs per plant were assessed, and the reproduction index (RI) was calculated as the percentage of eggs produced on the C. metuliferus accessions compared to those produced on the susceptible cultivars. The compatibility and fruit quality were assessed by grafting three scions, two of Charentais type and one of type piel de sapo, under commercial greenhouse conditions. The resistance level of both C. metuliferus accessions ranged from highly resistant (RI < 1%) to resistant (1% ≤ RI ≤ 10%) irrespective of Meloidogyne isolates. Melon plants grafted onto C. metuliferus accession BGV11135 grew as self‐grafted plants without negatively impacting fruit quality traits. Giant cells induced by Meloidogyne spp. on C. metuliferus were in general poorly developed compared to those on cucumber. Furthermore, necrotic areas surrounding the nematode were observed. Cucumis metuliferus accession BGV11135 could be a promising melon rootstock to manage Meloidogyne spp., irrespective of their Mi1.2 (a)virulence, without melon fruit quality reduction.

Fitness cost but no selection for virulence in Meloidogyne incognita after two consecutive crops of eggplant grafted onto Solanum torvum

“…In addition to the commercially available resistant tomato, pepper and eggplant cultivars and/or rootstocks, some other resistance sources in the Cucurbitaceae family such as Cucumis metuliferus and Citrullus amarus could be used as rootstocks in rotation schemes. Moreover, the resistance of C. metuliferus, C. amarus and S. torvum is also expressed against virulent populations to the Mi-1.2 and N resistance genes (Exp osito et al, 2018;Garc ıa-Mend ıvil et al, 2019b). Plant resistance is an effective and economically profitable control method (Sorribas et al, 2005) that can be durable if it is used in a proper manner (Djian-Caporalino et al, 2011).…”

Cucumis metuliferus reduces Meloidogyne incognita virulence against the Mi1.2 resistance gene in a tomato–melon rotation sequence

“…Paloma were used in the experiments. Seeds of C. metuliferus were germinated as reported in Expósito et al . Tomato seeds were sowed in sterile vermiculite at 25 ± 2 °C.…”

“…The nematode isolate was maintained in susceptible tomato cultivated in pots and identified by the morphology of the perineal pattern and by sequence‐characterized amplified region (SCAR) markers . The Mi1.2 gene and C. metuliferus avirulence status of the isolate were determined previously . The remaining 25% of the soil was planted with non‐inoculated tomato cv.…”

“…In the case of C. metuliferus , the resistance response to RKN is associated with hindrance of larval development, delayed development from second‐stage juveniles (J2) to adults, increased maleness of J2, migration of J2 from the root, differential expression of several genes related to plant defence mechanisms, and the appearance of necrotic areas surrounding the nematode . Rotation sequences including solanaceous and cucurbits species in protected cultivation are very common because these crops represent the main source of income for many growers .…”

“…So, alternating resistant solanaceous cultivars with resistant cucurbitaceous ones could be an efficient way to manage RKN densities by preventing the selection of virulent populations and consequently reducing crop yield losses. C. metuliferus is resistant to RKN populations that are virulent against the Mi1.2 gene, and it is compatible with melon rootstock …”