Mapping of the gene in tomato conferring resistance to root-knot nematodes at high soil temperature.

Root-knot nematodes (RKNs, Meloidogyne spp.) can cause severe yield losses in tomatoes. The Mi-1.2 gene in tomato confers resistance to the Meloidogyne species M. incognita, M. arenaria and M. javanica, which are prevalent in tomato growing areas. However, this resistance breaks down at high soil temperatures (>28°C). Therefore, it is imperative that new resistance sources are identified and incorporated into commercial breeding programmes. We identified a tomato line, MT12, that does not have Mi-1.2 but provides resistance to M. incognita at 32°C soil temperature. An F2 mapping population was generated by crossing the resistant line with a susceptible line, MT17; the segregation ratio showed that the resistance is conferred by a single dominant gene, designated RRKN1 (Resistance to Root-Knot Nematode 1). The RRKN1 gene was mapped using 111 Kompetitive Allele Specific PCR (KASP) markers and characterized. Linkage analysis showed that RRKN1 is located on chromosome 6 and flanking markers placed the locus within a 270 kb interval. These newly developed markers can help pyramiding R-genes and generating new tomato varieties resistant to RKNs at high soil temperatures.

First report of root-knot nematode, Meloidogyne incognita on calendula in Turkey.

Calendula officinalis L. (Asteraceae) is a traditional medicinal plant called pot marigold or English marigold. In this study, galled roots of pot marigold were collected from Balikesir province of Turkey and egg masses were picked up from the roots of each plant with fine forceps. DNA was then extracted from samples and analyzed by species-specific primers referring to the most common Meloidogyne spp. Our results showed that Meloidogyne incognita was found as the only species in all the samples taken. The determination of M. incognita on calendula was done for the first time in Turkey.

First report of root-knot nematode, Meloidogyne arenaria, on lavender in Turkey.

Lavender is a medicinal and aromatic plant that is widely grown in Turkey. Gall symptoms were observed on roots of lavender (Lavandula angustifolia Mill.) collected from Kirklareli and Edirne provinces. Egg masses were collected from galled roots. DNA isolated from all samples was screened by species-specific primers belonging to the most common species of root-knot nematodes and M. arenaria was the only species that was identified in all of the samples analyzed. This is the first report of M. arenaria infecting lavender in Turkey.Lavender is a medicinal and aromatic plant that is widely grown in Turkey. Gall symptoms were observed on roots of lavender (Lavandula angustifolia Mill.) collected from Kirklareli and Edirne provinces. Egg masses were collected from galled roots. DNA isolated from all samples was screened by species-specific primers belonging to the most common species of root-knot nematodes and M. arenaria was the only species that was identified in all of the samples analyzed. This is the first report of M. arenaria infecting lavender in Turkey.