Screening and Histopathological Characterization of Korean Carrot Lines for Resistance to the Root-Knot Nematode Meloidogyne incognita

Abstract

In total, 170 carrot lines developed in Korea were screened for resistance to Meloidogyne incognita race 1 to select parental genetic resources useful for the development of nematode-resistant carrot cultivars. Using the gall index (GI), gall formation was examined on carrot roots inoculated with approximately 1,000 second-stage juveniles of the nematode 7 weeks after inoculation. Sixty-one carrot lines were resistant (GI ≤ 1.0), while the other 109 were susceptible (GI > 1.0) with coefficient of variance (CV) of GI for total carrot lines 0.68, indicating low-variation of GI within the lines examined. The histopathological responses of two carrot plants from resistant and susceptible lines were examined after nematode infection. In susceptible carrots, giant cells formed with no discernible necrosis around the infecting nematodes. In the resistant carrot line, however, no giant cells formed, although modified cells were observed with extensive formation of necrotic layers through their middle lamella and around the infecting nematodes. This suggested that these structural modifications were related to hypersensitive responses governed by the expression of true resistance genes. Therefore, the Korean carrot lines resistant to the nematode infection are potential genetic resources for the development of quality carrot cultivars resistant to M. incognita race 1.

Potential Reasons for Prevalence of Fusarium Wilt in Oriental Melon in Korea

“…It is also noticed in our previous studies that remarkably large galls are formed in susceptible carrot lines infected with M. incognita (Seo et al, 2014, 2015). Above-ground symptoms caused by this root-knot nematodes are stunting and yellowing, and sudden wilting especially in hot and dry conditions in summer (Sardanelli et al, 1983).…”

“…Bugang) in a greenhouse (Seo et al, 2014). For inoculum preparation, the plants were uprooted and the entire root system was dipped in water to remove adhering soil.…”

Candidate Gene Analysis Reveals That the Fruit Color Locus C1 Corresponds to PRR2 in Pepper (Capsicum frutescens)

“…Both immature and mature fruit pericarps of AC08 accessions were longitudinally sliced to a thickness of 1 mm. Specimen preparation for TEM was done following the method described by Seo et al (2014). Polymerized samples were than trimmed, sliced to a thickness of 500 nm, stained with toluene blue, and examined under a light microscope.…”

Three-dimensional surface reconstruction and in situ site-specific cutting of the teliospores of Puccinia miscanthi causing leaf rust of the biomass plant Miscanthus sinensis

“…Leaf fragments were fixed and processed as previously reported (Seo et al, 2014). Fragments were immersed in a modified form of Karnovsky's fixative in 0.05 M sodium cacodylate buffer at 4 • C overnight.…”