New sources of resistance to Meloidogyne incognita race 3 in wild cotton accessions and histological characterization of the defence mechanisms
Carregando...
Data
2013
Título da Revista
ISSN da Revista
Título de Volume
Editor
Resumo
Accessions of Gossypium spp., some of them never previously tested, were evaluated for resistance to a local isolate of
Meloidogyne incognita race 3 in greenhouse experiments. Nematode infection was characterized based on the galling
and egg mass indexes and the reproduction factors (RF). Root-knot nematode reproduction among the newly tested
accessions varied from highly susceptible (AS0188, AS0189) to moderately resistant (MT123 no. 3), and some accessions
showed highly reduced nematode reproduction (CIR1343, CIR1348, Fai Mui). Histological observations of two
resistant accessions (G. barbadense CIR1348 and G. hirsutum TX-25, respectively) showed that resistance occurs
through a two-stage mechanism in the first accession and through a single-stage mechanism in the second. Parasitism is
blocked early after second-stage juvenile (J2) penetration or during its initial tissue migration (CIR1348) and the development
of later-stage juveniles into female adults is suppressed at a later stage (TX-25 and CIR1348). Fluorescence
and bright light microscopy showed that root cells surrounding nematodes exhibit a hypersensitivity-like reaction, with
the accumulation of presumably phenolic compounds and the presence of necrotic cells that limit the development of
nematodes and the formation of giant cells. Underdeveloped giant cells with degenerated cytoplasmic content were
found in small numbers in CIR1348 and in large numbers in TX-25, along with deformed nematodes. The full characterization
of the defence mechanisms of novel sources of resistance to the root-knot nematode in cotton constitutes a
first step towards their use in crop improvement.
Descrição
Palavras-chave
Gossypium spp., Meloidogyne incognita, Host plant resistance, Hypersensitive response
Citação
ROCHA, M. R. et al. New sources of resistance to race 3 in wild cotton accessions and histological characterization of the defence mechanisms. Plant Pathology, Worcester, v. 62, n. 13, p. 1173–1183 , Dec. 2013.