Abstract
Functional characterization of two novel endoglucanase genes, Pv-eng-5 and Pv-eng-8, of the root-lesion nematode Pratylenchus vulnus was carried out. In situ-hybridization experiments revealed that Pv-eng-8 transcript was localized in the pharyngeal glands. Silencing of Pv-eng-5 and Pv-eng-8 resulted in a significant reduction of expression level (52% and 67%, respectively). Furthermore, the silencing of Pv-eng-8 determined a reduction (41%) in nematode reproduction, suggesting that treated nematodes are much less able to process food. Surprisingly, no significant difference on reproduction rate was observed with Pv-eng-5 dsRNA nematodes, suggesting a neofunctionalization of Pv-eng-5 despite the high similarity with nematode endoglucanases. Pratylenchus species are poikilothermic organisms showing close relationships with the environmental temperature. The effects of different temperature ranges revealed that the reproductive potential of P. vulnus increased with increasing temperature from 23 °C to 28 °C, but no reproduction was observed at 33 °C. In real time, increasing temperature from 23 °C to 28 °C the heat shock gene Pv-hsp-90 was differentially expressed in adult stages, while the levels of the effector genes Pv-eng-1 and Pv-eng-8 in females showed no significant differences compared to those observed at 23 °C, only in males Pv-eng-8 level decreased (45%). The upregulation of Pv-hsp-90 in both adult stages suggests a protective mechanism in order to cope with unfavorable environmental conditions.
Highlights
Root-lesion nematodes (RLN) belonging to the genus Pratylenchus Filipjev 1936 [1] are among the most damaging plant parasitic nematodes for a wide range of horticultural and ornamental plants ranking third, in terms of worldwide economic losses [2,3,4]
All plant species contain the same sets of polysaccharides, their relative amounts and layout within the cell wall differ depending on the plant species, cell type, and position and phase of growth and differentiation
These cellulases, except for those found in B. xylophilus and X. index, belong to the glycosyl hydrolase family 5 (GHF5) of β-1,4-endoglucanases and comprise two main categories: catalytic domain with and without a cellulose binding domain
Summary
Root-lesion nematodes (RLN) belonging to the genus Pratylenchus Filipjev 1936 [1] are among the most damaging plant parasitic nematodes for a wide range of horticultural and ornamental plants ranking third, in terms of worldwide economic losses [2,3,4]. Pratylenchus spp. that do not have specialized feeding sites, need to secrete enzymes able to degrade cell wall polysaccharides and soften the walls, enabling the nematodes to feed, migrate, and at last to suppress host defenses. The numbers and types of cellulases produced were found to vary among different nematode species [8,9,13,14,19,20]. These cellulases, except for those found in B. xylophilus and X. index, belong to the glycosyl hydrolase family 5 (GHF5) of β-1,4-endoglucanases and comprise two main categories: catalytic domain with and without a cellulose binding domain
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