Unexpected effects of chitinases on the peach-potato aphid (Myzus persicae Sulzer) when delivered via transgenic potato plants (Solanum tuberosum Linné) and in vitro.
With the aim of producing insect-resistant potato plants, internode explants of Solanum tuberosum L. cv. Désirée were transformed with an Agrobacterium strain C58pMP90 containing an insect (Phaedon cochleariae: Coleoptera, Chrysomelidae) chitinase gene and the neomycin phosphotransferase (nptII) gene as selectable marker, both under the control of the viral CaMV 35S promoter. Three transformed potato lines (CH3, CH5 and CH25) exhibiting the highest chitinolytic activities were selected for feeding experiments with the peach-potato aphid, Myzus persicae (Sulzer), under controlled photoperiod and temperature conditions. Aphids fed on transgenic potato plants showed a reduced pre-reproductive period and an enhanced daily fecundity. Transgenic potato lines did not affect nymphal mortality, but improved several biological parameters related to aphid population's growth. Artificial diets were used to provide active (1, 10, 100 and 500 microg ml(-1)) and inactive (500 microg ml(-1)) bacterial (Serratia marcescens) chitinase to M. persicae. These compounds increased nymph survival at all active chitinase doses when compared to the control diet, while inactive chitinase did not. Although the pre-reproductive period was slightly shortened and the daily fecundity slightly higher, active and inactive chitinase provided as food led a reduction from 1 to 1.5 day population's doubling time. Therefore chitinase activity was responsible for the probiotic effects on aphids. Our results question the relevance of a chitinase-based strategy in the context of potato culture protection.
Saguez
Julien
J
Biologie des Entomophages (UPRES EA 3900), Université de Picardie Jules Verne, 33 rue Saint Leu, 80039 Amiens Cedex, France.
Hainez
Romaric
R
Cherqui
Anas
A
Van Wuytswinkel
Olivier
O
Jeanpierre
Haude
H
Lebon
Gaël
G
Noiraud
Nathalie
N
Beaujean
Antony
A
Jouanin
Lise
L
Laberche
Jean-Claude
JC
Vincent
Charles
C
Giordanengo
Philippe
P
D000818:Animals; D001042:Aphids / Q000472:pathogenicity*; D001483:Base Sequence; D015152:Blotting, Northern; D002688:Chitinases / Q000008:administration & dosage / Q000235:genetics / Q000494:pharmacology*; D017931:DNA Primers; D030821:Plants, Genetically Modified / Q000235:genetics*; D016133:Polymerase Chain Reaction; D027861:Prunus / Q000469:parasitology; D011198:Solanum tuberosum / Q000235:genetics* / Q000469:parasitology
D017931:DNA Primers; D002688:Chitinases