Will low-glucosinolate cultivars of the mustards Brassica juncea and Sinapis alba be vulnerable to insect pests?

Abstract

Will low-glucosinolate cultivars of the mustards Brassica juncea and Sinapis alba be vulnerable to insect pests? Can J. Plant Sci. 77: 283-287. Foliar concentrations of the predominant glucosinolates in the mustards B. juncea (allyl glucosinolate, sinigrin) and S. alba (p-hydroxybenzyl glucosinolate, sinalbin) were determined in lines that had been selected in breeding programs for low levels of glucosinolates in their seeds for the oilseed market. The glucosinolate concentrations found in the cotyledons and leaves of the selected lines were also low, often by three or more orders of magnitude, compared with the unselected parent. The flea beetle, Phyllotreta cruciferae Goeze, and the diamondback moth, Plutella xylostella (L.), (both crucifer specialists) fed at equal rates on B. juncea and its low-glucosinolate lines, indicating that these species are insensitive to sinigrin and suggesting that their pest status on low-glucosinolate lines of B. juncea will likely remain unchanged. By contrast, the bertha armyworm, Mamestra configurata Wlk. (a generalist) fed up to fivefold more on the leaves of low-glucosinolate lines, suggesting that its pest status on low-glucosinolate B. juncea is likely to worsen relative to the mustard B. juncea. Flea beetles, diamondback moth, and the bertha armyworm fed at equal rates on the mustard S. alba and a low-glucosinolate line indicating that the status of these pests on low-glucosinolate S. alba will unlikely be much different from the mustard S. alba.Lines of S. alba differing in their sinalbin concentration by 1000-fold had equal levels of antixenosis resistance in their cotyledons against flea beetles, leaving little doubt that this resistance is independent of glucosinolates. Flea beetle resistance was also detected in the cotyledons of a low-glucosinolate line of B. juncea. The resistance was not detected in the parental line or in another low-glucosinolate line and appears to have arisen fortuitously during crossing and selection. Since resistance occurs in a line with concentrations of sinigrin three or more orders of magnitude lower than non-resistant lines, this resistance is also unlikely to be glucosinolate based. The mustards S. alba and B. juncea are a useful source of cotyledon resistance against flea beetles that is compatible with the aims of oilseed breeding. , montrant que les deux espèces sont indifférentes à la présence de la sinigrine et que, par conséquent, elles conserveront vraisemblablement la même visibilité sur les lignées p.g. En revanche, la légionnaire bertha Mamestra configurata Wlk. (plus polyphage) se nourrissait jusqu'à cinq fois plus à même les feuilles des lignées à basse teneur en glucosinolates, ce qui laisse à penser que sa nuisibilité risque d'empirer sur les lignées de ce type, par rapport avec l'espèce d'origine chez Sinapis alba, le degré d'activité des altises, de la fausse-teigne et de la légion-naire bertha était sensiblement équivalent sur l'espèce non sélectionnée et sur sa lignée p.g., montrant que le degré de nuisibilité sur les...

Plant Growth Promoting Rhizobacteria (PGPR) and Plutella xylostella (L.) (Lepidoptera: Plutellidae) interaction as a resistance inductor factor in Brassica oleracea var. capitata

“…Sinigrin was used in this study as the basis of comparison between the visualized metabolic alterations. This could be related to the results obtained earlier by (29), where it was observed that the absence of sinigrin in plants did not alter the resistance response to the diamondback moth, suggesting that these results are consistent with those of (38). He reported that in Brassica, cultivars with low content of the glucosinolates sinigrin and sinalbin, showed no alteration in the susceptibility to Phyllotreta cruciferae and P. xylostella (specific to crucifers), despite noting a five-fold increase in susceptibility of these cultivars to Mamestra configurata (polyphagous insect).…”

Parental effects inPieris rapaein response to variation in food quality: adaptive plasticity across generations?

“…In other work with Brassica, seed glucosinolate concentrations have been shown to correlate with leaf glucosinolate concentrations and resistance to herbivory (Glen et al, 1990;Bodnaryk, 1997), however these lines represent extremely low levels of variation in glucosinolates compared with the levels in wild plants in the Brassicaceae, which are often orders of magnitude greater (Glen et al, 1990;Bodnaryk, 1997). Five seeds from each of the B. napus lines were planted in 500 ml pots in Pro-Mix soil (Red Hill, Pennsylvania).…”

Influence of prey host plant on a generalist aphidophagous predator: Episyrphus balteatus (Diptera: Syrphidae)

“…When the plant is dam aged and the cell integrity destroyed, the enzyme myrosinase catalyses the degradation of GLS to volatile molecules, mainly isothiocyanates (ITC) (Fahey et al, 2001). The latter are attrac tants and feeding stimulants for several crucifer specialist insects such as Phyllotreta cruciferae Goeze (Coleoptera: Chrysomelidae) and Plutella xylostella L. (Lepidoptera: Plutellidae) (Bodnaryk, 1997). Several Pieridae species such as Pieris rapae L. and P. napi oleracea Harris (Lepidoptera: Pieridae) also use GLS as oviposition stimulants (Huang & Renwick, 1994).…”