Biotech Updates

Expression of Cadherin, APN, and ALP Genes in Diamondback Moth Strains

November 11, 2011

Cadherin proteins, aminopeptidase N (APN), and alkaline phosphatase (ALP) bind to Bacillus thuringiensis (Bt) toxins in the lepidopteran midgut. However, the intrinsic functions of these receptors are not yet known. Z. -X. Yang of Hunan Agricultural University in China, together with other scientists, conducted a study to investigate if these receptors contribute to the resistance of lepidopteran insects to the Bt toxin.

Using real-time quantitative polymerase chain reaction, they examined the transcription patterns of the genes expressing the receptors in Bt toxin-susceptible diamondback moth (Plutella xylostella) strains and strains with high resistance to Bt toxin. The gene expressions of cadherin and APNs were found to be high in the midgut of fourth larval instars and present in the pupae. The transcription levels of cadherin, APN2, and ALP genes in the midgut were more abundant in the susceptible strain compared to the resistant strain. The transcription levels of cadherin increased as the insect developed.

These findings suggest that the differences in expression may be attributed to the adaptation of the resistance strain to the Bt toxin. The results also imply a possible relationship between the gene expression of cadherin, ALP, and APN2 and the resistance of diamondback moth to Bt.

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