Aphid Resistance in Florist's Chrysanthemum Induced by Sea Anemone Equistatin Overexpression

Florist's chrysanthemum (Chrysanthemum morifolium Ramat.) belongs to the Asteraceae family and represents the second most important floricultural crop in the world. Most genotypes are sensitive to aphids and infestations can seriously affect the economic value and cause transmission of viruses into this vegetatively propagated crop. The result of artificial diet bioassay showed that equistatin is readily toxic when digested by two tested aphids (Acyrthosiphon pisum, most susceptible and Aphis gossypii) and showed moderate growth inhibition of the peach-potato aphid Myzus persicae. We transformed genotypes 1581 and 4043 using Agrobacterium tumefaciens strain AGL-0 containing the binary vector pBINPLUS carrying the sea anemone equistatin gene under the control of the chrysanthemum RbcS promoter to induce aphid resistance. Leaf disk choice and non-choice as well as whole plant bioassays were carried out to analyze deleterious effect of SAE on population growth of both peach aphid Myzus persicae and cotton aphid Aphis gossypii. Transgenic line with highest expression of SAE in qRT-PCR showed the lowest population growth (about half of control population) in peach aphid and highest mortality (2.75 times of control) in cotton aphid.