Transgenic Tobacco Expressing Zephyranthes grandiflora Agglutinin Confers Enhanced Resistance to Aphids

Plant lectins have been reported as transgenic resistance factors against a variety of insect pests. Herein, homologous analysis demonstrated that Zephyranthes grandiflora agglutinin (ZGA) exhibited high similarity with other monocot mannose-binding lectins (MBLs). Phylogenetic analysis revealed that it had taxonomical relationships with insecticidal MBLs. Subsequently, a plasmid expression vector pBI121 containing zga gene (pBIZGA) was constructed using the zga sequence, under the control of CaMV35S promoter and nos terminator. pBIZGA was then integrated into the genome of Nicotiana tabacum L. Polymerase chain reaction and Southern blot analysis demonstrated that this zga gene was integrated into the plant genome. Western blotting and agglutinating activity analysis also showed that transgenic tobacco plants expressed different levels of ZGA. Carbohydrate inhibition analysis indicated that recombinant ZGA and the native shared the same carbohydrate-binding specificity. Moreover, genetic analysis confirmed Mendelian segregation (3: =1) of the transgenic in T1 progenies. In planta bioassays on T0 plants and their progenies indicated that expressed ZGA had an effect on reducing the survivability and fecundity of tobacco aphids (Myzus nicotianae). These findings demonstrate that the novel zga gene of ZGA can be expressed in crop plants susceptible to various sap-sucking insects.