Rice production is known to be severely affected by virus transmitting rice pests, brown planthopper (BPH) and green leafhopper (GLH) of the order hemiptera, feeding by phloem abstraction.
ASAL, a novel
lectin from leaves of garlic (Allium sativum) was previously demonstrated to be toxic towards hemipteran pests when administered in artificial diet as well as in
ASAL expressing transgenic plants. In this report
ASAL was targeted under the control of phloem-specific Agrobacterium rolC and rice
sucrose synthase-1 (RSs1) promoters at the insect feeding site into popular rice cultivar, susceptible to hemipteran pests. PCR, Southern blot and C-PRINS analyses of transgenic plants have confirmed stable
T-DNA integration and the transgenes were co-segregated among self-fertilized progenies. The T(0) and T(1) plants, harbouring single copy of intact
T-DNA expression cassette, exhibit stable expression of
ASAL in northern and western blot analyses. ELISA showed that the level of expressed
ASAL was as high as 1.01% of total soluble
protein. Immunohistofluorescence localization of
ASAL depicted the expected expression patterns regulated by each promoter type. In-planta bioassay studies revealed that transgenic
ASAL adversely affect survival, growth and population of BPH and GLH. GLH resistant T(1) plants were further evaluated for the incidence of tungro disease, caused by
co-infection of GLH vectored Rice tungro bacilliform virus (RTBV) and Rice tungro spherical virus (RTSV), which appeared to be dramatically reduced. The result presented here is the first report of such GLH mediated resistance to
infection by RTBV/RTSV in
ASAL expressing transgenic rice plant.