Transgenic elite indica rice plants expressing CryIAc delta-endotoxin of Bacillus thuringiensis are resistant against yellow stem borer (Scirpophaga incertulas).
Generation of insect-resistant, transgenic crop plants by expression of the insecticidal crystal protein (ICP) gene of Bacillus thuringiensis (Bt) is a standard crop improvement approach. In such cases, adequate expression of the most appropriate ICP against the target insect pest of the crop species is desirable. It is also considered advantageous to generate Bt-transgenics with multiple toxin systems to control rapid development of pest resistance to the ICP. Larvae of yellow stem borer (YSB), Scirpophaga incertulas, a major lepidopteran insect pest of rice, cause massive losses of rice yield. Studies on insect feeding and on the binding properties of ICP to brush border membrane receptors in the midgut of YSB larvae revealed that cryIAb and cryIAc are two individually suitable candidate genes for developing YSB-resistant rice. Programs were undertaken to develop Bt-transgenic rice with these ICP genes independently in a single cultivar. A cryIAc gene was reconstructed and placed under control of the maize ubiquitin 1 promoter, along with the first intron of the maize ubiquitin 1 gene, and the nos terminator. The gene construct was delivered to embryogenic calli of IR64, an elite indica rice cultivar, using the particle bombardment method. Six highly expressive independent transgenic ICP lines were identified. Molecular analyses and insect-feeding assays of two such lines revealed that the transferred synthetic cryIAc gene was expressed stably in the T2 generation of these lines and that the transgenic rice plants were highly toxic to YSB larvae and lessened the damage caused by their feeding.
Nayak
P
P
Plant Molecular and Cellular Genetics Section and Centre for Plant Molecular Biology, Bose Institute, Calcutta, India.
Basu
D
D
Das
S
S
Basu
A
A
Ghosh
D
D
Ramakrishnan
N A
NA
Ghosh
M
M
Sen
S K
SK
D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry; D001427:Bacterial Toxins; D001483:Base Sequence; D017931:DNA Primers; D004731:Endotoxins / Q000032:analysis / Q000096:biosynthesis* / Q000737:chemistry; D005813:Genes, Synthetic; D006460:Hemolysin Proteins; D007915:Lepidoptera / Q000472:pathogenicity*; D008969:Molecular Sequence Data; D012275:Oryza / Q000235:genetics*; D010572:Pest Control, Biological; D030821:Plants, Genetically Modified; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry; D015183:Restriction Mapping
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D017931:DNA Primers; D004731:Endotoxins; D006460:Hemolysin Proteins; D011994:Recombinant Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis