Enhancing rice resistance to fungal pathogens by transformation with cell wall degrading enzyme genes fromTrichoderma atroviride
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Three genes encoding for fungal cell wall degrading enzymes (CWDEs),ech42, nag70 andglu78 from the biocontrol fungusTrichoderma atroviride were inserted into the binary vector pCAMBIA1305.2 singly and in all possible combinations and transformed to rice plants. More than 1800 independently regenerated plantlets in seven different populations (for each of the three genes and each of the four gene combinations) were obtained. Theech42 gene encoding for an endochitinase increased resistance to sheath blight caused byRhizoctonia solani, while the exochitinase-encoding gene,nag70, had lesser effect. The expression level of endochitinase but exochitinase was correlated with disease resistance. Nevertheless, exochitinase enhanced the effect of endochitinase on disease resistance when the two genes co-expressed in transgenics. Resistance toMagnaporthe grisea was found in all kinds of regenerated plants including that with singlegluc78. A few lines expressing eitherech42 ornag70 gene were immune to the disease. Transgenic plants are being tested to further evaluate disease resistance at field level. This is the first report of multiple of expression of genes encoding CWDEs fromTrichoderma atroviride that result in resistance to blast and sheath blight in rice.
Key wordsAgrobacterium-mediated transformation Rice sheath blight Rice blast Trichoderma atroviride Chitinase Glucanase
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