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Title: Chitinase gene construct from Trichoderma harzianum proved effective against onion purple blotch caused by Alternaria porri
Authors: Mythili, J B
Chethana, B S
Rajeev, P R
Ganeshan, Girija
Keywords: Chitinase;Purple blotch;Transgenic plants;Tobacco;Trichoderma harzianum
Issue Date: Jan-2018
Publisher: NISCAIR-CSIR, India
Abstract: Purple blotch caused by Alternaria porri (Ellis) Ciffis the most devastating disease of onion prevalent in different parts of the country. In the absence of a resistant variety in the gene pool, gene transfer technique becomes appropriate as an alternative tool for genetic improvement. Accordingly, chitinase gene especially from the biocontrol agent Trichoderma harzianum┬áRifai which is used against several fungal pathogens was selected as the candidate gene. Onion transformation is difficult and Allium species are recalcitrant to transformation. Hence, before using this gene for transforming onion for conferring resistance/tolerance to Alternaria porri, chitinase gene was validated against purple blotch pathogen in a model plant system, tobacco. Tobacco transformants with T. harzianum chitinase (Th-chit) gene under the control of a strong constitutive CaMV 35S promoter with NPT-II selection marker were generated. The presence and expression of the transgene was confirmed through PCR and RT-PCR analysis, respectively. Bioassay of primary transgenic plants against A. porri through in vitro detached leaf bioassay revealed significant reduction in lesion size ranging from 73 - 100% as well as mycelial inhibition to the extent of 25 - 65% over the control (untransformed) plants. The results suggest that chitinase gene from T. harzianum can be used as a candidate gene for conferring resistance to A. porri in onion.
Page(s): 50-56
ISSN: 0975-0967 (Online); 0972-5849 (Print)
Appears in Collections:IJBT Vol.17(1) [January 2018]

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