Transgenic cucumber plants harboring a rice chitinase gene exhibit enhanced resistance to gray mold (Botrytis cinerea) |
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Authors: | Y Tabei S Kitade Y Nishizawa N Kikuchi T Kayano T Hibi K Akutsu |
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Institution: | (1) National Institute of Agrobiological Resources (NIAR), Tsukuba, Ibaraki 305, Japan Fax-no.: +81-298-38-7073 E-mail: tabei@s.affrc.go.jp, JP;(2) Faculty of Agriculture, Ibaraki University, Ami-machi, Ibaraki 300-03, Japan, JP;(3) Faculty of Agriculture, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan, JP |
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Abstract: | A rice chitinase cDNA (RCC2) driven by the CaMV 35S promoter was introduced into cucumber (Cucumis sativus L.) through Agrobacterium mediation. More than 200 putative transgenic shoots were regenerated and grown on MS medium supplemented with 100 mg/l kanamycin.
Sixty elongated shoots were examined for the presence of the integrated RCC2 gene and subsequently confirmed to have it. Of
these, 20 were tested for resistance against gray mold (Botrytis cinerea) by infection with the conidia: 15 strains out of the 20 independent shoots exhibited a higher resistance than the control
(non-transgenic plants). Three transgenic cucumber strains (designated CR29, CR32 and CR33) showed the highest resistance
against B. cinerea: the spread of disease was inhibited completely in these strains. Chitinase gene expression in highly resistant transgenic
strains (CR32 and CR33) was compared to that of a susceptible transgenic strain (CR20) and a control. Different responses
for disease resistance were observed among the highly resistant strains. CR33 inhibited appressoria formation and penetration
of hyphae. Although CR32 permitted penetration of hyphae, invasion of the infection hyphae was restricted. Furthermore, progenies
of CR32 showed a segregation ratio of 3:1 (resistant:susceptible). As the disease resistance against gray mold was confirmed
to be inheritable, these highly resistant transgenic cucumber strains would serve as good breeding materials for disease resistance.
Received: 31 March 1996 / Revision received: 2 July 1997 / Accepted: 18 July 1997 |
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Keywords: | Cucumber Transformation Agrobacterium tumefaciens Chitinase Botrytis cinerea Disease resistance |
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