Phytoparasitica (1997) 25, p. 232 (Chu et al.)

Paul Chu, Phil Larkin and T.J. Higgins (1997)
Transgenic white clover with immunity against Alfalfa mosaic virus (AMV)
Phytoparasitica 25 (3), 232-232
The Xth International Congress of Virology, August 11-16, 1996, Binyanei haOoma, Jerusalem, Israel, poster
Abstract: White clover is the most important pasture legume to the Australian dairy industry and is a major component of improved pastures in the temperate zones of the world. AMV is a major pathogen of white clover worldwide, causing reported yield reductions of up to 40% in infected plants. The objective of this project is to produce AMV-resistant white clover plants by Agrobacterium-mediated gene transfer methods. Several gene constructs comprising the AMV coat protein (CP) gene from either a subgroup I or a subgroup II AMV, driven by either the cauliflower mosaic virus 35S or the Arabidopsis small subunit (ASSU) promoter, and expressing the CP open-reading frame in either plus or minus sense, were transferred into white clover. Transgenic plants were tested for resistance to mechanical inoculation with AMV under glasshouse conditions. Three field isolates of AMV, including representatives of both subgroups of AMV, and mild and severe isolates from white clover, were used at inoculum levels of up to 200 µg/ml. Over 130 independent transgenic lines of white clover of the cvs. 'Haifa' and 'Waverley' were challenged. The results with cv. Haifa showed that when the CP is expressed in the plus sense, only one out of 13 (7.7%) lines was immune to all three AMV isolates when using the 35S promoter but 11 out of 33 (33%) were immune when using the ASSU promoter. However, when the minus sense CP was expressed using the ASSU promoter, no immune lines were obtained out of 28 lines tested. Similar results were obtained with cv. Waverley. In contrast, all the non-transgenic lines were susceptible, with average infection rates of ~85%. Southern, Northern and Western blot analyses showed that there is a direct correlation between immunity and CP expression.
Database assignments for author(s): Philip J. Larkin, Thomas J.V. Higgins

Research topic(s) for pests/diseases/weeds:
resistance/tolerance/defence of host
molecular biology - genes

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Alfalfa mosaic virus	Clover (Trifolium)