Field resistance to Fusarium oxysporum and Verticillium dahliae in transgenic cotton expressing the plant defensin NaD1.

Yolanda M Gaspar,Jillian Hinch,Robyn L Heath,Angela A Connelly,Simon Poon,James A Mckenna,Marilyn A Anderson,Bruce S Mcginness

doi:10.1093/jxb/eru021

Yolanda M Gaspar, Jillian Hinch + Show 6 more

Open Access

https://doi.org/10.1093/jxb/eru021

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Abstract

The plant defensin NaD1, from Nicotiana alata, has potent antifungal activity against a range of filamentous fungi including the two important cotton pathogens, Fusarium oxysporum f. sp. vasinfectum (Fov) and Verticillium dahliae. Transgenic cotton plants expressing NaD1 were produced and plants from three events were selected for further characterization. Homozygous plants were assessed in greenhouse bioassays for resistance to Fov. One line (D1) was selected for field trial testing over three growing seasons in soils naturally infested with Fov and over two seasons in soils naturally infested with V. dahliae. In the field trials with Fov-infested soil, line D1 had 2-3-times the survival rate, a higher tolerance to Fov (higher disease rank), and a 2-4-fold increase in lint yield compared to the non-transgenic Coker control. When transgenic line D1 was planted in V. dahliae-infested soil, plants had a higher tolerance to Verticillium wilt and up to a 2-fold increase in lint yield compared to the non-transgenic Coker control. Line D1 did not exhibit any detrimental agronomic features compared to the parent Coker control when plants were grown in non-diseased soil. This study demonstrated that the expression of NaD1 in transgenic cotton plants can provide substantial resistance to two economically important fungal pathogens.

Highlights

Fungal diseases are a major threat to global food security (Pennisi, 2010; Fisher et al, 2012) and are the major causal agent affecting agricultural crop yields (Oerke, 2006)
One line (D1) was selected for field trial testing over three growing seasons in soils naturally infested with Fov and over two seasons in soils naturally infested with V. dahliae
When transgenic line D1 was planted in V. dahliae-infested soil, plants had a higher tolerance to Verticillium wilt and up to a 2-fold increase in lint yield compared to the non-transgenic Coker control

Summary

Introduction

Fungal diseases are a major threat to global food security (Pennisi, 2010; Fisher et al, 2012) and are the major causal agent affecting agricultural crop yields (Oerke, 2006). There are several examples of improved host resistance to fungal pathogens created by the transgenic expression of plant defence molecules. These include proteins from several classes; hevein-like (Koo et al, 2002), glucanases and chitinases (Jach et al, 1995), protease inhibitors (Charity et al, 2005), thionins (Epple et al, 1997; Chan et al, 2005; Oard and Enright, 2006), and defensins (Terras et al, 1995; Gao et al, 2000). NaD1 inhibits the in vitro spore germination and growth of several agriculturally important fungal pathogens (Lay et al, 2003a; van der Weerden et al, 2008, 2010). Significant resistance of one transgenic cotton line to the fungal pathogens Fov and V. dahliae is demonstrated in 3 years of field trials

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