Abstract
Current and future global crop yields depend upon soil quality to which soil organisms make an important contribution. The European Union seeks to protect European soils and their biodiversity for instance by amending its Directive on pesticide usage. This poses a challenge for control of Globodera pallida (a potato cyst nematode) for which both natural resistance and rotational control are inadequate. One approach of high potential is transgenically based resistance. This work demonstrates the potential in the field of a new transgenic trait for control of G. pallida that suppresses root invasion. It also investigates its impact and that of a second transgenic trait on the non-target soil nematode community. We establish that a peptide that disrupts chemoreception of nematodes without a lethal effect provides resistance to G. pallida in both a containment and a field trial when precisely targeted under control of a root tip-specific promoter. In addition we combine DNA barcoding and quantitative PCR to recognise nematode genera from soil samples without microscope-based observation and use the method for nematode faunal analysis. This approach establishes that the peptide and a cysteine proteinase inhibitor that offer distinct bases for transgenic plant resistance to G. pallida do so without impact on the non-target nematode soil community.
Highlights
Arable agriculture must remain productive and become more sustainable than in past decades [1]
The second new aspect aimed to enhance biosafety of the transgenic approach by restricting expression of the peptide to root tips using a tissuespecific promoter (MDK4–20) that we have previously described from Arabidopsis [20]
Root exudates of all transgenic lines were screened for their ability to inhibit alkaline phosphatase in comparison to exudates from wild-type plants
Summary
Arable agriculture must remain productive and become more sustainable than in past decades [1]. An example consequence is that the pesticides currently applied to 23% of UK potato fields to control potato cyst nematode (PCN) may be withdrawn either abruptly or progressively thereby doubling the economic cost of this pest, in the UK alone, to £56 m/year [5,6] This is a serious concern as one of the two species of PCN, Globodera pallida, is difficult to control by either crop rotation or the partially resistant potato cultivars available against it [7]. The expression of a plant cysteine proteinase inhibitor (cystatin) in potato roots controls potato cyst nematode (Globodera spp) by impairing digestion of its dietary protein [8,9,10] Growth of these GMNR plants did not harm above ground organisms [11,12] or soil microarthropods [13] in potato fields. A second sensitive approach (community level physiological profiles) that measures substrate use by rhizosphere bacteria did not identify changes imposed by the cystatin-expressing transgenic potato plants but readily detected the consequences of growing different conventional crops [15]
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