Low Outcrossing from an Apple Field Trial Protected with Nets

Abstract

Regulatory compliance of experimental releases into the environment of not yet approved genetically modified plants often requires implementation of measures to reduce the dispersal of reproductive material. To study the impact of nets on pollen flow in an experimental field site in Switzerland, non-GM apple varieties ‘Ladina’ and ’Nicogreen’ were planted inside and outside a netted plot, respectively. Seeds harvested from mature fruits were germinated and the paternal variety of the seedlings was determined using simple sequence repeat (SSR) molecular markers. We demonstrate that pollination frequency from trees inside the netted plot to trees outside over a two-year (2018 and 2019) study of 4500 seedlings is 0.6% (26 seedlings). Moreover, these outcrossing events decreased with increasing distance from the pollen donor. Over the study period, we found on average 0.9%, 0.5%, 0.4% and 0.09% of the seedlings derived from apples of ‘Nicogreen’ trees at 8 m, 15 m, 72 m and 117 m being generated by fertilisations of ‘Ladina’ pollen, respectively. In comparison, 48.3% (2018 season) and 75.1% (2019 season) of examined ‘Ladina’ seedlings in the netted plot originated from ‘Nicogreen’ tree pollen outside the netted plot. The results suggest that insect netting is effective in minimizing egress of apple pollen from an experimental site and that the likelihood of outcrossing is reduced further (<0.1%) when there are no compatible apple trees within a radius of 100 m of the pollen donor. These data are important for biosafety research/regulation to aid understanding of pollen flow in experimental field sites.

A Drone-based Application for Scouting Halyomorpha halys Bugs in Orchards with Multifunctional Nets

“…Modern orchards use multifunctional nets on top and on sides not only to protect the crops from hail (see Fig. 2), but also to make it more difficult for for pests (both insects and birds) to enter and infest the trees [6], [7]. Due to the nets, drones cannot fly over the trees to take pictures of bugs, but can only move along the aisles.…”

Insect Pollinator Monitoring in and around a Netted Plot of Apple Trees—Biosafety Implications for Genetically Engineered Fruit Trees

“…The experimental field site is described in detail in [14]. In short, a netted plot (30 × 70 m) at Agroscope Reckenholz (Zurich, Switzerland; 47.4279 • N, 8.5225 • E) harboured trials with one cisgenic and six non-GE 'Gala' genotypes [2,14,21].…”

“…Because no prior knowledge about the effectiveness of netted orchards on reducing pollen dispersal was available, biosafety measures involved flower removal or emasculation of experimental and control plants so that no GE-pollen was released. The realized pollinations across the netting, however, was measured by Schlathölter et al [14] using two cross-compatible non-GE apple varieties, one inside and one outside the netted plot. The netting reduced cross-pollinations effectively, but could not prevent them completely.…”

“…The netting reduced cross-pollinations effectively, but could not prevent them completely. While [14] focused on genetic analyses of apple seedlings to detect in-and outcrossing events, the aim of the current study was to quantify arthropod populations, particularly pollinators, within and outside the netted plot. Over a four-year period (2016-2019), arthropods were monitored with coloured pan traps and flower visitation observations, two methods that are often used to monitor flower-visiting arthropods [15][16][17][18][19][20].…”

“…Over a four-year period (2016-2019), arthropods were monitored with coloured pan traps and flower visitation observations, two methods that are often used to monitor flower-visiting arthropods [15][16][17][18][19][20]. The obtained data are discussed in the context of the cross-pollination data [14].…”