Apple Micrografting Protocol to Establish Transgenic Clones on Field Ready Rootstock

Abstract

<jats:p>A protocol for micrografting shoot tips harvested from in vitro shoot cultures directly to transplanted rootstock plants in the greenhouse was developed. Shoot tips of the apple (<jats:italic>Malus domestica)</jats:italic> cultivars Golden Delicious, Granny Smith and Fuji clone, Nagafu12, were harvested, stored in a water bath then prepared for grafting by cutting the stem immediately below the tip into a wedge shape leaving the tip approximately 3 mm (0.12 inch) long. The rootstock cultivar, Malling 9 (M.9) (<jats:italic>M. domestica</jats:italic>), was prepared by cutting into a young fast growing side branch to expose the cambium, creating a pocket into which the shoot tip was inserted. The cut section of the tip was oriented so as to contact the exposed rootstock cambium and was held in place by wrapping with a strip of pliable plastic film. Two weeks later the wrapping was loosened and the grafted branch cut back. Side branches of the rootstock were not removed until later in order to support rootstock growth. The scion shoots developed into nursery whips suitable for transplanting to a screen house or field after 2 months. The protocol proved to be a simple efficient way to rapidly grow nursery trees from tissue culture clones developed in genetic modification experiments and was used to propagate several hundred plants. Grafting success was often 100% but was reduced if quality of shoot tips was poor due to injury indicated by brown tip color. The protocol eliminates the steps of rooting, acclimatizing and growing shoots into plants to serve as a scion wood source.</jats:p>

Overexpression of BpMADS4 from silver birch (Betula pendula Roth.) induces early‐flowering in apple (Malus × domestica Borkh.)

“…1977, Hipps 1992) as well as grafting of micrografts and apple seedling scions on to rootstocks could initiate the transition (Aldwinckle 1976, Hackett 1985, Richardson et al. 1996, Lane et al. 2003).…”

Shoot regeneration from organogenic callus of sweet cherry (Prunus avium L.)

“…For this reason, regenerated shoots were grafted rather than rooted. Advantages of grafting shoots are discussed in more detail by Lane et al (2003). Once grafted, scion growth occurs after the union of cambium tissue between the scion and rootstock, or graft union, is established (Raharjo and Litz 2005).…”

“…Once grafted, scion growth occurs after the union of cambium tissue between the scion and rootstock, or graft union, is established (Raharjo and Litz 2005). Acclimatization of the scion to greenhouse conditions is achieved as it emerges from the Parafilm covering (Lane et al 2003). Bhagwat and Lane (2004) achieved a high frequency of rooted shoots (85%) of the cultivar Lapins, but plantlet survival decreased during acclimatization to greenhouse conditions (20%).…”

“…Rootstocks broke dormancy 1 month after transfer to the greenhouse. Shoots were then maintained following the procedure of Lane et al (2003).…”

“…Grafting was performed according to the detailed protocol of Lane et al (2003). Briefly, scions were cut into a wedge shape and inserted into a slit made in the rootstock.…”