ARS | Publication request: Regeneration systems for pyramiding disease resistance into walnut rootstocks

Submitted to: Walnut Research Conference
Publication Type: Proceedings
Publication Acceptance Date: January 1, 2012
Publication Date: January 1, 2012
Citation: Preece, J.E., Vahdati, K., Compton, P., Ibanez, A., Tran, Q., Gunawan, D., Duggal, A., Leslie, C., Tricoli, D., Dandekar, A. 2012. Regeneration systems for pyramiding disease resistance into walnut rootstocks. Walnut Research Conference. 57-64.

Technical Abstract: This study was conducted to regenerate selected walnut rootstocks adventitiously. This is an essential step to be able to produce transgenic walnut rootstocks with superior traits, such as disease resistance. A series of plant tissue culture experiments were conducted on RX1 and VX211 rootstocks with the goal of regenerating plants for future transformation studies. Leaf, floral and microshoot tip explants were placed in vitro on media with different combinations of auxins and cytokinins. Because of a wet winter, floral explants were contaminated with microbes. Leaf explants produced callus, but not organized structures. It was determined that long exposure to 2,4-D was detrimental to growth. Microshoot tip explants established and responded well in vitro on the various media tested. Some microshoot tip explants began to grow preformed shoots. However, others appeared to form organized structures other than leaves that did not produce plants. In one experiment, at least half of RX1 microshoot tips produced 3-4 roots when exposed to low amounts of indolebutyric acid (IBA). A total of 200 microshoot tips of RX1 and 100 microshoot tips of VX211 were inoculated with Agrobacteriu