ARS | Publication request: Can Pierce’s disease PdR1 resistance introgressed into Vitis vinifera be translocated from a resistant rootstock to a susceptible scion?

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: November 1, 2012
Publication Date: December 12, 2012
Citation: Stenger, D.C., Ramming, D.W., Rogers, E.E. 2012. Can Pierce’s disease PdR1 resistance introgressed into Vitis vinifera be translocated from a resistant rootstock to a susceptible scion?. CDFA Pierce's Disease Control Program Research Symposium. p. 193-196.

Interpretive Summary: Pierce’s Disease (PD) resistance from wild grapevine species has been transferred into Vitis vinifera via classical (non-transgenic) breeding. However, given the extensive number of wine, raisin, and table grape varieties susceptible to PD, introgression into each will be time consuming and costly. In this research, proof of concept experiments were conducted in greenhouse trials to determine if PD resistance in a V. vinifera selection used as a rootstock may be translocated to susceptible V. vinifera scions. Based on first year data, the answer to the question posed by the title is “no”.

Technical Abstract: The goal of this research is to evaluate the potential of a non-transgenic, PD resistant Vitis vinifera selection used as an experimental rootstock to confer systemic resistance to PD susceptible V. vinifera scions. Source of PD susceptible plant material was the wine grape variety ‘Chardonnay’, known to support high populations of Xylella fastidiosa and exhibit severe PD symptoms. Source of PD resistant material was a modified backcross generation 2 (mBC2) raisin selection with PD resistance locus PdR1 introgressed from 89-F0908 (V. rupestris X V. arizonica). Scions were mechanically inoculated with X. fastidiosa strain Stags Leap. PD severity was visually assessed using a nominal 0-5 rating scale where 0 corresponds to no visual symptoms and 5 corresponds to death of the plant. Following development of PD symptoms on the positive control (‘Chardonnay’ as both scion and rootstock), at 14 weeks post inoculation, tissue samples (petioles) were assayed for X. fastidiosa titer by real-time PCR. Results of the first year experiment indicated that PD symptom expression and X. fastidiosa titer in ‘Chardonnay’ scions were not significantly different when grafted onto PD-susceptible or PD-resistant rootstocks. Thus, the preliminary answer to the question posed in the title is “no”. Replication of the experiment in the second year is in progress.