DEVELOPMENT OF ENDOPHYTE-MEDIATED DISEASE RESISTANCE IN HYBRID POPLAR

Phase I technical objectives address the most pressing consideration in the commercialization of endophyte-mediated resistance (EMR), namely the correlation between lab assays and field results. There are four technical objectives to be resolved in Phase I for effective execution of the Phase II project.Successful endophyte selection and propagation- Objectiveiis to complete thein agarolaboratory assays ofSeptoriaantagonists and thein plantagreenhouse trials ofMelampsoraantagonists. Endophytes gotten from tree and grass seed have already been cultured and are being maintained at the George Newcombe lab in Moscow, Idaho. Objectiveialso encompasses the development of multiplication procedures for scaling the most promising endophytes for Phase I and Phase II field trials. Critical questions are:Is a 'biocontrol complex' that includesBacillus subtilis,and other closely related species, a robust endophyte source for antagonists of poplar's two main fungal pathogens in laboratory and greenhouse trials?How rapidly can endophytes be scaled to quantities sufficient for field trials?The lone technical risk is lab safety. We consider the risk minimal, but standard operating procedures will nonetheless be closely followed.2. Successful test plot establishment- Objectiveiiwill establish replicated test plots in two locations utilizing an experimental design to support objectivesiiiandivand Phase II's analytical priority. One test plot is established at Westport with nineP. × generosavarieties. A land lease with Mississippi State University to install a second test plot, during Phase I, at the Delta Research and Education Center (DREC) in Stoneville with nineP. deltoides×P. maximowicziiclonal varieties. All varieties are Poplar Innovations proprietary property. Technical risks of establishment will be mitigated by:Poplar Innovations' experience in poplar cultivation and plot management that hasproven successful over the past three decades. The Westport plot will be managed by Poplar Innovations' staff. The Stoneville plot will be cared for by DREC personnel who will be guided by Poplar Innovations.Risk factors are wind throw, defoliating insects,and unseasonable drought. Annual coppicing will minimize wind throw at Westport. Irrigation is available at both locations to minimize the drought risk. Cottonwood leaf beetle isexpected at Stoneville, but frequent monitoring and timely applications of insecticide will minimize the defoliation risk.3. Successful endophyte inoculation protocol- A Phase I priority is to determine whether the endophyte inoculation procedure is dependable for Phase II work in which the Westport trial will test for the difference in Melampsora leaf rust infection between treated and control plots while the Stoneville trial will test for differences in Septoria infection. Two technical questions will be considered for objectiveiii:Following an aqueous spray of the bacterium preparation, can the endophyte inoculum be confirmed in treated plots but not in the control plots (i.e. no unintended drift)?Will the volume and distribution of the endophyte spray applied to the field trials during Phase I be adequate or will adjustments be needed?Successful disease evaluation protocol- The objective is to ensure Poplar Innovations has a thorough procedure for Phase II evaluation. Both the Westport and Stoneville trials will be assessed for the EMR effect using a combination of standard and novel evaluation techniques. The technical question is:Can proficiency be developed in using novel evaluation techniques?