Propagation of edible Pecan Truffle (Tuber lyonii) in pecan nurseries

Propagation of edible Pecan Truffle (Tuber lyonii) in pecan nurseries

Summary

This project is focused on the Propagation of the edible Pecan Truffle (Tuber lyonii) in pecan nurseries. There are two main goals for the SARE grant on the pecan truffle: 1) identify the current distribution of the pecan truffle in pecan nurseries, and 2) develop protocols to inoculate seedlings using high-throughput nursery approaches. We have made significant progress on both fronts.

In order to identify the distribution of Tuber lyonii in pecan nurseries, our research team visited 12 pecan nurseries in six states from Texas to Florida during summer 2014. We sampled ectomycorrhizal roots from 60 plants (5 randomly-selected seedings per nursery). The roots from these seedlings were examined microscopically and will soon be submitted for fungal rDNA community sequencing. Results are expected for this aspect of the project during July 2015 and we hope to be able to fully document the frequency and abundance of Tuber lyonii as well as documenting the fungal communities in the pecan nurseries to see the diversity and to determine whether Tuber lyonii commonly co-occurs with some taxa. 

In terms of our efforts to initiate high-throughput inoculation techniques to establish Tuber lyonii on the roots of pecan seedlings, we have established plots of inoculated seedlings at three pecan nurseries in Georgia. Two of the nurseries could only be established in fumigated sites but the third site has been established at the University of Georgia pecan orchard site near Ty Ty, GA. This third orchard is established in a block design that allows for analysis of effects of Tuber inoculation and fumigation in four treatments (Tuber+/Fumigation+, Tuber-/Fumigation+, Tuber+/Fumigation-, Tuber-/Fumigation-). We also have an additional treatment at each site to look at the effect of inoculation dosage. These test nursery sites were established during 2014 but ectomycorrhizal root tips will be harvested at the end of Summer 2015 in order to analyze the results. Preliminary root analysis from a few “early harvest” seedings suggests that: 1) Tuber lyonii was established on inoculated trees in both the Fumigation + and Fumigation – treatments, 2) the community of ectomycorrhizal fungi appears to be very limited in all of the Fumigation+ sites but with only slightly higher diversity in Fumigation – plots. 

Objectives/Performance Targets

Goal 1) identify the current distribution of the pecan truffle in pecan nurseries –
Sampling was rapid and sufficient for this part of the project but the graduate student who had been performing this work has dropped out of graduate school. This has slowed the progress of this work but a new postdoc is now taking up the sequencing and analysis. This new employee is currently reviving this avenue of work.

2) develop protocols to inoculate seedlings using high-throughput nursery approaches – seedlings were successfully established with minimal problems and collaborators have remained helpful and engaged. Once the plants are old enough we will be ready to harvest but preliminary results look strong. 

Accomplishments/Milestones

see above in Summary Section

Impacts and Contributions/Outcomes

Student Maxwell Reitman created and presented a poster for the Mycological Society of America 2014 annual meeting in Michigan to give an overview of this work. Preliminary restuls and outreach were also presented by collaborator Tim Brenneman at the Georgia Pecan growers meeting during 2014. 

Collaborators: