1. Please state project objectives and what work was done this quarter to address them:
This project aims to test SAMP efficacy tests in the field and greenhouse on important citrus varieties in Florida and California. Dr. Megan Dewdney is in charge of all the field trials in FL. A large scale field test on 240 young Hamlin trees with 3 different treatments and 1 control set was laid out in a completely randomized design. A second field test on infected 4-year old Hamlin sweet orange bearing trees was also initiated. In addition, we also performed new greenhouse tests on important citrus varieties in collaboration with Dr. Kris Godfrey (UCD). Fruthermore, we also have surprising findings that SAMP may also suppress CLas in ACP in collaboration with entomologists Dr. Kris Godfrey and Dr. Kerry Mauck (UCR). Thus, SAMP is the only antimicrobial peptide that we know of that has three biological functions: 1) bactericidal activity, 2) inducing host immunity activity and 3) inhibiting ACP activity.
2. Please state what work is anticipated for next quarter:
Test I: Field Test I- SAMP efficacy test on 240 newly planted Hamlin sweet orange trees
Dr. Megan Dewdney started a field trial with a total 240 young Hamlin sweet orange trees to determine the SAMP efficacy on newly planted trees against HLB. The trial will last for at least 2-3 years. The experiment was laid out in a completely randomized design with three treatments and sixty trees per treatment. The treatments are 1. Untreated control, 2. Treatment in the nursery 1 week prior to planting and field applications (10 µM in 158 ml/tree) every 2 months, 3. No nursery treatment with field applications every 2 months starting 10 days post-planting, 4. The injection treatment with Invaio simple injection device. It is expected that the treatment volume will increase as the trees grow over the next two years (Figure 1). We will monitor the tree growth, disease rating, and CLas titer in trees and ACP after this summer.
Test II: Field Test II- SAMP efficacy test on 125 infected 4-year old Hamlin sweet orange trees.
The second field trial was set up to test if SAMP can remediate an HLB-affected young citrus grove. This experiment is ongoing in the Ridge region of Florida on the deep sandy soils. We have located a four-year-old commercial Hamlin sweet orange grove in the Lake Wales region. The trial involves total of 125 bearing trees and was laid out as a randomized complete block design with five blocks and five replicates per block. The treatments in this trial were an untreated control and bimonthly foliar application. Three additional treatments from an additional funding source are to look at the peptide as various injection treatments. These treatments are 2 injections in spring and summer, 3 injections in spring, summer, and fall, and 3 injections per year starting at the same time as the foliar spray (Figure 2). The treatment started from August 2021. We expect to monitor the trial at least for 2 years. We will monitor the tree growth, disease rating, and CLas titer in trees and ACP.
Test III: Three greenhouse trials with important varieties of California which were conducted in BSL3-UC Davis :
A. Tests of SAMP treatment using trunk injection and foliar spray on the early infected tree with Washington Navel orange and Tengo Mandarin trees (Table 1, Figure 3 and 4).Total of 30 Navel trees and 22 Tengo trees
B. Test of using SAMP foliar spray to protect trees from CLas infection with 16 Washington Navel orange.
SAMP has clear disease control and plant protection effect on all the three trials.
3. Please state budget status (underspend or overspend, and why): The budget was spent in full to purchase 100g SAMP.