Wednesday, May 7, 2025
University of Hawaii at Manoa
University of Hawaii System
College of Tropical Agriculture and Human Resources
 
Submit Samples for GUS
Procedure for Collecting Papaya Leaf Samples for GE Testing via the GUS Assay

Here we describe how you can collect and submit a free leaf tissue sample to determine if your papaya plant is genetically engineered (GE)!

1. Collect an immature leaf from the top of the papaya plant. Avoid leaves from side branches. The sample leaf must be a small, immature leaf from the top (growing point) of the plant. It will be yellow- green and transparent; do not sample larger leaves that are dark green and opaque—they are too mature. The petiole (stalk) of the leaf should be less than 2 inches long. The longest dimension of the leaf blade should be about 1–11/2 inches.


2. Put the sampled leaf (with its petiole attached) into a plastic zip-lock bag, and mark the bag clearly with an identification code that will allow you to find the plant again. Use a separate bag for each tree sampled. Fill in the form available at www.ctahr.hawaii.edu/nelsons/GE_sample_form.pdf and include it with the samples. Note: Samples sent without this GUS form will not be processed or tested.

3. If many trees are sampled, make a map with the tree locations and codes for future reference. Samples that are not adequately labeled to identify the sample site will not be accepted for analysis.

4. Send the samples to the laboratory as soon as possible. The samples should be kept cool and steps should be taken to prevent over-heating in shipment. If samples cannot be mailed or delivered immediately, they should be refrigerated (do not freeze them) until mailing or delivery is possible.

Samples may need to be taken again if the leaf sample received is severely deteriorated (the fee for the original sample submission will cover analysis of the re-sampled tissue).

Submitting papaya leaf samples for the GUS assay

 Use the following link to download the sample submission form needed for GUS testing to determine the GE status of your papaya plant(s): www.ctahr.hawaii.edu/nelsons/GE_sample_form.pdf
Hand delivery


Hand deliver papaya leaf samples to either of the following addresses:

Pic-a-Papaya Program
UH Magoon Research & Instructional Facilities

2717 Woodlawn Drive

Honolulu, HI 96822

Hours: M-F 7:00 AM - 3:00 PM

Pic-a-Papaya Program

UH Urban Garden Center

955 Kamehameha Highway

Pearl City, HI 96782

Hours: M-F 7:45 AM - 4:30 PM

Mail 

Would you rather mail your leaf sample for the GE test? If so, you may post to the following address:


Pic-a-Papaya Program
TPSS Department

University of Hawaii at Manoa

3190 Maile Way

Honolulu, HI 96822


E-mail: carica@hawaii.edu
When to deliver?

Samples submitted through our offices should be freshly taken and received at those offices on Mondays or before noon on Tuesdays. 

This will ensure that they are delivered to us in a timely fashion that avoids tissue deterioration.


 

Mahalo for your participation!
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