Team:Hong Kong HKUST/HP Product Design

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Product Design - Background

Our circuit, the tri-stable switch, has many possible functions, ranging from bio-computing, cell differentiation to biosensors. This year, we decided to apply our tri-stable switch on something beneficial for the Hong Kong community, which is a biosensor for fungal diseases in trees. By using the tri-stable switch, the chemical which has the highest concentration out of three different target substances can be detected. When used as the tree biosensor, the switch will be used to detect tree wounds as well as two different kinds of fungi which live on the roots of trees. After detecting the presence of a fungus or a wound, the device will release chemicals that can either kill the parasite or heal the tree wounds. We plan to use Liana plants as a potential host for easier delivery of the device to the trees. We hope that this biosensor design would be able to help the Hong Kong Government in reducing accidents caused by falling trees. In the future, the circuit can also be used to detect pests in plants grown in commercial farms.

1) Principle Behind Application: Tree diseases detector

The system senses tree wounds and two fungi that devour the trees’ rigid structural components. The following are the functions of the promoters used:

Promoter Function
1st Promoter
  • Detect phenolic compounds secreted by tree wounds (i.e. phenols, flavonoids and proanthocyanidins) (Vek, Oven, Humar 2012)
  • Induce the switch to produce certain colour of chromoprotein in the sap flow through the surface of the bark.
2nd Promoter
  • Detect acetic acid secreted by Brown Rot fungi (Wang et al., 2014)
3rd Promoter
  • Detect compound like Fe3+ and H2O2 produced by White Rot fungi (Teunissen, Pauline, 2001)

Dealing with infection by two fungal diseases (More than one stimulus stimulating our switch)

  • Detect the dominating inducer, and produce chromoproteins of color in response to that particular stimuli - chemicals will then be used to treat the tree wounds or kill the fungi depending on which color shows up.
  • After the first dominating inducer is dealt with, the next dominating inducer will be detected.

Host Organism of the sensor

  • Liana (climbing plants)
    • Shares the same habitat as the fungus in temperate forest (Schnitzer et al, 2014)
    • Implant the sensor in leaves
    • Go up along the tree trunks and branches
    • Carry the sensor and check every corner of the tree

2) Product Description

  • The product is in the form of genetically engineered Liana plant. It will be planted near the target tree, enabling it to grow and climb up the tree without much care needed.
  • Normal Liana leaves are green-colored. However, when a wound is detected, the Liana sap close to it will turn orange.
  • When there is a presence of brown rot fungi, the sap turns red.
  • When the tree has white rot, the sap turns blue.
  • Liana will be removed if it covers most of the surface area of the tree leaves.

3) Opportunities and Challenges

Aspect Opportunities & Challenges
Technological Opportunities:
  1. The existence of Science Park in Hong Kong as a biotechnology equipment hub.
  2. Tailor made for consumer as the parts can be change to detect other types of fungi and wounds. Tool kit and specific sites for changing the parts will be provided.
Challenges:
  1. Range of concentration by which phenolic and sap flow compounds can be detected is minimal.
  2. Inability to differentiate between damage from fungi versus natural occurrences.
Economical Opportunities:
  1. The parts are reusable, the average cost drops and reduces the invention costs.
  2. Interchangeable. Setting up a library for certain companies, inventors and scientists to access and exchange their parts.
  3. Protection of public property and human life: Prevent the trees to accidentally fall down.
  4. Reduce the cost of maintenance, human resources need to take care of trees.
  5. Reduce pesticide usage. Once the product is applied, no refill is needed.
  6. Early diagnosis: It can be used to prevent tree from falling down.
Legal Opportunities:
  1. Risk assessment protocols have not yet been developed to assess the potential ecological risks associated with synthetic biology and the product.
Challenges:
  1. Environmental safety protocols that regulate the release of biotechnology devices into nature are mostly against constructs made through synthetic biology.
  2. Must seek approval from Convention of Biological Diversity in order to proceed with product development (UNEP, 2012).
Environmental Opportunities:
  1. Protect the Heritage Trees: Old and valuable trees
  2. Reduce fungicides usage: Pesticides can diminish biodiversity, disrupt natural biological equilibrium and contaminate other non-target areas.
Challenges:
  1. Using hosts with short reproductive cycle such as Lianas may enable a rapid distribution of the tri-stable trait across the species, which can create consequences that are unknown to us.
  2. Disruption of the flora’s rhizosphere due to unknown interactions.
Political Challenges:
  1. Hong Kong government is setting up a Biodiversity Strategy and Action Plan – which means that tighter supervision and higher standards will be given by the Innovation and Technology Bureau towards newly formed biotechnological projects such as the tri-stable switch (HK Policy Address, 2016).
Social Challenges:
  1. Safety concerns being raised from the public – mostly due to their lack of awareness and trust towards the Chinese technology regulatory system.

Finally, we cannot finish our project without helps from professors that we had interviewed during summer period. We really appreciate their time answering our questions through email, skype, or face to face interview. These are the name of the professors who assist us with human practices project:

  1. Matthew R. Bennett, Ph.D.
  2. Dr WONG, Alan Siu Lun 黃兆麟
  3. Dr. Daniel Lee
  4. Professor HUANG, Jiandong 黃建東
  5. Professor Adison Wong