Plant Metabolic Engineering: Opportunities for Plant Phenotyping

During the course of the past decade our research has focused on engineering sugarcane to produce high levels of the biopolymer polyhydroxyalkanoate (PHA), and aromatic feedstock chemical p-hydroxybenzoic acid.  Our goal is to help wean the world off of petroleum by generating high biomass feedstock crops with value added products for lignocellulosic biorefineries. Producing PHA in these types of crops has advantages for both sides.  As the plants are dismantled to get the sugars out of the cellulose and hemicellulose, our biopolymer is released from where it is manufactured in the plant cells. The PHA isolated is then a value added chemical right at the beginning of biorefinery process. The energy used to make the polymer comes directly from sunshine which is free and the substrate to make the polymer is atmospheric CO₂, both of which are free. The plant makes the acetyl-CoA and supplies the reducing power. We have successfully targeted PHA production to the plastids and peroxisomes of the entire sugarcane plant or just to the leaves.  This engineering has resulted in plants that have a range of phenotypes.  Some phenotypic changes include stunting, thinner stalks, reduced sugars and starch and mild chlorosis. To speed up this research, it is essential that high throughput phenotyping tools are developed that allow us to screen and identify varieties that produce high levels of polymer with little or no impact on the plants ability to grow and thrive under a range of agricultural conditions. We are at a critical time on this planet where continuing the rapid consumption of fossil fuels is leading us to a tipping point where climate change can have dire impacts on human civilization. Some of the tools already in existence could be adapted to our needs.  For instance, in sugarcane mills around the world near infrared (NIR) cameras are used routinely to screen the juice stream after the crushing of the sugarcane stalks. These cameras are determine a range of information from the juice including, BRIX, POL, fiber and levels of contaminants.  Researchers at Sugar Research Australia (SRA) have also used NIR to look at waxes from sugarcane stalks and leaves and have been able to not only differentiate varieties but also to screen for pest and disease resistance.  We have also used NIR to detect PHA in sugarcane leaf tissue. This talk will focus on the need for high throughput large plant phenotyping to develop next generation high biomass biofactory crops for use as feedstocks for lignocellulosic biorefineries.