Has it been awhile since you took a biology class? Never had the opportunity to study plant molecular biology or plant biochemistry? Never fear. Following below we have provided definitions for key terms we commonly use when describing our research and development activities which are focused on devising new ways to produce step-change improvements in crop yield.
Crops for feed or food are based on plants that have a certain set of characteristics, or traits, that can include, for example, how much seed or biomass yield they will produce under typical field conditions. Historically crop yield has been addressed by adding traits that control weeds or pests, attempting to limit crop loss that may otherwise occur. At Yield10, we are focused on identifying new yield traits that will bring step-change improvements to crop yield by enabling crops to fix and capture more carbon and then target that additional carbon to the seed.
In plants, global transcription factors act as “master switches” for regulating expression of certain genes. Modification of the expression of GTFs represent promising new targets for achieving yield improvements in that they control expression of multiple genes in different biochemical pathways.
In plant biotechnology, stacked traits refer to the scenario where two or more new traits have been introduced into the plant to produce improvements in the field or improvements in yield.
In plants, photosynthesis is the fundamental process by which energy from the sun converts CO2 from the air into organic molecules needed for plant growth. Through this process, plants produce biomass, fruit and seed. Photosynthesis takes place in the chloroplast where a light reaction and a carbon reaction (known as the Calvin cycle) occur.
The Rubisco enzyme, which is the predominant protein in plant leaves, drives the first reaction of the Calvin cycle where CO2 is converted to sugar and other molecules needed for plant growth. The Rubisco enzyme also catalyzes a second wasteful competing reaction which fixes oxygen instead of CO2. This side reaction of Rubisco reduces the efficiency of photosynthetic carbon fixation in C3 plants in a process known as photorespiration.
When the Rubisco enzyme wastefully fixes O2, a toxic molecule is produced that must be removed. During the course of this process, the plant uses up valuable energy and some of the carbon is lost as carbon dioxide. This is a major bottleneck for crops with C3 photosynthesis. Photorespiration has been a major topic in plant science and researchers have employed multiple strategies in attempts to reduce photorespiration in C3 plants to improve yield. Yield10 is taking a systems approach to boosting yield in C3 plants with the goal of reducing photorespiration using yield targets such as C3003 from our “Smart Carbon Grid” discovery platform.
Plants utilizing the “C3 photosynthesis” process produce a three carbon molecule when the RuBisCo enzyme fixes CO2. Due to photorespiration, it is estimated that C3 plants can lose up to 50% of all CO2 fixed during photosynthesis. It is well established that C3 plants produce much lower yields that their C4 cousins. C3 plants include canola, soybeans, rice, potato and wheat which are all crops of significant value for food and feed production around the world.
C4 plants, which evolved later than C3 plants, reduce photorespiration by sequestering the RuBisCo enzyme in cells where the levels of CO2 are high and there is very little oxygen. This is achieved with a specialized anatomy of the leaf in C4 plants. A preliminary CO2 fixation step occurs as carbon enters the leaves forming a four carbon molecule (thus the name of C4 photosynthesis) that is then shuttled, through a series of steps, to another cell type that contains Rubisco. CO2 is released from the four carbon molecule making it available to Rubisco for photosynthesis. Plants such as sugarcane, corn, sorghum and switchgrass are examples of C4 photosynthetic plants.
In plants, the original source of carbon comes from CO2 in the air. Once the CO2 enters the chloroplast it is converted by a series of biochemical reactions into the organic molecule building blocks of the plant to make biomass, fruit and seed.
As plants grow, the carbon captured by the plant can be used to make biomass, fruit and seed. Efforts to modify carbon partitioning can be used to direct more of the carbon to increase biomass or seed preferentially thereby increasing crop yield.
Plant germplasm that has been selectively bred and optimized to a specific environment is referred to as “elite” germplasm. New traits developed through biotechnology are typically bred into elite germplasm plant lines prior to regulatory testing and commercialization.
Plants that are “transgenic” contain genes that have been inserted through a number of different methods. These genes are strategically inserted to impart new traits into plants.
Gene editing is a type of genetic engineering in which DNA is inserted, deleted or replaced in the genome of an organism using engineered nucleases, or “molecular scissors.” The CRISPR/cas9 technology is one system to achieve genome editing and it has received considerable attention as a means to modify DNA in plants and other organisms. This relatively new technology has been of considerable interest to plant scientists as it may represent a way to modify and improve plants without introducing any additional DNA by precisely deleting small pieces of the host plants DNA. Yield10 has identified a number of gene targets may be useful as gene editing targets.
Genetically modified crops, sometimes referred to as “GMO crops,” are plants used in agriculture containing DNA which has been modified using genetic engineering methods. Genes for beneficial traits such as herbicide resistance or pest tolerance have been successfully introduced into plants such as corn and soybean.
The plant Camelina sativa is an oilseed crop cultivated in North America and Europe. Camelina has received recent attention as an industrial oilseed for the production of biofuels, novel industrial lipids, and oleochemicals. Its meal has been targeted as an animal and fish feed supplement.
Canola and soybean are oilseed crops grown commercially to produce seeds that are harvested primarily for their oil for use in food and feed applications.
Crops grown expressly for biomass used for feeding livestock are known as forage crops. Typical forage crops which can be annual or perennial include various grasses, corn, alfalfa and sorghum.