During the George W. Bush presidency era, biomass made from bioenergy-rich sorghum and especially switchgrass were touted as a “great white hope” for more eco-friendly producable biomaterials from which to make biofuels than agriculture-intensive and valuable food crops like corn, wheat, or oilseeds.
President Bush suggested in his 2006 State of the Union address that “We must also change how we power our automobiles. We will increase our research in better batteries for hybrid and electric cars, and in pollution-free cars that run on hydrogen. We’ll also fund additional research in cutting-edge methods of producing ethanol, not just from corn, but from wood chips and stalks, or switchgrass. Our goal is to make this new kind of ethanol practical and competitive within six years.”
President Bush’s suggestion that scientists could use switchgrass, which few had ever heard of, to make biofuels, got reflexively lampooned by talk show hosts and comics, but his contention was supported by science. Switchgrass is a bioenergy-rich warm season prairie grass that needs little cultivation and can be converted into large amounts of biomass to create cellulosic ethanol.
One researcher who took President Bush’s comments seriously, was a Texas A&M AgriLife scientist who had been working on biofuels development for years. Dr. Jorge da Silva, ETF Professor of Soil & Crop Sciences, Molecular Genetics, and Plant Breeding at the Texas A&M Agrilife Research and Extension Center at Weslaco, now predicts he will release second-generation bioenergy plants from his laboratory within two years, but it will be based on sugarcane and not switchgrass as feedstock. Dr. da Silva says that sugarcane better lends itself to being redesigned and reengineered to help fulfill George W. Bush’s State of the Union dream of “providing 30 percent of our transportation fuel by 2030.”
“Our program’s goal is the improvement of sugarcane for sustainable productivity in South Texas and improvement of energy cane for the Southeast U.S., says Dr. da Silva in a TAMU Agrilife release. “Our research activities focus on the tolerance and resistance to abiotic (drought and cold) and biotic stress (Ratoon Stunting Disease and Mexican Bore); the development of sugarcane clones with improved performance and quality (high sucrose content); the introgression of exotic germplasm and the application of molecular techniques in plant breeding.”
The overall goal of this project is on developing bioenergy feedstocks to produce high tonnage per acre, with low delivered cost and optimized for highest performance in the conversion technology.
“Unlike corn, or even switchgrass, sugarcane is unique in that it can be crossed with different species, including sorghum,” Dr. da Silva explains, “to create new plant varieties with favorable traits that are competitive with corn in producing biofuels.”
The main focus of Dr. da Silva’s research is development of molecular markers associated with traits of interest in order to assist and speed up the selection of superior genotypes in the breeding program, which aims at improving feedstock crops for bioenergy such as sugarcane and its wide hybrids, adapted to the Southeast U.S. growing conditions. High-throughput next-generation sequencing technologies are being used to generate massive amounts of DNA sequence data, aiming at developing large numbers of informative markers to help to understand the genetic architecture of complex agronomic traits, such as yield, drought and cold tolerance, resistance to insects and pathogens. It also allows the identification of alternative forms of major genes controlling these traits from different germplasm accessions, to introduce them into the commercial varieties for improved field performance and biomass production.
Using genetic markers, Dr. da Silva transfers favorable genetic traits from a variety of plant sources to sugarcane to make new plant material called wide-hybridization. These new plant varieties are earmarked to become the world’s second generation of bioenergy plants, with potential to eventually replace corn and even sugarcane in the production of ethanol, da Silva told TAMU Agrilife science writer and release author Rod Santa Ana, noting that “Those were the first generation plants, corn and sugarcane. The starch from corn and the sugar from sugarcane were converted to ethanol. But both are food plants that when used to make fuel create a conflict with their ability to produce food.
“An increased demand on corn, which is used as animal feed, is reflected throughout the food chain in higher prices. That is a major disadvantage and is one reason why corn is not sustainable as a feedstock for biofuel.”
Conversely, Da Silva’s hybridized plants, the result of conventional breeding and selecting methods, mix the plants’ biomass – stalks and leaves — with enzymes to more efficiently create ethanol. “What we end up with,” he says, “is a sugarcane-based plant with biomass that is at least nine times more efficient in producing ethanol than corn biomass.”
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Santa Ana notes that creating new fuel-producing plant material from sugarcane has challenged Dr. da Silva throughout his 12-year career with AgriLife Research, and while sugarcane’s genetic makeup, developed naturally over thousands of years, can be revamped to better serve growers and consumers, it’s not a process that can be executed overnight.
Dr. da Silva observes that “It took Mother Nature a long time to develop the plant species we see on the planet now. Even if it takes an entire generation to develop a favorable variety, it’s still a relatively short period of time compared to the many years it took to evolve naturally.”
He notes that a major challenge in breeding sugarcane is its complex genetic composition, explaining that some grasses, especially sugarcane, have many more genes and chromosomes than even human beings. While humans have two copies of each gene — one each from the mother and father — sugarcane has ten copies of each gene. “This genetic complexity creates many variables that are not under our control, making it difficult to predict agronomic performance, how it will yield and react in the field,” he observes.
Important among a number of major genetic improvements to sugarcane for biofuels will be engineering its ability to grow outside its comfort zone, One reason what corn has been widely used as a feedstock for biofuel in the U.S. is because massive corn acreage is already in place and because corn grows well in temperate zones, Dr. da Silva explained, while sugarcane, however, is a tropical and subtropical plant, a limitation that disadvantages it competition with corn as a biofuels feedstock.
“We want [sugarcane] to be able to grow outside the tropics like corn is, to be cold tolerant, drought tolerant, and resistant to diseases and insects,” Dr. da Silva says. “It’s called pyramiding, assembling and stacking from different sources favorable genes that control traits,” also noting that working in his favor in meeting the challenges, is Texas A&M University’s global reputation, and an efficient plant replication method that rids plants of disease.
“Texas A&M is known to be a place of excellence in plant sciences,” he observes in the TAMU release. “People come here to our center in Weslaco from all over the world to witness our science in action and get trained. Texas A&M has a strong relationship with Brazil so we’re fortunate in that graduate students are willing to come here to train in the techniques we use in genetics and molecular biology.”
Rob Santa Ana notes that one of the techniques used in Dr. da Silva’s lab is a process called micropropagation, whereby plants to be evaluated can be reproduced much more quickly than through the natural seed-to-plant method and the resulting clonal plant material is free of any disease its ancestors may have carried — a highly reliable method that allows da Silva to plant bigger research field plots at more sites to gather data on a larger scale.
“Producing these plants via tissue culture is faster and ensures that we’re not spreading plant diseases as these new plants go to the field,” da Silva says. “And we use bioreactors, some of which were recently purchased from Belgium, to speed up the multiplying process, using less labor and less laboratory space.”
Dr. da Silva’s hybridization crosses and selections have been narrowed down from hundreds of thousands of possibilities to what he calls elite lines — hybrid plants with favorable traits needed to more efficiently produce biofuels, and which are now being tested in various locations throughout Texas.
And while he expects to produce half a dozen varieties ready for release in about two years, this sort of hybridization is a dynamic process that will likely never end. “Plant varieties will always be improved upon because there are always new challenges to plant production,” Dr. da Silva says. “We’re always seeing new diseases, new pests, the industry changes, economics change — it will always be a dynamic, evolving process.”
Texas AgriLIFE Research at Weslaco was established in 1923 as a response to the growing needs and with federal and state legislative authorization, named Substation Number 15 and located east of the newly created town of Weslaco (named after the W.E. Steward LAnd COmpany) on 60 acres purchased by the state and another 60 acres donated by local citizens. This land had formerly been known as Llano Grande (large plain). In 1964 the Weslaco research facility’s name was officially changed from “Substation Number 15” to Rio Grande Valley Research and Extension Center, and later to Texas A&M University Agricultural Research and Extension Center at Weslaco. For almost a century, a hugely successful agricultural industry there has served as a catalyst for the area’s tremendous economic and population growth, and the Center continues to play a major role as the state’s premier research agency in agriculture, natural resources, and the life sciences in keeping South Texas agriculture second to none. A member of The Texas A&M University System, AgriLife Research collaborates with the Texas A&M University College of Agriculture and Life Sciences, the Texas A&M AgriLife Extension Service, and many others to help fulfill the A&M System’s land-grant mission of teaching, research, extension, and service.
Sugarcane photo from http://latimesblogs.latimes.com