MicroRNAs hold significant potential for the plant biotechnology industry. Stemming from their role as master regulators of gene expression, microRNAs are believed to play a critical role in each major step in plant and algal development and may therefore affect biotech-related traits such as oil and starch content, stress-tolerance, growth rate, yield, and more.

—Dr. Rudy Maor, Head of Research and Development at Rosetta Green

Algae consist of three primary components from a bio-products frame of reference: oil, which can be converted into a fuel via a variety of processes; carbohydrates, which can be fermented into fuel; and protein, which can be used for food or feed. (Algal biomass could also be used as a feedstock for power generation or syngas.)

For much of the nascent algal biofuel industry, the oil content of the organism under cultivation is a critical factor in the potential economic success of the initiative—i.e., upping the percentage content per cell is required to make the economics viable. A number of other factors go into that economic viability, including volumetric yield at a large scale, and harvesting of the oil, which is not easy.

While a number of environmental stress techniques have been used to increase lipid production in algae (such as nitrogen-deficiency), work done by the National Renewable Energy Laboratory (NREL) between 1978 and 1996 on algae biodiesel found that increased oil content of algae under environmental stress does not necessarily lead to increased overall productivity of oil. Higher levels of oil in the cells induced by environmental stress can be more than offset by lower rates of cell growth in response to that same stress.

At the recent 2008 Algae Biomass Summit (earlier post), many of the projections for potential oil yield from algae used a 50% oil content in the organism. As NREL detailed in its wrap-up report on its project, the 50% content assumption was fundamental to achieving high productivity, and some algal species have been show oil contents as much as 80% of the dry weight.

However, experimental results on increasing lipid (oil) content during the NREL work showed uneven results. Practical experience reported at the Algae Biomass Summit suggested lipid content ranging between 20-50%. Sustained increases in oil content combined with volumetric yield may be in the realm of genetic engineering.

MicroRNAs have been established as key regulators of protein expression and their aberrant regulation in humans is associated with many serious diseases. However, microRNAs’ potential is not limited to humans.

Since our founding in 2000, we have maintained that small non-protein coding RNA—what we now know are microRNAs—play a critical role in many cellular processes. There is a large and growing body of evidence, including research we have been conducting in-house, pointing to the importance of microRNAs in plants and algal development, which may have potential applications in a wide range of plant-based biotech products. We feel it is critical at this point in time to explore this important field to ensure Rosetta Genomics remains at the forefront of research, development and commercialization of microRNA-based products.

—Amir Avniel, CEO of Rosetta Genomics

MicroRNAs (miRNAs) are naturally occurring, short non-coding RNAs that regulate gene expression in plants, humans, and have been recently discovered in algae. The ability to selectively regulate gene expression through microRNAs could provide the means to enhance a wide range of plant and algal characteristics.

Resources

• A Look Back at the US Department of Energy’s Aquatic Species Program: Biodiesel from Algae

• Tao Zhao, Guanglin Li, Shijun Mi1, Shan Li1, Gregory J. Hannon, Xiu-Jie Wang, and Yijun Qi1 (2007) A complex system of small RNAs in the unicellular green alga Chlamydomonas reinhardtii.Genes & Development 21:1190-1203 doi: 10.1101/gad.1543507