Tree Micropropagation Technique Developed

By Jan Suszkiw
December 3, 2004

A new tool to help with reforestation efforts has been developed by Agricultural Research Service scientists. In studies at the ARS National Center for Agricultural Utilization Research, in Peoria, Ill., plant physiologist Brent Tisserat and colleagues devised an automated system that, combined with elevated carbon dioxide (CO2) levels, bolsters the yield and survival of tissue-cultured shoots.

Transplanted to soil, these shoots readily take root and become whole, free-living plantlets that can be transferred to the field. Some reforestry managers prefer such plantlets over fertilized seed because they're genetically identical and the resulting harvest yields are predictable, according to Tisserat, at the Peoria center's New Crops and Processing Technology Research Unit. A major micropropagation problem is that many cultured shoots don't survive transplanting to soil, thereby slowing reforestation efforts.

In 1996, Union Camp of Savannah, Ga., asked Tisserat to investigate methods of mass-producing sweetgum shoots and improving their survival during soil transplantation. The traditional solution to the problem would have involved changing the nutritional composition of the agar-based growth medium on which the shoots are cultured.

Tisserat, however, decided to change how the medium is applied to the shoots, and the physical environment in which they are cultured. He also switched from traditional glass tubes to larger growth chambers. Tisserat's so-called automated plant culture system (APCS) is also set to periodically immerse shoot cultures in media. In trials, this resulted in a 10-fold increase in shoot yields compared to standard methods, and a 14-fold increase in fresh weight. By pumping ultra-high levels of CO2 into the chamber, Tisserat increased the shoots' transplantation survival rate by 94 percent.

According to Tisserat, the APCS' startup costs may limit its use to large-scale operations, such as those conducted by wood products companies, which replanted more than 1.1 million acres of trees in 1999, according to the American Forest Foundation.

Read more about the research in the December issue of Agricultural Research magazine.

ARS is the U.S. Department of Agriculture's chief scientific research agency.