Agricultural Research, Dec, 2004 by Jan Suzkwi
Reforestation efforts may get a lift thanks to a new advance in plant-tissue culturing at ARS's National Center for Agricultural Utilization Research, Peoria, Illinois. Plant physiologist Brent Tisserat has devised an automated plant culture system (APCS), coupled with enhanced CO2 treatments that bolsters yield and survival of delicate shoots.
In reforestry operations, budding shoots are cultured inside small glass tubes or in Magenta vessels and nourished on an agar gel. Tissue culturists treat these shoots, originally derived from leaves, with growth regulators to coax them into multiplying secondary shoots. Transplanted to soil, these shoots eventually root and become whole, free-living plantlets that can then be put in the field.
With this technique, known as micropropagation, forest-product companies can restock plantations with millions of genetically identical tree plantlets. The yield of trees clonally derived from these plantlets is much more predictable than that from fertilized seed, says Tisserat.
Even so, not all micropropagated shoots survive transplanting--especially "vitrified" shoots, the source of axillary branches that do not readily root. In contrast, nonvitrified shoots readily form roots but produce few axillary branches.
The standard approach to solving yield problems would have involved tweaking the agar medium's nutritional composition. But Tisserat changed the way nutrient medium is applied to the shoots, modified the physical environment in which they are grown, and switched from Magenta vessels to larger growth chambers, which provide the tender shoots with much more space and media.
Tisserat's APCS uses an automated pump to microirrigate the shoots with liquid medium piped in from a separate tank. The medium is applied and removed several times over a 24-hour period. In trials, this resulted in a 10-fold increase in shoot yields compared to traditional culture methods and a 14-fold increase in fresh weight.
The CO2 treatments resulted in a 94percent survival rate for transplanted shoots (including vitrified ones). The APCS also speeds seedling growth of loblolly pine, a chief lumber resource in the southeastern United States. Tisserat and co-investigators had earlier success micropropagating and rooting peas, lettuce, tomatoes, beans, and spearmint.
This research is part of Quality and Utilization of Agricultural Products, an ARS National Program (#306) described on the World Wide Web at www.nps.ars. usda.gov.
Brent Tisserat is in the USDA-ARS Fermentation Biotechnology Research Unit, National Center for Agricultural Utilization Research, 1815 University St., Peoria, IL 61604; phone (309) 681-6289, fax (309) 681-6427, e-mail tisserbh@ ncaur.usda.gov.
COPYRIGHT 2004 U.S. Government Printing Office
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