Paul P. Kormanik

Differentiation of Plantlets in Longleaf Pine (Pinus palustris Mill.) Tissue Cultured In vitro

Embryos of longleaf pine (Pinus palustris Mill.) were induced to form numerous adventitious buds along their cotyledons when placed in culture on chemically defined nutrient media. The buds when excised and transferred to other media form roots and vigorous plantlets. Plantlets were obtained from numerous embryos using three different seed sources. Histological observations describing these patterns of differentiation are presented.

Lenticel and Water Root Development of Swamp Tupelo Under Various Flooding Conditions

Seedlings of swamp tupelo (Nyssa sylvatica var. biflora [Walt.] Sarg.) were grown in nonflooded soil or soil that was intermittently flooded, continuously flooded, or surface-saturated with moving or stagnant water. Lenticels on nonflooded seedlings were round, only slightly hypertrophied, and had few closing layers. Degree of hypertrophy and number of closing layers per lenticel increased with surface saturation and intermittent flooding, but closing layers were absent under continuous flooding. Flooded lenticels remained nearly round despite variations in hypertrophy. In all treatments, intercellular spaces were abundant in the complementary tissue and phellogen because of the spherical shape of these cells. Although the continuity of intercellular spaces was interrupted because the closing layers anastomosed, breaks within the closing layers prevented these spaces from being completely blocked. Water roots developed primarily under continuous flooding in moving water, some apparently originating beneath the phellogen of a lenticel and others within the phellogen or its derivatives.

Heritability of first-order lateral root number in Quercus : implication for artificial regeneration of stands

Natural regeneration of oak (Quercus) species in the USA has been easy to obtain on the lower quality xeric sites (site index u206420 m at age 50) by developing advanced oak reproduction before stands are harvested. This approach has not been successful with Q. rubra, Q. pagoda, or Q. alba growing on highly productive river bottom, cove or other mesic sites (site index u206523 m at age 50) because developing seedlings are overtopped by initially faster-growing and more shade-tolerant competitor species common on these sites. Artificial regeneration to increase percentages of these three valuable multiple-use species in specific stands has not been satisfactory because of limitations imposed by planting stock quality and by the traditional technology used to manage newly established stands. After the number of first-order lateral roots (FOLR) produced by an individual seedling was shown to be a highly heritable trait, artificial regeneration trials were started by the USDA Forest Service’s Institute of Tree/Root Biology. A nursery fertility protocol was developed that could reliably and consistently produce seedlings of specific sizes. Thereafter, a seedling evaluation system was developed utilizing the parameters of FOLR, root collar diameter (RCD), and height (HT) for selecting seedling for outplanting. On mesic sites, survival and early growth for Q. rubra has been very good, with height growth of 4–5 m in 3–8 years. Trials are now being conducted with Q. pagoda and Q. alba. Methods for developing evaluation systems for oak species grown in nurseries under conditions different than the ones used in this study are discussed.

Pyrophosphate Dependent Sugar Metabolism in Mycorrhizal Tree Roots

Abstract Trees exhibit alternative enzymes for sugar metabolism particularly at steps in glycolysis and gluconeogenesis involving pyrophosphate (PPi). But these activities seem to be independent of root mycorrhizal infection and of soil phosphorus levels. PPi serves as an energy source with certain enzymes, specifically with the PPi-dependent phosphofructokinase (PFK), even better than ATP. Hence PPi is a new energy source in tree metabolism. We earlier established the presence of fructose 2,6-biphosphate (Fru 2,6-P2) in trees and here demonstrate that Fru 2,6-P2 regulates the tree root PPi-PFK. Fru 216-P2 also activates the breakdown of sucrose in tree sink tissues such as roots or terminal buds. Sucrose breakdown via the sucrose synthase pathway is dependent upon PPi and it is strongly activated by Fru2,6-P2 in sucrose sink tissues such as tree roots.

Suppressed Buds on Lateral Roots of Liquidambar styraciflua

Suppressed buds have been found imbedded in the periderm of lateral roots in sweetgum (Liquidambar styraciflua L.). These buds, when released from inhibition by natural or artificial means, may form typical short shoots or develop into normal long shoots during the season of release. The vascular traces of the suppressed buds may extend from the periderm to the primary xylem of the stele, which would indicate origin from primary tissues, or they may extend only through several growth rings to a point of earlier root injury. This is apparently the first observation of suppressed buds on roots of woody plants, but it is likely that they are present in other woody species that reproduce by root-suckers.