Alan R. Langille

Plant Hormones Isolated from “Katahdin” Potato Plant Tissues and the Influence of Photoperiod and Temperature on Their Levels in Relation to Tuber Induction

Qualitative and quantitative analyses were carried out on vegetative tissues of potato (Solanum tuberosum cv. “Katahdin”) in search of natural products thought to play a role in tuber induction. Tissues were obtained from plants initially grown in a growth chamber under noninducing conditions (30°C day and 28°C night with an 18-h photoperiod), and then half of the plants were moved to inducing chambers (28°C day and 13°C night with a 10-h photoperiod) for 10 days prior to tissue harvest. Plants from each chamber were then harvested at 2-day intervals for 10 days, separated into above- and belowground portions, and the lyophilized tissues were extracted and subjected to rigorous purification and separation using high-performance liquid chromatography. This was followed by identification and quantification using combined gas chromatography-mass spectrometry. Compounds isolated and identified included gibberellic acid; cytokinins cis-zeatin riboside, trans-zeatin, trans-zeatin riboside, and isopentenyladenine; and jasmonates jasmonic acid, tuberonic acid and its methyl ester, methyl 7-isocucurbate, and 9,10-dihydromethyljasmonate. Methyl 7-isocucurbate and 9,10-dihydromethyljasmonate were detected for the first time in potato tissue as endogenous compounds. Cytokinin and jasmonate levels generally increased under inducing conditions, whereas gibberellic acid levels declined progressively during the 10-day sampling period. Only gibberellic acid, jasmonic acid, and cis-zeatin riboside levels were significantly influenced by induction.

Effect of three anti-gibberellin growth retardants on tuberization of induced and non-induced Katahdin potato leaf-bud cuttings

Katahdin potato plants were grown in a growth chamber undernoninducing conditions and treated with three anti-gibberellin growth retardants. Other plants were sprayed with gibberellic acid and placed in aninducing growth chamber adjusted to promote tuber induction. Treatments were repeated the following week. After final treatment, apical, sub-apical, medial and basal leaf-bud cuttings were taken from each plant and placed in a mist chamber. After two weeks, cuttings were examined for tuberization. Two of the retardants were associated with approximately 3 and 2 fold increases in tuberization over the non-induced control. Although induced control cuttings exhibited almost complete tuberization, application of gibberellic acid to plants grown under identical conditions, reduced tuberization 14 fold. Tuberization response of induced control cuttings was unaffected by stem location. In non-induced control and quaternary ammonium compound-treated cuttings, basal cuttings tuberized significantly better than those taken from higher on the stem. This pattern was eliminated for plants treated with the triazole compound. Below-ground portions of donor plants were also examined and showed a significant increase in average rhizome number and total rhizome length associated with inducing conditions. Tuber number of donor plants was also increased for those plants grown under inducing conditions or treated with the triazole compound under noninducing conditions.CompendioSe cultivaron plantas de papa Katahdin en una cámara de crecimiento bajo condiciones no inducidas y tratadas con tres giberilinas retardadoras del crecimiento. Otras plantas fueron asperjadas con ácido giberélico y colocadas en una cámara de crecimiento inducido regulada para promover la inducción de tubérculos. Los tratamientos se repitieron a la siguiente semana. Despueés del tratamiento final, se tomaron de cada planta esquejes de hoja-yema apicales, subapicales, medios y basales y se les colocó en una cámara nebulizadora. Después de dos semanas, se examinó la tuberización de los esquejes. Dos de los retardadores estuvieron asociados con incrementos en la tuberización que fueron aproximadamente el triple o el doble que los del control no inducio. No obstante que los esquejes del control inducido mostraron una tuberización casi completa, la aplicación de ácido giberélico a las plantas mantenidas bajo condiciones idénticas redujo la tuberización 14 veces. La respuesta en la tuberización de los esquejes del control inducido no fue afectada por la ubicación del tallo. En los esquejes del control no inducido y de aquellos tratados con compuesto de amonio cuaternario, los esquejes basales tuberizaron significativamente mejor que aquellos tornados a mayor altura del tallo. Esta situación quedó eliminada en las plantas tratadas con el compuesto triazole. Las partes, de las plantas madres, bajo el nivel del suelo fueron tamién examinadas y mostraron un incremento significativo, asociado con las condiciones de inducción, en el número promedio de rizomas y en la longitud total del rizoma. El número de tubérculos de las plantas madres también se incrementó para aquellas tratadas con el compuesto triazole bajo condiciones de no inducción.

Seeking improved nutritional properties for the potato: Ethionine-resistant protoclones

Russet Burbank leaf protoplasts were cultured in Shepard’s (1980) cell layer (CL) medium containing the amino acid analog ethionine (ETN), at concentrations ranging from 0 to 6 µM. Repeated counts of viable cells and dividing colonies during the 21 day incubation period permitted calculation of plating efficiencies for each ETN concentration. Plating efficiency was observed to decrease when ETN concentration in CL exceeded 3 µM. Calli which developed were placed on Shepard’s (1980) C media containing ETN concentrations up to 200 µM; however, few calli survived concentrations above 100 µM. Regenerated plants were grown to maturity and resulting tubers were analyzed for free methionine content. Selected protoclones produced tubers with free methionine content as much as 2.66 times that of the Russet Burbank control.ResumenProtoplastos de hojas de Russet Burbank se cultivaron en capa celular de Shepard (1980), medio conteniendo al aminoácido análogo etionina (ETN) en concentraciones que oscilaban entre 0 y 6 M. Contajes repetitivos de células viables y colonias en división durante los 21 días de la incubación de ETN. Se observó que el rendimiento de las plantas disminuyó cuando las concentraciones de ETN excedían los 3M.Los callos que desarrollaron fueron colocados en medio C Shepard conteniendo concentraciones hasta 200 M de ETN; sin embargo, algunos callos sobrevivieron a concentraciones por encima de los 100M.Las plantas regneradas se dejaron crecer hasta la madurez y los tubérculos resultantes fueron analizados para su contenido de metionina. Los protoclones seleccionados produjeron tubérculos con un contenido de metionina libre de más de 2,66 que el control de Russet Burbank.

Influence of zinc concentration in nutrient solution on growth and elemental content of the Katahdin potato plant

Hoagland’s solutions containing nine levels of zinc ranging from 0 to 50 ppm were applied as a drench tri-weekly to potato plants (cultivar Katahdin) growing in perlite. Although no deficiency symptoms were observed during the 46-day growing period, varying degrees of toxicity were associated with solution concentrations of 25 ppm Zn and higher. The tissue concentration necessary to induce toxicity symptoms appeared to fall between 648 and 932 ppm Zn, with an indication that growth may be reduced at tissue concentrations less than 648 ppm. Solution concentrations in excess of 20 ppm Zn caused a significant reduction in dry weight of top, root and rhizome portions, and number of secondary rhizomes. Increasing Zn treatment concentrations influenced elemental tissue content as follows: Al, Ca, Mn, Mo and Zn increased, B increased only at 40 ppm Zn or above, N and K decreased and P, Mg and Fe contents were generally decreased by the addition of Zn. Cu content was unaffected.ResumenSoluciones Hoagland conteniendo nueve niveles de Zn entre 0 y 50 ppm fueron aplicadas por saturación tres veces por semana a plantas de papa (cultivar Katahdin) desarrolladas en perlita.Si bien no se observó síntomas de deficiencia durante los 46 días del período de crecimiento, variables grados de toxicidad exstuvieron asociados con las concentraciones desde 25 ppm y de Zn. las concentraciones del tejido necesarias para inducir síntomas de toxicidad parecieron caer en el rango entre 648 y 932 ppm de Zn, indicando que el crecimiento puede ser reducido a concentraciones menores de 648 ppm. Concentraciones de la solutión en exceso de 20 ppm de Zn causaron una significativa reductión en el peso seco de la parte aérea, raíces y rizomas y el número de rizomas secundarios. El incremento de las concentraciones de Zn influyó en el contenido de elementos en el tejido, así tenemos que: el Al, Ca, Mn, Mo y Zn fueron incrementados, el B incrementó solamente desde 40 ppm de Zn; el N y el K decrecieron y el contenido de P, Mg y el Fe fue generalmente disminuído por la adición de Zn. El contenido de Cü no fue alterado.

Effects of the amino acid analog, 5-methyltryptophan on protoplast survival, plating efficiency and free tryptophan levels in tubers of regenerated potato plants

In an attempt to improve nutritional qualities of the potato by exploiting variation associated with protoplast regeneration, Russet Burbank leaf protoplasts were cultured in cell layer (CL) medium containing the amino acid analog, 5-methyltryptophan (5-MT) at concentrations from 0 to 286 μM. At three day intervals, numbers of viable cells and dividing colonies were recorded to determine effects of 5-MT concentration on cell viability during the 14 day incubation period. Repeated count data were used in a computer program to construct survival profiles. Decline in cell populations was generally slight during the first 5 days in culture. Between day 5 and 11, survival rate dropped dramatically, averaging 10–12% per day regardless of concentration. As surviving cells began to divide, a leveling trend in the curves was noted between days 11 and 14. Reduced plating efficiency was only associated with the 103 and 286 μM treatments. No plants were regenerated from colonies exposed to 5-MT concentrations in CL greater than 34.4 μM nor were differences in free tryptophan found between tubers of protoclones and Russet Burbank.

Evidence of absorption and translocation of foliar applied kinetin-8-C14 in the potato plant

The causal factors involved in tuberization of the pota to plant have intrigued workers for many years. Several reports (1, 2, 5) have suggested the existence of a tuberizing factor which is formed in the leaves and translocated to the rhizome region to exert its influence. Although several candidate compounds have been suggested, studies by Palmer and Smith (8, 10) and more recently f rom this laboratory (3, 6) have supported the opinion that the tuberizing factor may be one of the naturally occurring cytokinins. In order for this information to be of practical importance, it is necessary to demonstrate that cytokinins, compounds reportedly recalcitrant in leaf absorption, can indeed be absorbed and translocated by the potato plant. Accordingly, the following experiment was carried out. Twelve uniform plants cv Katahdin were planted in 15 cm plastic pots containing a soil-Perlite (2:1) mixture. Plants were grown in a growth chamber adjusted to 20°C day and 10°C night with a 15 hr photoperiod until heights o f 35-40 cm were reached and treatments were initiated. Treatments consisted of two solvent mixtures, each containing kinetin-8-C TM (specific activity: 25 mCi /mmol ) 4 with six replications per treatment. The solvents used were water alone and 10°70 M e O H in water with .1°70 Tween 20 and adjusted to p H 5.5. Applications were made to the first lateral leaflet of the fifth leaf above the soil surface. The application leaf was supported with a board held by a ring stand and a 0.95 cm brass washer was placed over the main vein on the abaxial side of the leaflet (Figure 1). Lanolin paste was used to ensure a seal between the leaf and washer. One hundred microliters (0.5 m Ci) of each kinetin-8-C 1 treatment solution were placed in the washer of appropriate plants 1 hr after commencement of the photoper iod and allowed to dry. Five days after application, plants were harvested and prepared for autoradiography and counting. Preparat ion for autoradiography consisted of removing the treated leaves at the axillary bud, placing them in a plant press, freezing at 20°C and lyophilizing for 24 hrs. These leaves were then mounted on stiff bonded paper, covered with Saran wrap, placed in a cassette with x-ray film and exposed for 6 weeks, prior to development.

Call for papers for the 1981 Annual Meeting

s will be multilithed and distributed with registration material at the Annual Meeting and published after the meeting in the American Potato Journal. Content of the abstracts should not exceed 200 words, should agree with the paper presented, and should not be written until the data collected are complete. All papers should be of publication quality and i f ready for publication, present three (3) copies to the Editor or Secretary at the time of presentation. Visual aids should be clear, instantly readable, uncluttered, well prepared, and contain only material pertinent to the paper presented. We solicit papers pertaining to all facets of the potato industry. Extension and industry persons are encouraged to present papers. Early response to this Call for Papers and Abstracts will assure presentation in the discipline of your choice and help the Secretary to arrange, print and distribute the program and abstracts on schedule. Late titles and abstracts, along with papers based on one years data, may be returned. Please bring this announcement to the attention of your colleagues, graduate students, and other persons who may want to attend our meetings or present a paper. 630 AMERICAN POTATO JOURNAL (Vol. 57 Graduate students planning to present papers in the Graduate Student Competition should send abstracts of the papers to Secretary Langille and to the Chairman of the Graduate Student Awards Committee who is: Dr. Elmer E. Ewing Department of Vegetable Crops Cornell University Ithaca, New York 14853 Guidelines for Graduate Student competition will be published in two issues of the Journal. Chairmen of Sections, standing committees, and special committees who desire to hold meetings during the Annual Meeting period are requested to make arrangements for meeting rooms with Mr. J. Ewen Campbell, Co-Chairman of the Local Arrangements Committee for our Annual Meeting. His address: P.O. Box 1240 Charlottetown, Prince Edward Island Canada C1A 2J5 Time and place of section and committee meetings may be published in the program. Alan R. Langille, Secretary The Potato Association of America October 1, 1980