Potato Shoot Research Articles

The Canon of Potato Science: 18. Parasitic Weeds

Two weedy parasites are known in potato: Orobanche spp. (O. ramose, O. aegyptiaca and O. cernua )p arasitize potato roots, andCuscuta spp. (mainly C. campestris) parasitize potato shoots. Orobanche spp. is an important pest of many crops in Mediterranean countries in the Middle East and in Africa, extending eastwards to central Asia, India, China, and southern Russia, and northward to Central and Eastern Europe. Orobanche seeds are 0.2–0.3 mm long, and can remain viable in soil for decades, waiting for appropriate germination conditions. These include a few days under suitable temperatures and humidity, and a chemical stimulus from host roots. After germination, the parasite attaches to root surface, and develops a haustorium that penetrates host root tissues. The haustorium serves as a physiological bridge that directly connects the parasite to the vascular systems of its host, allowing the uptake of water, nutrients, and assimilates. After initial connection to potato roots the parasite can also connect to potato tubers. All Orobanche species have no photosynthetic capabilities. After penetration and establishment in the host tissues, the parasite develops a tubercle and then also a shoot that emerges above soil surface and flowers. An individual parasite produces thousands of seeds. Most of the damage caused by Orobanche occurs prior to shoot emergence.

Influence of Thaxtomins in Different Combinations and Concentrations on Growth of Micropropagated Potato Shoot Cultures

Plant-pathogenic Streptomyces species produce a variety of different phytotoxic 4-nitroindol-3-yl-containing 2,5-dioxopiperazines (thaxtomins) that induce scab symptoms on potato tubers (Solanum tuberosum). The possible mutual synergistic or antagonistic effects of thaxtomins are unknown. Modified methodology using column chromatography allowed the purification of thaxtomin A in large quantities (27 mg, HPLC purity of 97%). Thaxtomin A ortho isomer, thaxtomin B, and C-14 deoxythaxtomin B (thaxtomin D) were also purified. All four compounds induced similar symptoms of reduced root and shoot growth, root swelling (10-200 ppb), or necrosis (200-1000 ppb) on micropropagated in vitro cultures of potato. The scab-resistant potato cvs. Sabina and Nicola were more tolerant to thaxtomins than was the scab-susceptible cv. Matilda. Thaxtomins applied in combinations showed additive effects but no synergism, whereas thaxtomins A and B displayed antagonism with thaxtomin A ortho isomer.

Effects of medium composition and culture duration on in vitro morphogenesis of sweet potato

In vitro morphogenesis of sweet potato (Ipomoea batatas) shoot explants after cultures in callus initiation medium (CIM) with two sucrose contents and plant regeneration medium (PRM) with three growth regulator combinations for different durations was studied. After 4 weeks, explants on 5 % sucrose CIM had significantly more shoots but similar or lower root fresh mass and callus fresh mass than those on 3 % sucrose CIM subsequent to transfer for 6 weeks on all three PRM. Cultures transferred to growth regulator-free PRM after 4 and 12 weeks on 5 % sucrose CIM formed plants through organogenesis and embryogenesis, respectively. Embryogenic cultures from 4 weeks on CIM + 10 weeks on callus proliferation medium when transferred to PRM without growth regulator for 4 and 8 weeks produced multiple embryos in the prior and both embryos and shoot buds in the later.

The role of GA, IAA and BAP in the regulation of in vitro shoot growth and microtuberization in potato

The effect of auxin, GA and BAP on potato shoot growth and tuberization was investigated under in vitro condition. The shoot length of potato explants increased with the increasing of concentrations (0.5 – 10 mg dm−3) of IAA treatment especially with the addition of GA3 (0.5 mg dm−3), but was inhibited by BAP (5 mg dm−3). The root number and root fresh weight of potato explants increased with the increasing of IAA levels either in the presence of GA3 (treatment IAA+GA) or not (IAA alone). However, no root was observed in the treatment IAA+BAP, instead there were brown swollen calli formed around the basal cut surface of the explants. The addition of GA3 remarkably increased the fresh weight and diameter of calli. Microtubers were formed in the treatments of IAA+BAP and IAA + GA + BAP but not observed in the treatments of IAA alone or IAA + GA. IAA of higher concentrations (2.5 – 10 mg dm−3) was helpful to form sessile tubers. With the increasing of IAA levels, the fresh weight and diameter of microtubers increased progressively. At 10 mg/L IAA, the fresh weight and diameter of microtubers in the treatment of IAA + GA + BAP were 409.6 % and 184.4 % of that in the treatment of IAA + BAP respectively, indicating the interaction effect of GA and IAA in potato microtuberization.

Influence of Root Zone Calcium on Maintenance of Potato Shoot Tip

Calcium deficiency in the potato shoot results in sub-apical necrosis. This is a physiological condition whereby necrotic lesions form a few millimeters below the shoot apex ultimately causing shoot tip senescence, loss of apical dominance, and the release of axillary buds. Using a Dark Red Norland tissue culture system, we studied the relationship of root zone calcium levels to shoot tip maintenance. Root zone calcium levels lower than 50 ppm resulted in shoot tip death and prolific branching from axillary buds. Chelator studies with EGTA and tracer studies with 45 Ca, indicated a direct involvement of calcium at the shoot tip for shoot tip maintenance. Interestingly, low root zone calcium deficiency syptoms could be mitigated with 0.001 to 0.01 μM of the auxin analog NAA. Developmental studies of calcium deficiency symptoms indicate no anatomical relationship with shoot tip necrosis as xylem conducting elements were found near the shoot apex regardless of the root zone calcium level. These results have important implications for potato shoot development especially during the early development stage from the seed piece.

Effects of Genotype, Benzylaminopurine and Sucrose Concentration on Microtuberization of Layered Shoots of Potato (Solanum tuberosum L.) through Meristem Culture

The aim of this study was to assess the suitable hormonal balance on potato microtuberization from the plantlets which had been in heat therapy condition before culturing the meristem. The effects of different levels of BAP and sucrose concentration were studied 16 weeks after the last culture in two genotypes. Explants from meristem were propagated in vitro in several stages and then subcultured with MS medium containing the combination of BAP (three levels) and sucrose (three levels). Then they were transferred to a completely dark incubation room at 22 °C. In vitro tuber formation was analyzed 16 weeks later. Traits which studied were: length, diameter, fresh weight and number of micro tubers. There was no significant difference among the genotypes for all the traits. The micro tuber number was significantly different among the levels of BAP concentration and the BAP and sucrose interaction was significant for the diameter. The micro tuber fresh weight and diameter were highly significant for the sucrose levels. The sucrose and genotype interaction for micro tuber length; sucrose and BAP interaction for micro tuber length and diameter were significant. Also the genotype, BAP and sucrose interaction was significant for the micro tuber fresh weight.

Effect of Meloidogyne incognita and Pratylenchus brachyurus on leaf growth of sweetpotato

AbstractMeloidogyne incognita and Pratylenchus brachyurus reduced leaf growth on shoots of sweet potato. M. incognita had a greater effect than P. brachyurus. Copyright © 2004 Whurr Publishers Ltd

Effect of sealed and vented gaseous microenvironments on the hyperhydricity of potato shoots in vitro

Different types of ventilation of the culture vessel with and without the ethylene inhibitor KMnO 4 in the culture media were investigated in terms of their effect on hyperhydricity of in vitro cultured potato shoots. The shoots grown in a completely sealed vessel (CSV) were severely vitrified, but the shoots cultured in a gas permeable vessel (GPV) showed normal shoot proliferation. Dry weight percentage and chlorophyll content were lower in the vitrified shoots than in the normal shoots. The levels of ethylene and CO 2 were significantly higher in the CSV, but little ethylene was detected in the GPV system. When an ethylene scrubber (perlite treated with KMnO 4) was applied to the CSV, the shoots exhibited normal growth without any sign of vitrification. In addition, no ethylene was found in CSV with the ethylene scrubber (CSVE). These results indicate that hyperhydricity is related to the ethylene accumulated in the culture vessel during the in vitro culture of potato shoots. It is suggested to use CSVE to reduce the ethylene level and overcome hyperhydricity.

Glomus clarum e G. etunicatum: cultivo em solo e aeroponia

Foi avaliada em casa de vegetacao, a producao de inoculo dos fungos micorrizicos arbusculares (FMA) Glomus clarum e G. etunicatum em cultura aeroponica e em solo. O experimento foi conduzido em delineamento inteiramente casualizado com arranjo fatorial de 2 × 2 × 5, sendo: 2 tratamentos relativos a inoculacao (Glomus clarum e G. etunicatum) × 2 sistemas de cultivo (solo e aeroponia) × 5 periodos de avaliacao (0, 30, 60, 90 e 120 dias) e cinco repeticoes. Ramas de batata-doce desinfestadas com hipoclorito de sodio foram plantadas em 120 potes com solo + vermiculita, sendo a metade inoculada com 50 esporos de G. clarum e o restante com 50 esporos de G. etunicatum. Apos 64 dias, metade das plantas foi transferida para câmaras aeroponicas (uma para cada fungo) contendo agua destilada + solucao nutritiva a pH 6,0. A solucao nutritiva foi aplicada por microaspersao por um minuto com intermitencia de tres minutos. A colonizacao das raizes e a producao de esporos foram avaliadas aos 0, 30, 60, 90 e 120 dias de crescimento. G. clarum promoveu extensiva colonizacao das raizes quando comparado a G. etunicatum,com densidade de esporos semelhantes. Maiores niveis de esporulacao e colonizacao foram obtidos no cultivo em solo, com melhor tempo de cultivo aos 60 dias, independentemente do FMA. No entanto, a maior producao de inoculo foi obtida no solo, apesar do sistema aeroponico tambem ter sido bastante promissor aos FMA, principalmente aos 90 dias de crescimento.

A selection system for transgenic plants based on galactose as selective agent and a UDP-glucose:galactose-1-phosphate uridyltransferase gene as selective gene

A new selection system based on galactose as selective agent and a UDP-glucose:galactose-1-phosphate uridyltransferase gene as selective gene is presented. A broad range of plant species, including agronomically important crops such as maize and rice, is sensitive to low dosages of galactose. The toxicity of galactose is believed to be due to accumulation of galactose-1-phosphate, generated by endogenous galactokinase after uptake. Here, it is demonstrated that this toxicity can be sufficiently alleviated by the Agrobacterium tumefaciens-mediated introduction of the E. coli UDP-glucose:galactose-1-phosphate uridyltransferase (galT) gene, driven by a 35S-promoter, to allow transgenic shoots of potato and oil seed rape to regenerate on galactose containing selection media, resulting in high transformation frequencies (up to 35% for potato). Analysis of genomic DNA and UDP-glucose:galactose-1-phosphate uridyltransferase activity in randomly selected potato transformants confirmed the presence and active expression of the galT gene. The agricultural performance of transgenic potatoes was evaluated by monitoring the phenotype and tuber yield for two generations and these characters were found to be indistinguishable from non-transgenic controls. Thus, the galactose selection system provides a new alternative being distinct from conventional antibiotic and herbicide selection systems as well as so-called positive selection systems where the selective agent has a beneficial effect.

Contribution of oxidative stress to the development of cold-induced damage to leaves of chilling-sensitive plants: 3. Injury of cell membranes by chilling temperatures

Changes in permeability of cell membranes (judged from electrolyte leakage) were examined on leaves of 7- to 11-day-old seedlings of maize (Zea mays L.), cucumber (Cucumis sativus L.), millet (Panicum miliaceum L.), and on etiolated shoots of potato (Solanum tuberosum L.) immediately after cooling plants for 1–24 h at 2°C and one day after a 24-h chilling treatment. A gradually increasing leakage of ions from the cells was observed upon prolongation of chilling exposure, with the maximum attained by the end of 24-h chilling treatment. The leakage of electrolyte was slightly reduced in the post-treatment period but it was still higher than the electrolyte leakage from the control samples (untreated plants). The cold treatment of chilling-sensitive plants (but not of potato) revealed a positive correlation between the rates of lipid peroxidation, indicative of chilling injury, and the electrolyte efflux (r = 0.61–0.96). The evaluation of plant susceptibility to injury showed that millet and potato plants recovered from the chilling damage in 24 h after the treatment, whereas maize and cucumber plants did not show such a recovery.

Secondary metabolites in transgenic tobacco and potato: high accumulation of 4-hydroxybenzoic acid glucosides results from high expression of the bacterial gene ubiC

The bacterial gene ubiC encodes chorismate pyruvate-lyase (CPL), which converts chorismate to 4-hydroxybenzoate (4HB). The ubiC gene was expressed in tobacco (Nicotiana tabacum L., Solanaceae) and potato (Solanum tuberosum L., Solanaceae) under the control of the very strong constitutive plant promotor (ocs3) mas. High accumulation of 4HB glucosides as new, artificial secondary metabolites was observed in the transgenic plants. 4HB glucoside content reached 5.1% of dry weight in tobacco cell cultures and 4.0% of dry weight in the leaves of potato shoots. This is the highest content of an artificial secondary metabolite produced by genetic engineering of plants reported so far. Surprisingly, no growth retardation and no phenotypical changes were observed in the transgenic cell cultures and plants. Glucosylation of 4HB was achieved by endogeneous, constitutively expressed glucosyltransferases. The total amount of 4HB glucoside acccumulated showed a strict linear dependence on the expression level of ubiC.

Effect of Shoot Removal During Tuberization on Volunteer Potato (Solanum tuberosum) Tuber Production1

Volunteer potato can be a host of serious pest problems in potato and could provide a source of inoculum for subsequent potato crops. Volunteer potato can also be difficult to control in many rotational crops. Potato shoots were removed once, twice, and throughout the growing season, beginning at early and late tuberization. Compared with no shoot removal, two or more shoot removal treatments reduced the number of tubers 42% or more. A single shoot removal treatment at early tuberization reduced tuber biomass 37%, compared with 65% when shoot removal was initiated several weeks later. Regardless of timing, a single shoot removal increased the number and biomass of small tubers (≤ 57 g each). Control tactics that remove or kill volunteer potato shoots require repeated application or integration with other management practices to suppress the weed. Nomenclature: Volunteer potato, Solanum tuberosum L.; potato, Solanum tuberosum L. ‘Russet Burbank’. Additional index words: Groundkeeper, time of removal.

Inhibition of low-density lipoprotein oxidation and up-regulation of low-density lipoprotein receptor in HepG2 cells by tropical plant extracts.

Twelve edible plant extracts rich in polyphenols were screened for their potential to inhibit oxidation of low-density lipoprotein (LDL) in vitro and to modulate LDL receptor (LDLr) activity in cultured HepG2 cells. The antioxidant activity (inhibition of LDL oxidation) was determined by measuring the formation of conjugated dienes (lag time) and thiobarbituric acid reagent substances (TBARS). Betel leaf (94%), cashew shoot (63%), Japanese mint (52%), semambu leaf (50%), palm frond (41%), sweet potato shoot, chilli fruit, papaya shoot, roselle calyx, and maman showed significantly increased lag time (>55 min, P < 0.05) and inhibition of TBARS formation (P < 0.05) compared to control. LDLr was significantly up-regulated (P < 0.05) by Japanese mint (67%), semambu (51%), cashew (50%), and noni (49%). Except for noni and betel leaf, most plant extracts studied demonstrated a positive association between antioxidant activity and the ability to up-regulate LDL receptor. Findings suggest that reported protective actions of plant polyphenols on lipoprotein metabolism might be exerted at different biochemical mechanisms.

In situ hybridization of the MADS-box gene POTM1 during potato floral development.

The potato MADS-box gene POTM1 is a member of the SQUA-like family of plant MADS-box genes. The amino acid sequence of POTM1 most closely matches the sequence of PFG (Petunia Flowering Gene), a petunia MADS-box gene involved in the transition from vegetative to reproductive development. To examine the likely role of POTM1 in potato reproductive tissue, in situ hybridizations were performed on sections of the potato shoot apex at various stages during the transition to flowering. Scanning electron micrographs provide a reference for each stage to illustrate the progression from vegetative meristem to inflorescence meristem and floral organs. POTM1 mRNA accumulates in vegetative, inflorescence and floral meristems. Transcripts are present in petal primordia during the later stages of petal development and they accumulate later during floral development inside the stamens and carpels, but not in carpel walls. This widespread pattern of mRNA accumulation is unique among the SQUA-like genes and indicates that POTM1 is active during a variety of stages of development, and may function in regulating cell determination in transitional phases of both vegetative and floral meristems.

Cryopreservation of shoot tips from in vitro plants of sweet potato [Ipomoea batatas (L.) Lam.] by vitrification.

Routine cryopreservation of shoot tips from sweet potato [Ipomoea batatas (L.) Lam] has been hampered by their survival variability after cryogenic exposure. We examined the effects of light conditions on stock plants, sucrose preculture and cryoprotectant loading on survival after vitrification using PVS2 solution. The survival of vitrified sweet potato shoot tips cooled to approximately -208 °C was increased by preculturing with 0.3 M sucrose for 24 h at 22 °C. Survival was also enhanced by excising shoot tips immediately after the 8-h dark photoperiod. The best survival after cryogenic exposure was obtained using 2 M glycerol +0.4 M sucrose for 1 h at 22 °C followed by dehydration with PVS2 for 16 min at 22 °C. Rapid cooling was used and achieved by the immersion of foil strips into partially solidified nitrogen. Successfully vitrified and warmed shoot tips directly developed shoots on a medium containing 1 μM NAA, 0.5 μM BA and 0.1 μM kinetin with only minimum callus formation. Shoot formation occurred in all surviving shoot tips. This procedure shows promise for cryopreserving sweet potato shoot tips.

Modulation of Solanum tuberosum L. Morphogenesis and Antioxidative Status in a Stem Explant Culture by Limitation of Gas Exchange: Putative Effects of Ethylene

Summary The main objective of the present study was to test the hypothesis that increased concentrations of ethylene under conditions of limited gas exchange during in vitro cultivation of potato ( Solanum tuberosum L.) stem explants may lead to increased capaciry of antioxidative defense. By varying the tightness of closure and application of inhibitors of ethylene biosynthesis it was possible to accumulate various concentrations of ethylene in the internal atmosphere of culture flasks, which depended on excision-stress induced ethylene biosynthesis. In tightly closed cultures inhibition of linear growth, promotion of radial expansion and development of an apical hook occurred. Treatment with inhibitors of ethylene action and ethylene biosynthesis prevented the inhibition of shoot growth. The results suggest that the accumulation of endogenously produced ethylene in culture flasks due to limitation of gas exchange and following wounding stress may cause changes in potato shoot morphogenesis. Ascorbate peroxidase activiry was induced in. newly developing shoots by both limited gas exchange and ethephon treatment. Limitation of gas exchange led to increased activities of other enzymes of the antioxidative system as well. A permanent effect of precultivation in high ethylene concentration on ethylene production and anti oxidative status of potato microplants during subsequent cultivation was found. The data suggest that cultivation of potato stem tissues at increased concentrations of ethylene may lead to improved endogenous oxidative stress tolerance.

Potassium uptake efficiency of potato and wheat in relation to growth in flowing solution culture

Uptake efficiency (in terms of shoot K content) of potato decreased with time compared to that of wheat at a deficient K level of 1.5 μM. This resulted from the decrease in root-shoot ratio with time for potato only. Both shoot and root growth rates of potato depended on solution K levels in the initial stages and were greater at higher K levels. At optimum K, uptake efficiency of potato increased with time and this was due to the increased K-influx with time. The K concentration of 4–5% in the potato shoot was sufficient to achieve 90% of maximum shoot growth rate. Plants grown at optimum K concentration attained shoot K content of 4–5% rapidly and achieved maximum shoot growth rate faster than those grown at low K concentration.

Anthocyanins from tubers and shoots of the purple potato, Solanum tuberosum

SummaryThe anthocyanin content of tubers and shoots of the purple potato, Solanum tuberosum cv. Congo has been determined using various chromatographic and spectroscopic techniques to be petanin and the novel 3-O-[6-(4-ferulyl-O-α-rhamnopyranosyl)-β-glucopyranoside]-5-O-β-glucopyranosides of petunidin and malvidin. Acylated pigments constitute more than 98% of the total anthocyanin content both in tubers and shoots.

Phloroglucinol enhances growth and rate of axillary shoot proliferation in potato shoot tip cultures in vitro

Efficacy of phloroglucinol in promoting growth and development of in vitro-derived shoot tips was studied in six potato (Solanum tuberosum L.) genotypes. Different concentrations of phloroglucinol (0, 0.08, 0.4, 0.8, 1.2 and 1.6 mM) were tested in combination with either 0.1 or 0.2 M sucrose in shoot tip proliferation medium based on MS (Murashige and Skoog, 1962) medium supplemented with 5.8 μM GA3 (gibberellic acid), 1.1 μM BA (N6-benzyladenine) and 8.39 μM D-calcium pantothenate. Phloroglucinol fostered multiple shoot formation, promoted axillary shoot proliferation in terms of shoot tip fresh weight and shoot length, and stimulated root formation on the shoot tips. There was significant phloroglucinol × sucrose interaction for number of shoots developed per shoot tip, shoot tip fresh weight and number of roots induced per shoot tip. The beneficial effect of phloroglucinol on shoot tip survival was conspicuous only in genotypes that showed poor survival in the control proliferation medium. There were significant differences in response between the two sucrose levels with regard to shoot tip fresh weight and number of roots per shoot tip. Phloroglucinol in combination with 0.2 M sucrose induced maximum number of roots per shoot tip. Optimum shoot tip growth was fostered in medium containing 0.8 mM phloroglucinol and 0.2 M sucrose. High frequency multiple shoot formation in this medium ensures a faster rate of potato shoot tip multiplication within a limited time and space.