Cuticular waxes from potato (Solanum tuberosum) leaves

The qualitative and quantitative compositions of leaf cuticular waxes from potato (Solanum tuberosum) varieties were studied. The principal components of the waxes were very long chain n-alkanes, 2-methylalkanes and 3-methylalkanes (3.1-4.6 microg cm(-2)), primary alcohols (0.3-0.7 microg cm(-2)), fatty acids (0.3-0.6 microg cm(-2)), and wax esters (0.1-0.4 microg cm(-2)). Methyl ketones, sterols, beta-amyrin, benzoic acid esters and fatty acid methyl, ethyl, isopropyl and phenylethyl esters were found for the first time in potato waxes. The qualitative composition of the waxes was quite similar but there were quantitative differences between the varieties studied. A new group of cuticular wax constituents consisting of free 2-alkanols with odd and even numbers of carbon atoms ranging from C25 to C30 was identified.     

Chloroplast DNA variation between the common cultivated potato (Solanum tuberosum ssp. tuberosum) and several South American relatives

Summary Chloroplast DNA (ctDNA) from the tuberbearing Solanum species tuberosum, vernei, phureja, and chacoense has been compared by restriction endonuclease analysis. Digestion by Hind III or Xba I reveal no differences, but digestion with Bam HI and Eco RI reveals minor differences in the ctDNA among these species. The ctDNA restriction patterns of the tetraploid common cultivated potato of North America and Europe, S. tuberosum ssp. tuberosum and the South American tetraploid, S. tuberosum ssp. andigena are identical for all four restriction endonucleases. These data suggest that ssp. tuberosum and ssp. andigena contain similar ctDNA and therefore may share a common ancestor, or direct lineage. The ctDNA restriction patterns of S. vernei and S. chacoense are identical for all four restriction endonucleases, and S. phureja ctDNA, can be distinguished from the other diploid ctDNAs by digestion with Bam HI. None of the diploids analyzed contain ctDNA identical to the tetraploids and therefore either did not contribute their chloroplast genomes to the evolution of the tetraploids, or the ctDNA has diverged since this evolutionary event. The ctDNAs studied did not contain restriction polymorphisms which could be correlated to cytoplasmic male sterility in Solanum. This is the first demonstration of ctDNA diversity in the tuber-bearing Solanum species.     

Identification of 2n breeding lines and 4n varieties of potato (Solanum tuberosum,ssp. tuberosum) with RFLP-fingerprints

Summary The possibility of genotype identification with RFLP fingerprints was examined with 20 tetraploid potato varieties and 38 diploid potato lines. By using a sensitive detection system for small restriction fragment length differences and highly variable potato sequences as probes, all genotypes (diploids and tetraploids) were distinguished by a minimum of two probe/enzyme combinations. The best single probe/enzyme combination distinguished 19 out of 20 4n varieties and 33 out of 38 2n lines. Intravarietal variability was very small compared to the intervarietal variability, and patterns obtained with different DNA sources of the same genotype were identical.     

Purification and characterization of β-amylase from leaves of potato (Solanum tuberosum)

Amylolytic activity is widely distributed in plants. In potato leaves ( Solanum tuberosum L.) the abundant amylolytic activity was found to be β-amylase (EC 3.2.1.2, a-1,4-D-glucan maltohydrolase). β-Amylase from potato leaves was purified to homogeneity for study of enzyme characteristics. The purification steps included ammonium sulphate precipitation, anion exchange chromatography, affinity chromatography and gel filtration. The end product of α-1,4-glucan degradation was maltose. The protein is a 111-kDa homo-dimer with a subunit molecular mass of 56 kDa and a pl of 5.6. The pH-optimum is 6.5 using p -nitrophenylmaltopentaoside (PNPG5) as substrate. The optimal temperature for hydrolysis is at 40°C. The enzyme is unstable at temperatures above 40°C. The K_nt-value for PNPG5 is 0.73 m M and the activity is inhibited by cyclodextrins. At a concentration of 1 m M , β-cyclodextrin is a stronger inhibitor than α-cyclodextrin (68 and 20% inhibition, respectively). Branched glucans (e.g. starch and amylopectin) are superior substrates as compared to long, essentially unbranched glucans (e.g. amylose). This study of the catalytic properties of β-amylase from potato leaves indicates the importance of β-amylase as a starch degrading enzyme.     

Fructose 2,6-bisphosphate levels in mature leaves of tobacco (Nicotiana tabacum) and potato (Solanum tuberosum)

Here we show that fructose 2,6-bisphosphate cannot be reliably measured in mature leaves of tobacco (Nicotiana tabacum L.), potato (Solanum tuberosum L.), or stinging nettle (Urtica dioica L.) using conventional extraction techniques, since the recoveries of fructose 2,6-bisphosphate added during extraction are poor. However, fructose 2,6-bisphosphate could be extracted by boiling leaves in ethanol and aqueous buffer. Evidence for the reliability of this technique is provided by high recovery measurements of fructose 2,6-bisphosphate added to the leaves before extraction. This extraction method was used to measure changes in the level of fructose 2,6-bisphosphate throughout the photoperiod in tobacco and potato leaves. These changes are compared with the rate of accumulation of sucrose and starch in the leaf samples. Variations in the levels of fructose 2,6-bisphosphate, and the relationship between this metabolite and sucrose and starch accumulation in these leaves during the photoperiod are similar to the pattern observed in leaves of other plant species.Abbreviations BSA bovine serum albumin - Fru-2,6-P₂ fructose 2,6-bisphosphate This research was supported by the Agricultural and Food Research Council (Grant no. PG43/531), and the Royal Society.     

Drought and chlorophyll fluorescence in field-grown potato (Solanum tuberosum)

Light interception, stomatal conductance and chlorophyll fluorescence were measured in potato ( Solanum tuberosum L.) grown either irrigated, or droughted from the time of plant emergence. Compared with the irrigated treatment, drought reduced both light interception and stomatal conductance. In both treatments, the yields of variable fluorescence in the dark- and light-adapted states (F_y/F_m and F'_v/F'_m, respectively) were negatively correlated with photosynthetic photon flux density (PPFD) and mirrored daytime changes in PPFD. Photochemical quenching was positively correlated with PPFD, but the dominant effect of F'_v/F'_m resulted in a decrease in the quantum yield of photosystem II (PSII) electron transport with increasing PPFD.
Drought had no significant effect on the functioning of PSII and the balance between photochemical and non-photochemical quenching was unaffected. Non-photochemical quenching was not increased by drought and the quantum yield of PSII electron transport was unaffected. It is concluded that, in leaves of droughted plants, excess energy, resultant of stomatal limitation of photosynthesis, was dissipated by photochemical quenching such as increased photorespiration.     

Transformation of potato (Solanum tuberosum) using particle bombardment

Internodes, leaves and tuber slices from potato (Solanum tuberosum), genotype 1024-2, were subjected to particle bombardment. Transient expression was optimized using the uidA and the luc reporter genes that encode #-glucuronidase (GUS) and luciferase, respectively. Stable transformation was achieved using the neomycin phosphotransferase (nptII) gene, which confers resistance to the antibiotic kanamycin. The influence of biological parameters (tissue type, growth period before bombardment, pre- and post-bombardment osmoticum treatment) and physical parameters (helium pressure, tissue distance) that are known to possibly affect stable transformation were investigated. Putative transgenic plants, which rooted in media containing kanamycin, were obtained from all of the tissues tested although there were large differences in the efficiency: internodes (0.77 plants per bombarded explant), microtuber slices (0.10 plants per bombarded explant) and leaves (0.02 plants per bombarded explant). Southern blot analysis of putative transgenic plants confirmed the integration of the transgenes into plant DNA. The results indicate that an efficient particle bombardment protocol is now available for both transient and stable transformation of potato internodal segments, thus contributing to an enhanced flexibility in the delivery of transgenes to this important food crop.     

Allelic state of the molecular marker for golden nematode (Globodera rostochiensis) resistance gene H1 among Ukrainian and world potato (Solanum tuberosum ssp. tuberosum) cultivars

The purpose of this study was to determine the allelic state of the resistance gene H1 against the Ro1 and Ro4 pathotypes of the golden potato cyst nematode (Globodera rostochiensis) among Ukrainian and world potato (Solanum tuberosum ssp. tuberosum) cultivars. The allelic state of the TG689 marker was determined by PCR with DNA samples isolated from potato tubers and primers, one pair of which flanked the allele-specific region and the other one was used to control the DNA quality. Among 77 potato cultivars analyzed, the allele of the marker associated with the H1-type resistance was found in 74% of Ukrainian and 90% of foreign cultivars, although some of them proved to be susceptible to the potato cyst nematode in the field. The obtained data confirm the presence of H1 resistance against golden nematode pathotypes Ro1 and Ro4 among Ukrainian potato cultivars and the efficiency of the used marker within the accuracy that has been declared by its authors.     

Accumulation of vitamin E in potato (Solanum tuberosum) tubers

Vitamin E (tocopherol) is a powerful antioxidant essential for human health and synthesized only by photosynthetic organisms. The effects of over-expression of tocopherol biosynthetic enzymes have been studied in leaves and seeds, but not in a non-photosynthetic, below-ground plant organ. Genetic and molecular approaches were used to determine if increased levels of tocopherols can be accumulated in potato (Solanum tuberosum L.) tubers through metabolic engineering. Two transgenes were constitutively over-expressed in potato: Arabidopsis thaliana p-hydroxyphenylpyruvate dioxygenase (At-HPPD) and A. thaliana homogentisate phytyltransferase (At-HPT). α-Tocopherol levels in the transgenic plants were determined by high-performance liquid chromatography. In potato tubers, over-expression of At-HPPD resulted in a maximum 266% increase in α-tocopherol, and over-expression of At-HPT yielded a 106% increase. However, tubers from transgenic plants still accumulated approximately 10- and 100-fold less α-tocopherol than leaves or seeds, respectively. The results indicate that physiological and regulatory constraints may be the most limiting factors for tocopherol accumulation in potato tubers. Studying regulation and induction of tocopherol biosynthesis should reveal approaches to more effectively engineer crops with enhanced tocopherol content.     

Studies on the chemical modification of potato (Solanum tuberosum) lectin and its effect on haemagglutinating activity

1. Modification of potato (Solanum tuberosum) lectin with acetic anhydride blocked 5.1 amino and 2.7 tyrosyl groups per molecule of lectin and decreased the haemagglutinating activity of the lectin. De-O-acetylation regenerated 2.0 of the tyrosyl groups and resulted in a recovery of activity. 2. Modification with citraconic anhydride or cyclohexane-1,2-dione did not greatly affect activity, although modification of amino and arginyl groups could be demonstrated. 3. Treatment with tetranitromethane nitrated 3.7 tyrosine residues per molecule of lectin with concomitant loss of activity. The presence of 0.1m-NN′N″-triacetylchitotriose (a potent inhibitor of the lectin) in the reaction medium protected all the tyrosyl residues from nitration and the lectin was fully active. 4. Modification of tryptophyl groups with 2-hydroxy-5-nitrobenzyl bromide and 2,3-dioxoindoline-5-sulphonic acid modified 0.9 and 2.6 residues per molecule of lectin respectively with a loss of activity in each case. Reaction of potato lectin with 2,3-dioxoindoline-5-sulphonic acid in the presence of inhibitor protected 2.4 residues of tryptophan from the reagent. Loss of haemagglutination activity was prevented under these conditions. 5. Reaction of carboxy groups, activated with carbodi-imide, with α-aminobutyric acid methyl ester led to the incorporation of 5.3 residues of the ester per molecule of lectin. Presence of inhibitor in this case, although protecting activity, did not prevent modification of carboxy groups; in fact an increase in the number of modified residues was seen. This effect could be imitated by performing the reaction in 8m-urea. In both cases the number of carboxy groups modified was close to the total number of free carboxy groups as determined by the method of Hoare & Koshland [(1967) J. Biol. Chem. 242, 2447–2453]. Guanidination of lysine residues after carboxy-group modification gave less homoarginine than did the unmodified lectin under the same conditions, suggesting the formation of intramolecular cross-links during carbodi-imide activation. 6. It is suggested from the results presented that amino, arginyl, methionyl, histidyl and carboxyl groups are not involved in the activity of the lectin and that tyrosyl and tryptophyl groups are very closely involved. These findings are similar to those reported for other proteins that bind N-acetylglucosamine oligomers and also fit the general trend in other lectins.     

Effects of ethylene on the tuberization of potato (Solanum tuberosum) cuttings

Ethylene, applied as ethephon, inhibited the elongation of etiolated, axillary potato shoots cultured in vitro and it stimulated radial growth along the whole length of these shoots. The same phenomena were observed when ACC, the precursor of ethylene, was added to the medium, whereas silver ions reversed these effects. However, tuber formation in vitro was suppressed by ethephon. This indicates a dual role of ethylene in the induction of tuber formation in potatoes: it had a positive effect by blocking the elongation of stolons and it suppressed tuber initiation.     

Temperature regulates tuber-inducing lipoxygenase-derived metabolites in potato (Solanum tuberosum)

Temperature is one of the major environmental factors affecting potato tuberization. It has been suggested that lipoxygenase (LOX) mediates between temperature and tuber induction. In this study, the contents of the LOX-derived metabolites hydroperoxylinolenic acid (HPOT), jasmonic acid (JA), tuberonic acid (TA) and tuberonic acid glucoside (TAG) were analyzed in leaves of potatoes growing at different temperatures. At low, tuber-inducing temperature, endogenous levels of JA, TA and TAG rise, indicating their crucial role in tuber induction. The concentration of 13(S)-HPOT seems not to be directly affected by temperature. Instead, the molecule has only a short half-life in leaves and is readily metabolized.     

Aldehyde oxidase isoenzymes (E.C. 1.2.3.1) in potato tubers (Solanum tuberosum)

Two isoenzymes of aldehyde oxidase (E.C. 1.2.3.1 [EC] ) can be separatedfrom potato tubers (Solanum tuberosum) by polyacrylamide gelelectrophoresis. The pH optima of these two isoenzymes werepH 7.5. Both enzymes can oxidize different aldehydes, e.g. crotonaldehyde,Propionaldehyde, acetaldehyde, formaldehyde, glyoxal and benzyl-aldehyde.The isoenzymes could not use xanthine as a substrate. Formaldehydewas oxidized only in the presence of phosphate ions. A substratedependent inhibition of the enzyme activity is possible throughchloral hydrate. PMS, FMN, riboflavine, cytochrome c and O₂ serve as electronacceptors. (Received December 12, 1973; )     

QTL mapping of yield, agronomic and quality traits in tetraploid potato (Solanum tuberosum subsp. tuberosum)

Interval mapping of quantitative trait loci (QTL) for 16 yield, agronomic and quality traits in potato was performed on a tetraploid full-sib family comprising 227 clones from a cross between processing clone 12601ab1 and table cultivar Stirling. Thirty-eight AFLP primer combinations and six SSRs provided 514 informative markers which formed a molecular marker map comprising 12 linkage groups (LGs) in 12601ab1 (nine with four homologous chromosomes) which were aligned with 12 in Stirling (11 with four homologous chromosomes), with four partial groups remaining in 12601ab1. Two LGs were identified unequivocally as chromosomes IV and V and eight others were tentatively assigned with chromosomes VII and X unidentified. All of the traits scored had moderately high heritabilities with 54–92% of the variation in clone means over 3 years and two replicates being due to genetic differences. A total of 39 QTLs were identified. A QTL for maturity was identified on chromosome V which explained 56% of the phenotypic variance, whereas the other QTLs individually explained between 5.4 and 16.5%. However, six QTLs were detected for after-cooking blackening and four for each of regularity of tuber shape, fry colour both after storage at 4 and 10°C and sprouting. Just two QTLs were found for each of yield, the two ‘overall’ scores, crop emergence, tuber size and common scab and just one QTL was detected for each of dry matter content, keeping quality, growth cracks and internal condition. The implications for practical potato breeding and for practical linkage and QTL analysis in autotetraploids are discussed.     

Expression of the IL-2 gene in the potato (Solanum tuberosum cv. Superior)

We intended to examine the expression of the T-cell growth factor (human interleukin-2) so that a binary vector, pSSK-1, carrying the IL-2 gene was constructed and transferred intoA. tumefaciens for the purpose of the transformation of the potato (Solanum tuberosum cv. Superior). All of theAgrobacterium-infected potato explants were regenerated to shoots in modified MS medium and 81% of them rooted on the medium containing kanamycin (200 mg/L). Southern and Northern analysis were performed to verify the transformation events. EL-ISA test indicated that IL-2 protein was produced from IL-2-transformed potatoes. These results suggested expression and production of the IL-2 protein from the transgenic potato.