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PubMed1989

Polyamine metabolism of potato seed-tubers during long-term storage and early sprout development.

Growth potential of potato (Solanum tuberosum L.) plants is influenced by seed-tuber age. After 24 days of growth, single-eye seedcores from 7-month-old seed-tubers produced 64% more foliar dry matter than those from 19-month-old seed-tubers, reflecting a higher growth rate. This study was initiated to determine if differences in polyamine (PA) metabolism are associated with aging and age-reduced vigor of potato seed-tubers. As tubers aged in storage, putrescine (Put) increased 2.2-fold, while spermidine (Spd) and spermine (Spm) decreased 33% and 38%, respectively. Ethylene content of the tuber tissue also increased with advancing age, suggesting that during the aging process S-adenosylmethionine was directed toward ethylene biosynthesis at the expense of the PAs. Single-eye cores from 7- and 19-month-old tubers were sown and PA levels in core and shoot tissues were monitored during plant development. Put titer of younger cores increased 8.8-fold by 12 days. In contrast, the increase in Put over the initial titer in older cores was 2.9-fold. The reduced ability of older cores to synthesize Put during plant establishment is probably due to a 45% decline in ornithine decarboxylase activity between 12 and 16 days after planting. Lack of available Put substrate limited the biosynthesis of Spd and Spm, and thus their concentrations remained lower in older cores than in younger cores. Lower PA titer in older cores during plant establishment is thus coincident with reduced growth potential. Concentrations of Put and Spd were higher in shoots developing from older cores throughout the study, but there was no age-related difference in Spm content. In contrast, activities of arginine and S-adenosylmethionine decarboxylases were higher in shoots from younger cores during establishment. The results indicate that aging affects PA metabolism in both tuber and developing plant tissues, and this may relate to loss of growth potential with advancing seed-tuber age.

Journal Article↗
PubMed2000

Laboratory evaluation of lufenuron on immature stages of potato tuber moth (Lepidoptera: Gelechiidae).

The effects of the chitin synthesis inhibitor lufenuron against potato tuber moth, Phthorimaea operculella (Zeller), eggs were determined by topically exposing different age groups of eggs (1-4 d old) to treated potato tubers (Solanum tuberosum L.) under laboratory conditions. Larval hatch from both treated (4 and 12 g [AI]/100 liter) and untreated tubers was >95%, but mortality of first instars was high in treated tubers (>90%) compared with untreated tubers. Examination of the treated tubers showed that most of the larvae were unable to penetrate or cause any noticeable damage to the potato tubers. However, the few first instars that survived were able to penetrate the tubers and continue their development to the pupal or adult stages. At 12 g (AI)/100 liter, adult emergence was <2% and most of the emerged adults had morphological deformities such as reduced wing size and they were unable to free themselves from the pupal sacs. These data suggest that topical application of lufenuron to eggs before larval hatch would reduce the amount of damage caused by potato tuber moth as part of integrated pest management program.

Animals↗
PubMed1997

Potato tuber formation in the spaceflight environment.

Five potato (Solanum tuberosum L.) leaf cuttings were flown on STS-73 in late October, 1995 as part of the 16-day USML-2 mission. Preflight studies were conducted to study tuber growth, determine carbohydrate concentrations, and examine the developing starch grains within the tuber. In these tests, tubers attained a fresh weight of 1.4 g tuber-1 after 13 days. Tuber fresh mass was significantly correlated to tuber diameter. Greater than 60% of the tuber dry mass was starch and the starch grains varied in size from 2 to 40 micrometers in the long axis. For the flight experiment, cuttings were obtained from 7-week-old Norland potato plants, kept at 5 degrees C for 12 h then planted into arcillite in the ASTROCULTURE(TM) flight hardware. The flight package was loaded on-board the orbiter 22 h prior to launch. During the mission, the flight hardware maintained an environment around the cuttings of 22 +/- 2 degrees C, 81 +/- 7% RH, and a 12-h photoperiod using red and blue light-emitting diodes at a photosynthetic photon flux of 150 micromol m-2 s-1. CO2 concentration exceeded 4000 ppm during the dark period and was controlled during the light period to approximately 400 ppm. Video downlinking of images of the plants and CO2 exchange data during the flight demonstrated plant vitality for the first 12 days of the mission followed by senescence of the leaves. The flight package was received 4 h after landing at the Kennedy Space Center and postflight processing of the samples was completed within 3 h. Four out of the five space-grown cuttings produced tubers that were similar in appearance and dimension to the ground control tubers. This is an important finding if potatoes are to be used as part of a bioregenerative life support system for long-term space exploration.

Biomass↗
PubMed1999

A comparison of cell phenotypes in hemimegalencephaly and tuberous sclerosis.

Hemimegalencephaly, an uncommon sporadic nonfamilial congenital dysplastic abnormality of the central nervous system, constitutes a pathological spectrum of neuronal migration disorders, but consistently includes abnormal large neurons similar to those in the cortical tubers of tuberous sclerosis. Microscopically, there are also cells with homogeneous and weakly eosinophilic cytoplasm with a single eccentric nucleus, sometimes called balloon cells (likewise prominent in tuberous sclerosis). We looked for immunohistochemical and ultrastructural differences in the large neurons and balloon cells between hemimegalencephaly and tuberous sclerosis. Microtubule-associated protein 1B and 2, phosphorylated and non-phosphorylated neurofilament and synaptophysin identify the large neurons and distinguish them from balloon cells in both entities. Balloon cells in hemimegalencephaly showed no immunoreactivity for TSC2 gene product, tuberin, and vimentin, but similar cells in tuber tissue showed consistent immunoreactivity. Balloon cells in hemimegalencephaly showed no immunoreactivity for glial fibrillary acidic protein, but some cells in tubers showed such immunoreactivity. Ultrastructurally, balloon cells in hemimegalencephaly contained very few lysosomes, microfilaments, and microtubules, but abundant lipofuscin granules. Similar cells in tubers had prominent lysosomes, more microfilaments and microtubules, and very few lipofuscin granules. The resemblance between abnormal cells in hemimegalencephaly and tuberous sclerosis is superficial; their immunohistochemistry and electron microscopic profiles show distinct differences.

Adolescent↗
PubMed2025

An allelic resolution gene atlas for tetraploid potato provides insights into tuberization and stress resilience.

Tubers are modified underground stems that enable asexual, clonal reproduction and serve as a mechanism for overwintering and avoidance of herbivory. Potato (Solanum tuberosum L.) is cultivated for its tubers, which serve as a major crop. Genes responsible for tuber initiation and disease resistance have been characterized in potato including StSP6A, a homolog of flowering time, that functions as a tuberigen, the equivalent of a florigen. To elucidate additional molecular and genetic mechanisms underlying potato biology including tuber initiation, tuber development, and stress responses, we generated a developmental and abiotic/biotic-stress gene expression atlas from 34 tissues and treatments of the tetraploid potato cultivar, Atlantic. Using the haplotype-phased tetraploid Atlantic genome assembly and expression abundances of 129&#x2009;218 genes, we constructed gene coexpression modules that represent networks associated with distinct developmental stages as well as stress responses. Functional annotations were given to modules and used to identify genes involved in tuberization and stress resilience. Structural variation from a pan-genomic analysis across four cultivated potato genome assemblies as well as domestication and wild introgression data allowed for deeper insights into the modules to identify key genes involved in tuberization and stress responses. This study underscores the importance of transcriptional regulation in tuberization and provides a comprehensive framework for future research on potato development and improvement.

Solanum tuberosum↗
PubMed1994

Tuberous sclerosis in Western Sweden. A population study of cases with early childhood onset.

OBJECTIVE: To study the prevalence of tuberous sclerosis in children and adolescents. DESIGN: Previously published diagnostic criteria for tuberous sclerosis were used. All physicians likely to encounter young patients with tuberous sclerosis were contacted by way of a screening questionnaire. SETTING: The study was performed in a circumscribed geographic area (western Sweden). PATIENTS AND OTHER PARTICIPANTS: The sample was population based. However, only patients with such severe and early symptoms that referral to a physician had been considered necessary and relatives of these patients with tuberous sclerosis could be included. This was because there is currently no diagnostic marker for tuberous sclerosis that could be used as a screening tool. RESULTS: The peak prevalence (one in 6800 individuals) for tuberous sclerosis was found in the 11- to 15-year-old age group. For the whole age cohort, 0 to 20 years, the prevalence was one in 12,900 individuals. CONCLUSIONS: The prevalence for the school-age group was the highest ever reported in the literature on tuberous sclerosis. However, it is likely that the true prevalence of tuberous sclerosis in the general population is even higher.

Adolescent↗
PubMed1997

Association of tuberous sclerosis of temporal lobes with autism and atypical autism.

BACKGROUND: Tuberous sclerosis (TS) is a multisystem genetic disorder that is associated with mental retardation, autism, and atypical autism. We investigated the basis for these associations by examining whether the liability to mental retardation and autism or atypical autism is related to the number and distribution of hamartomatous brain growths (cortical tubers) that characterise TS. METHODS: 18 patients consecutively referred to our clinic were assessed for the presence of autism or atypical autism, and their IQs were estimated (without awareness of brain-scan results). Brain scans were reviewed by a neuroradiologist (unaware of clinical diagnoses), and the number and location of cortical tubers was examined in relation to the liability to psychopathology. FINDINGS: Nine of the 18 patients had autism or atypical autism (two with IQ > or = 70; four with IQ 51-69, three with IQ < or = 50; eight with a history of epilepsy). The remaining patients had various other psychiatric disorders (five with IQ > or = 70; four with IQ 51-69; seven had a history of epilepsy). In the group as a whole, the number of tubers was significantly greater (p = 0.005) in patients with mental retardation (median 6 [IQR 4-9]) than in those of normal intelligence (1 [0-3]), and the degree of mental retardation was significantly correlated with the number of brain tubers (rs = 0.64; p = 0.008). Similarly, the number of tubers was significantly greater (p = 0.02) in individuals with a diagnosis of autism or atypical autism (6 [4-8]) than in those without this diagnosis (2 [1-4]). Eight of the nine patients with autism or atypical autism, but none of the non-autistic individuals, had tubers located in the temporal lobes (p = 0.0004). Otherwise, no particular distribution of cortical tubers was associated with a diagnosis of autism or atypical autism. INTERPRETATION: Our investigation provides evidence of an association between a gross, focal brain abnormality detectable on neuroimaging and autism or atypical autism. The results show the importance of scan findings in the prognosis of TS, and also suggest that temporallobe neurodevelopmental abnormalities may create a risk for autism or atypical autism.

Adolescent↗
PubMed2002

Neuro-epileptic determinants of autism spectrum disorders in tuberous sclerosis complex.

Tuberous sclerosis is one of the few established medical causes of autism spectrum disorder and is a unique neurogenetic model for testing theories about the brain basis of the syndrome. We conducted a retrospective case study of the neuro-epileptic risk factors predisposing to autism spectrum disorder in individuals with tuberous sclerosis to test current neurobiological theories of autism spectrum disorder. We found that an autism spectrum disorder diagnosis was associated with the presence of cortical tubers in the temporal but not other lobes of the brain. Indeed, the presence of tubers in the temporal lobes appeared to be a necessary but not sufficient risk factor for the development of an autism spectrum disorder. However, contrary to the predictions of some theories, the location of tubers in specific regions of the temporal lobe, such as the superior temporal gyrus or the right temporal lobe, did not determine which individuals with temporal lobe tubers developed an autism spectrum disorder. Instead, outcome was associated with various indices of epileptic activity including evidence of temporal lobe epileptiform discharges on EEG, the age to onset of seizures in the first 3 years of life and a history of infantile spasms. The results indicated that individuals with tuberous sclerosis are at very high risk of developing an autism spectrum disorder when temporal lobe tubers are present and associated with temporal lobe epileptiform discharges and early-onset, persistent spasm-like seizures. These risk markers constitute useful clinical indicators of prognosis, but further research is required to identify the neurobiological mechanisms responsible for their association with outcome. Most especially, it will be important to test whether, as the findings suggest, there is a critical early stage of brain maturation during which temporal lobe epilepsy perturbs the development of brain systems that underpin 'social intelligence' and possibly other cognitive skills, thereby inducing an autism spectrum disorder.

Autistic Disorder↗
PubMed2003

Expression of a bacterial xylose isomerase in potato tubers results in an altered hexose composition and a consequent induction of metabolism.

Here we investigate the role of hexoses in the metabolism of the developing potato (Solanum tuberosum) tuber by the expression of a bacterial xylose isomerase which catalyzes the interconversion of glucose and fructose. Previously, we found that glycolysis was induced in transgenic tubers expressing a yeast invertase in the cytosol and postulated that this was due either to the decreased levels of sucrose or to effects downstream of the sucrose cleavage. In the present study xylose isomerase was expressed under the control of the tuber-specific patatin promoter. Selected transformants exhibited minor changes in the levels of tuber glucose and fructose but not in sucrose. Analysis of the enzyme activities of the glycolytic pathway revealed minor yet significant increases in the maximal catalytic activities of aldolase and glyceraldehyde 3-phosphate dehydrogenase but no increase in the activities of other enzymes of glycolysis. These lines were also characterized by an elevated tuber number, glycolytic and sucrose synthetic fluxes and in some metabolite levels downstream of glycolysis. When considered together these data suggest that the perturbation of hexose levels can result in increased glycolytic and sucrose (re)synthetic fluxes in the potato tuber even in the absence of changes in the level of sucrose. The consequences of altering hexose levels in the tuber are, however, not as severe as those observed following perturbation of the level of tuber sucrose.

Aldose-Ketose Isomerases↗
PubMed2005

Tuber-specific cytosolic expression of a bacterial phosphoglucomutase in potato (Solanum tuberosum L.) dramatically alters carbon partitioning.

Constitutive antisense inhibition of the cytosolic isoform of phosphoglucomutase in the potato (Solanum tuberosum L.) results in restriction of photosynthesis, growth inhibition and modified tuber morphology, and a severe restriction of tuber starch synthesis. Here we describe the consequences of the tuber-specific expression of an Escherichia coli phosphoglucomutase in the cytosol. Analysis of [14C]glucose metabolism by tuber discs isolated from wild type and transformants revealed that the rates of sucrose and starch synthesis were unaltered but that the rate of glycolysis was depressed in the transgenics. The transformant tubers also contained dramatically reduced amino acid content and significantly higher levels of ADP, but were characterized by elevated levels of Krebs cycle intermediates and an unaltered rate of respiration. In addition to these metabolic consequences of the overexpression of the E. coli enzyme, we observed morphological changes in tubers, with the transformants having a smaller number of larger tubers which exhibited delayed rates of sprouting with respect to the wild type. These results are discussed with respect to current models of the regulation of central plant metabolism and tuber dormancy.

Adenosine Monophosphate↗
PubMed2005

Inhibition of de novo pyrimidine synthesis in growing potato tubers leads to a compensatory stimulation of the pyrimidine salvage pathway and a subsequent increase in biosynthetic performance.

Pyrimidine nucleotides are of general importance for many aspects of cell function, but their role in the regulation of biosynthetic processes is still unclear. In this study, we investigate the influence of a decreased expression of UMP synthase (UMPS), a key enzyme in the pathway of de novo pyrimidine synthesis, on biosynthetic processes in growing potato (Solanum tuberosum) tubers. Transgenic plants were generated expressing UMPS in the antisense orientation under the control of the tuber-specific patatin promoter. Lines were selected with markedly decreased expression of UMPS in the tubers. Decreased expression of UMPS restricted the use of externally supplied orotate for de novo pyrimidine synthesis in tuber tissue, whereas the uridine-salvaging pathway was stimulated. This shift in the pathways of UMP synthesis was accompanied by increased levels of tuber uridine nucleotides, increased fluxes of [(14)C]sucrose to starch and cell wall synthesis, and increased amounts of starch and cell wall components in the tubers, whereas there were no changes in uridine nucleotide levels in leaves. Decreased expression of UMPS in tubers led to an increase in transcript levels of carbamoylphosphate synthase, uridine kinase, and uracil phosphoribosyltransferase, the latter two encoding enzymes in the pyrimidine salvage pathways. Thus, the results show that antisense inhibition of the de novo pathway of pyrimidine synthesis leads to a compensatory stimulation of the less energy-consuming salvage pathways, probably via increased expression and activity of uridine kinase and uracil phosphoribosyltransferase. This results in increased uridine nucleotide pool levels in tubers and improved biosynthetic performance.

Down-Regulation↗
PubMed2004

Diagnosis of tuberous sclerosis complex.

Tuberous sclerosis complex is a dominantly inherited disorder affecting multiple organs; because of its phenotypic variability, the diagnosis of tuberous sclerosis complex can be difficult in the young or in individuals with subtle findings. Recently revised consensus diagnostic criteria for tuberous sclerosis complex reflect an improved understanding of its clinical manifestations and its genetic and molecular mechanisms. The diagnostic criteria are based on the premise that there are probably no truly pathognomonic clinical signs for tuberous sclerosis complex; signs that were once regarded as specific occur as isolated findings in individuals with no other clinical or genetic evidence of tuberous sclerosis complex. Consequently, the revised criteria require tuberous sclerosis complex-associated lesions of two or more organ systems or at least two dissimilar lesions of the same organ to confirm the diagnosis. The addition of DNA testing complements clinical diagnosis and allows more precise genetic counseling and, in some individuals, prenatal diagnosis. Nevertheless, the 15% false-negative rate for DNA testing and the occurrence of germline mosaicism in about 2% of individuals with tuberous sclerosis complex make it difficult to exclude the diagnosis of tuberous sclerosis complex in family members.

Child↗
PubMed2004

Epilepsy surgery for children with tuberous sclerosis complex.

Tuberous sclerosis complex is associated with medically refractory seizures and developmental delay in children. These epilepsies are often resistant to antiepileptic drugs, can be quite severe, and usually have a negative impact on the child's neurologic and cognitive development. It is believed that functional outcome is improved if seizures can be controlled at an early age. The surgical treatment of intractable epilepsy in children and adults with tuberous sclerosis complex has gained significant interest in recent years. Previously published studies have shown a potential benefit from resection of single tubers, with most of the results noted in relatively older children. All of these reports support the idea that if a single primary epileptogenic tuber or region can be identified, then a surgical approach is appropriate. However, most children with tuberous sclerosis complex have multiple potentially epileptogenic tubers, rendering localization challenging, and they are therefore rejected as possible surgical candidates. We have used a novel surgical approach using invasive intracranial monitoring, which is typically multistaged and bilateral. This multistage surgical approach has been useful in identifying both primary and secondary epileptogenic zones in patients with tuberous sclerosis complex with multiple tubers. Multiple or bilateral seizure foci are not necessarily a contraindication to surgery in selected patients. Long-term follow-up will determine whether this approach has durable effects. We await better methods for identifying the epileptogenic zone, both noninvasive and invasive.

Age Factors↗
PubMed1999

Vigabatrin in the treatment of infantile spasms in tuberous sclerosis: literature review.

The purpose of this report is to review the efficacy and safety of vigabatrin in the treatment of infantile spasms in infants suffering from tuberous sclerosis complex. We reviewed all studies published in the English-language literature investigating the use of vigabatrin in the treatment of infantile spasms. Ten studies gave results for the efficacy of vigabatrin in infantile spasms for infants both with and without underlying diagnoses of tuberous sclerosis. Of the 313 patients without tuberous sclerosis complex, 170 (54%) had complete cessation of their infantile spasms; of the 77 patients with tuberous sclerosis complex, 73 (95%) had complete cessation of their seizures. We conclude that vigabatrin should be considered as first-line monotherapy for the treatment of infantile spasms in infants with either a confirmed diagnosis of tuberous sclerosis or those at high risk, ie, those with a first-degree relative with tuberous sclerosis complex. Paradoxically, in those without tuberous sclerosis complex, vigabatrin might be less efficacious than suggested by studies including patients with tuberous sclerosis complex.

Anticonvulsants↗
PubMed1976

Comparative effectiveness of preoptic and tuberal stimulation for luteinizing hormone release and ovulation in two strains of rats.

Proestrous rats under pentobarbital anesthesia during the 'critical period' were electrically stimulated in either the medial preoptic area (mPOA) or the anterior basal tuber. In Osborne-Mendel (O-M) and Charles River CD rats, comparisons were made of the ovulatory responses to trains of matched biphasic pulse pairs of different microamperage, 30 sec on and 30 sec off for 45 min. In CD rats, comparisons were made of the relative efficiencies of stimulation through a coaxial platinum electrode near the midline and a pair of platinum electrodes spaced bilaterally 2 mm apart across either the mPOA or the tuber. Other comparisons, with either type of electrode in the basal tuber, were made between 4-day and 5-day cyclic CD rats with respect both to the ovulatory responses and to the serum concentrations of LH 90 min after the start of the 45-min stimulus. In both O-M and CD rats, tuberal stimulation was more effective for ovulation than mPOA stimulation. CD rats were much less responsive to mPOA stimulation (spaced electrodes) than O-M rats, but the responses of both strains to tuberal stimulation were essentially alike. In 4-day cyclic CD rats, the ovulatory responses to mPOA stimulation with the coaxial electrode were much superior to those from spaced-electrode stimulation. In contrast, tuberal stimulation with either type of electrode gave equivalent ovulation frequencies and equivalent tubal ovum numbers in both 4-day and 5-day cyclic rats. However, the serum LH concentrations disclosed somewhat better responses to stimulation with the coaxial electrode (coaxial/spaced=1.57). The advantage of stimulation with the coaxial electrode may be due to high current density or, at least in part, to its more medial location. The results are compatible with the concept of preoptic-tuberal neuronal system, diffuse rostrally and convergent upon the medial basal tuber, controlling the ovulatory surge of LH.

Animals↗
PubMed1995

MR findings in tuberous sclerosis complex and correlation with seizure development and mental impairment.

PURPOSE: To correlate the findings on MR scans of the brain in patients with tuberous sclerosis complex with mental disability and the type and age at onset of the first seizure. METHODS: Patients with tuberous sclerosis complex who had MR brain scans were identified. The diagnosis was confirmed, and the clinical information on each patient was updated. The number, site, and area of abnormal signals were recorded on each scan. The presence of sulcal islands, gyral cores, and migration lines or wedges was recorded. RESULTS: Seventy-five patients were studied. Twenty-nine patients who had infantile spasms had more tubers than the 26 who presented with other types of generalized seizures. These patients had more tubers than the 15 patients with partial seizures. Significantly more tubers were found in patients with seizure onset before 1 year of age and mental disability. Gyral cores, sulcal islands, and radial migration lines or wedges were more common in patients with infantile spasms who had an early seizure onset and were mentally disabled. Patients who did not have seizures had no mental disability. CONCLUSIONS: A greater number of tubers occurred in patients who had infantile spasms, had their first seizure before 1 year of age, or had a mental disability. These features reflect the degree of cerebral dysfunction caused by the tubers. Gyral cores, sulcal islands, and migration lines or wedges also reflect cerebral dysfunction. MR scans correlate well with the clinical features and are valuable in assessing patients with tuberous sclerosis complex.

Age of Onset↗
PubMed2002

The effect of foliar application of phosphonate formulations on the susceptibility of potato tubers to late blight.

Foliar sprays of potato plants with phosphonic acid (partially neutralised with potassium hydroxide to pH 6.4) substantially reduced infection of the tubers by Phytophthora infestans, the cause of late blight, in glasshouse and field experiments over a 4-year period. Healthy tubers of blight-susceptible cultivars removed from treated plants and artificially inoculated by spraying with sporangial/zoospore suspensions of P infestans did not develop disease symptoms, demonstrating that the phosphonate applications had directly reduced the susceptibility of tubers to infection, probably as a result of translocation into tuber tissue. In contrast, foliar application of fosetyl-aluminium did not significantly reduce tuber blight development following inoculation. Five to six sprays of partially neutralised phosphonic acid (2 kg ha-1) applied at 10-14 day intervals resulted in the least tuber infection, but such a treatment regime may not be economic. In trials where the effect of timing and rate of application of 2-4 kg phosphonic acid ha-1 was examined, a single treatment of 4 kg ha-1 applied mid- or late-season proved the most effective. A spray programme in which one or two applications of phosphonic acid are combined with use of a non-systemic or systemic fungicide to enhance foliar protection offers the possibility of controlling both foliage and tuber blight and could have a major impact in reducing overwinter survival of P infestans in tubers.

Biological Transport↗
PubMed1991

Patatin and four serine proteinase inhibitor genes are differentially expressed during potato tuber development.

A highly efficient and synchronous in vitro tuberization system is described. One-node stem pieces from potato (Solanum tuberosum cv. Bintje) plants grown under short day-light conditions containing an axillary bud were cultured in the dark on a tuber-inducing medium. After 5 or 6 days all axillary buds started to develop tubers. To study gene expression during tuber development, RNA isolated from tuberizing axillary buds was used for both in vitro translation and northern blot hybridizations. The genes encoding the proteinase inhibitors I and II (PI-I and PI-II), a Kunitz- and a Bowman-Birk-type proteinase inhibitor were already expressed in uninduced axillary buds. The length of the day-light conditions differently influenced the expression level of the individual genes. In addition, the expression of each of these genes changed specifically during the development of the axillary bud to tuber. In contrast to the expression of these proteinase inhibitor genes, patatin gene expression was only detectable from the day tuberization was manifested as a radial expansion of the axillary bud. These results are discussed with respect to the regulation of the expression of the genes studied in relation to the regulation of tuber development.

Blotting, Northern↗