Effect of Genotype and Environment on the Glycoalkaloid Content of Rare, Heritage, and Commercial Potato Varieties

peer-reviewedPotatoes accumulate toxic steroidal compounds that could be harmful for humans if consumed in high quantities and must be controlled. In this study, we were interested in assessing the levels and variation of glycoalkaloid content in 60 varieties of potato planted in 2 trial sites over 2 y. Total glycoalkaloid levels ranged from 4 to 957 mg/kg of dry weight in the flesh and from 150 to 8133 mg/kg in the skin, with the latter accumulating generally more α-chaconine than α-solanine. Contents in the flesh were below the safe limit for all varieties, but were generally above in the skin. Maximum values in each site and year of cultivation were found for varieties “Beauty of Hebron,” “May Queen,” and “Arran Pilot” in the skin and “Beauty of Hebron,” “International Kidney,” and “Congo” in the flesh. Year of cultivation had a significant effect on total glycoalkaloid content (P < 0.0001), with interactions between variety and site of cultivation and variety and year of cultivation also significant (P < 0.0001), implying that environmental effects seem to act differentially and could induce high levels in genetically predisposed varieties.Teagasc Walsh Fellowship Programm

GAME9 regulates the biosynthesis of steroidal alkaloids and upstream isoprenoids in the plant mevalonate pathway

Steroidal glycoalkaloids (SGAs) are cholesterol-derived molecules produced by solanaceous species. They contribute to pathogen defence but are toxic to humans and considered as anti-nutritional compounds. Here we show that GLYCOALKALOID METABOLISM 9 (GAME9), an APETALA2/Ethylene Response Factor, related to regulators of alkaloid production in tobacco and Catharanthus roseus, controls SGA biosynthesis. GAME9 knockdown and overexpression in tomato and potato alters expression of SGAs and upstream mevalonate pathway genes including the cholesterol biosynthesis gene STEROL SIDE CHAIN REDUCTASE 2 (SSR2). Levels of SGAs, C24-alkylsterols and the upstream mevalonate and cholesterol pathways intermediates are modified in these plants. Delta(7)-STEROL-C5(6)-DESATURASE (C5-SD) in the hitherto unresolved cholesterol pathway is a direct target of GAME9. Transactivation and promoter-binding assays show that GAME9 exerts its activity either directly or cooperatively with the SlMYC2 transcription factor as in the case of the C5-SD gene promoter. Our findings provide insight into the regulation of SGA biosynthesis and means for manipulating these metabolites in crops

Ecological factors affecting the establishment of the biological control agent Gargaphia decoris Drake (Hemiptera: Tingidae) : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Plant Science at Massey University, Manawatu, New Zealand

The Brazilian lace bug (Gargaphia decoris Drake (Hemiptera:Tingidae)) was released in New Zealand in 2010 for the biological control of the invasive weed woolly nightshade (Solanum mauritianum Scopoli (Solanaceae)). Currently there is scarce information about the potential effect of ecological factors on the establishment of this biological control agent. This study investigated: 1) the effect of maternal care and aggregation on nymphal survival and development; 2) the effect of temperature, photoperiod and humidity on G. decoris performance; and 3) the effect of light intensity on S. mauritianum and G. decoris performance. Maternal care and aggregation are characteristic behaviours of G. decoris. These behaviours have an adaptive significance for the offspring and are key determinants for the survival of the species under natural conditions. Maternal care is reported to increase the survival and development of offspring under field conditions, and higher aggregations to increase the survival of the offspring. However, in this study, maternal care negatively affected the survival and development of the offspring, and higher aggregations had no significant impact on offspring survival. The availability of host plants under laboratory conditions may have influenced the expression of these behaviours. Climate is a factor that constrains insect development and therefore establishment. In this study, temperature affected the survival, nymphal development, life cycle, adult longevity, female reproductive success (i.e. total number of eggs, number of eggs laid per female, number of egg batches, number of eggs per batch, pre-oviposition period, percent females that oviposited successfully, number of eggs in the first batch and percentage of eggs that hatched from the first batch) and population growth parameters (i.e. life table). Temperatures between 20 – 25 °C were the optimal temperatures for G. decoris establishment. Photoperiod affected the mean percentage of egg hatch (i.e. emergence of nymphs in egg batch collected from colony) and total nymphal survival (i.e. egg to adult emergence), adult longevity and population growth parameters. The photoperiod 16L:8D was the optimal photoperiod for insect establishment. Humidity affected the mean percentage of egg hatch, adult longevity and population growth parameters. G. decoris population growth was highest at 70 ± 10% RH but the population growth was faster at 50 ± 10%. The CLIMEX model predicted that G. decoris could occupy broader regions not only on its native range (i.e. Brazil and Argentina) but also other regions where S. mauritianum is considered invasive (i.e. New Zealand and South Africa). G. decoris is predicted to be able to establish optimally in most of New Zealand North Island, except in regions with altitudes higher than 1300 meters above sea level. Most of the South Island is considered unsuitable for G. decoris establishment, except parts of the West Coast, Nelson and the Tasman region, which are predicted to be moderately to marginally suitable. Light intensity and plant age (i.e. day of harvest) affected host plant quality and had an indirect impact on insect establishment. Light intensity and plant age affected key physiological, morphological and defensive traits of S. mauritianum. Three compounds appeared to be involved, and were positively identified as glycoalkaloids: α-solamargine/β- solamarine, solauricine/solasonine, and unknown-954. The reproductive performance of G. decoris was affected because females avoided ovipositing on unshaded plants. The presence of trichomes and an increase in concentration of glycoalkaloids in the second harvest affected the nymphal performance and was reflected in adults, which had smaller bodies and wings. The results of my study have implications for using the Brazilian lace bug G. decoris in biological control programmes. The ecological factors included in this study work synergistically rather than independently and are important to consider when deciding the best locations in which the insect could be liberated

Biologically active compounds in tomatoes from various fertilisation systems

The aim of this study was to investigate the effect of way of tomatoes cultivation on content of both health promoting and toxic components representing by carotenoids (lycopene, β-carotene), vitamin C and glycoalkaloids (α-tomatine, dehydrotomatine). The levels of biologically active compounds were shown to be strongly affected by the degree of maturity of fruit and varied among system with various fertilizers. Slurry, organic fertilizer with high fertilization efficiency, is good alternative to mineral fertilization. Lower content of toxic glycoalkaloids was found in tomatoes from organic and combined “low input” farming. The differences were variety depended in some extent

Organic versus conventional potatoes – is there basis for consumers preference?

The aim of this study was to investigate the influence of growing conditions on the quality of potatoes from organic farming systems as compared to that from conventional farming. In our previous study conducted in the years 1996 – 1999 we recognised some differences between the potatoes (Solanum tuberosum) from organic and conventional farming. To demonstrate the general validity of observed trends, follow up study was established in Czech Republic in the years 2002-2005. The ultimate goal of the project was to collate data for the assessment of a potential influence of foods from organic production system on consumers´ health by studying differences between potatoes grown in both systems (for this purpose the levels of potentially toxic compounds as well as nutritionally valuable components with regard to variety, geo-graphical location and inter-annual variation were determined)

Interspecific hybrids of potato : determination of glycoalkaloid aglycones and influence of bacterial infection

v2004okKJB. Yksikön huom.: KJBDiss. : Helsingin yliopisto, 200

Interaction effects between the peach potato aphid Myzus Persicae and secondary plant metabolites occurring in potato Solanum Tuberosum L.

Peach potato aphids Myzus persicae (Sulzer) (Homoptera: Aphididae) were reared on artificial diets containing the steroidal glycoalkaloids (GAs) a-solanine and a- chaconine in concentrations lower or similar to those observed in potato leaves. The parameters used to measure the aphid performance were the total individual adult cumulative fecundity, diet uptake and mortality the mean relative growth rate (MRGR) and the intrinsic rate of natural increase (IRI). The adults proved to be susceptible to high concentrations (80-160 mg GA /100ml of diet) showing reduced fecundity, diet uptake and increased mortality in comparison to controls. Ingestion of these artificial diets by nymphs delayed maturity and decreased the intrinsic rate of natural increase. GAs in low concentrations marginally stimulated the reproductive performance and diet acceptability of this aphid.The effects of nitrogen fertilisation and pesticide (Aldicarb) application on the foliar total and individual GA production of two potato cultivars King Edward and Maris Piper were examined using a semi-hydroponic culture system. Nitrogen deficient potato plants produced elevated concentrations of GAs. The two cultivars reacted in a different way on pesticide application. Cv. King Edward produced elevated amounts of GAs in the low pesticide treatment when no differences were observed between pesticide treatments on cv. Maris Piper.Glycoalkaloid production of potato plants subjected to stress induced by peach potato aphid M. persicae infestation was investigated in a glasshouse, a plant growth room, and an open-air field experiment. In both glasshouse and plant growth room experiments aphid infested potato plants produced reduced amounts of total and individual GAs compared to these produced by non infested plants. This reduction was attributed to the sugar deficiency induced to the plants due to the dense aphid colonisation. However results from the field experiment showed a temporal increase of the glycoalkaloids produced by the potato cv. King Edward plants subjected to aphid infestation. It is concluded that aphid infestation as a stress inducing factor possibly affects that part of secondary metabolism responsible for the glycoalkaloid production in potato

Fourier transform infrared spectroscopic study on glycoalkaloid concentration in varieties of solanum tuberosum

The potential of Fourier transform infrared spectroscopy used for predicting the concentration of glycoalkaloids in varieties of potato tuber, waxy and starchy (Solanum Tuberosum) was investigated in this study,a-solanine and a-chaconine are the main glycoalkaloids of potato tubers. Potato glycoalkaloids are the cholinesterase inhibitors and cause poisoning which is leading to accumulation of acytylcholine and even death. This will happen after consuming of potatoes with excessive glycoalkaloid level by human. One of the major factors affecting glycoalkaloid concentration in potato is its variety. In the present investigation the most popular varieties of potatoes waxy and starchy are subjected to FT-IR spectral analysis to determine the concentration of glycoalkaloid contents and the various nutrients. The implications of the results in terms of food safety are discussed