Potato tubers naturally contain a number of defense substances, some of which are of major concern for food safety. Among these substances are the glycoalkaloids and calystegines. We have here analyzed levels of glycoalkaloids (α-chaconine and α-solanine) and calystegines (A₃, B₂, and B₄) in potato tubers subjected to mechanical wounding, light exposure, or elevated temperature: stress treatments that are known or anticipated to induce glycoalkaloid levels. Basal glycoalkaloid levels in tubers varied between potato cultivars. Wounding and light exposure, but not heat, increased tuber glycoalkaloid levels, and the relative response differed among the cultivars. Also, calystegine levels varied between cultivars, with calystegine B4 showing the most marked variation. However, the total calystegine level was not affected by wounding or light exposure. The results demonstrate a strong variation among potato cultivars with regard to postharvest glycoalkaloid increases, and they suggest that the biosynthesis of glycoalkaloids and calystegines occurs independently of each other.

Steroidal glycoalkaloids (SGA) are sterol-derived neurotoxic defence substances present in several members of the Solanaceae. In the potato (Solanum tuberosum), high SGA levels may render tubers harmful for consumption. Tuber SGA levels depend on genetic factors, and can increase as a response to certain stresses and environmental conditions. To identify genes underlying the cultivar variation in tuber SGA levels, we investigated two potato cultivars differing in their SGA accumulation during wounding or light exposure; two known SGA-inducing treatments. Using microarray analysis coupled to sterol and SGA quantifications, we identified a small number of differentially expressed genes that were associated with increased SGA levels. Two of these genes, encoding distinct types of sterol Δ24-reductases, were by sense/antisense expression in transgenic potato plants shown to have differing roles in sterol and SGA metabolism. The results show that an increased SGA level in potato tubers during both wounding and light exposure is mediated by coordinated expression of a set of key genes in isoprenoid and steroid metabolism, and suggest that differences in this expression underlie cultivar variations in SGA levels. These results may find use within potato breeding and quality assessment.

BACKGROUND: RNA-mediated interference (RNAi) has become a promising biopesticide technology with which to direct sequence-specific gene knockdown of key targets in the potato psyllid (PoP) Bactericera cockerelli, resulting in significant mortality. In this study, three strategically selected target genes, ATF4, C7 and D24, essential for the biosynthesis and regulation of ecdysteroids, were evaluated for knockdown and mortality using oral delivery of individual, paired and all three doublestranded RNAs (dsRNAs), in five replicated experiments. Knockdown was determined as the fold-change in gene expression using a quantitative polymerase chain reaction.RESULTS: Knockdown of the D24 target, at 39%-45%, resulted in 51% PoP mortality by 10 days post-ingestion (dpi) of dsRNA. Knockdown of C7, at 38%-61%, resulted in 53% mortality by 10 dpi, whereas dsD24 ingestion resulted in 65% mortality by 10 dpi when dsD24 and dsC7 were co-delivered. Three phenotypes, INCOMEC, PREMEC and SWOLLEN, were observed at a frequency of 4%-12%, and are consistent with incomplete ecdysis in immature and/or adult PoP. Adult PoP exhibiting INCOMEC survived for several days but were unable to mate or fly, whereas SWOLLEN and PREMEC were lethal to the immature instars. Knockdown of ATF4 did not result in the mortality or malformations in immature and adult PoP.CONCLUSIONS: Compared with knockdown of individual D24 and C7 targets, significantly greater RNAi penetrance was achieved following delivery of combined dsRNAs. The highest knockdown that resulted in incomplete ecdysis and/or mortality was obtained for targets with predicted involvement in the same or interacting pathway(s). Knockdown of ATF4 was apparently "rescued" by uncharacterized compensatory gene(s) or effects.

Background: Most of the medicinal plants are available as wild or weeds in the world including Pakistan. It was reported by many researchers that Pakistan is rich with medicinal flora based upon the surveys conducted in the Northern areas but still there are some areas other than Northern parts in Pakistan that has not been studied so far. There is a need to explore the medicinal flora from neglected area where most of the people still rely on local medicinal plants to cure their diseases by means of indigenous knowledge. District Gujrat is among those area that has not been explored to study the medicinal flora.Methods: Surveys were conducted to collect the indigenous knowledge and medicinal significance of seasonal weeds in Gujrat, Punjab, Pakistan in winter 2018 and summer 2019. Information collected through questionnaire and interviews.Results: Weeds have much importance among local inhabitants to cure many diseases as respiratory disorders, kidney and liver disorders, muscle and skeletal disorders, ear, nose and throat problems, dermatological disorders, fever, diabetes, cancer etc. The plant parts and its percentage used by local inhabitants were leaves (58%), fruits (36%), seeds (25%), whole plant (34%), roots (32%), milky latex (1%), flowers (8%) and stem (3%). The most important families were Asteraceae, Poaceae, Fabaceae, Polygonaceae and Solanaceae. Cichorium intybus L. (Asteraceae) had 100% Fidelity Level (FL) value as liver tonic and blood purifier. Highest 0.76 Informant Consensus Factor (ICF) values were noted against stomach, gastric, intestinal and digestive problems. Achyranthes aspera L. (Amaranthaceae) showed the highest Fidelity Level (FL) values that was 93% used gastrointestinal disorders and menstrual pain.Conclusions: It was concluded that the area of Gujrat, Punjab, Pakistan is a rich source of important medicinal weeds that needs to be utilized for useful medicinal purpose. There is need to create awareness among the farmers and local people about the efficacy of weeds.