Impact of amino acids and sugars after thermal processing on acrylamide formation in synthetic potato models and real potatoes

Amino acids and sugars, along with the thermal processing, are considered the main parameters to control acrylamide formation in fried potatoes. To evaluate which of these parameters had the greatest influence, 10 synthetic potato-starch-based models formulated in different amino acid and/or sugar combinations and three potato cultivars were assigned. High-performance-liquid chromatography and gas chromatography flame-ionized-detectors were applied to quantify amino acids, sugars, and acrylamide. Results showed that reducing sugars and sucrose significantly increased acrylamide formation amongst all potato samples. Synthetic potato models Asn-GFS contained the highest amount of acrylamide compared to Glu-Fru and real potatoes (Agria and Kennebec). Thus, sugars were considered critical factors for acrylamide formation in potatoes and remained the most practical way of reducing its production.

Potato (Solanum tuberosum L.) Leaf Extract Concentration Affects Performance and Oxidative Stress in Green Peach Aphids (Myzus persicae (Sulzer)

This study was conducted to determine the aphicidal effect of a leaf extract of the Atlantic potato cultivar on the performance of green peach aphids. Three concentrations of the leaf extract (100, 75, and 50% potato extract), synthetic pesticide (Beta cypermethrin 4.5%), and distilled water (control) treatments were applied in a greenhouse experiment. The results showed that the synthetic pesticide, which was used as a standard check, caused the maximum aphid mortality, followed by the 100% potato leaf extract. Compared with the other botanical treatments, the 100% extract produced low mean rates of survival, aphids' average daily reproduction, the number of nymphs per plant, and the number of nymphs per adult. This treatment also increased the accumulation of hydrogen Peroxide (H₂O₂) and malondialdehyde (MDA), glutathione-s-transferase, mixed-function oxidase, and carboxylesterase content in the green peach aphid. Moreover, the 100% extract also protected the host plants against green peach aphid attacks by demonstrating higher chlorophyll content, net photosynthesis, above-ground fresh weight, and above-ground dry weight of the host plant. This study demonstrates that the highest concentration of potato (Atlantic cultivar) leaf extract (100% extract) could be used as the appropriate dosage for the control of green peach aphids on potatoes, which could greatly reduce the use of synthetic insecticides and promote ecosystem sustainability.

Soil microbial community assembly and stability are associated with potato (Solanum tuberosum L.) fitness under continuous cropping regime

Continuous cropping obstacles caused by the over-cultivation of a single crop trigger soil degradation, yield reduction and the occurrence of plant disease. However, the relationships among stability, complexity and the assembly process of soil microbial community with continuous cropping obstacles remains unclear. In this study, molecular ecological networks analysis (MENs) and inter-domain ecological networks analysis (IDENs), and a new index named cohesion tools were used to calculate the stability and complexity of soil microbial communities from eight potato cultivars grown under a continuous cropping regime by using the high-throughput sequencing data. The results showed that the stability (i.e., robustness index) of the bacterial and fungal communities for cultivar ZS5 was significantly higher, and that the complexity (i.e., cohesion values) was also significantly higher in the bacterial, fungal and inter-domain communities (i.e., bacterial-fungal community) of cultivar ZS5 than other cultivars. Network analysis also revealed that Actinobacteria and Ascomycota were the dominant phyla within intra-domain networks of continuous cropping potato soil communities, while the phyla Proteobacteria and Ascomycota dominated the correlation of the bacterial-fungal network. Infer community assembly mechanism by phylogenetic-bin-based null model analysis (iCAMP) tools were used to calculate the soil bacterial and fungal communities' assembly processes of the eight potato cultivars under continuous cropping regime, and the results showed that the bacterial community was mainly dominated by deterministic processes (64.19% - 81.31%) while the fungal community was mainly dominated by stochastic processes (78.28% - 98.99%), indicating that the continuous-cropping regime mainly influenced the potato soil bacterial community assembly process. Moreover, cultivar ZS5 possessed a relatively lower homogeneous selection, and a higher TP, TN, AP and yield than other cultivars. Our results indicated that the soil microbial network stability and complexity, and community assemble might be associated with yield and soil properties, which would be helpful in the study for resistance to potato continuous cropping obstacles.

Evaluation of Effects of Chemical Soil Treatments and Potato Cultivars on Spongospora subterranea Soil Inoculum and Incidence of Powdery Scab and Potato Mop-Top Virus in Potato

Spongospora subterranea is a soilborne plasmodiophorid that causes powdery scab in potato. It also transmits potato mop-top virus (PMTV), which causes necrotic arcs (spraing) in potato tubers. Three field experiments were conducted in naturally S. subterranea-infested soil to investigate the effects of two chemicals, Omega 500F (fluazinam) and FOLI-R-PLUS RIDEZ (biological extract), on powdery scab, PMTV, and changes in S. subterranea inoculum with six different potato cultivars. The efficacy of soil treatment with these two chemicals on tuber lesions, root galling, and pathogen population was also assessed in greenhouse trials. The chemical treatments did not reduce powdery scab, root gall formation, or S. subterranea inoculum in the field or greenhouse trials. Postharvest S. subterranea soil inoculum in fields varied across farms and among potato cultivars but the pathogen population consistently increased by the end of the growing season. The evaluated russet cultivars were more tolerant to powdery scab than the yellow- or red-skinned cultivars but all were susceptible to PMTV. In the field, powdery scab indices and soil inoculum changes were positively correlated, while postharvest S. subterranea inoculum was positively correlated with root galling in both greenhouse trials. Powdery scab and PMTV occurred in noninoculated potting mix, indicating that peat-based potting mix is a source for both pathogens. These results demonstrate that chemical management methods currently used by farmers are ineffective, that S. subterranea and PMTV in potting mix can cause severe epidemics in greenhouses, and that potato cultivar choices impact inoculum increases in soil.

The Leaf Wettability of Various Potato Cultivars

Leaf wettability has an impact on a plant's ability to retain water on its leaf surface, which in turn has many environmental consequences. In the case of the potato leaf (Solanum tuberosum L.), water on the leaf surface may contribute to the development of a fungal disease. If fungal disease is caused, this may reduce the size of potato harvests, which contribute significantly to meeting global food demand. The aim of this study was to assess the leaf wettability of five potato cultivars (i.e., Bryza, Lady Claire, Rudawa, Russet Burbank, Sweet Caroline) in the context of its direct and indirect impact on potato yield. Leaf wettability was assessed on the basis of contact angle measurements using a sessile drop method with an optical goniometer. For Bryza and Rudawa cultivars, which showed, respectively, the highest and the lowest contact angle values, light microscopy as well as scanning electron microscopy analyses were performed. The results of the contact angle measurements and microscopic image analyses of the potato leaf surfaces indicated that the level of wettability was closely related to the type of trichomes on the leaf and their density. Therefore, higher resistance of the Rudawa cultivar to biotic stress conditions could be the result of the presence of two glandular trichome types (VI and VII), which produce and secrete metabolites containing various sticky and/or toxic chemicals that may poison or repel herbivores.

Effects of Potato Cultivars on Some Physiological Processes of Leptinotarsa decemlineata (Coleoptera: Chrysomelidae)

Colorado potato beetle, Leptinotarsa decemlineata (Say), is an important pest of potato throughout the world. Here, the effects of six potato cultivars including 'Arinda,' 'Sprit,' 'Markiez,' 'Lotta,' 'Santae,' and 'Agria' were studied on nutritional indices, digestive enzymes, and some components involved in intermediary metabolism of L. decemlineata. Nutritional indices of the larvae and the adults were significantly different followed by feeding on various potato cultivars. The individuals fed on Agria showed the highest activity of digestive proteases although cathepsin B demonstrated same Activity on Santae and Lotta. The highest activity of α-amylase was found in the larvae fed on Arinda, but the adults demonstrated the highest amylolytic activities on Santae and Agria. Both larvae and adults of L. decemlineata fed on Santae revealed the highest α- and β-glucosidase activities. No significant differences were found in lipase activity of larvae, but the highest lipase activity was found in the adults fed on Santae. The highest activities of transaminases were found in the larvae and adults fed on the Agria except for γ-glutamyl transferase. In case of aldolase, the highest activities were observed in the larvae and adults fed on Santae and Sprit. The highest activities of lactate dehydrogenase were obtained in the larvae and adults fed on Santae. The highest amount of low-density lipophorin was measured in both individuals fed on Santae. There were no significant differences in high-density lipophorin amount of adults, but the highest value was found in the larvae fed on Agria. The lowest amounts of protein and triglyceride were observed in both individuals fed on Santae and Agria, respectively. These results revealed Santae is the most suitable cultivar for L. decemlineata based on digestion and intermediary metabolism findings, but Lotta is an unsuitable cultivar and could be considered for integrated pest management.