Sucrose is the main form of assimilated carbon which is produced during photosynthesis and then transported from source to sink tissues via the phloem. This disaccharide is known to have important ...roles as signaling molecule and it is involved in many metabolic processes in plants. Essential for plant growth and development, sucrose is engaged in plant defense by activating plant immune responses against pathogens. During infection, pathogens reallocate the plant sugars for their own needs forcing the plants to modify their sugar content and triggering their defense responses. Among enzymes that hydrolyze sucrose and alter carbohydrate partitioning, invertases have been reported to be affected during plant-pathogen interactions. Recent highlights on the role of invertases in the establishment of plant defense responses suggest a more complex regulation of sugar signaling in plant-pathogen interaction.
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•Storage at low temperature (4 °C) is efficient to control sprouting.•Three Cold Induced Sweetening (CIS)-resistant varieties were identified: Verdi, Lady Claire and ...Kiebitz.•CIS-resistant varieties had good crisp color quality.•Correlations between VInv gene expression and glucose content in tubers were observed.•Reconditioning from 4 °C to 15 °C reduced glucose and acrylamide contents in tubers from the CIS-susceptible variety Markies.
Low temperature storage as an alternative to anti-sprouting chemicals in potato storage may induce reducing sugars (RS) accumulation (i.e. glucose and fructose) in potato tubers. This phenomenon is called “cold induced sweetening” (CIS) and occurs in certain varieties. CIS leads to a decrease in the organoleptic qualities and darkening of processed potato and the accumulation of toxic molecules such as acrylamide. To identify potato varieties suitable for storage at low temperatures, we screened six commercial processing varieties: Lady Claire (LC), Verdi, Kiebitz (KB), Pirol, Agria and Markies for their CIS characteristics and sprout-forming potential after storage at 4 °C and 8 °C. Our findings reveal that 4 °C storage allows for efficient sprout reduction in all six tested varieties for up to 4.5 months of storage. Three CIS-resistant varieties, namely Verdi, Lady Claire and Kiebitz, were identified as able to be stored for up to four months at 4 °C with limited increase in glucose content. Conversely, Pirol, Agria and Markies showed an increase in glucose content with a decrease in storage temperature and can be considered as CIS-susceptible varieties. After processing into crisps, the CIS-susceptible varieties displayed poor crisp color quality (brown to black color crisps) after storage for two months at 4 °C compared to the storage at 8 °C, whereas the CIS-resistant varieties had good crisp color quality (pale yellow color crisps) after storage at both 4 and 8 °C. Interestingly, the trends of total RS and/or glucose content in the CIS-resistant and in the CIS-susceptible varieties were correlated with the trends in Vacuolar Invertase (VInv) gene expression for most varieties, as well as with the trends in acrylamide content after processing. In addition, reconditioning of Markies variety after storage at 4 °C by gradually increasing the temperature to 15 °C resulted in a significant decrease of VInv transcript levels (reduction of 80 %), acrylamide content (reduction of 75 %) and glucose content when compared to a storage at 4 °C without reconditioning. Those results demonstrate that the reconditioning technique is a key factor for a sustainable potato storage and for improving the quality of processed potatoes.
To investigate the influence of ultraviolet-C (UVC) radiation pretreatment on the sugar metabolism of yellow peaches (cv. Beinong2 × 60–24–7) during storage, the concentrations of soluble sugar ...(sucrose, fructose, glucose, and sorbitol), and related gene expression were determined. During UVC pretreatment, peaches were subjected to a dose of 4 kJ·m −2 when they were placed at 15 cm under a UVC lamp tube for 10 minutes at 25 °C. Then, they remained at 15 ± 2 °C for 10 days. Peaches stored at 15 ± 2 °C immediately after picking were used as the control group (CG). UVC pretreatment reduced the ethylene production rate and resulted in a significant increase in the accumulation of sucrose during days 2 to 8 of the storage period, followed by a lower concentration of fructose and glucose and the upregulation of PpaSS1. The expression levels of PpaSPS2 , PpaSS1 , and PpaST3 were significantly correlated with fructose concentration, and those of PpaSPS2 and PpaST2 were significantly correlated with glucose concentration. The enzyme activity of sucrose phosphate synthase (SPS) was positively correlated with PpaSPS2, PpaSS2 , and PpaST2 . The enzyme activities of sucrose synthase (SS), acid invertase (AI), and neutral invertase (NI) were positively correlated with PpaSS1, PpaST1 , and Ppani , respectively. Expressions of PpSPS1 and PpSPS2 in UVC-pretreated peaches were upregulated on storage days 8 and 2, and there was a UVC-induced peak in SPS activity on storage days 4 and 8, which resulted in the rapid accumulation of sucrose. UVC pretreatment could upregulate the gene expression of PpaSS1 on day 2, which could improve and maintain the quality of peaches for consumption.
•Processing and non-processing potato cultivars vary in sugar content.•Reducing sugar content significantly increased in cold-stored (4 °C) potato tubers.•Reducing sugar content remained low in ...processing cultivars after cold storage.•Sequence diversity of the vacuolar invertase inhibitor gene revealed four alleles.•SNPs suspected to play a role in cold-induced sweetening process of potato tubers.
The aim of this study was to examine the variations in sugar content and identify the polymorphism in vacuolar invertase inhibitor (INH2) gene from Indian non-processing (Kufri Jyoti, Kufri Pukhraj and PU1) and exotic processing (Atlantic and Frito Lay-1533) potato cultivars. Upon cold storage (4 °C) processing cultivars maintained low reducing sugars as compared to non-processing cultivars. Sequencing of the INH2 gene identified four alleles of which three identified as novel alleles. A total twelve SNPs resulted in silent mutations, with five conferring the amino acid substitutions. Phylogenetic analysis suggests a highly conserved nature of the INH2 gene. The 3D predicted structures generated for all the alleles revealed slight variations in the orientation of the helices (α1-3) in N-terminal region. Sequence polymorphism observed in INH2 alleles in processing and non-processing potato cultivars can be correlated with the observed variations in the sugar content suggesting a possible role in cold-induced sweetening.
Bud dormancy enables deciduous fruit trees to endure unfavorable conditions during winter, and considerably impacts growth and reproduction in spring. We investigated acid invertase activities during ...dormancy release until bud break under natural (orchard) conditions in two consecutive years. Our aim was to relate the activity patterns to the developmental progression and to air temperature, which is a major factor influencing the developmental processes at that stage. The enzyme assays were performed on extracts from leaf buds of the cultivar Idared, sampled from early March to April in the years 2020 and 2021. The air temperature was continually monitored during the observation periods. cwINV activity showed a trend of slight increase at the earlier developmental stages and sharply increased during bud break in both years. cwINV is known to contribute to organ sink strength. Its up-regulation may, therefore, be related to the increasing developmental demand for carbohydrates in apple leaf buds during dormancy release until bud break. vacINV activity was relatively constant at the earlier stages and also showed a pronounced increase in activity during bud break in both years. However, in both years, we observed drops in vacINV activity following cold spells. vacINV activity has been associated with growth via cell elongation through the regulation of cell turgor and may, thus, be involved in bud break. Therefore, we suggest that the down-regulation of vacINV activity as a consequence of cold spells might contribute to a delay in bud break to protect young leaf tissues from exposure to cold stress conditions.
Cold storage of potato tubers is commonly used to reduce sprouting and extend postharvest shelf life. However, cold temperature stimulates the accumulation of reducing sugars in potato tubers. Upon ...high‐temperature processing, these reducing sugars react with free amino acids, resulting in brown, bitter‐tasting products and elevated levels of acrylamide—a potential carcinogen. To minimize the accumulation of reducing sugars, RNA interference (RNAi) technology was used to silence the vacuolar invertase gene (VInv), which encodes a protein that breaks down sucrose to glucose and fructose. Because RNAi often results in incomplete gene silencing and requires the plant to be transgenic, here we used transcription activator‐like effector nucleases (TALENs) to knockout VInv within the commercial potato variety, Ranger Russet. We isolated 18 plants containing mutations in at least one VInv allele, and five of these plants had mutations in all VInv alleles. Tubers from full VInv‐knockout plants had undetectable levels of reducing sugars, and processed chips contained reduced levels of acrylamide and were lightly coloured. Furthermore, seven of the 18 modified plant lines appeared to contain no TALEN DNA insertions in the potato genome. These results provide a framework for using TALENs to quickly improve traits in commercially relevant autotetraploid potato lines.
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