The effects of phytosulfokine-α (PSK-α) treatment on postharvest peach fruit CI were studied. Results showed that PSK-α treatment inhibited the increase of browning index, electrolyte leakage and ...malondialdehyde content of peach fruit and delayed the decline of hardness. In addition, PSK-α treatment did not change the types of volatile substances and reduced the acidity of the fruit, so as to maintain the good flavor of peach fruit. PSK-α can improve the antioxidant capacity of peach fruit by promoting the activity of some antioxidant enzymes, increasing the content of ascorbic acid, glutathione and inhibiting the production of reactive oxygen species. At the same time, PSK-α treatment delayed the degradation of cell wall materials by inhibiting the activity of polygalacturonase, pectin methylesterase, cellulase and some glycosidases. Generally, PSK-α treatment can maintain fruit quality and reduce the CI of peach fruit by improving antioxidant capacity and maintaining the stability of cell wall structure.
•Phytosulfokine-α (PSK-α) treatment can improve the cold resistance of postharvest peach fruit.•PSK-α treatment maintained the quality and flavor of peach fruit under low temperature storage.•PSK-α treatment inhibited the production of ROS and improved the antioxidant capacity.•PSK-α treatment inhibited the degradation of cell wall polysaccharides and maintained the stability of cell wall structure.
•By endogenous PSKα signaling, cytosolic cGMP signaling supports flower bud opening.•By triggering PDE expression, laying off cytosolic cGMP signaling accelerates flower senescence.•Exogenous PSKα ...suppresses PDE expression by triggering endogenous PSKα signaling.•Exogenous PSKα preserves membrane integrity, as shown by lower electrolyte leakage and MDA accumulation.•Exogenous PSKα delays senescence and prolongs vase life to 16 days from 12 days.
This study investigated the endogenous phytosulfokine α (PSKα) signaling during opening and senescence in rose flowers. Our results showed that the higher phytosulfokines (PSKs) and tyrosyl protein sulfotransferase (TPST) expression could be responsible for higher endogenous PSKα accumulation in petals during rose flowers opening (stages 2 and 3). By triggering the endogenous PSKα signaling, higher phytosulfokine receptor 1 (PSKR1) expression could be responsible for higher cytosolic cyclic guanosine monophosphate (cGMP) accumulation in petals during rose flowers opening (stages 3 and 4). Higher protein kinase G (PKG) and cyclic nucleotide-gated ion channel 1 (CNGC1) expression accompanying higher plasma membrane intrinsic protein 2 (PIP2) and tonoplast intrinsic protein 1 (TIP1) expression in petals during rose flowers opening may arise from higher cytosolic cGMP accumulation giving rise to higher petals relative water content (RWC) (stage 4). Triggering phosphodiesterase (PDE) expression lay off cytosolic cGMP signaling. Suppressing PKG and CNGC1 expression accompanying lower PIP2 and TIP1 expression accelerates petals senescence in rose flowers representing by deteriorating petals membrane integrity revealed by higher electrolyte leakage and malondialdehyde (MDA) accumulation (stage 5 and 6). For delaying petals senescence and prolonging vase life in cut rose flowers, we employed exogenous PSKα treatment at the commercial harvest stage (stage 3). Our results showed that the suppressing PDE expression in petals by exogenous 150 nM PSKα treatment could be responsible for allowing cytosolic cGMP signaling ongoing for supporting PKG and CNGC1 expression accompanying by higher PIP2 and TIP1 expression. Exogenous 150 nM PSKα treatment, outperforming cut rose flowers by delayed senescence and prolonged vase life to 16 days from 12 days could be ascribed to preserving membrane integrity revealed by lower electrolyte leakage and MDA accumulation. Our results could be proposed that exogenous PSKα treatment and endogenous PSKα signaling for employing in the floriculture industry for delaying petals senescence and prolonging the vase life of cut rose flower.
Microspore embryogenesis (ME) is the most powerful tool for creating homozygous lines in plant breeding and molecular biology research. It is still based mainly on the reprogramming of microspores by ...temperature, osmotic and/or nutrient stress. New compounds are being sought that could increase the efficiency of microspore embryogenesis or even induce the formation of haploid embryos from recalcitrant genotypes. Among these, the mitogenic factor phytosulfokine alpha (PSK-α) is promising due to its broad spectrum of activity
and
. The aim of our study was to investigate the effect of PSK-α on haploid embryogenesis from microspores of oilseed rape (
L., DH4079), one of the most important oil crops and a model plant for studying the molecular mechanisms controlling embryo formation. We tested different concentrations (0, 0.01, 0.1 and 1 µM) of the peptide and evaluated its effect on microspore viability and embryo regeneration after four weeks of culture. Our results showed a positive correlation between addition of PSK-α and cultured microspore viability and a positive effect also on the number of developed embryos. The analysis of transcriptomes across three time points (day 0, 2 and 4) with or without PSK-α supplementation (15 RNA libraries in total) unveiled differentially expressed genes pivotal in cell division, microspore embryogenesis, and subsequent regeneration. PCA grouped transcriptomes by RNA sampling time, with the first two principal components explaining 56.8% variability. On day 2 with PSK, 45 genes (15 up- and 30 down-regulated) were differentially expressed when PSK-α was added and their number increased to 304 by day 4 (30 up- and 274 down-regulated).
,
, and
gene expression analysis revealed dynamic patterns, with
displaying the highest increase and overall expression during microspore culture at days 2 and 4. Despite some variations, only
showed significant differential expression upon PSK-α addition. Of 16 ME-related molecular markers, 3 and 15 exhibited significant differential expression in PSK-supplemented cultures at days 2 and 4, respectively. Embryo-specific markers predominantly expressed after 4 days of culture, with higher expression in medium without PSK, while on day 0, numerous sporophyte-specific markers were highly expressed.
Phytosulfokine-α (PSK-α) is a disulfated pentapeptide (YIYTQ) acting as an intercellular signal peptide and growth factor. It was originally isolated from conditioned medium of asparagus mesophyll ...cell cultures in 1996 and later characterized as a hormone-like signal molecule with important roles in numerous processes of
plant growth and development. It is currently becoming a valuable mitogenic factor in plant breeding and biotechnology due to its stimulatory effect on
cell elongation, proliferation and differentiation. The focus of our work was to review current knowledge about the roles of PSK-α in plant biotechnology and to evaluate its influence on the regeneration of protoplasts of four
cultivars (two cauliflower and two cabbage) cultured under two distinctive protocols and with different protoplast densities. Protoplast regeneration was studied due to its high value for plant genome editing, which is generally limited by the inefficient regeneration of treated protoplasts of numerous important plant genotypes. Our hypothesis was that the stress related to PEG-mediated protoplast transformation and the following decrease in viable protoplast density in culture could be alleviated by the addition of PSK-α to the culture medium. We therefore tested whether PSK-α could increase cell division at the early stages of culture (5 and 15 days after protoplast isolation) and stimulate the formation of microcallus colonies up to the 30st day of culture and to evaluate its influence on callus organogenesis leading to shoot regeneration. The PSK-α showed a strong stimulatory effect on untransformed protoplast regeneration already during the first days of culture, accelerating cell division up to 5.3-fold and the formation of multicellular microcallus colonies up to 37.0-fold. The beneficial influence was retained at later stages of regeneration, when PSK improved shoot organogenesis even if it was present only during the first 10 days of culture. The highest numbers of shoots, however, were regenerated when PSK was present during the first days of culture and later in solid shoot regeneration medium. Finally, the addition of PSK-α to PEG-transformed protoplasts significantly enhanced their division rate and the formation of microcallus colonies in selection media, up to 44.0-fold.
Kiwifruit fruit stored at low temperatures are susceptible to chilling injury, leading to rapid softening, which therefore affects storage and marketing. The effect of 150 nM mLsup.−1 of exogenous ...phytosulfokine α (PSKα) on reactive oxygen species (ROS) metabolism, Casup.2+ signaling, and signal-transducing MAPK in kiwifruit, stored at 0 °C for 60 days, was investigated. The results demonstrated that PSKα treatment effectively alleviated chilling injury in kiwifruit, with a 15% reduction in damage compared to the control on day 60. In addition, PSKα enhanced the activities and gene expression levels of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), Casup.2+−ATPase, and mitogen−activated protein kinase (MAPK). In contrast, the activities and gene expression levels of NADPH oxidase (NOX) were inhibited, leading to a lower accumulation of Osub.2 sup.− and Hsub.2Osub.2, which were 47.2% and 42.2% lower than those in the control at the end of storage, respectively. Furthermore, PSKα treatment enhanced the calmodulin (CaM) content of kiwifruit, which was 1.41 times that of the control on day 50. These results indicate that PSKα can mitigate chilling injury and softening of kiwifruit by inhibiting the accumulation of ROS, increasing antioxidant capacity by inducing antioxidant enzymes, activating Casup.2+ signaling, and responding to MAPK protein kinase. The present results provide evidence that exogenous PSKα may be taken for a hopeful treatment in alleviating chilling injury and maintaining the quality of kiwifruit.
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•Phytosulfokine α delays senescence in strawberry fruit.•Phytosulfokine α signaling triggers cytosolic guanosine cyclic monophosphate accumulation.•Phytosulfokine α promotes melatonin ...biosynthesis and accumulation.•Phytosulfokine α promotes phenols, flavonoids and anthocyanins accumulation.•Phytosulfokine α improves DPPH and ABTS scavenging capacity.
In this study, the mechanism by which the exogenous application of 150 nM signaling bioactive peptide phytosulfokine α (PSKα) delays senescence and improves antioxidant nutrient accumulation in strawberry fruit during storage at 4 °C for 18 d was investigated. Results showed that the higher endogenous accumulation of PSKα in strawberry fruit treated with 150 nM PSKα may result from the higher expression of PSK3 and PSK6 genes. Besides, the higher endogenous accumulation of Ca2+ in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher cytosolic accumulation of cGMP, resulting from the triggering of endogenous PSKα signaling pathway, represented by higher expression of PSKR1 gene. Besides, the higher endogenous melatonin accumulation resulting from higher expression of TDC, T5H, SNAT, and ASMT genes in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher endogenous accumulation of Ca2+. Moreover, the higher ABTS and DPPH scavenging capacity in strawberry fruit treated with 150 nM PSKα may be ascribed to the higher accumulation of phenols, flavonoids, and anthocyanins, resulting from higher gene expression and activities of PAL and CHS. Based on our findings, the exogenous application of PSKα could be employed as a beneficial procedure for delaying senescence and improving antioxidant nutrient accumulation in strawberry fruit during cold storage, by triggering endogenous PSKα signaling, promoting endogenous melatonin accumulation, and activating the phenylpropanoid pathway.
Protoplasts of six cabbage accessions were isolated from leaf mesophyll and cultured in the presence of 0.01, 0.1 and 1.0 µM phytosulfokine–α (PSK-α) and in a PSK-free control medium. PSK-α was ...applied for 10 days and later, protoplast-derived cells were cultured in the PSK-free medium. Supplementation of the culture medium with PSK-α showed a dose-dependent effect on the mitotic activity of cultured cells. On the 15th day of culture, the highest mitotic activity of protoplast-derived cells was observed in cultures treated with 0.1 µM of PSK-α, and ranged from 14 to 60% dependent on the accession. The number of multi-cell structures was also higher (90–93%) on this medium compared to the control (77–80%). Analysis of cellulose regeneration in cultured protoplasts after Calcofluor White staining showed that this process was not synchronous, but depended instead on the presence of PSK-α in the culture medium, and was more pronounced in the low-responding accession. Sustained cell divisions led to formation of microcallus colonies, subjected to regeneration on solid media. Supplementation of the regeneration media with 0.1 µM of PSK significantly increased shoot regeneration compared to the control media. Moreover, enhanced regeneration was observed from calluses developed from cells treated with PSK-α at the early stages of development and later transferred for regeneration onto the media supplemented with 0.1 µM of this peptide.
Key message
Over-production of functional PSK-α in Arabidopsis caused increases in both plant cell growth and biomass and induced male sterility by regulating cell wall development.
Phytosulfokine-α ...(PSK-α) is a novel disulfated pentapeptide hormone that is involved in promoting plant cell growth. Although a role for PSK-α in stimulating protoplast expansion has been suggested, how PSK-α regulates cell growth in planta remains poorly understood. In this study, we found that overexpression of the normal PSK-α precursor gene
AtPSK4
, which resulted in high levels of PSK-α, caused longer roots and larger leaves with enlarged cells. As expected, these changes were not observed in transgenic plants overexpressing mutated
AtPSK4,
which generated unsulfated PSK-α. These findings confirmed the role of PSK-α in promoting plant cell growth. Furthermore, we found that overexpressing
AtPSK4
, but not mutated
AtPSK4
, induced a phenotype of male sterility that resulted from the failure of fibrous cell wall development in the endothecium. In addition, overexpressing
AtPSK4
enhanced expression of a number of genes encoding expansins, which are involved in cell wall loosening. Accordingly, in addition to its role in cell growth, we propose a novel function for PSK-α signaling in the modulation of plant male sterility via regulation of cell wall development.
Kiwifruit fruit stored at low temperatures are susceptible to chilling injury, leading to rapid softening, which therefore affects storage and marketing. The effect of 150 nM mL−1 of exogenous ...phytosulfokine α (PSKα) on reactive oxygen species (ROS) metabolism, Ca2+ signaling, and signal-transducing MAPK in kiwifruit, stored at 0 °C for 60 days, was investigated. The results demonstrated that PSKα treatment effectively alleviated chilling injury in kiwifruit, with a 15% reduction in damage compared to the control on day 60. In addition, PSKα enhanced the activities and gene expression levels of superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), Ca2+−ATPase, and mitogen−activated protein kinase (MAPK). In contrast, the activities and gene expression levels of NADPH oxidase (NOX) were inhibited, leading to a lower accumulation of O2− and H2O2, which were 47.2% and 42.2% lower than those in the control at the end of storage, respectively. Furthermore, PSKα treatment enhanced the calmodulin (CaM) content of kiwifruit, which was 1.41 times that of the control on day 50. These results indicate that PSKα can mitigate chilling injury and softening of kiwifruit by inhibiting the accumulation of ROS, increasing antioxidant capacity by inducing antioxidant enzymes, activating Ca2+ signaling, and responding to MAPK protein kinase. The present results provide evidence that exogenous PSKα may be taken for a hopeful treatment in alleviating chilling injury and maintaining the quality of kiwifruit.
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