Comparative analysis of the phenolic contents and antioxidant activities of different parts of two pomegranate (Punica granatum L.) Cultivars: 'Tunisia' and 'Qingpi'.

Pomegranate (Punica granatum L.), with its abundant phenolic substances and strong antioxidant activity, holds significant research and utilization potential across various organs. However, there have been few studies on the phenolic content and antioxidant activity of different parts of pomegranate, especially the placenta. This study investigated the phenolic content and antioxidant activity of fruits, flowers, and leaves of two pomegranate varieties, 'Tunisia' and 'Qingpi', throughout their growth and development. Results indicated significant variations in phenolic content among different organs, with petals exhibiting the highest total polyphenol content (TPC, 49.40 mg GAE/g FW) and total anthocyanin content (TMAC, 1938.54 nmol/g FW). Placenta contained the highest levels of total flavonoids (TFC, 173.58 mg RE/g FW) and punicalagin (109.30 mg/g FW). The peel had the highest content of total flavanols (TFAC, 19.42 mg CE/g FW). Over the course of pomegranate development, total polyphenols, total flavonoids, total flavanols, punicalagin, and antioxidant activity declined in different organs. Antioxidant activity followed the order: fruit > flower > leaf, with the placenta exhibiting the highest antioxidant activity among fruits. Antioxidant activity showed a significant positive correlation with total polyphenols (R2 = 0.77-1.00), total flavonoids (R2 = 0.71-0.99, except tegmens), and punicalagin (R2 = 0.71-1.00). This study provides a comparative analysis of the phenolic content and antioxidant activity in different organs of pomegranate, highlighting the placenta as the primary source of punicalagin. This study provides a theoretical basis for the development and utilization of pomegranate phenolic compounds.

Effects of L-Cysteine and γ-Aminobutyric Acid Treatment on Postharvest Quality and Antioxidant Activity of Loquat Fruit during Storage.

Sichuan is the China's leading producer of loquat, with the largest cultivation area and yield ranked first in China. Loquat is a seasonal fruit highly appreciated by consumers; however, the fruit is prone to browning and lignification after harvest, affecting its storage quality. The effects of L-Cysteine (L-Cys, 0.01, 0.05, 0.1, 0.2%) and γ-aminobutyric acid (GABA, 0.025, 0.05, 0.075, 0.1%) on the sensory quality and antioxidant activity of loquat fruit during cold storage at 4 °C for 35 days and simulated shelf life for 5 days were investigated. The results showed that after 40 days of storage, compared with the control, 0.05% L-Cys and 0.05% GABA treatment of 'Zaozhong No. 6' loquat fruit effectively reduced the weight loss rate, browning index, decay index, respiratory rate, firmness, and lignin content and slowed the decreases in total soluble solids, soluble sugar, titratable acidityand vitamin C contents. The application of 0.05% L-Cys and 0.05% GABA significantly increased the contents of total phenols, total flavonoids, flavanols, and carotenoids; delayed the increase of relative electric conductivity, MDA, POD, and PPO activities; and significantly enhanced the activities of SOD and CAT, DPPH free radical scavenging ability, and FRAP, thereby improving antioxidant capacity. In summary, 0.05% L-Cys and 0.05% GABA treatment promotes the quality of loquat fruit after 40 days of storage, and significantly enhances antioxidant capacity, thus delaying senescence after harvest.

Artemisia argyi water extract promotes selenium uptake of peach seedlings.

Soil in most areas of the world is selenium (Se) deficient, which results a low Se content in agricultural products. To improve the fruit tree Se accumulation, the effects of different Artemisia argyi water extract concentrations (0, 100, 200, 300, and 400-fold dilutions) on the growth and Se accumulation of peach seedlings were studied by a pot experiment. A 300- and 400-fold dilution of A. argyi water extract increased the root and shoot biomass (dry weight), leaf chlorophyll a content, superoxide dismutase (SOD) activity, and peroxidase (POD) activity of peach seedlings, but decreased the leaf chlorophyll a/b. Different A. argyi water extract concentrations had no significant effects on peach leaf chlorophyll a content of peach seedlings, but increased the leaf carotenoid content, catalase (CAT) activity, and soluble protein content. Different A. argyi water extract concentrations increased the total Se, inorganic Se, and organic contents in roots and shoots of peach seedlings to some extent. Furthermore, A. argyi water extract concentration exhibited a linear relationship with the root and shoot total Se contents. Compared with the control, the 100-, 200-, 300-, and 400-fold dilutions of A. argyi water extract increased the shoot total Se content by 18.95%, 31.31%, 39.32%, and 51.59%, respectively. Different A. argyi water extract concentrations also increased the leaf Se metabolism-related enzyme activities of peach seedlings, including the activities of adenosine triphosphate sulfurase (ATPS), adenosine 5'-phosphosulfate reductase (APR), and serine acetyltransferase (SAT), as well as selenocysteine methyltransferase (SMT) to some extent. Moreover, correlation and grey relational analyses revealed the root total Se content, CAT activity, and ATPS activity to be closely associated with the total shoot Se content. Therefore, applying A. argyi water extract can thus promote the growth and Se uptake of peach seedlings, and the future study should focus on the application effects of Se uptake in peach fruits.

An amino acid fertilizer improves the emergent accumulator plant Nasturtium officinale R. Br. phytoremediation capability for cadmium-contaminated paddy soils.

Cadmium (Cd) contamination of paddy soil affects safe crop production. This study aimed to evaluate the effects of plant biostimulant amino acid fertilizer on the phytoremediation capability of an emergent accumulator plant Nasturtium officinale R. Br. for Cd-contaminated paddy soils. A pot study was carried out to study the effects of different concentrations of amino acid fertilizer on the Cd accumulation of N. officinale grown in Cd-contaminated paddy soil. The amino acid fertilizer increased the biomass of N. officinale. The amino acid fertilizer concentration exhibited a quadratic polynomial regression relationship with the root and shoot biomass. The fertilizer also increased the photosynthetic pigment (chlorophyll and carotenoid) contents, peroxidase (POD; EC 1.11.1.7) activity, and catalase (CAT; EC 1.11.1.6) activity of N. officinale, but decreased the soluble protein content and had no significant effect on the superoxide dismutase (SOD; EC 1.15.1.1) activity. Furthermore, the amino acid fertilizer increased the Cd content and Cd extraction of N. officinale. The shoot Cd extraction increased by 29.06%, 63.05%, 77.22%, and 17.40% at 1500-, 1200-, 900-, and 600-fold dilutions of the amino acid fertilizer, respectively, compared with the control. Moreover, the amino acid fertilizer promoted the Cd transport from the roots to shoots of N. officinale. The amino acid fertilizer concentration also exhibited a quadratic polynomial regression relationship with the root Cd content, shoot Cd content, root Cd extraction, and shoot Cd extraction, respectively. The correlation, grey relational, and path analyses revealed that the root biomass, shoot biomass, chlorophyll content, catalase activity, shoot Cd content, and root Cd extraction were closely associated with the shoot Cd extraction. Therefore, the amino acid fertilizer can promote Cd uptake and improve the phytoremediation capability of N. officinale to remediate Cd-contaminated paddy soils, and 900-fold dilution is the most suitable concentration.

Effects of intercropping with Solanum photeinocarpum and its post-grafting generations on cadmium accumulation in loquat (Eriobotrya japonica).

Cadmium (Cd) contamination of orchard soils is a global problem that has been increasing. To decrease the Cd accumulation in fruits, intercropping the orchard crops with hyperaccumulator plants has been used for soil remediation. A pot and a field experiment were conducted to study the effects of intercropping the potential Cd-hyperaccumulator Solanum photeinocarpum and its post-grafting generations with loquat (Eriobotrya japonica) on the growth and Cd uptake of these two plant species. In the pot experiment, intercropping improved the biomass, Cd content, Cd extraction, and root-to-shoot Cd translocation in both species. Intercropping increased the DNA methylation levels, antioxidant enzyme activity, and soluble protein content of loquat seedlings. These results indicate that intercropping could improve the phytoremediation of S. photeinocarpum and its post-grafting generations and increase the Cd uptake in loquat seedlings. In the field experiment, intercropping increased the Cd contents in the old branches, while it decreased that in the young branches and fruits of loquat. These findings indicate that intercropping could increase the Cd uptake in old tissues but reduce the Cd uptake in young tissues and fruits of loquat. So, intercropping loquat with S. photeinocarpum and its post-grafting generations could be used in Cd-contaminated orchards.

Intercropping the potential Cd-hyperaccumulator Solanum photeinocarpum and its post-grafting generations with loquat mutually promoted the growth of two plant species, and also promoted the cadmium uptakes in S. photeinocarpum and old branches of loquat, while inhibited the Cd uptake in the loquat young tissues (young branches and fruits). These results are the new findings of the intercropping.

Effects of reciprocal grafting on cadmium accumulation in post-grafting generations of two ecotypes of Solanum photeinocarpum.

Farmland and mining ecotypes of the potential cadmium (Cd)-hyperaccumulator Solanum photeinocarpum were collected to study the effects of reciprocal grafting on the growth of, and Cd accumulation in, the post-grafting generations. The post generations of the following plant materials were evaluated in a pot experiment: the un-grafted farmland ecotype, grafted plants with the farmland ecotype as the scion or the rootstock, the un-grafted mining ecotype, and grafted plants with the mining ecotype as the scion or the rootstock. The results showed that reciprocal grafting increased the biomass, the activities of superoxide dismutase, peroxidase, and catalase, and the soluble protein content in the post-grafting generations of both ecotypes S. photeinocarpum. Reciprocal grafting also increased the Cd content in, and amount of Cd extracted by, the post-grafting generations of both ecotypes S. photeinocarpum as a result of lower soil pH and higher soil available Cd concentrations. Additionally, grafting affected the DNA methylation levels by inducing hypermethylation or demethylation in the post-grafting generation. Therefore, reciprocal grafting can enhance the Cd accumulation (phytoremediation) capacity of post-grafting generations of both ecotypes S. photeinocarpum by affecting DNA methylation levels.

Melatonin Accumulation in Sweet Cherry and Its Influence on Fruit Quality and Antioxidant Properties.

Although the effects of melatonin on plant abiotic and biotic stress resistance have been explored in recent decades, the accumulation of endogenous melatonin in plants and its influence on fruit quality remains unclear. In the present study, melatonin accumulation levels and the expression profiles of five synthesis genes were investigated during fruit and leaf development in sweet cherry (Prunus avium L.). Melatonin was strongly accumulated in young fruits and leaves, then decreased steadily with maturation. Transcript levels of PacTDC and PacSNAT were highly correlated with melatonin content in both fruit and leaves, indicating their importance in melatonin accumulation. Furthermore, application of 50 and 100 µmol·L-1 of melatonin to leaves had a greater influence on fruit quality than treatments applied to fruits, by significantly improving fruit weight, soluble solids content, and phenolic content including total phenols, flavanols, total anthocyanins, and ascorbic acid. Meanwhile, melatonin application promoted the antioxidant capacity of fruit assayed by 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azinobis (3-ethylben zothiazoline-6-sulfonic acid) (ABTS), and ferric reducing antioxidant power (FRAP). These results provide insights into the physiological and molecular mechanisms underlying melatonin metabolism of sweet cherry.

Effects of reciprocal hybridization on cadmium accumulation in F1 hybrids of two Solanum photeinocarpum ecotypes.

In this study, farmland and mining ecotypes of Solanum photeinocarpum (a potential cadmium (Cd) hyperaccumulator plant) were reciprocally hybridized each other, and the Cd accumulation characteristics of the F1 hybrids were studied. In pot experiments, higher biomasses and Cd extraction abilities were found for two S. photeinocarpum F1 hybrids than for the parents, but the Cd contents in various organs were lower in the hybrids than the parents. However, the differences between the Cd contents in the two hybrids were not significant. The antioxidant enzyme (superoxide dismutase and peroxidase) activities were higher for the S. photeinocarpum F1 hybrids than the parents. Less DNA methylation was found in the hybrids than the parents because more demethylation occurred in the hybrids than the parents. The biomass, Cd content, and Cd extraction ability effects in field experiments were similar to the effects in the pot experiments. It was concluded that reciprocally hybridizing different S. photeinocarpum ecotypes improved the ability of S. photeinocarpum to be used to phytoremediate contaminated land.

Effects of different rootstocks on cadmium accumulation characteristics of the post-grafting generations of Galinsoga parviflora.

A pot experiment was conducted to study the effects of different rootstocks on the cadmium (Cd) accumulation characteristics of the post-grafting generations of Cd-hyperaccumulator Galinsoga parviflora plants. Five treatments, ungrafted and G. parviflora seedlings grafted on the rootstocks of Kalimeris indica, Senecio scandens, Conyza canadensis, and Artemisia sieversiana, were utilized. The four rootstock grafts decreased the shoot biomass of the G. parviflora post-grafting generation compared with ungrafted. The K. indica and S. scandens grafts increased the Cd concentration in shoots of the G. parviflora post-grafting generation by 15.06% and 14.40%, respectively, compared with ungrafted, while the C. canadensis and A. sieversiana grafts had no significant effects. K. indica grafts increased the amount of Cd extracted by shoots of the G. parviflora post-grafting generation by 10.59% compared with ungrafted, while the other treatments resulted in decreases. Compared with ungrafted, the different rootstocks had no significant effects on the photosynthetic pigment content of the G. parviflora post-grafting generation, and only C. canadensis grafts increased the superoxide dismutase activity level, while only K. indica grafts increased the peroxidase activity level. Therefore, the K. indica rootstock could increase the phytoremediation capability of G. parviflora post-grafted plants grown in Cd-contaminated soil.

Self-rooted grafting influences the growth and cadmium accumulation characteristics in the post generation of Cosmos sulphureus.

To determine whether self-rooted grafting increases the cadmium (Cd) accumulation in post generations of hyperaccumulator or accumulator plants, a pot experiment was conducted to study the effects of self-rooted grafting on growth and Cd accumulation in the post generation of the accumulator plant Cosmos sulphureus. Four treatments were applied in the experiment with soil Cd concentration of 5 mg kg-1: ungrafted (UG), self-rooted grafting of the same C. sulphureus seedling (SG), self-rooted grafting of two C. sulphureus seedlings at the same growth stage (TG), and self-rooted grafting of two C. sulphureus seedlings at different developmental stages (DG). Compared with those of UG plants, the SG, TG, and DG treatments increased the root, stem, leaf, and shoot biomasses of plants in the post-grafting generation, consistent with the rank order DG > TG > SG > UG. The SG, TG, and DG treatments decreased the Cd contents in different organs of the post-grafting generation compared with those of UG plants. Only DG increased Cd extraction by the shoots in the post-grafting generation, which was increased by 6.28% compared with that of the UG treatment. In addition, SG, TG, and DG increased the photosynthetic pigment contents and enhanced antioxidant enzyme activities in the post-grafting generation compared with those of the UG treatment. Thus, self-rooted grafting promoted growth of C. sulphureus plants in the post generation. The DG treatment increased Cd extraction by C. sulphureus plants in the post-grafting generation, which may be exploited for phytoremediation of urban Cd-contaminated soil.

Effects of intercropping with floricultural accumulator plants on cadmium accumulation in grapevine.

Grapevine (Vitis vinifera L.) intercropping with floricultural cadmium (Cd) accumulator plants (Helianthus annuus L., Cosmos sulphureus Cav., Cosmos bipinnata Cav., and Impatiens balsamina L.) in Cd-contaminated soils (5 mg/kg) was conducted in pot experiment to screen the floricultural Cd-accumulator plants that can effectively reduce Cd uptake in grapevine. Intercropping with H. annuus, C. sulphureus, and I. balsamina decreased the biomass of grape plants compared with that of the grape monoculture, whereas intercropping with C. bipinnata did not show differences in grape plant biomass both as compared to monoculture in Cd-contaminated soils and to control plants, grown in the same soil without Cd spiking. The superoxide dismutase and catalase activities, as well as soluble protein content, were increased by intercropping with C. bipinnata compared with the grape monoculture, but were decreased by the other intercropping treatments. In general, intercropping with the four floricultural Cd-accumulator plants decreased the Cd content in grape plants compared with the monoculture, and the Cd content in grapevine for the different treatments was as follows: monoculture > intercropped with I. balsamina > intercropped with C. bipinnata > intercropped with H. annuus > intercropped with C. sulphureus. As for the amount of Cd accumulated by shoots of the floricultural plants, the ranking was as follows: I. balsamina > C. sulphureus > H. annuus > C. bipinnata. Therefore, intercropping with floricultural Cd-accumulator plants could effectively decrease Cd accumulation in grape plants, and intercropping with C. sulphureus gave the best results in this study.

Effects of intercropping with Bidens species plants on the growth and cadmium accumulation of Ziziphus acidojujuba seedlings.

To study the effects of intercropping with accumulator plants on heavy metal accumulation of fruit trees, plants of three Bidens species (Bidens pilosa, Bidens biternata, and Bidens parviflora) were intercropped with Ziziphus acidojujuba seedlings under cadmium (Cd)-contaminated conditions (5 mg kg-1). Intercropping with Bidens species increased the biomass and chlorophyll b content of Z. acidojujuba seedlings compared with monoculture, but decreased their carotenoid content. Intercropping with Bidens species also improved the activity of superoxide dismutase, peroxidase, and catalase in Z. acidojujuba seedlings compared with monoculture. Intercropping with Bidens species decreased the Cd content in the roots of Z. acidojujuba seedlings compared with monoculture. Conversely, when intercropped with B. pilosa, B. biternata, and B. parviflora, the Cd content in the shoots of Z. acidojujuba seedlings increased by 62.18%, 60.10%, and 62.18%, respectively, compared with that of those monocultured. When intercropped with Z. acidojujuba seedlings, the Cd accumulation amount of three Bidens species plants were ranked B. parviflora > B. biternata > B. pilosa. Therefore, intercropping with plants of three Bidens species is not suitable for Cd-contaminated jujube orchards.

Cutting after grafting affects the growth and cadmium accumulation of Nasturtium officinale.

The growth and cadmium (Cd) accumulation of emergent plant Nasturtium officinale R. Br. cuttings taken from plants grafted onto rootstocks of four terrestrial Cruciferae species were studied in a pot experiment. Scions from N. officinale seedlings were grafted onto rootstocks of Brassica chinensis L., Raphanus sativus L., Brassica napus L., and Rorippa dubia (Pers.) H. Hara. Cuttings were taken after 1 month and grown in Cd-contaminated soil (10 mg Cd kg-1) for 60 days. Compared with non-grafted N. officinale, grafting onto R. sativus and B. napus rootstocks increased the root, shoot, and whole plant biomasses of N. officinale cuttings. Brassica napus rootstock was more effective than R. sativus rootstock for increasing the biomass of N. officinale cuttings. The four rootstocks decreased or had no significant effect on photosynthetic pigment contents in N. officinale cuttings compared with non-grafted N. officinale. Only grafting onto B. napus rootstock enhanced antioxidant enzyme activities. Compared with non-grafted N. officinale, R. sativus and B. napus rootstocks decreased the Cd contents in roots and shoots of N. officinale cuttings, whereas the other rootstocks had no significant effect on the shoot Cd content. The four rootstocks had no increase effects on Cd extraction by N. officinale cuttings. Therefore, cutting after grafting did not enhance the phytoremediation ability of N. officinale for growth in Cd-contaminated soil. However, R. sativus and B. napus rootstocks decreased the Cd content in N. officinale cuttings, which offers a potential approach for N. officinale safety production as a wild vegetable in Cd-contaminated soils.

Effects of living hyperaccumulator plants and their straws on the growth and cadmium accumulation of Cyphomandra betacea seedlings.

To determine whether the living hyperaccumulator plants and their straws have the same effects on the growth and heavy metal accumulation of common plants, two pot experiments (intercropping experiment and straw mulch experiment) were conducted to study the effects of living hyperaccumulator plants (Solanum photeinocarpum, Tagetes erecta, Galinsoga parviflora and Bidens pilosa) and their straws on the growth and cadmium (Cd) accumulation of common plant Cyphomandra betacea seedlings. Intercropping with T. erecta or B. pilosa promoted the growth of C. betacea seedlings compared with the monoculture, while intercropping with S. photeinocarpum or G. parviflora inhibited that. Intercropping with S. photeinocarpum decreased the Cd contents in the roots and shoots of C. betacea seedlings compared with the monoculture, but intercropping with the other plants did not. In the straw mulch experiment, the straw of S. photeinocarpum or T. erecta promoted the growth of C. betacea seedlings compared with the control, while the straw of G. parviflora or B. pilosa did not. The straw of S. photeinocarpum or T. erecta decreased the Cd contents in the shoots of C. betacea seedlings, and the straw of G. parviflora or B. pilosa increased the shoot Cd contents. Thus, intercropping with S. photeinocarpum and applying S. photeinocarpum or T. erecta straw can reduce the Cd uptake of C. betacea.