Postharvest treatments influenced the incidence of internal browning, phenol, ABA, AND GA3 contents of two pineapple clones

Internal browning of pineapple (Ananas comosus L.) fruit and endogenous concentrations of abscisic acid and gibberellins during low temperature storage

ABSTRACTInternal browning (IB) is a main problem of Queen pineapple during cold storage. The effects of exogenous salicylic acid (SA) or abscisic acid (ABA) on IB alleviation of the pineapple during cold storage were investigated. ‘Sawi’ pineapples were peduncle-infiltrated with 2 mM SA or 380 µM ABA for 3 d at 13°C followed storage at 13°C for 14 d. IB incidence and IB-related factors including lipid peroxidation, antioxidant capacity and antioxidant enzymes activities of the tissue adjacent to core were investigated after storage for 7 and 14 d followed by 2 d at room temperature (RT). Both SA and ABA treatments obviously alleviated IB development. ABA lowered TP content, MDA accumulation and the activities of LOX, PAL and PPO and induced POD activity. SA lowered PAL and PPO activity, delayed LOX activity and MDA increase, enhanced phenols, antioxidant activity and both antioxidant enzyme yields. Both ABA and SA peduncle infiltration alleviated IB incidence of Queen pineapple during cold storage. Although ABA could reduce the IB incidence better than SA, due to the efficiency of lower reactions of browning-related enzymes and lipid peroxidation, exogenous SA application might be a better choice for commercial use.Abbreviations: Total phenols (TP), Malondialdehyde (MDA), Lipoxygenase (LOX), Phenylalanine ammonia lyase (PAL), Polyphenol oxidase (PPO), Peroxidase (POD) and Internal browning (IB)

This study was conducted to find out the relationship between ascorbic acid (AA), and internal browning (IB) incidence in Hindi Be-sennara mango fruits (Mangifera indica L.) during cold storage (4 o C).Ascorbic acid content in two main parts (stem and calyx end of fruit) and three sub-main parts (peels, inner and outer pulps) of the fruits were measured.Internal browning in mango fruits found to be dependant on the fruit AA content.Exogenous application of AA (5.6 mM) decreased IB incidence when the fruits immersed for 24 hour compared to these immersed in water for the same time and stored at ambient conditions for 35 days.Mango fruits pre-storage immersing in diluted AA (5.6 mM), water is absorbed throughout the peel cells causing an increase on AA content and a decrease on its concentration.The decrease of IB incidence was appeared due to such increase on AA content in inner and outer parts of the fruit.This protection of the treated fruits may be related to the consumption of the externally added AA.Therefore, it could be said that the application of AA increases mango fruit quality, through protecting the from development of IB, also, the obtained results indicated that such treatment maintain the total phenols (TP) content in fruits during cold storage constant.

Endogenous free abscisic acid (ABA), indole‐3‐acetic acid (IAA) and gibberellins (GAs) were identified and quantified in whole white spruce (Picea glauca [Moench] Voss) seeds, zygotic embryos and megagametophytes by high performance liquid chromatography and gas chromatography‐selected ion monitoring‐mass spectrometry. In seeds, the ABA content was high at the early embryo developmental stage and underwent a further rapid increase at the precotyledonary stage about 4 weeks after pollination (AFP). This latter increase in ABA corresponded with an increase in seed dry weight 4–6 weeks AFP. Increases of ABA continued until the late maturation stage (8 weeks AFP). The endogenous ABA concentration on a dry weight basis was higher in embryos than in megagametophytes, but the total ABA content per structure was lower in embryos than in megagametophytes because the size and weight of these two structures were different. At the late maturation stage, ABA amounts decreased earlier in embryos (8 weeks AFP) than in megagametophytes (10 weeks AFP). Low concentrations of ABA were observed in embryos and megagametophytes of stored seeds. During development, the endogenous IAA amount in the megagametophytes declined after pollination. This was followed by an increase from 2 to 6 weeks AFP. During late maturation, the IAA content increased in megagametophytes but decreased in the embryos. Throughout seed development, GA4 slightly decreased while GA9 increased. Endogenous GA7 remained very low throughout. In stored seeds, amounts of both IAA and GAs were lower than in developing seeds. Concomitant with a rapid increase in seed dry weight, seed moisture content (MC) decreased sharply between precotyledonary stage and early cotyledonary stage (4 and 6 weeks AFP). Seeds could absorb water and germinate after a significant decrease of MC and at a high endogenous ABA content (8 weeks AFP). These results suggest that endogenous ABA, IAA and GAs are involved in white spruce embryogenesis. There are relatively high ABA and IAA contents in the embryo environment but the GAs checked in this study are low.

Vigor reduction of sweet cherry varieties by dwarfing rootstock is well known, but the mechanism by which a rootstock induces dwarfing is not well understood. Plant hormones have been associated with dwarfing mechanism. This study was conducted, with the main purpose of determining the correlation between of endogenous abscisic acid (ABA) and indole acetic acid (IAA) and vigor of 10 selected dwarf mahaleb (Prunus mahaleb L.) genotypes. Endogenous IAA and ABA levels of selected dwarf genotypes were evaluated, which indicated significant differences for most traits. The IAA level in the shoot bark was the highest in H24 and lowest in M96 genotypes, while ABA level in the shoot bark was highest in M96 and lowest in H14. The mean ABA content decreased as the invigoration capacity of the genotype increased. ABA generally is regarded as an inhibitor of elongation. In our experiment, the endogenous ABA content was negatively correlated with shoot growth. ABA: IAA ratio in shoot bark decreased with increasing genotype vigor. ABA: IAA ratio of the dwarfing genotype M96 was about 1.118. Correlation coefficient showed a significant correlation between crown width, trunk diameter, crown volume, total IAA, total ABA, IAA: ABA and tree vigor. The concentration of ABA in shoot bark showed a good relationship with vigor, thus the content of this phytohormone in shoot bark could be a useful marker of dwarfing character in mahaleb genotype selections. Key words: Mahaleb, Dwarf rootstock, indole acetic acid (IAA), abscisic acid (ABA).

Radial water (J(V)) and abscisic acid (ABA) flows (J(ABA)) through maize root seedlings have been investigated under different conditions of nutrient deficiency. Whereas J(V) was reduced under nitrogen deficiency, potassium deficiency stimulated J(V). A substantial increase of J(ABA) was observed in roots kept under potassium deficiency. The observed changes of J(V) might have resulted from changed barrier properties of the endodermis. Nitrogen and potassium deficiency also caused an accumulation of endogenous ABA in root tissues. Under all conditions studied, except under K(+)-deficiency, external ABA (100 nM) caused an increase of J(V). The data of this study were used to analyse the relations between internal and endogenous root ABA, J(V), and J(ABA). The internal ABA of root tissues was positively correlated with J(V) and was highly significant (P <0.001 for internal and P=0.03 for endogenous root ABA) within the range 2-300 pmol g(-1) FW. It was also highly positively correlated to the radial ABA flows. There was also a highly positive correlation between J(V) and J(ABA). The data of this study indicate, for the first time, the relations between internal ABA, water, and ABA flows. Independent of treatment with external ABA, an ABA transport by solvent drag across the endodermis is confirmed.

The aim of this research was to study the effect of abscisic acid pre-harvest treatment on the phenolic composition of olive fruits. To that end we applied abscisic acid (i.e., 50 mg/L and 100 mg/L) on Arbequina and Picual olive trees. Two different days of harvesting (i.e., day 3 and 6 after treatment) were also included in the study. Although the results obtained depended on the cultivar and on the day of harvesting a general trend was established. The treatment with 50 mg/L of abscisic acid resulted in higher total phenol content but significant decrease in the DPPH activity. In contrast, olives treated with 100 mg/L abscisic acid resulted in higher total phenol content, DPPH activity and contents of oleuropein, hydroxytyrosol and phenolic acids as compared with controls. The best values of total phenol content and IC50 were obtained for treated Picual olives (727.75 mg gallic kg-1 and 889.72 µg/ml, respectively) whereas the highest values of oleuropein and hydroxytyrosol were measured for treated Arbequina olives (508.94 and 559.67 mg kg-1, respectively). Phenolic acid content was also higher in Picual olives treated with 100 mg/L of abscisic acid. Particulary, values ranged from 7.26 mg kg-1 for caffeic acid to 92.38 mg kg-1 for chlorogenic acid. Exogenous abscisic acid applied to olive trees is a promising agronomic practice to obtain olives enriched in antioxidants.

Abscisic acid (ABA) plays important roles in positively or negatively regulating plant disease resistance to pathogens. Here, we reassess the role of endogenous and exogenous ABA by using: 35S::ABA2, a previously reported transgenic Arabidopsis line with increased endogenous ABA levels; aba2-1, a previously reported ABA2 mutant with reduced endogenous ABA levels; and exogenous application of ABA. We found that bacterial susceptibility promoted by exogenous ABA was suppressed in 35S::ABA2 plants. The 35S::ABA2 and aba2-1 plants displayed elevated and reduced levels, respectively, of bacterial flagellin peptide (flg22)-induced H2O2. Surprisingly, ABA pre-treatment reduced flg22-induced H2O2 generation. Exogenous, but not endogenous ABA, increased catalase activity. Loss of nicotinamide adenine dinucleotide phosphate oxidase genes, RBOHD and RBOHF, restored exogenous ABA-promoted bacterial susceptibility of 35S::ABA2 transgenic plants. In addition, endogenous and exogenous ABA had similar effects on callose deposition and salicylic acid (SA) signaling. These results reveal an underlying difference between endogenous and exogenous ABA in regulating plant defense responses. Given that some plant pathogens are able to synthesize ABA and affect endogenous ABA levels in plants, our results highlight the importance of reactive oxygen species in the dual function of ABA during plant-pathogen interactions.

Coordinated regulation between jasmonic acid and abscisic acid mediates drought tolerance in sweetpotato.

Bulb abscisic acid (ABA) concentration has been shown to decrease in stored onions, and onset of sprouting to occur at minimal ABA concentration. It was postulated that increasing prestorage bulb ABA concentration could increase storage life. Analogues of ABA that enhance biological activity and resist degradation are available and are becoming commercially viable. Exogenous ABA and an ABA analogue (8′-methylene ABA methyl ester; PBI-365) were applied separately as preharvest foliar sprays to six onion cultivars with varying storage potential. Quality indicators including pyruvate, total soluble solids and firmness were determined at regular intervals during storage. Neither ABA treatment increased endogenous bulb ABA concentration. Bulb ABA concentration decreased during storage and the onset of sprouting occurred at a minimal ABA concentration (ca. 50–120 ng g−1 DW). This was followed by an increase in ABA concentration as sprout growth continued. No straightforward relationship between ABA and carbohydrate metabolism could be determined.

SummaryChanges in the severity of pulp browning, endogenous abscisic acid (ABA) and ethylene concentrations, and related gene expression in peach (Prunus persica L. ‘Bayuecui’) fruit stored at the biological freezing-point temperature (BFT; 1ºC), at 4ºC, or at room temperature (20ºC; as a control) were investigated.The results showed that fruit stored at room temperature showed climacteric changes in ethylene and ABA concentrations and in levels of expression of the corresponding ethylene synthetase genes (PpACS1, PpACO1) and the gene for a key enzyme of ABA synthesis (PpNCED), concomitant with a significant decrease in fruit firmness and an increase in juice yield. Meanwhile, two sucrose synthase genes (PpSUS1 and PpSUS2) were expressed at relatively low levels. However, fruit firmness decreased slightly and chilling injury (CI) increased significantly 40 d after storage (DAS) at 4ºC, with a significant accumulation of proline [from 8.33 µg g–1 (at t = 0 d) to 9.125 µg g–1 (at t = 40 d)]. In contrast, fruit firmness decreased slowly and pulp browning increased slightly 80 DAS at the BFT ( 1ºC), with a lower accumulation of proline than in fruit stored at 4ºC. The concentrations of soluble sugars and titratable acidity decreased during storage at 1ºC, 4ºC, or 20ºC, but there was a peak of soluble sugars at a late stage of storage at the BFT ( 1ºC). The fruit browning index was significantly and positively correlated (R 2 = 0.967) with ABA concentration. The decrease in ABA concentration in cold-stored fruit (at both 1ºC and 4ºC) inhibited ethylene production. Moreover, there was no significant correlation between CI in fruit and ethylene production. In conclusion, the decrease in ABA concentration reduced ethylene concentrations and inhibited the development of pulp browning, which resulted in an improved taste, but crisper fruit, when fruit were stored at the BFT (–1ºC).

Antagonistic interaction between endogenous sugar status and abscisic acid (ABA) signaling was examined in Arabidopsis. Endogenous ABA content in suspension-cultured cells and seedlings grown in the dark increased following reduction in endogenous sugar content. Expression of Arabidopsis 9-cis epoxycarotenoid dioxygenase (AtNCED ) genes, which encode key enzymes for ABA biosynthesis and ABSCISIC ACID INSENSITIVE 3 (ABI 3) which controls ABA sensitivity was enhanced by sugar starvation. GUS activity analysis in transgenic Arabidopsis carrying GUS controlled by the ABI3 promoter showed that ABI3 was expressed, when sugar was depleted and thereby leaf development was terminated, in the shoot apical meristem. We conclude that sugar depletion promotes ABA signaling to terminate leaf development in Arabidopsis seedlings. Antagonistic effects of sugar on ABA signaling in the process of vegetative quiescence processs are discussed.

Main ConclusionThe drought conditions and the application of ABA reduce the photosynthetic activity, and the processes related to the transpiration of Dracocephalum moldavica L. At the same time, the plant increases the production of phenolic compounds and essential oil as a response to stress conditions.In the semi-arid regions, drought stress is the most important environmental limitations for crop production. Abscisic acid (ABA) plays a crucial role in the reactions of plants towards environmental stress such as drought. Field experiments for two consecutive years in 2016 and 2017 were conducted to evaluate the effect of three watering regimes (well-watered, moderate and severe drought) and five exogenous ABA concentrations (0, 5, 10, 20 and 40 μM) on growth, photosynthesis, total phenolic and essential oil content of Dracocephalum moldavica L. Without ABA application, the highest photosynthetic rate (6.1 μmol CO2 m−2 s−1) was obtained under well-watered condition and, moderate and severe drought stress decreased photosynthesis rate by 26.39% and 34.43%, respectively. Some growth parameters such as stem height, leaf area, leaf dry weight and biological yield were also reduced by drought stress. ABA application showed a decreasing trend in photosynthesis rate and mentioned plant growth parameters under all moisture regimes. The highest seed yield (1243.56 kg ha−1) was obtained under well-watered condition without ABA application. Increasing ABA concentration decreased seed yield in all moisture regimes. The highest total phenolic content (8.9 mg g−1 FW) and essential oil yield (20.58 kg ha−1) were obtained from 20 and 5 μM ABA concentration, respectively, under moderate drought stress.

The effect of exogenous abscisic acid, provided to somatic embryos during the maturation step, on endogenous abscisic acid and its main conjugated form (abscisic acid glucose ester), germination and conversion frequencies is presented in this paper. Abscisic acid measurements were obtained after a methanolic extraction, a fractionation through high performance liquid chromatography, quantitation with an immunoassay and identification of the quantitated compound using gas chromatography-mass spectrometry. Results show that endogenous abscisic acid and abscisic acid glucose ester levels are clearly correlated with the exogenous abscisic acid concentration provided to the embryos. Maturation was clearly enhanced by exogenous abscisic acid, but no correlation was found between abscisic acid concentration and germination frequency. Conversely, development of the aerial part of the germinated somatic embryos was dependent upon the abscisic acid concentration in the culture medium and results suggest that this dependence could be related to the endogenous abscisic acid content.

The aim of the present study was to estimate the endogenous abscisic acid (ABA) content in tulip 'Apeldoorn' torpedo and mature somatic embryos. Moreover, the effect of exogenous ABA and/or its inhibitor fluridone on somatic embryo maturation and conversion into plantlets was investigated. Torpedo-stage somatic embryos were subcultured on media containing 5 μM of picloram and 1 μM of 6-benzyl-aminopurine (BAP)—control, and combinations of ABA (0 or 10 μM) and/or fluridone (0 or 30 μM) for 1 week. Then, the torpedo embryos were transferred to a maturation medium containing 0.25 μM of α-naphthaleneacetic acid (NAA) and 2.5 μM of BAP, without ABA and fluridone treatment, and cultivated under darkness or light for ten weeks. Endogenous ABA content (first time measured in tulip somatic embryos) was evaluated by ELISA test. The obtained results revealed that the highest level of endogenous ABA, at 17.45 nmol g−1 dry weight (DW), was recorded in torpedo-stage of tulip embryo development, only after 1 week of ABA treatment, and was nearly 10 times higher in comparison with the control. Simultaneous addition of ABA and fluridone to the medium resulted in the lowering of the ABA concentration to 9.58 nmol g−1 DW. During ten weeks of maturation of the embryos, the endogenous ABA content in mature tissue of tulip somatic embryo considerably decreased to an amount 0.87–1.33 nmol g−1 DW (irrespective of ABA and fluridone treatment) and did not differ significantly from control (0.59 nmol g−1 DW). Exogenous ABA and fluridone significantly decreased the growth value of fresh weight (FW) of the tulip torpedo-shaped and mature embryos under light conditions. Percentage of the DW of the torpedo embryos treated with exogenous ABA was significantly higher (15.43–17.02) in comparison with the control (10.87). Three to three and a half times more malformed mature embryos were noted under light conditions than in darkness, irrespective of ABA and fluridone treatment. The highest percentage of mature embryos forming shoots (conversion) was observed under light conditions in the control and after fluridone treatment (26 and 20%, respectively).