Antonio Ferrante

Chlorophyll a Fluorescence as a Tool in Evaluating the Effects of ABA Content and Ethylene Inhibitors on Quality of Flowering Potted Bougainvillea

Flowering potted plants during the postproduction stage are usually stored in inadequate environmental conditions. We evaluated the effect of the most common storage conditions and treatments on two Bougainvillea cultivars after harvest and during recovery. Flowering potted Bougainvillea plants were treated with 100 mL 2 mM amino-oxyacetic acid (AOA) or 500 ppb 1-methylcyclopropene (1-MCP) prior storage in dark at 14°C for simulating transport or storage conditions and, subsequently, transferred to growth chambers at 20°C in the light for one week for evaluating the recovery ability. The plant stress during the experiments was assessed by ethylene, ABA, and chlorophyll a fluorescence measurements. Ethylene production was affected by temperature rather than treatments. ABA concentration declined in leaves and flowers during storage and was not affected by treatments. Fluorescence parameters appear to be very useful for screening Bougainvillea cultivars resistant to prolonged storage periods.

Current understanding on ethylene signaling in plants: the influence of nutrient availability.

The plant hormone ethylene is involved in many physiological processes, including plant growth, development and senescence. Ethylene also plays a pivotal role in plant response or adaptation under biotic and abiotic stress conditions. In plants, ethylene production often enhances the tolerance to sub-optimal environmental conditions. This role is particularly important from both ecological and agricultural point of views. Among the abiotic stresses, the role of ethylene in plants under nutrient stress conditions has not been completely investigated. In literature few reports are available on the interaction among ethylene and macro- or micro-nutrients. However, the published works clearly demonstrated that several mineral nutrients largely affect ethylene biosynthesis and perception with a strong influence on plant physiology. The aim of this review is to revisit the old findings and recent advances of knowledge regarding the sub-optimal nutrient conditions on the effect of ethylene biosynthesis and perception in plants. The effect of deficiency or excess of the single macronutrient or micronutrient on the ethylene pathway and plant responses are reviewed and discussed. The synergistic and antagonist effect of the different mineral nutrients on ethylene plant responses is critically analyzed. Moreover, this review highlights the status of information between nutritional stresses and plant response, emphasizing the topics that should be further investigated.

Biostimulants and crop responses: a review

Agricultural growing practices have been evolving towards organic, sustainable or environmental friendly systems. The aim of modern agriculture is to reduce inputs without reducing the yield and quality. These goals can be achieved by breeding programmes but would be species specific and time consuming. The identification of organic molecules able to activate plant metabolism may allow an improvement in plant performance in a short period of time and in a cheaper way. Biostimulants are plant extracts and contain a wide range of bioactive compounds that are mostly still unknown. These products are usually able to improve the nutrient use efficiency of the plant and enhance tolerance to biotic and abiotic stresses. In this review, the state of the art and future prospects for biostimulants are reported and discussed. Moreover, particular attention has been paid to intensive agricultural systems such as horticultural and floricultural crops. In vegetables, the application of biostimulants allowed a reduction in fertilizers without affecting yield and quality. In leafy vegetables susceptible to nitrate accumulation, such as rocket, biostimulants have been able to improve the quality and keep the nitrates under the limits imposed by EU regulations. Moreover in leafy vegetables, biostimulants increased leaf pigments (chlorophyll and carotenoids) and plant growth by stimulating root growth and enhancing the antioxidant potential of plants. In floriculture, biostimulants used in bedding plant production stimulated the growth of plants, which reached the blooming and commercial stages earlier, thus optimizing space in the greenhouse.

Thidiazuron —a potent inhibitor of leaf senescence in Alstroemeria

Abstract The time to flower senescence and leaf yellowing in 20 cut flower cultivars of Alstroemeria was studied. In deionized water (DI), the time to abscission of the first petal ranged from 9 to 16 days. Time to leaf yellowing ranged from 5 to 18 days. These two processes proceeded independently so that in some cultivars leaf yellowing occurred long before flower senescence, and in others, much later. Thidiazuron (TDZ, N -phenyl- N′ -1,2,3-thiadiazol-5-ylurea), a substituted phenylurea with cytokinin-like activity, markedly extended leaf longevity. TDZ was much more effective than two other substituted phenyl-urea compounds tested, in delaying leaf yellowing. A single 24-h pulse treatment with 10 μM TDZ prevented yellowing of isolated leaves for more than 2 months.

Nitrates and Glucosinolates as Strong Determinants of the Nutritional Quality in Rocket Leafy Salads

Rocket is an important leafy vegetable crop and a good source of antioxidants and anticancer molecules such as glucosinolates and other sulfur compounds. Rocket is also a hyper-accumulator of nitrates which have been considered for long time the main factors that cause gastro-intestinal cancer. In this review, the content of these compounds in rocket tissues and their levels at harvest and during storage are discussed. Moreover, the effect of these compounds in preventing or inducing human diseases is also highlighted. This review provides an update to all the most recent studies carried out on rocket encouraging the consumption of this leafy vegetable to reduce the risk of contracting cancer and other cardiovascular diseases.

Effects of abscisic acid on ethylene biosynthesis and perception in Hibiscus rosa-sinensis L. flower development

The effect of the complex relationship between ethylene and abscisic acid (ABA) on flower development and senescence in Hibiscus rosa-sinensis L. was investigated. Ethylene biosynthetic (HrsACS and HrsACO) and receptor (HrsETR and HrsERS) genes were isolated and their expression evaluated in three different floral tissues (petals, style–stigma plus stamens, and ovaries) of detached buds and open flowers. This was achieved through treatment with 0.1 mM 1-aminocyclopropane-1-carboxylic acid (ACC) solution, 500 nl l−1 methylcyclopropene (1-MCP), and 0.1 mM ABA solution. Treatment with ACC and 1-MCP confirmed that flower senescence in hibiscus is ethylene dependent, and treatment with exogenous ABA suggested that ABA may play a role in this process. The 1-MCP impeded petal in-rolling and decreased ABA content in detached open flowers after 9 h. This was preceded by an earlier and sequential increase in ABA content in 1-MCP-treated petals and style–stigma plus stamens between 1 h and 6 h. ACC treatment markedly accelerated flower senescence and increased ethylene production after 6 h and 9 h, particularly in style–stigma plus stamens. Ethylene evolution was positively correlated in these floral tissues with the induction of the gene expression of ethylene biosynthetic and receptor genes. Finally, ABA negatively affected the ethylene biosynthetic pathway and tissue sensitivity in all flower tissues. Transcript abundance of HrsACS, HrsACO, HrsETR, and HrsERS was reduced by exogenous ABA treatment. This research underlines the regulatory effect of ABA on the ethylene biosynthetic and perception machinery at a physiological and molecular level when inhibitors or promoters of senescence are exogenously applied.

Ethylene Role in Plant Growth, Development and Senescence: Interaction with Other Phytohormones

The complex juvenile/maturity transition during a plant’s life cycle includes growth, reproduction, and senescence of its fundamental organs: leaves, flowers, and fruits. Growth and senescence of leaves, flowers, and fruits involve several genetic networks where the phytohormone ethylene plays a key role, together with other hormones, integrating different signals and allowing the onset of conditions favorable for stage progression, reproductive success and organ longevity. Changes in ethylene level, its perception, and the hormonal crosstalk directly or indirectly regulate the lifespan of plants. The present review focused on ethylene’s role in the development and senescence processes in leaves, flowers and fruits, paying special attention to the complex networks of ethylene crosstalk with other hormones. Moreover, aspects with limited information have been highlighted for future research, extending our understanding on the importance of ethylene during growth and senescence and boosting future research with the aim to improve the qualitative and quantitative traits of crops.

Carbon-Deprivation-Driven Transcriptome Reprogramming in Detached Developmentally-Arresting Arabidopsis Inflorescences

Senescence is genetically controlled and activated in mature tissues during aging. However, immature plant tissues also display senescence-like symptoms when continuously exposed to adverse energy-depleting conditions. We used detached dark-held immature inflorescences of Arabidopsis (Arabidopsis thaliana) to understand the metabolic reprogramming occurring in immature tissues transitioning from rapid growth to precocious senescence. Macroscopic growth of the detached inflorescences rapidly ceased upon placement in water in the dark at 21°C. Inflorescences were completely degreened by 120 h of dark incubation and by 24 h had already lost 24% of their chlorophyll and 34% of their protein content. Comparative transcriptome profiling at 24 h revealed that inflorescence response at 24 h had a large carbon-deprivation component. Genes that positively regulate developmental senescence (ARABIDOPSIS NAC DOMAIN CONTAINING PROTEIN92) and shade-avoidance syndrome (PHYTOCHROME INTERACTING FACTOR4 [PIF4] and PIF5) were up-regulated within 24 h. Mutations in these genes delayed degreening of the inflorescences. Their up-regulation was suppressed in dark-held inflorescences by glucose treatment, which promoted macroscopic growth and development and inhibited degreening of the inflorescences. Detached inflorescences held in the dark for 4 d were still able to reinitiate development to produce siliques upon being brought out to the light, indicating that the transcriptional reprogramming at 24 h was adaptive and reversible. Our results suggest that the response of detached immature tissues to dark storage involves interactions between carbohydrate status sensing and light deprivation signaling and that the dark-adaptive response of the tissues appears to utilize some of the same key regulators as developmental senescence.

Effect of thidiazuron and gibberellic acid on leaf yellowing of cut stock flowers

Plant hormones such as cytokinins and gibberellins are able to inhibit leaf yellowing in different species of cut flowers and potted plants. These hormones can be used alone or in combination among them for preserving chlorophyll in floriculture items. In the present study thidiazuron was tested alone or combined with GA3 for delaying leaf yellowing of cut stock flowers during vase life. Cut flowers were placed in a controlled environment and treated for 24 hours with the following solutions: distilled water (control) or solutions containing 5, 10 µM thidiazuron (TDZ), 0.5 mM gibberellic acid (GA3), or a combination of 0.5 mM GA3 with 5 µM TDZ. The effect of treatments was evaluated by measuring chlorophyll content, ethylene production, leaf gas exchanges and chlorophyll a fluorescence. Results showed that TDZ was able to delay leaf yellowing in light during whole experimental period (30 days). The effect of TDZ on dark stored flowers was less effective, and also delayed chlorophyll losses for 10–12 days. TDZ and GA3 combination did not show any synergistic nor beneficial effect. Gas exchange values such as net photosynthesis, vapour pressure deficit, stomatal conductance and water use efficiency were higher in the TDZ only treatment.

Changes in Abscisic Acid During Leaf Yellowing of Cut Stock Flowers

Leaf pigments, such as chlorophyll and carotenoids, are essential plant molecules. They provide carbohydrates and energy during all plant life. Leaf pigments are also important parameters of decorative plants, such as floriculture items, cut foliage and flowers. Leaf yellowing is a form of senescence caused by an internal hormone imbalance, such as a lack of cytokinins. The aim of this study was to investigate the changes in total carotenoids and endogenous ABA in cut flower stock leaves during post-harvest life. The effect of pulse treatment with 5 or 10 μM thidiazuron (TDZ), 150 mg l−1 8-hydroxyquinoline sulphate (8-HQS) and combinations of TDZ with 8-HQS on total carotenoids and ABA concentration was also investigated. Results showed that total carotenoids drastically decreased from 1548 μg cm−2, until reaching 565 μg cm−2 at the end of vase life. Endogenous ABA strongly increased at the same time, going from 167 ng g−1 DW at the beginning of the experiment to 1322 ng g−1 DW at the end of vase life. The TDZ inhibited carotenoid degradation, but did not affect the ABA concentration, while the 8-HQS did not prevent carotenoid degradation and the ABA concentration was only slightly affected. ABA seems to be a secondary senescence bio-product that may have a synergic effect with other senescence inducers dramatically accelerating leaf senescence.