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In two poplar species with contrasting growth performance, sugar metabolism in xylem and cambial regions can explain their different grades of tolerance to drought and their recovery rates following water deficits., Drought dramatically affects wood production by adversely impacting cambial cells and their derivatives. Photosynthesis and assimilate transport are also affected by drought conditions. Two poplar genotypes, Populus deltoides ‘Dvina’ and Populus alba ‘Marte’, demonstrated contrasting growth performance and water–carbon balance strategies; a mechanistic understanding of the water deficit response was provided by these poplar species. ‘Marte’ was found to be more anisohydric than ‘Dvina’. This characteristic was associated with the capacity to reallocate carbohydrates during water deficits. In contrast, ‘Dvina’ displayed more conservative water management; carbohydrates were preferably stored or used for cellulose production rather than to achieve an osmotic balance between the phloem and the xylem. Data confirmed that the more ‘risk-taking’ characteristic of ‘Marte’ allowed a rapid recovery following water deficit and was connected to a different carbohydrate metabolism.

Background : The Zolfino bean is a variety of Phaseolus vulgaris , which is cultivated in a limited area of Tuscany, Italy, and is widely appreciated for its flavor and culinary uses. Objectives : A yellow Zolfino landrace cultivated in the Leccio-Reggello area was characterized and compared with three other varieties of Phaseolus vulgaris (i.e. the Borlotto, Cannellino, and Corona beans) in terms of its general features and potential as an antioxidant/anti-inflammatory agent. Design : The length, width, thickness, equatorial section surface, weight, volume, and seed coat section were measured in all the beans. The seed surface area was also estimated by an original empirical method. The ability of the different beans to interfere with the enzymes of the polyol pathway (that is, aldose reductase (AR) and sorbitol dehydrogenase) was tested using the supernatant after soaking the beans at room temperature and after thermal treatment, which simulated the bean-cooking process in a controlled fashion. Results : Concerning the general features, Zolfino was comparable with other beans, except Corona, in terms of surface–volume ratio, which possesses the lowest tegument thickness. Moreover, Zolfino appears the most effective in inhibiting AR activity. The inhibitory ability is unaffected by thermal treatment and appears to be associated with compound(s) present in the coat of the bean. Conclusions : The ability of Zolfino to inhibit AR, thus reducing the flux of glucose through the polyol pathway, highlights the features of Zolfino as a functional food, potentially useful in treating the dysfunctions linked to the hyperactivity of AR, such as diabetic complications or inflammatory responses. Keywords: Zolfino bean; Phaseolus vulgaris; aldose reductase; sorbitol dehydrogenase; polyol pathway (Published: 12 July 2016) Citation: Food & Nutrition Research 2016, 60: 31792 - http://dx.doi.org/10.3402/fnr.v60.31792

Yeasts from the Rhodotorula genus can accumulate large amounts of carotenoids and fatty acids in their cells. This study aimed to evaluate the potential of using cassava wastewater as a low-cost alternative substrate for the growth of Rhodotorula glutinis intended for the production of carotenoids and fatty acids. High growth of the yeast (10.28 g·L-1), as well as high productions of carotenoids (0.98 mg·L-1) and lipids (1.34 g·L-1), were obtained when Rhodotorula glutinis was cultivated in cassava wastewater as the sole source of nutrients. Moreover, the fatty acids accumulated in the yeast cells were mostly (over 50%) unsaturated, where high percentages (%) of oleic acid (59.76 ± 0.58) and linoleic acid (7.59 ± 1.18) were found when the alternative substrate was used. Results suggest that cassava wastewater presents the potential to be applied as a sole source of nutrients to support Rhodotorula glutinis growth and metabolites accumulation in its cells.

In the present work, we investigated the response to Cd in Leptodictyum riparium, a cosmopolitan moss (Bryophyta) that can accumulate higher amounts of metals than other plants, even angiosperms, with absence or slight apparent damage. High-performance liquid chromatography followed by electrospray ionization tandem mass spectrometry of extracts from L. riparium gametophytes, exposed to 0, 36 and 360 &micro, M Cd for 7 days, revealed the presence of &gamma, glutamylcysteine (&gamma, EC), reduced glutathione (GSH), and traces of phytochelatins. The increase in Cd concentrations progressively augmented reactive oxygen species levels, with activation of both antioxidant (catalase and superoxide dismutase) and detoxifying (glutathione-S-transferase) enzymes. After Cd treatment, cytosolic and vacuolar localization of thiol peptides was performed by means of the fluorescent dye monochlorobimane and subsequent observation with confocal laser scanning microscopy. The cytosolic fluorescence observed with the highest Cd concentrations was also consistent with the formation of &gamma, EC-bimane in the cytosol, possibly catalyzed by the peptidase activity of the L. riparium phytochelatin synthase. On the whole, activation of phytochelatin synthase and glutathione-S-transferase, but minimally phytochelatin synthesis, play a role to counteract Cd toxicity in L. riparium, in this manner minimizing the cellular damage caused by the metal. This study strengthens previous investigations on the L. riparium ability to efficiently hinder metal pollution, hinting at a potential use for biomonitoring and phytoremediation purposes.

Changes in the concentrations of bioactive gibberellins and abscisic acid in the cambial region of white poplar (Populus alba L.) were investigated in 1-year-old plants, to highlight how these phytohormone signals are modulated in response to water deficit. Plants were cultivated in pots outdoor and, at the time of maximum cambial growth (T 0), irrigation was withdrawn for 8 days, inducing a mild water deficit, thus mimicking a condition that is recurrent in Mediterranean climates when white poplar attains its maximum growth rate. The water deficit was suspended by resuming irrigation (T max) throughout a recovery period of 2 weeks (T rec). Cambial tissues were sampled at T 0, T max, and T rec. Significant changes of leaf and stem relative water content, leaf water potential, stomatal conductance, transpiration, carbon assimilation, stem shrinkage, and leaf number were induced by soil water shortage, which also negatively affected cambium development. Nevertheless, these responses were almost fully reversed following the resumption of irrigation. Water deficit induced the accumulation of large amounts of abscisic acid in cambial tissues, but the hormone was brought back to pre-stress levels after the recovery period. With regard to bioactive gibberellins, GA1 was several folds more abundant than GA4 and reached the greatest level in the plants recovering from the water status imbalance. The possible functions of gibberellins and abscisic acid in the response of cambial tissues to water deficit are discussed in view of the known physiological roles and molecular mechanisms of action of these hormonal signals.

The radial growth of plant stem is based on the development of cribro-vascular cambium tissues. It affects the transport efficiency of water, mineral nutrients and photoassimilates and, ultimately, also plant height. The rate of cambial cell divisions for the assembly of new xylem and phloem tissue primordia and the rate of differentiation of the primordia into mature tissues determine the amount of biomass produced and, in the case of woody species, the wood quality. These complex physiological processes proceed at a rate which depends on several factors, acting at various levels: growth regulators, resource availability and environmental factors. Several hormonal signals and, more recently, further regulatory molecules, have been shown to be involved in the induction and maintenance of cambium and the formation of secondary vascular tissues. The control of xylem cell patterning is of particular interest, because it determines the diameter of xylem ves- sels, which is central to the efficiency of water and nutrient transport from roots to leaves through the stem and may strongly influence the growth in height of the tree. Increasing scientific evidence have proved the role of other hormones in cambial cell activities and the study of the hormonal signals and their crosstalking in cambial cells may foster our understanding of the dynamics of xylo- genesis and of the mechanism of vessel size control along the stem. In this article, the role of the hormonal signals involved in the control of cambium and xylem develop- ment in trees and their crosstalking are reviewed.

The patterns of auxin concentration and metabolism were investigated in distinct kiwifruit portions and compared with the rate of fruit growth during early developmental stages. Indole-3-acetic acid (IAA) level was higher in inner fruit tissues, particularly in younger fruit, while the hormone was barely detectable in outer tissues. Modulation of free IAA concentration did not appear to depend tightly on conjugation of the hormone. Despite the lack of a strong correlation between the levels of IAA and enzymes involved in its catabolism, in some portions of the fruit a low hormone level corresponded to a higher IAA degradation activity. An inverse correlation was also observed between hormone levels and the appearance/increase in some bands with high mobility in peroxidase gel activity assay. Phenols, compounds with a potential auxin-protecting activity, appeared to be involved mostly in photoprotection of the fruit than in the regulation of IAA levels. Beyond catabolism and conjugation, other metabolic pathways, particularly those occurring in the developing seeds, may have decisively influenced auxin levels in fruit tissues, as well as the amount of the hormone exported from the fruit. The latter, estimated by analyzing the concentration of IAA in the sap exuded from the pedicel, showed a time course which was similar to that displayed by inner fruit tissues. Furthermore, similarities were found between the pattern of IAA concentration in inner fruit tissues and fruit growth rate. The possible role of IAA in promoting growth during early fruit development is discussed.

The role of strigolactones as plant growth regulators has been demonstrated through research on biosynthesis and signaling mutant plants and through the use of GR24, a synthetic analog of this class of molecules. Strigolactone mutants show a bushy phenotype and GR24 application inhibits the growth of axillary buds in these mutants, thus restoring the phenotype of a wild plant, which is characterized by a stronger apical dominance. In this work, we tested the effectiveness of this chemical on pea (Pisum sativum) plants following apex removal, which disrupts apical dominance and leads to axillary bud outgrowth. Moreover, we searched for relationships between the response to the strigolactone and gibberellin metabolism by applying GR24 to both climbing and dwarf peas, the latters being mutants for gibberellin biosynthesis. The results suggest that the endogenous level of the bioactive gibberellin GA1 might modulate the response of decapitated pea plants to GR24, by changing bud sensitivity to the applied strigolactone.

The vegetation profile and the photosynthetic efficiency, oxidative damage, and stomatal conductance in the evergreen dwarf shrub Calluna vulgaris (L.). Hull was analyzed in a Mediterranean ecosystem characterized by intense geothermal activity. Among the higher plants present in the area, this species appears to be the sole to possess the ability to grow near the geothermal sources. The hot fluid springs strongly alter the environment in their proximity: the emitted water vapor, CO2, H2S, CH4, H3BO3, SO4 2−, and NH4 + partly condensate and precipitate to the soil, thus leading to its extreme acidification and nutrient depletion. Furthermore, the temperature starts to rise sharply just a few centimeters under the soil surface. Under this multiple stress, the individuals of C. vulgaris growing within a few meters from the springs showed lower photosystem II efficiency, higher oxidative damage to the biomembranes, and lower stomatal conductance than the individuals growing farther away. Drought and high air temperatures occurring in summer exacerbate these harsh conditions, but only the plants closer to the springs did undergo an acute, yet transient crisis, as shown by the analyzed parameters. These results suggest that the main factors of stress are related to the physical and chemical features of the soil, while the adverse climate conditions apparently are of secondary importance. The possible role of reduced stomatal conductivity in enhancing the resistance of C. vulgaris to this hostile environment is discussed.

Summary • Downwardly-growing grapevine shoots have smaller and more frequent vessels than upwardly-growing ones and, as a consequence, a lower hydraulic conductivity. Here, grapevine ( Vitis vinifera L.) shoot growth orientation was manipulated to test whether downward shoot orientation negatively affects vessel growth in the apex via a shortage of water and nutrients. • The orientation of the central vine shoot portion was inverted by two consecutive 135° bends, resulting in double-bent N-shaped vines; the central downward shoot portion was of different lengths in the experimental treatments to induce increasing reductions of shoot conductivity. These treatments reduced shoot conductivity and water flow, but had no effects on vessel development and frequency in the apex. • In a second experiment, auxin concentration was assessed in shoots of upwardly- and downwardly-growing plants. IAA concentration at the apical internodes was higher in downwardly-oriented shoots than in shoots growing upwards. In addition, a higher density and a lower vessel diameter were observed in the lower, than the upper side, of the downwardly-oriented shoot, suggesting increased accumulation of auxin in the lower side. • These results suggest that the downward orientation induces accumulation of auxin in the apex, which in turn affects the density and the size of the xylem vessels, causing reduction of hydraulic conductivity.

Potato seed tubers may suffer from premature sprouting during storage, thus limiting their suitability for cultivation. Commonly used sprout suppressant treatments negatively affect but viability and therefore a reliable method to inhibit bud development must still be found for seed tubers. The monoterpene carvone ((S)-(+)-carvone) was tested in small scale experiments. The vapour of this compound fully inhibited bud growth of tubers cv. Monalisa stored at 23°C without affecting bud viability throughout 6 months of treatment. The most effective range of carvone vapour concentrations was between 0.34 and 1.06 μmol mol−1. With these qualities we can expect carvone to become a suitable sprout suppressant for seed tubers.

Summary Tubers cv. Monalisa were analysed to determine the content of abscisic acid (c-t-(+)ABA) and related metabolites in three tuber parts (eyes, sub-eye tissues and pith). Analyses were performed from the last period of tuber growth until sprouting under two different storage temperatures (3 °C and 23 °C). ABA content rises in eyes and sub-eye tissues as sprouting approaches, regardless of storage temperature. Dihydrophaseic acid is the main ABA metabolite while phaseic acid was not detected, probably because of its further metabolization to DPA. ABA-glucose ester concentrations are generally low in all tissues except in eyes before harvest. The results are discussed in relation to the current hypotheses on the role of ABA in the control of potato tuber dormancy.

Plant growth regulators are involved in the control of potato (Solanum tuberosum) tuber dormancy. Evidence concerning the role of IAA is controversial; we therefore investigated its role by analyzing two cultivars with varying lengths of dormancy. We examined the time course of free and conjugated IAA in tuber tissue isolates from the final stages of tuber growth to the end of dormancy, the distribution of free IAA in tuber tissues by in situ analysis, and the biosynthesis of the hormone by feeding experiments. The time course of free IAA showed marked differences between the examined cultivars, although the concentration of the auxin generally was the highest at the early stages of tuber dormancy. Immunodetection showed a similar pattern of IAA distribution in both genotypes: in dormant buds from freshly harvested tubers, the free hormone accumulated mostly in apical meristem, leaf and lateral bud primordia, and differentiating vascular tissues underlying the apical meristem, while at the end of the storage period only axillary bud primordia from growing buds displayed appreciable auxin levels. Feeding experiments indicated that changes in IAA biosynthesis rate were a major cause of auxin variation in buds. In both cultivars, dormancy apparently ceased when free IAA fell below a threshold value. Despite this, our data led us to conclude that IAA would not be directly responsible for inhibiting sprouting. Instead, auxin might shorten dormancy, in a cultivar-dependent manner, by enhancing early developmental processes in buds, ultimately leading to dormancy termination.

We investigated the role of auxin on stem elongation in pea (Pisum sativum L.) grown for 10d in continuous darkness or under low-irradiance blue, red, far red and white light. The third internode of treated seedlings was peeled and the tissues (epidermis and cortex+central cylinder) were separately analyzed for the concentration of free and conjugated indole-3-acetic acid (IAA). Under red, far red and white light internode elongation was linearly related with the free IAA content of all internode tissues, suggesting that phytochrome-dependent inhibition of stem growth may be mediated by a decrease of free IAA levels in pea seedlings. The correlation between IAA and internode elongation, however, did not hold for blue light-grown seedlings. The hypothesis that the growth response under low-irradiance blue light might be correlated with the lack of phytochrome B signalling and changes in gibberellin metabolism is discussed in view of current knowledge on hormonal control of stem growth.

The time course of free and conjugated indole-3-acetic acid (IAA) concentrations was investigated in three distinct parts (eyes, subeye tissues and pith) of potato (Solanum tuberosum L. cultivar Monalisa) tubers, from the last period of tuber growth to sprouting under two different storage temperatures (3 and 23˚C). The highest levels of both free and conjugated IAA were detected in eyes, which showed a significant increase of the free hormone concentration from harvest to the end of dormancy, regardless of storage temperature. The concentration of conjugates was higher than free IAA in eyes and subeye tissues at 23˚C, while at 3˚C conjugates prevailed only in eyes. Present results suggest the involvement of IAA in the control of potato tuber dormancy.