Bruno Romano

The influence of air temperature on the starting dates of the pollen season of alnus and populus

Abstract In this work we have studied the influence of air temperature on the starting dates of Alnus and Populus pollination in two different climatic regions in Europe: central Italy and The Netherlands. The start of the Alnus pollen season varied between 27th January and 16th February in the Italian stations while in The Netherlands it showed an average delay of about one month. For Populus the beginning of the pollen season was delayed on an average 15 days at Dutch places compared to central Italy. In the former it varied between 14th March and 21st April while in the latter between 28th February and 24th March. Significant correlations exist between the beginning of pollination for these taxa and temperature conditions in the preceding periods. The highest correlations found were with daily mean decade temperature for three decades before the average starting dates of the pollen season. These correlations were better for The Netherlands than for central Italy perhaps because the temperature in Holla...

Ozone and nitric oxide induce cGMP‐dependent and ‐independent transcription of defence genes in tobacco

Here, we analyse the temporal signatures of ozone (O3)-induced hydrogen peroxide(H2O2) and nitric oxide (NO) and the role of the second messenger guanosine3′,5′-cyclic monophosphate (cGMP) in transcriptional changes of genes diagnostic for biotic and abiotic stress responses. Within 90 min O3 induced H2O2 and NO peaks and we demonstrate that NO donors cause rapid H2O2 accumulation in tobacco (Nicotiana tabacum) leaf. Ozone also causes highly significant, late (> 2 h) and sustained cGMP increases, suggesting that the second messenger may not be required in all early (< 2 h) responses to O3,but is essential and sufficient for the induction of some O3-dependent pathways.This hypothesis was tested resolving the time course of O3-induced transcript accumulation of alternative oxidase (AOX1a), glutathione peroxidase (GPX),aminocyclopropancarboxylic acid synthase (ACS2) that is critical for the synthesis of ethylene, phenylalanine ammonia lyase (PALa) and the pathogenesis-related protein PR1a.The data show that early O3 and NO caused transcriptional activation of the scavenger encoding proteins AOX1a, GPX and the induction of ethylene production through ACS2 are cGMP independent. By contrast, the early response of PALa and the late response of PR1a show critical dependence on cGMP.

A predictive study on the beginning of the pollen season for Gramineae andolea europaea L.

SummaryOn the basis of the results of seven years (1982–1988) of pollen and meteorological monitoring in the atmosphere of Perugia and Ascoli Piceno (central Italy) beginning of pollen season forecasts for Gramineae and Olea europaea L. are reported. The beginning of the pollen season for grass varied between May 2 nd and May 27th while for Olea it varied between May 26 th and June 23rd. By a statistical analysis of these data several significant correlations were found between the onset of the principal period of pollination and the air temperature in the preceding months and the number of «heat units» required to flower. Utilizing multiple regressions a predictive method of the beginning of pollen season for both the taxa is reported.

NO release by nitric oxide donors in vitro and in planta

Artificial nitric oxide (NO) donors are widely used as tools to study the role of NO in plants. However, reliable and reproducible characterisation of metabolic responses induced by different NO donors is complicated by the variability of their NO release characteristics. The latter are affected by different physical and biological factors including temperature and light. Here we critically evaluate NO release characteristics of the donors sodium nitroprusside (SNP), S-nitrosoglutathione (GSNO) and nitric oxide synthase (NOS), both in vitro and in planta (Nicotiana tabacum L. cv. BelW3) and assess their effects on NO dependent processes such as the transcriptional regulation of the mitochondrial alternative oxidase gene (AOX1a), accumulation of H(2)O(2) and induction of cell death. We demonstrate that, contrary to NOS and SNP, GSNO is not an efficient NO generator in leaf tissue. Furthermore, spectrophotometric measurement of NO with a haemoglobin assay, rather than diaminofluorescein (DAF-FM) based detection, is best suited for the quantification of tissue NO. In spite of the different NO release signatures by SNP and NOS in tissue, the NO dependent responses examined were similar, suggesting that there is a critical threshold for the NO response.

Comparative study of airborne pollen concentrations in central Italy and the Netherlands (1982–1985)

Abstract Airborne pollen concentrations, measured continuously with a volumetric method at two places in central Italy and in The Netherlands, are compared with respect to both their quantitative and seasonal aspects. Special attention was given to three taxa which occur in the two geographically distinct regions and are known to cause allergic sensitization: Alnus (alder), Poaceae (wild grasses), and Artemisia (mugwort). Averagely, total pollen concentrations are slightly higher in central Italy. The start and the main period in early spring of the season of Alnus pollen, which is more common in The Netherlands, is rather variable from year to year, in both regions correlated with the air temperature in the preceding months. Poaceae pollen, making up to 10 to 20% of the total annual pollen concentrations in both regions, has its start and main season in late spring about one month earlier in central Italy than in The Netherlands, strongly correlated with air temperatures in April and May. The main period...

Aeropalynological and phenological study in two different Mediterranean olive areas: Cordoba (Spain) and Perugia (Italy)

ABSTRACT An aerobiological and phenological investigation on the olive tree was carried out during three years in two areas: Cordoba (Spain) and Perugia (Italy). In these countries, this species is economically important and those areas were chosen because of the long series of aeropalynological data (1982–1998) available, obtained by means of identical volumetric pollen traps. The aim of this study was to use phenological observations to prove the real contribution to the pollen curves in different cultivated areas. Results show that in Cordoba province (302.152 ha) the pollen curve is characterised by different peaks because of the pollination of different cultivated crops. In some cases, these crops are located far from the pollen trap (50 km) but pollen is transported thanks to favourable winds during the flowering period. In Perugia (750 ha) the pollen curve is characterised by only one peak; it is very concentrated because of the proximity of the investigated crops. The objective of this research was to obtain information on this species in order to elaborate statistical models aimed at forecasting the potential fruit production based on the amount of pollen released into the atmosphere.

A regression model for the start of the pollen season in Olea eropaea

The relationship between the timing of olive pollination and some parameters which can influence this phenomenon was investigated. A model is presented which shows a strong relationship between timing of pollination, selected meteorological variables (temperature and precipitation) and annual pollen quantity. The most important correlations are with mean temperature in February, and precipitation in May. The positive correlation with annual pollen quantity confirms the relationship of this variable to the time of pollination.

Apospory and parthenogenesis may be uncoupled in Poa pratensis: a cytological investigation

Despite the potential that apomixis has for agriculture, there is little information regarding the genetic control of its functional components. We carried out a cytohistological investigation on an F1 segregating population of Poa pratensis obtained from a cross between a sexual and an apomictic parent. About half of the F1 progeny plants were parthenogenic, as adjudicated by an auxin test. The degree of parthenogenesis ranged from 1.44% to 92.9%. Apospory was detected in parthenogenetic plants as well as in two non-parthenogenetic individuals. These results indicate that two distinct genetic factors control apospory and parthenogenesis in P. pratensis and that apospory and parthenogenesis may be developmentally uncoupled

Patterns of cell division and expansion in developing petals of Petunia hybrida

Abstract. The definition of the patterns of cell division and expansion in plant development is of fundamental importance in understanding the mechanics of morphogenesis. By studying cell division and expansion patterns, we have assembled a developmental map of Petunia hybrida petals. Cycling cells were labelled with in situ markers of the cell cycle, whereas cell expansion was followed by assessing cell size in representative regions of developing petals. The outlined cell division and expansion patterns were related to organ asymmetry. Initially, cell divisions are uniformly distributed throughout the petal and decline gradually, starting from the basal part, to form a striking gradient of acropetal polarity. Cell areas, in contrast, increased first in the basal portion and then gradually towards the petal tip. This growth strategy highlighted a cell size control model based on cell-cycle departure time. The dorso-ventral asymmetry can be explained in terms of differential regulation of cell expansion. Cells of the abaxial epidermis enlarged earlier to a higher final extent than those of the adaxial epidermis. Epidermal appendage differentiation contributed to the remaining asymmetry. On the whole our study provides a sound basis for mutant analyses and to investigate the impact of specific (environmental) factors on petal growth.

Reproductive biology of Olive (Olea europaea L.) DOP Umbria cultivars

Olive trees have a plentiful bloom but a low percentage of normal fruit set. To improve fruit set, numerous investigations have sought to identify the obstacles that prevent full production. In this work, flower development in five DOP Umbria cultivars (Leccino, Frantoio, Moraiolo, Dolce Agogia and San Felice) was studied throughout different developmental phases, from before microsporogenesis and megasporogenesis to post-anthesis, by morphological and cyto-histological observations. Dolce Agogia was the most precocious cultivar, while full flowering was simultaneous in Leccino, Frantoio, Moraiolo and San Felice. Frantoio and Leccino were also good pollen producers, having the highest percentage of pollen viability and germinability. Dolce Agogia can also be considered a good pollen producer in terms of the high quantity of released pollen, but it had the lowest levels of pollen viability and germinability and the highest percentage of aborted flowers and ovaries. Morphological and cyto-histological observations on the number of flowers per inflorescence and the number of aborted flowers and ovaries suggest that fruit set was not influenced by the number of flowers per inflorescence, but rather by the number of inflorescences, which depends on the global fruiting potential of the tree.