Gian Lorenzo Calzoni

In vitro germination of apple pollens

Abstract In order to characterize pollen viability and germinability by biochemical parameters, an introductory investigation was made of the germinability in vitro of pollen of 2 apple cultivars, ‘Golden Delicious’ and ‘Starkrimson’, partially self-incompatible and totally self-incompatible, respectively. Best results of percent germination were obtained for both cultivars after 120 min incubation in Petri dishes at 30°C in a medium containing 0.2 M sucrose, 20 μg/ml H 3 BO 3 , 300 μg/ml Ca(NO 3 ) 2 · 4H 2 O. Optimum pH was 6.0 for ‘Starkrimson’ and 7.0 for ‘Golden Delicious’.

Insect controlled pollination in Japanese plum (Prunus salicina Lindl.)

Abstract Trials were performed in a commercial orchard of self-incompatible plum, whose pollination and fruit yield often are a real problem in this early blooming crop. For this reason we introduced in the orchard honey bees, mason bees, and bumble bees. The efficiency of pollinator insects was evaluated in the open field by counting—for 3 h a day in five sampling areas of the orchard—the number of visits to the flowers of the main cultivar. No bumble bees were detected visiting the flowers of the main cultivar. The other two pollinators showed a foraging activity which decreases by increasing the distance from their respective starting points. In each sampling area, the total number of visits was strongly related to fruit number and total yield. No significant differences were detected regarding fruit quality. Fruit yield of the most visited areas was very close to that obtained after mechanical pollination by pollen spray. Pollination was also performed on caged trees, using the different insects separately in order to evaluate their respective efficiency.

Weak Extremely High Frequency Microwaves Affect Pollen-Tube Emergence and Growth in Kiwifruit: Pollen Grain Irradiation and Water-Mediated Effects

OBJECTIVE This study was designed to evaluate the effects of weak-intensity extremely high frequency (EHF) microwaves in a model system-the plant organism pollen grain-lacking the placebo effect, available in large populations, to ensure accurate statistical analysis, and whose sensitivity is closely relevant to animal and human biology. DESIGN This study was blinded using an in vitro pollen germination technique. SUBJECTS AND STUDY INTERVENTIONS: Pollen of kiwifruit (Actinidia deliciosa) was either directly irradiated or grown in a medium prepared with irradiated water, using a CromoStim 2000, (PromoPharma, Republic of San Marino) designed for EHF microwave resonance therapy (MRT). It produces weak intensity EHF radiations (40-78 GHz), either continuous wave (cw) or modulated, at a 10 Hz-frequency, with infrared (IR) carried to 635-950 nm, and with an impedance (IPD) of 10(-21) W/Hz cm(2) and a power supply from 0 to 20 mW. OUTCOME MEASUREMENTS Pollen-tube emergence was expressed as a percent of grains producing a tube and tube elongation was measured at 4 hours of incubation by a turbidimetric assay (A(500)) of cultures, expressed as the net absorbance increase over time 0. RESULTS At days 2 and 4 during aging, both percent of germination and tube growth significantly and consistently improved over controls in kiwifruit pollen grains irradiated for 30 minutes at day 0 at 10 Hz frequency with the CromoStim 2000. Highly significant effects, either stimulant or inhibitory, were also observed on kiwifruit pollen (stressed or not) growing in a medium prepared with water previously irradiated either cw or modulated. Irradiated water affected pollen germination immediately and even after several days following EHF treatment. CONCLUSIONS Either direct or indirect EHF irradiation performed by the CromoStim 2000 is effective on pollen growth processes. In both cases, water seemed to play a primary role. According to the quantum electrodynamical coherence theory, our work could also have implications for homeopathy, suggesting a key to explain the efficacy of high dilutions and succussion procedures.

Cytochalasin B Affects Protein Secretion in Germinating Pollen of Malus domestica Borkh.

Summary Apple pollen sensitivity to cytochalasin B was studied during germination in vitro, with consideration of the effect on tube emergence and growth, on protein release in the culture medium, and on secretion of tube wall proteins. Cytochalasin B from 0.05 to 1.0 μg ml−1 induced strong inhibition of tube elongation, whereas the pure emergence was less affected by the drug. At 0.1μg ml−1 the cytochalasin blocked protein export from 90 min germinated pollen tubes and markedly reduced 3H-proteins of the ionically-bound fraction of tube walls. The inhibition of protein secretion agrees with numerous ultrastructural observations on the cytochalasin B effect in pollen tubes or other plant systems. In the case of pollen, the ionic protein fraction of the tube wall is important for communication with the stigma or style during the progamic phase of fertilization.

Effect of methanol and gamma irradiation on enzymatic activity of apple pollen

Abstract In order to characterize devitalized pollen (which can be used as a “mentor” in mixed pollinations), certain hydrolase activities were spectrophotometrically tested in normal and in methanol or gamma irradiation-treated pollen of Malus domestica Borkh. cultivar ‘Golden Delicious’, and in normal pollen of the cultivar ‘Starkrimson’. Enzymatic activities of methanol-treated pollen were somewhat decreased, except for acid phosphatase which was enhanced over the control. This increase could be due to a higher hydrolysis rate by the alcohol, and/or to enzyme activation after damage of the lytic organelle membranes. Amylase, cellulase, ribonuclease and particularly acid phosphatase activities were stimulated in irradiated pollen. It was hypothesized that there was an enzyme leakage from the lytic compartment following pollen irradiation. On the basis of these data on enzymatic activities, it can be concluded that comparable effects were induced by either methanol or irradiation treatment of apple pollen.

Protein targeting by ubiquitin during anther and pollen development in male and female flowers of kiwifruit ( Actinidia deliciosa )

For the success of male reproductive processes, anther and pollen development are finely timed and choreographed (Koltunow et al. 1990; Scott et al. 1991). Gene expression is temporally and spatially regulated during anther development, producing highly differentiated cells and tissues responsible for non-reproductive and reproductive functions. Anther-specific mRNAs have been shown to encode a number of proteins (Goldberg et al. 1993; McCormick 1991). Multiple molecular events under tight gene control are also involved in the progression of microspores through the pollen developmental pathway (Bedinger and Edgerton 1990). Variations in the protein patterns of male gametophytes related to different stages of development have been widely demonstrated (Bedinger and Edgerton 1990; Delvallee and Dumas 1988; Hruba and Tupy 1998; Stinson et al. 1987; Tupy et al. 1983; Vergne and Dumas 1988). Therefore, the importance of protein degradation and turnover closely associated to the pathway of anther and pollen development can be hypothesized.

Effect of the Carboxylic Ionophore Monensin on the Growth and Protein Pattern of Pollen Tubes

Tip growth is a process in which the relations between structure and function, as well as between the single organelles and the cell as an integral whole are perhaps more evident than in other examples of cell morphogenesis (Sievers and Schnepfs, 1981).

In Vitro Pollen-Style Interactions in Malus Domestica

Gametophytic self-incompatibility (GSI) is an “ancient” system, perhaps acquired during early stages of the evolution of the Angiosperms (Gibbs, 1986). A very attractive general theory for the GSI mechanism has been advanced by Heslop-Harrison (1983), who proposes that, on the pistil side, S-specific glycoproteins with lectin-like properties, present in surface secretions and/or in the stylar transmitting tracts, are able to bind to specific complementary sugar sequences exhibited by components of the incompatible pollen-tube wall, leading to a disruption of apical growth. Recognition and inhibitory reaction in the Angiosperm selfincompatibility process should thus involve specific adhesion mediated by protein-carbohydrate complementation, as in many examples of cell recognition in various animal and plant systems.