Summary
Effects of simulated acid precipitation on pollination in Oenothera parviflora L. from different populations were examined both in vitro and in vivo. The responses of pollen to acidity (pH 5.6 to 2.6) in standing drop cultures and the stigma receptivity of flowers under field simulations of acid rain were observed. The response of pollen in vitro indicated significant inhibitory effects of pH, and demonstrated that pH values ≤ 3.6 were inhibitory to both germination and tube growth, when compared with the treatment of pH 5.6. Dosages of LD50 for in vitro pollen germination, taken as the initial pH of cultures for the different pollens, ranged from pH 3.49 to 3.72. Stigma receptivity assessed by germination and initial tube growth on the stigmatic surface also declined significantly (P < 0.01) in response to acid rain simulation prior to hand pollinations. Again simulants ≤ pH 3.6 significantly reduced stigma receptivity compared with the treatment at pH 5.6. Here LD 50, dosages, taken as the pH of the simulant, were pH 3.45 and 4.66 for the failure of potentially viable pollen to germinate, or produce tubes three times the length of the grain, respectively. These results are discussed in relation to rain chemistry in Southern Ontario, Canada.

https://nph.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1469-8137.1984.tb04109.x

Sensitivity of forest plant reproduction to long range transported air pollutants: in vitro and in vivo sensitivity of oenothera parviflora l. pollen to simulated acid rain

The structure of stigma — style tissues in kiwifruit (Actinidia chinensis Planch. cv. ‘Hayward’) flowers was examined before, and after, hand-pollination and the course of pollen tube development was followed. At the time of flower opening the style had a well defined canal which opened at its distal end to form a V-shaped stigmatic furrow. The surface of the furrow was covered with unicellular papillae. The exposed wall of each papilla was covered with a cuticle and a distinct pellicle. The papillae were supported by a layer of hypodermal cells and an extensive layer of thin-walled transmitting cells. The transmitting tissue extended from the tip of the style through the stylar canal to its junction with the ovary. A single vascular strand, which extended along the length of the style adjacent to the stylar canal, branched into the stylar parenchyma on each side of the V-shaped furrow. Pollen grains germinated on the stigmatic papillae and grew through the intercellular spaces of the transmittin...

https://www.tandfonline.com/doi/pdf/10.1080/0028825X.1979.10426897

Pollination of kiwifruit (Actinidia chinensis Planch.): Stigma-style structure and pollen tube growth

Genetically controlled incompatibility systems in the homomorphic angiosperms fall into two categories: (i) gametophytic and (ii) sporophytic (Lewis 1954; Crowe 1964; Williams 1964). The two systems differ basically in the control of the incompatibility reaction of the pollen, whether it is determined by the genotype of the pollen-grain (hence gametophytic), or it is imposed by parental genotype (hence sporophytic) and consequently all the pollen from a given plant show the same reaction irrespective of their genotype. Furthermore, some characteristics seem to be intimately or rather fundamentally linked with the two systems (Brewbaker 1957, 1959; Pandey 1960; Lundqvist, Osterbye, Larsen & Linde-Laursen 1973), particularly cytology of pollen at dehiscence, site of inhibition of incompatible pollen and the allelic interactions in the style (table 1). Such characteristics help in the inference of the system; although Pandey (1960) has pointed out three exceptions to these broad correlations, the uniformity of the system within families with homomorphic incompatibility still holds. In the family Cruciferae, Bateman (1954, 1955) not only invoked a 1-locus sporophytic system for the SI Iberis amara but also made a reinterpretation of the earlier data in the three crucifers accommodating them in the Iberis scheme. Later workers have confirmed the uniformity of the sporophytic system in the family Cruciferae (Sampson 1957 a , b , 1964; Thompson 1957; Haruta 1962). However, the only report contradictory to Bateman’s generalization of the Crucifer system is that of Narsingdas (see Singh 1958) in Eruca sativa (an oleiferous crop) wherein he explained his results on the gametophytic system (cf. Kakizaki 1930). This prompted a reinvestigation of E. sativa in order to determine the nature and genetics of the system involved. To our surprise, the intrafamilial pollinations of F1 families revealed very abnormal data (Barjinder 1968) and the confirmation of the genetic interpretation invoked necessitated detailed analyses of F2 families (Indra 1970), which, in turn, made it imperative to pursue the case to F3 families involving larger numbers of plants in each family. This communication is intended to present the data, particularly of F2 and F3 families worked out by Miss Indra Dhir and Miss Renuka Malik respectively, and to interpret the same regarding the nature of the incompatibility system. The hypothesis has been tested in two F4 families derived from selfings of individuals from two F3 families. A new model proposed by D. Lewis, based on more than two loci with sporophytic control has been adopted, and at least two loci are analogous to the S and Z loci in grasses (Lundqvist 1956). The details of the genetics of the proposed model are presented in the following paper by Lewis (1976).

Genetics of the incompatibility system in the crucifer Eruca sativa L

After germination, pollen grains of Lilium longiflorum became very sensitive to short periods of heat stress as shown by the greatly reduced germination percentages upon subsequent incubation at the optimal temperature. Addition of proline to the incubation medium made pollen more resistant to heat. It was demonstrated that in a short time a large amount of proline was taken up by the cell. Germination and metabolic functions were completely or partially protected from heat damage by proline treatment. As well, it was shown that proline treatment at least partially protected pollen grains from cold stress. These results suggest that the high proline concentrations found in pollen of many species may confer resistance to germinating pollen grains at unfavourable temperatures thereby enhancing the chances of successful fertilization.

Protection of pollen germination from adverse temperatures: a possible role for proline

(1972). Staining Pollen Tubes in the Styles of Cereals with Cotton Blue; Fixation by Ethanol-Lactic Acid for Enhanced Differentiation. Stain Technology: Vol. 47, No. 2, pp. 107-108.

Staining pollen tubes in the styles of cereals with cotton blue; fixation by ethanol-lactic acid for enhanced differentiation.

Pollen tubes passing through the style are fixed in acetic-alcohol (1 : 1) at 60 C for 30 min; softened by boiling in water 5–30 min; cleared in lactic acid at 60 C, 30 min; stained in lactophenol-cotton blue (1%) at 60 C, 15–30 min; and mounted in lactic acid. This procedure was found to be more generally applicable to angiosperms than carmine, applied in propionic-lactic acid mixtures. It has been tested on 36 species, including 4 monocotyledons and 32 dicotyledons.

Anita Naug

Papers

Staining Pollen Tubes in the Style; Cotton Blue versus Carmine for General Use