Incompatibility, stamen movement and pollen economy in a heterostyled tropical forest tree, Cratoxylum formosum (Guttiferae)

1982 ◽  
Vol 214 (1195) ◽  
pp. 273-283 ◽  
Keyword(s):  
Critical Level ◽  
Pollen Grains ◽  
Forest Tree ◽  
Incompatible Pollen ◽  
Insect Visitation ◽  
Small Pollen ◽  
Evolutionary Step ◽  
Novel Method ◽  
Compatible Pollinations ◽  
Compatible Pollen

Cratoxylum formosum shows all the classical features of a distylic species. The two types are: long-styled plants with short stamens and small pollen grains and short-styled plants with long stamens and large pollen grains. Compatible pollinations are only between the two types; incompatible pollen tubes are inhibited in the style. A significant morphological feature distinguishes Cratoxylum from distylic plants in other families. Instead of having a small number of anthers making well separated narrow discs in the two types, Cratoxylum has many anthers (144) and they are arranged on staminal bundles that produce long cylinders of anthers that partially occupy similar height zones in the two types of flower. A novel method of separation of the two height zones is achieved by the bending of the stamens of the long-styled type when the flower opens, which converts the cylinder to a narrow disc of anthers at the same height as the ‘short’ stigma. The bending coincides with anther dehiscence and is slightly later than the first daily insect visitation. The anthers return to the upright position later in the day, when the pollination is complete. There was a 20-fold difference between the amounts of pollen deposited on the two types of stigmas. The ‘long’ stigmas received 1200 pollen grains per flower, in the ratio of 46 ‘long’ to 54 ‘short’, which is close to the ratio of two types of pollen produced in the population. This random deposition of pollen on ‘long’ stigmas is, however, more than adequate for the 36 seeds produced per flower. ‘Short’ stigmas received only 64 pollen grains per flower, in the ratio of 90 ‘long’ to 10 ‘short’, and several flowers had below the critical level of 36 compatible pollen grains for full seed production. Pollen loads of the pollinating bee, Apis javana , consisted of ‘long’ and ‘short’ pollen on the thorax in the ratio found on the ‘long’ stigma, and on the head of the bee in a ratio close to the 9:1 found on the ‘short ’ stigma. The corbicular loads reflected accurately the pollen of the tree in which the bee was caught. For Cratoxylum the accurate positioning of the anthers of the long-styled plant in relation to the visiting bees head was an important evolutionary step in the effective pollination of the short-styled form, which, at least in this species, is one critical and highly selected feature of the system.

The effect of pollination intensity and incompatible pollen on seed set in Turnera ulmifolia (Turneraceae)

1984 ◽  
Vol 62 (6) ◽  
pp. 1298-1303 ◽  
Author(s):  
Joel S. Shore ◽  
Spencer C. H. Barrett
Keyword(s):  
Regression Analysis ◽  
Seed Set ◽  
Pollen Grains ◽  
The Self ◽  
Time Intervals ◽  
Pollination Experiments ◽  
Controlled Pollination ◽  
Incompatible Pollen ◽  
Turnera Ulmifolia ◽  
Compatible Pollen

Controlled pollination experiments were performed on the self-incompatible distylous herb Turnera ulmifolia L. to investigate the effects of pollination intensity and large amounts of incompatible pollen on seed set. In the first experiment, known numbers of compatible pollen grains ranging from 1 to 100 were applied to stigmas of the floral morphs. In both morphs, increasing amounts of pollen generally resulted in increased levels of seed set, although considerable variance was observed at all pollination intensities. Approximately two to seven pollen grains are required to produce a single seed and more than 95 grains are required to achieve maximum seed set in T. ulmifolia. Regression analysis of the seed set data failed to detect a difference in the response of the floral morphs to pollination intensity. In the second experiment, known proportions of compatible and incompatible pollen were applied to stigmas at various time intervals. Most treatments involving mixtures of compatible and incompatible pollen had no significant effect on seed set when compared with the controls. Clogging was only observed in the long-styled morph when one anther of compatible pollen was applied to stigmas 1.5 and 3.0 h after pollination with five anthers of incompatible pollen. The clogging of stigmas by incompatible pollen seems unlikely to have played a major role in the evolution and maintenance of distyly in Turnera ulmifolia.

ENHANCEMENT OF POLLEN GERMINATION BY PROMOTIVE FACTORS IN INCOMPATIBLE POLLEN

1999 ◽  
Vol 47 (3) ◽  
pp. 165-168
Author(s):  
Dan Eisikowitch ◽  
Hazel Y. Wetzstein
Keyword(s):  
Pollen Grains ◽  
Commercial Production ◽  
In Vitro Assays ◽  
Viable Seed ◽  
Inhibitory Effects ◽  
Incompatible Pollen ◽  
Elemental Analyses ◽  
Compatible Pollen ◽  
Selection Of

Cultivated and wild almonds are self-incompatible and thus require outcrossing by insect pollinators to produce viable seed. In commercial production, considerable efforts are directed towards placement and selection of cultivars for cross-pollination. However, since honeybees do not distinguish between the different cultivars, stigmas are usually covered by a mixture of both compatible and incompatible pollen. Using in vitro assays, we demonstrated that pollen extracts promoted germination in self pollen with no inhibitory effects observed. Elemental analyses of pollen extracts showed that enhanced levels of Ca, Mg, K, Na, and P were eluted from the grains. From this, we raise the question of possible interaction between compatible and incompatible pollen, and speculate that incompatible pollen grains may support and enhance germination of adjacent compatible pollen.

Virola dominicana sp. nov. (Myristicaceae) from Dominican amber

Botany ◽  
2013 ◽  
Vol 91 (8) ◽  
pp. 530-534 ◽  
Author(s):  
George Poinar ◽  
Royce Steeves
Keyword(s):  
New Species ◽  
Intraspecific Variation ◽  
Pollen Grains ◽  
First Record ◽  
Western Hemisphere ◽  
Dominican Amber ◽  
The Family ◽  
Small Pollen ◽  
Male Flowers ◽  
Staminal Column

The Myristicaceae is a member of the early diverging angiosperm order Magnoliales; however, the family is poorly represented by fossil collections. We describe Virola dominicana sp. nov. (Myristicaceae), the first record of fossilized Myristicaceae flowers, from mid-Tertiary (45–15 million years ago) Dominican amber. The description is based on 24 male flowers in 17 pieces of amber, thus providing some indication of intraspecific variation, including a two-tepaled flower. Diagnostic characters of the new species are the long-simple or few-branched trichomes on the perianth margins, the small pollen grains, and a short staminal column. These fossils also show co-occurring insects, some of which could be Virola pollinators. It is speculated that V. dominicana disappeared from Hispaniola during the Pliocene–Pleistocene cooling events leaving no native members of the Myristicaceae in this region today. Additionally, these fossils demonstrate that Myristicaceae was present in the Western Hemisphere during the mid-Tertiary.

The formation of the tryphine coating the pollen grains of Raphanus , and its properties relating to the self-incompatibility system

1973 ◽  
Vol 184 (1075) ◽  
pp. 149-165 ◽  
Keyword(s):  
Granular Material ◽  
Pollen Grains ◽  
The Self ◽  
Self Incompatibility ◽  
Pollen Maturation ◽  
Incompatible Pollen ◽  
Incompatibility System ◽  
Two Stages ◽  
Stimulation Of ◽  
Incompatible Pollen Tube

The tryphine that coats the pollen grains of Raphanus is tapetally synthesized and is composed of a fibro-granular and a lipidic component. The fibro-granular material is proteinaceous and is secreted by cisternae of the endoplasmic reticulum. The lipidic component is derived, mainly, from degraded elaioplasts. The fibro-granular material is applied to the pollen exine first, followed by the lipidic mass. The tryphine condenses during the final stages of pollen maturation and dries down to form a thick, highly viscous coating. The major part of the condensation appears to result from dehydration. The tryphine, extracted from the pollen by a centrifugal method and mounted in a membrane, appears to be capable of penetrating the outer layers of a stigma of the same species and, if the pollen from which it was derived is incompatible with respect to the stigma, the stimulation of the production of the callosic reaction body in a manner similar to an incompatible pollen tube. It is proposed that, in Raphanus , substances responsible for the initiation of at least two stages in the self-incompatibility system are held in the tryphine.

scholarly journals Two groups of Arabidopsis receptor kinases preferentially regulate the growth of intraspecies pollen tubes in the female reproductive tract

2020 ◽  
Author(s):  
Hyun Kyung Lee ◽  
Daphne R. Goring
Keyword(s):  
Pollen Tube ◽  
Reproductive Tract ◽  
Cell Communication ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Female Reproductive Tract ◽  
Wild Type ◽  
Knockout Mutant ◽  
Receptor Kinases ◽  
Compatible Pollen

SummaryIn flowering plants, continuous cell-cell communication between the compatible male pollen grain/growing pollen tube and the female pistil is required for successful sexual reproduction. In Arabidopsis thaliana, the later stages of this dialogue are mediated by several peptide ligands and receptor kinases that guide pollen tubes to the ovules for the release of sperm cells. Despite a detailed understanding of these processes, a key gap remains on the nature of the regulators that function at the earlier stages. Here, we report on two groups of A. thaliana receptor kinases, the LRR-VIII-2 RK subclass and the SERKs, that function in the female reproductive tract to regulate the compatible pollen grains and early pollen tube growth, both essential steps for the downstream processes leading to fertilization. Multiple A. thaliana LRR-VIII-2 RK and SERK knockout mutant combinations were created, and several phenotypes were observed such as reduced wild-type pollen hydration and reduced pollen tube travel distances. As these mutant pistils displayed a wild-type morphology, the observed altered responses of the wild-type pollen are proposed to result from the loss of these receptor kinases leading to an impaired pollen-pistil dialogue at these early stages. Furthermore, using pollen from related Brassicaceae species, we also discovered that these receptor kinases are required in the female reproductive tract to establish a reproductive barrier to interspecies pollen. Thus, we propose that the LRR-VIII-2 RKs and the SERKs play a dual role in the preferential selection and promotion of intraspecies pollen over interspecies pollen.

Ultrastructural Aspects of the Self-Incompatibility Mechanism in Lycopersicum Peruvianum Mill

1973 ◽  
Vol 12 (2) ◽  
pp. 403-419 ◽  
Author(s):  
D. DE NETTANCOURT ◽  
M. DEVREUX ◽  
A. BOZZINI ◽  
M. CRESTI ◽  
E. PACINI ◽  
...  
Keyword(s):  
Pollen Tube ◽  
Tube Wall ◽  
Degradation Mechanism ◽  
Embryo Sac ◽  
Pollen Tubes ◽  
Self Incompatibility ◽  
Weak Reaction ◽  
General Hypothesis ◽  
Incompatible Pollen ◽  
Compatible Pollen

The experimental results obtained show that the tip of the incompatible pollen tube bursts open after the outer-wall has considerably expanded in the intercellular spaces of the conducting tissue and the inner-wall has disappeared and numerous particles have accumulated in the tube cytoplasm. These particles, which measure approximately 0.2 µm in diameter and give a weak reaction to the test of Thiéry, differ in many respects from the vesicles normally present in compatible pollen tubes growing through the style; they appear to resemble, in some cases, the spheres which are discharged by the compatible pollen tubes after they have reached the embryo-sac. It is considered that these observations support the current belief that the tube wall is the site of action for the incompatibility proteins and suggest that self-incompatibility is not a passive process resulting from lack of growth stimulation but an active event which leads to the destruction of the incompatible pollen tubes. The degradation mechanism involved appears similar to the one which enables the compatible pollen tube to release its contents in the degenerated synergid and presents some analogies with the lytic process taking place in virus-infected cells. The general hypothesis is presented that the particles observed in the cytoplasm of self-incompatible pollen tubes consist of a mixture of incompatibility proteins and of basic constituents of the tube wall.

scholarly journals Breeding biology and distyly in Palicourea rigida H. B. & K. (Rubiaceae) in the Cerrados of Central Brazil

2010 ◽  
Vol 24 (3) ◽  
pp. 686-696 ◽  
Author(s):  
Adriana de Oliveira Machado ◽  
Ana Palmira Silva ◽  
Helder Consolaro ◽  
Mariluza A. Granja e Barros ◽  
Paulo Eugênio Oliveira
Keyword(s):  
Reproductive Success ◽  
Fruit Set ◽  
Pollen Grains ◽  
Floral Biology ◽  
Nectar Production ◽  
Central Brazil ◽  
Palicourea Rigida ◽  
Floral Visitors ◽  
Compatible Pollen ◽  
Incompatibility Reactions

Distyly is a floral polymorphism more common among the Rubiaceae than in any other angiosperm group. Palicourea rigida is a typically distylous species of the Rubiaceae widely distributed in the Brazilian Cerrados. This work aimed to study the floral biology and breeding system of P. rigida in order to verify if there wasasymmetry between floral morphs. The work was carried out at Fazenda Água Limpa, Brasília-DF, from 1993 to 1995; and at Serra Caldas Novas State Park-Goias and in Clube Caça e Pesca Itororó de Uberlândia-Minas Gerais in 2005 and 2006. Density, height and pin/thrum ratio were assessed for flowering individuals in all areas. Plants were investigated for differences in floral morphology, nectar production, reproductive success and site of self incompatibility reactions. Blooming period was long and concentrated during the rains. Flowers were clearly distylous and with reciprocal herkogamy. They produced nectar and lasted for a single day. In spite of differences in density and height, populations were mostly isoplethic. Nectar production varied in volume and concentration but the differences could not be associated with floral morphs. The species is self-incompatible but reproductive success was always high and independent of floral morphs. There were differences in the site of incompatibility barriers between floral morphs, which were similar to those observed for other Rubiaceae. The main floral visitors and pollinators were the hummingbirds Colibri serrirostris and Eupetomena macroura. High fruit-set indicates that the pollinators transported enough compatible pollen grains between floral morphs, despite their territorial behavior.

scholarly journals The Genetical Control of Incompatibility in Phalaris Coerulescens Desf.

1956 ◽  
Vol 9 (3) ◽  
pp. 321 ◽  
Author(s):  
DL Hayman
Keyword(s):  
Day Treatment ◽  
Pollen Grains ◽  
Pollen Tubes ◽  
Multiple Alleles ◽  
Incompatible Pollen ◽  
Genetical Control

Pha/a1'is roau/c8CeJ18 Des!'. is a completely Relf-incompatible, diploid, perennial gmss. incompatible pollen gmins germinate normally but the pollen tubes fail to penetrate far into tho 8Lyle. The ineompatibility interrelationships of parents and progenios were dotermined by olmen-ing the pollen tubes and pollen grains after pollination. This eould be clone successfully only in plants induced to Hower early by eXJlosure to 100tg day treatment. Incompatibility is controlled by two loci, each with a series of multiple alleles. The loci are probably not linked but the data would not. allow detection of loose linlmge. Pollen determination is gametophytic, and the genes aet indepoudelltly in the style. 'eho rolationship of this incompatihility system to previously described systems is eonsid(lred, and theoretically possible incompatihility systems based on genetical eOlltrol nt. two loci are suggested.

Pollen viability and germination in some neotropical aroids

Botany ◽  
2008 ◽  
Vol 86 (1) ◽  
pp. 98-102 ◽  
Author(s):  
Denis Barabé ◽  
Karine Lavallée ◽  
Marc Gibernau
Keyword(s):  
Pollen Viability ◽  
Pollen Grains ◽  
Total Loss ◽  
Small Pollen

Pollen viability and germination were observed in six species of neotropical Araceae. In Anaphyllopsis americana (Engl.) A. Hay, 50% of pollen grains remain viable after 70 h following dehiscence, and it takes over 210 h for total loss of viability to occur. In Montrichardia arborescens (L.) Schott, approximately 50% of pollen grains are not viable after 24 h, and no germination occurs after 36 h. Monstera adansonii Schott and Philodendron pedatum (Hook.) Kunth have the lowest initial pollen viability (40%–55%) and lose half of this viability after approximately 30 h. Pollen grains of Monstera adansonii remain viable for at least 60 h and that of P. pedatum for approximately 40 h, and constitute another group with a similar viability pattern. In Philodendron melinonii Brongn. ex Regel and Philodendron solimoesense A.C. Sm., pollen loses 50% of its viability after 24 h, but remains viable for at least 48 h. The percentage of viability decreases in a pattern from species having a long flowering cycle and small pollen grains (A. americana) to species with a short flowering cycle and large pollen grains (M. arborescens).

scholarly journals Hormonal Changes after Compatible and Incompatible Pollination in Theobroma cacao L.

HortScience ◽  
1997 ◽  
Vol 32 (7) ◽  
pp. 1231-1234 ◽  
Author(s):  
R. Paul Baker ◽  
Karl H. Hasenstein ◽  
Michael S. Zavada
Keyword(s):  
Pollen Tube ◽  
Theobroma Cacao ◽  
Hormonal Changes ◽  
Ethylene Evolution ◽  
Incompatible Pollen ◽  
Incompatibility System ◽  
Incompatible Pollination ◽  
Compatible Pollinations ◽  
Indole 3 Acetic Acid ◽  
Theobroma Cacao L

In order to characterize the self-incompatibility system in Theobroma cacao, the levels of ethylene, indole-3-acetic acid (IAA), and abscisic acid (ABA) were determined after pollination with compatible and incompatible pollen and in unpollinated flowers. Pollen tube growth rates after incompatible and compatible pollinations were identical, and the majority of the pollen tubes reached the ovules between 12 and 20 hours after pollination. ABA levels rose in incompatibly pollinated flowers, and fell in compatibly pollinated flowers, prior to pollen tube—ovule contact. Ethylene evolution remained stable in compatibly pollinated flowers and rose in incompatibly pollinated flowers. IAA concentrations increased in compatibly pollinated flowers, and remained stable in incompatibly pollinated flowers after pollination and subsequent to pollen tube—ovule contact.

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