scholarly journals Distance Dependent Contribution of Ants to Pollination but Not Defense in a Dioecious, Ambophilous Gymnosperm

2021 ◽  
Vol 12 ◽  
Author(s):  
Adriana Aranda-Rickert ◽  
Javier Torréns ◽  
Natalia I. Yela ◽  
María Magdalena Brizuela ◽  
Verónica S. Di Stilio
Keyword(s):  
Plant Defense ◽  
Field Experiments ◽  
Seed Set ◽  
Airborne Pollen ◽  
Pollen Viability ◽  
Pollen Flow ◽  
Wind Pollination ◽  
Dioecious Plants ◽  
Relative Contribution ◽  
Seed Cone

Dioecious plants are obligate outcrossers with separate male and female individuals, which can result in decreased seed set with increasing distance between the sexes. Wind pollination is a common correlate of dioecy, yet combined wind and insect pollination (ambophily) could be advantageous in compensating for decreased pollen flow to isolated females. Dioecious, ambophilous gymnosperms Ephedra (Gnetales) secrete pollination drops (PDs) in female cones that capture airborne pollen and attract ants that feed on them. Plant sugary secretions commonly reward ants in exchange for indirect plant defense against herbivores, and more rarely for pollination. We conducted field experiments to investigate whether ants are pollinators and/or plant defenders of South American Ephedra triandra, and whether their contribution to seed set and seed cone protection varies with distance between female and male plants. We quantified pollen flow in the wind and assessed the effectiveness of ants as pollinators by investigating their relative contribution to seed set, and their visitation rate in female plants at increasing distance from the nearest male. Ants accounted for most insect visits to female cones of E. triandra, where they consumed PDs, and pollen load was larger on bigger ants without reduction in pollen viability. While wind pollination was the main contributor to seed set overall, the relative contribution of ants was distance dependent. Ant contribution to seed set was not significant at shorter distances, yet at the farthest distance from the nearest male (23 m), where 20 times less pollen reached females, ants enhanced seed set by 30% compared to plants depending solely on wind pollination. We found no evidence that ants contribute to plant defense by preventing seed cone damage. Our results suggest that, despite their short-range movements, ants can offset pollen limitation in isolated females of wind-pollinated plants with separate sexes. We propose that ants enhance plant reproductive success via targeted delivery of airborne pollen, through frequent contact with ovule tips while consuming PDs. Our study constitutes the first experimental quantification of distance-dependent contribution of ants to pollination and provides a working hypothesis for ambophily in other dioecious plants lacking pollinator reward in male plants.

scholarly journals Three options are better than two: compensatory nature of different pollination modes in Salix caprea L.

2021 ◽  
Vol 28 ◽  
pp. 75-89
Author(s):  
Kaz Ohashi ◽  
Andreas Jürgens
Keyword(s):  
Seed Set ◽  
Pollen Limitation ◽  
Pollen Viability ◽  
The Other ◽  
Wind Pollination ◽  
Cold Night ◽  
Flower Opening ◽  
Mate Availability ◽  
Salix Caprea ◽  
Moth Pollination

Mixed pollination systems have been reported for many angiosperms. Here, we report on a dioecious willow, Salix caprea L., which employs three pollination modes, namely pollination by wind, nocturnal moths, and diurnal bees. In four field populations of S. caprea in Germany, we addressed the following questions: (a) How are the pollination modes affected by local mate availability? (b) What is the contribution of each pollination mode to seed set? (c) How does flower opening time affect pollination? We compared seed set among seven pollination treatments (wind pollination, diurnal pollination, nocturnal pollination, natural pollination, apomictic reproduction, daytime/night-time artificial pollination). Pollen limitation was observed across populations. On the other hand, limitations in mate availability affected the pollination modes differently. Insect pollination outperformed wind pollination in situations where nearby males were few or all positioned in the same direction from the females. The contribution of nocturnal moths was lower than that of the other pollen vectors. However, moth pollination worked complementarily with bee pollination in compensating for the lack of wind pollination. Furthermore, we found that the onset of flower anthesis peaked at sunset, and that cold night temperatures had no negative effect on seed set or pollen viability. Thus, nocturnal anthesis and prior pollination by moths may minimize male fitness loss due to pollen collection and grooming by bees. We suggest that S. caprea maximizes its fitness by combining multiple pollination modes that work in different environmental conditions, while optimizing the anthesis so that more pollen would be delivered to stigmas. 

Spikelet fertility and heat shock transcription factor (Hsf) gene responses to heat stress in tolerant and susceptible rice (Oryza sativa L.) genotypes

2019 ◽  
Vol 157 (04) ◽  
pp. 283-299 ◽  
Author(s):  
C. Malumpong ◽  
S. Cheabu ◽  
C. Mongkolsiriwatana ◽  
W. Detpittayanan ◽  
A. Vanavichit
Keyword(s):  
Heat Stress ◽  
Pollen Germination ◽  
Seed Set ◽  
Oryza Sativa L ◽  
Flag Leaf ◽  
Pollen Viability ◽  
Spikelet Fertility ◽  
Anther Dehiscence ◽  
Spikelet Sterility ◽  
Plant Parts

AbstractThe reproductive stage of rice is the most sensitive to heat stress, which can lead to spikelet sterility. Thus, heat-tolerant and heat-susceptible genotypes were used to investigate their differences in terms of phenotypic responses and expression changes of Hsf genes at the pre-flowering stage under heat stress. Results clearly showed that panicles had the highest temperature compared with other plant parts under both natural and heated conditions. However, the temperatures of tolerant and susceptible genotypes were not significantly different. In terms of spikelet fertility, the tolerant lines M9962 and M7988 had high seed set because their anther dehiscence, pollen viability and pollen germination were only slightly affected. In contrast, the susceptible line Sinlek showed severe effects at all steps of fertilization, and the pollen viability of M7766 was slightly affected under heat stress but was more affected in terms of anther dehiscence and pollen germination. Both susceptible lines showed dramatically decreased seed set. In addition, the expression of six HsfA genes in the flag leaves and spikelets at the R2 stage of plants under heat stress showed different responses. Notably, expression of the HsfA2a gene was predominantly upregulated in the flag leaf and spikelets under heat stress in M9962. Therefore, it can be concluded that heat stress has severe effects on the stamen, and that different genotypes have different susceptibilities to heat stress.

scholarly journals Potential Fertilization Capacity of Two Grapevine Varieties: Effects on Agricultural Production in Designation of Origin Areas in the Northwestern Iberian Peninsula

Agronomy ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 961
Author(s):  
J. Antonio Cortiñas Rodríguez ◽  
María Fernández-González ◽  
Estefanía González-Fernández ◽  
Rosa A. Vázquez-Ruiz ◽  
F. Javier Rodríguez-Rajo ◽  
...  
Keyword(s):  
Airborne Pollen ◽  
Germination Rate ◽  
Pollen Viability ◽  
Weather Conditions ◽  
Triphenyl Tetrazolium Chloride ◽  
Tetrazolium Chloride ◽  
The Mean ◽  
Study Sites ◽  
Fertilization Capacity

In the present study, we analyzed the main parameters related with the potential fertilization ability of two grapevine varieties, Godello and Mencía, during the years 2017 and 2018. The research was carried out in two vineyards of the Galician winegrowing Designation of Origin areas of Ribeiro and Ribeira Sacra. Ten vines of each variety were selected for bunch and flower counting, pollen calculations, pollen viability studies by means of aceto-carmine (AC) stain and 2, 3, 5-triphenyl tetrazolium chloride (TTC) methods, and the determination of their germination rate. In all vineyards the 50% fruitset was reached, except for Godello in Cenlle during 2017. The mean coulure value was higher for Godello (40.5%) than for Mencía (31%). Analyzing the pollen production per plant and airborne pollen levels, we observed important discordances between them, which can be due to the influence of weather conditions and be related with self-pollination processes. We found important differences on pollen viability depending on the applied method and variety, with higher values for the AC method than the TTC for both varieties in all study plots, and higher values for Mencía variety than Godello. Regarding germination rates, we observed a marked reduction in 2017 with respect to 2018, in all study sites and for both varieties. The analyzed parameters were useful to explain the different productive abilities of Godello and Mencía varieties in the two studied bioclimatic regions of Ribeiro and Ribeira Sacra.

scholarly journals Evidence for improved pollen viability as the mechanism for film antitranspirant mitigation of drought damage to wheat yield

2016 ◽  
Vol 67 (2) ◽  
pp. 137 ◽  
Author(s):  
Minuka M. Weerasinghe ◽  
Peter S. Kettlewell ◽  
Ivan G. Grove ◽  
Martin C. Hare
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Pollen Viability ◽  
Wheat Yield ◽  
Spray Application ◽  
Grain Number ◽  
Climatic Zones ◽  
Boot Stage ◽  
Wide Range ◽  
Drought Damage

Application of film antitranspirant to wheat during late stem extension reduces drought damage to yield, but the mechanism is unknown. Field experiments under rain shelters were conducted over 3 years to test the hypothesis that film antitranspirant applied before meiosis alleviates drought-induced losses of pollen viability, grain number and yield. The film antitranspirant di-1-p-menthene was applied at third-node stage, and meiosis occurred at the early boot stage, with a range of 11–16 days after spray application in different years. Irrigated, unsprayed plots were included under the rain-shelters, and pollen viability, measured in 2 years in these plots, averaged 95.3%. Drought reduced pollen viability to 80.1% in unirrigated, unsprayed plots, but only to 88.6% in unirrigated plots treated with film antitranspirant. Grain number and yield of irrigated plots, measured in all years, were 16 529 m–2 and 9.55 t ha–1, respectively, on average. These were reduced by drought to 11 410 m–2 and 6.31 t ha–1 in unirrigated, unsprayed plots, but only to 12 878 m–2 and 6.97 t ha–1 in unirrigated plots treated with film antitranspirant. Thus compared with unirrigated, unsprayed plots, antitranspirant gave a grain yield benefit of 0.66 t ha–1. Further work is needed to validate the pollen viability mechanism in different climatic zones and with a wide range of cultivars.

Optimization of chromosome doubling treatment for efficient in vivo doubled haploid production in maize

2021 ◽  
pp. 1-10
Author(s):  
Sourbh Kumar ◽  
Uttam Chandel ◽  
Satish Kumar Guleria
Keyword(s):  
Doubled Haploid ◽  
Seed Set ◽  
Chromosome Doubling ◽  
Pollen Viability ◽  
Haploid Inducer ◽  
Haploid Production ◽  
Maize Genotypes ◽  
Different Doses

Abstract An investigation to optimize the protocol for application of colchicine for enhancing the doubled haploid production in maize was done. 106 maize genotypes were used as maternal parents, whereas, pollen source involved tropically adopted haploid inducer (TAIL P1 and TAIL hybrid). After the elimination of chromosomes of inducer lines, haploid seeds were obtained from the crosses. Haploid seedlings were treated with three different doses, such as 0.04, 0.06 and 0.08 per cent of colchicines for different durations (8, 12 and 15 hours). The response of various colchicine concentrations applied for different time durations revealed significant differences at P ≤ 0.05 for various parameters viz., per cent plants survivability, stalk colour, the fertility of tassel, silk present/absent, pollen viability, seed set and per cent doubled haploid formation. In maize, colchicine doses of 0.04 per cent for 12 hours and 0.06 per cent for 8 hours, respectively were established as optimum for enhanced doubled haploid production. But among these two, 0.04 per cent for 12 hours was observed to be best dose for doubled haploid production in maize.

Effect of potato spindle tuber viroid on sexual reproduction and viroid transmission in true potato seed

1986 ◽  
Vol 64 (2) ◽  
pp. 336-340 ◽  
Author(s):  
M. E. Grasmick ◽  
S. A. Slack
Keyword(s):  
Fruit Development ◽  
Seed Weight ◽  
Seed Set ◽  
Transmission Rate ◽  
Pollen Viability ◽  
Polyacrylamide Gel Electrophoresis ◽  
Potato Spindle Tuber Viroid ◽  
Potato Seed ◽  
True Potato Seed ◽  
Viroid Infection

The effect of potato spindle tuber viroid infection on pollen viability, fruit-set, botanical seed set, seed weight, and seed germination in potatoes was determined. Pollen collected from the infected cultivar 'Monona' was less viable than pollen collected from healthy plants. Pollen collected from infected plants reduced seed set significantly but did not reduce fruit development or seed set in all cultivars tested. For some cultivars, infected maternal plants increased the frequency of fruit development and seed weight compared with healthy controls. True potato seed from viroid-infected 'Katahdin' × 'Superior' crosses germinated at a higher rate than did seed from comparable uninfected parents. Progeny from viroid-infected parents that exhibited potato spindle tuber viroidlike symptoms did not always test positive for potato spindle tuber viroid by bioassay or polyacrylamide gel electrophoresis tests. Efficiency of potato spindle tuber viroid detection by bioassay was highest for seedlings 2 weeks after imbibition. Potato spindle tuber viroid was detected in 100% of the progeny tested after true potato seed was stored at 4 °C for 12 years. Tests on selfed true potato seed from the viroid-infected cultivar 'Monona' demonstrated a transmission rate of 100% after subinoculation of initial bioassay plants.

scholarly journals Why so many flowers? A preliminary assessment of mixed pollination strategy enhancing sexual reproduction of the invasive <i>Acacia longifolia</i> in Portugal

Web Ecology ◽  
2018 ◽  
Vol 18 (1) ◽  
pp. 47-54 ◽  
Author(s):  
Manuela Giovanetti ◽  
Margarida Ramos ◽  
Cristina Máguas
Keyword(s):  
Invasive Plant ◽  
Seed Set ◽  
Pollen Grains ◽  
Striking Difference ◽  
Pollination Syndromes ◽  
Pollination Success ◽  
Relative Contribution ◽  
Acacia Longifolia ◽  
Exclusion Experiments ◽  
Pollination Strategy

Abstract. Acacia longifolia, a native legume from Australia, has been introduced in many European countries and elsewhere, thus becoming one of the most important global invasive species. In Europe, its flowering occurs in a period unsuitable for insect activity: nonetheless it is considered entomophilous. Floral traits of this species are puzzling: brightly coloured and scented as liked by insects, but with abundant staminate small-sized flowers and relatively small pollen grains, as it is common in anemophilous species. Invasion processes are especially favoured when reshaping local ecological networks, thus the interest in understanding pollination syndromes associated with invasive plant species that may facilitate invasiveness. Moreover, a striking difference exists between its massive flowering and relatively poor seed set. We introduced a novel approach: first, we consider the possibility that a part of the pollination success is carried on by wind and, second, we weighted the ethological perspective of the main pollinator. During the flowering season of A. longifolia (February–April 2016), we carried on exclusion experiments to detect the relative contribution of insects and wind. While the exclusion experiments corroborated the need for pollen vectors, we actually recorded a low abundance of insects. The honeybee, known pollinator of acacias, was relatively rare and not always productive in terms of successful visits. While wind contributed to seed set, focal observations confirmed that honeybees transfer pollen when visiting both the inflorescences to collect pollen and the extrafloral nectaries to collect nectar. The mixed pollination strategy of A. longifolia may then be the basis of its success in invading Portugal's windy coasts.

scholarly journals Meiotic Chromosome Behavior and Capsule Setting in Doritaenopsis Hybrids

2008 ◽  
Vol 133 (1) ◽  
pp. 107-116 ◽  
Author(s):  
Pablo Bolaños-Villegas ◽  
Shih-Wen Chin ◽  
Fure-Chyi Chen
Keyword(s):  
Cell Division ◽  
Pollen Mother Cell ◽  
Chromosome Pairing ◽  
Chromosomal Aberrations ◽  
High Frequency ◽  
Mother Cell ◽  
Seed Set ◽  
Pollen Viability ◽  
High Pollen ◽  
Mother Cells

The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.

Distance-dependent pollen limitation of seed set in some insect-pollinated dioecious plants

2005 ◽  
Vol 28 (3) ◽  
pp. 331-335 ◽  
Author(s):  
Tom J. de Jong ◽  
Judith C. Batenburg ◽  
Peter G.L. Klinkhamer
Keyword(s):  
Seed Set ◽  
Pollen Limitation ◽  
Dioecious Plants

The effects of frequency and extent of defoliation, summer irrigation, and fertilizer on the production and survival of the grass Danthonia caespitosa Gaud

1976 ◽  
Vol 27 (6) ◽  
pp. 755 ◽  
Author(s):  
KC Hodgkinson
Keyword(s):  
Seed Production ◽  
Death Rate ◽  
Field Experiments ◽  
Seed Set ◽  
Floral Induction ◽  
Early Winter ◽  
Phosphorus Fertilizer ◽  
Nitrogen And Phosphorus ◽  
Plant Survival ◽  
Growth And Survival

The effects of extent and frequency of defoliation on the growth and survival of Danthonia caespitosa were measured in a series of field experiments. Additional treatments, of summer irrigation and application of nitrogen and phosphorus fertilizer, were included in some of the experiments to assess how they modified the effects of defoliation. During the summer, complete defoliation increased the shoot yield of plants which had not been irrigated, but yield was decreased in the irrigated treatments. Frequent, partial defoliation increased yields of irrigated plants but decreased yields of plants not irrigated. Depression of yields was caused by both tiller death and reduced regrowth of individual tillers. In an experiment lasting 2 years, plants were completely defoliated monthly, bimonthly or tri-monthly or left intact, and shoot yields, tillering characteristics and plant survival under the treatments were compared. Monthly defoliation depressed yields and rate of tillering and accelerated the death rate of plants, particularly during the summer and autumn periods. Plants also died when cut bimonthly but the rate was slower. Plants irrigated during the first summer generally died at a faster rate than plants not irrigated. Tillering was more rapid during the autumn and early winter months. Midwinter application of fertilizer to plants cut bimonthly greatly stimulated shoot yields and seed production in the spring but not in the following year. Examination of tiller apices showed that floral induction took place prior to the beginning of July. Many apices were elevated above the 'grazing level' by early September, and flowering and seed set occurred in October.

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