Triploidy causes sexual infertility in Cyrtanthus breviflorus (Amaryllidaceae)

2011 ◽  
Vol 59 (3) ◽  
pp. 238 ◽  
Author(s):  
Mike Ramsey ◽  
Glenda Vaughton ◽  
Glendon D. Ascough ◽  
Steven D. Johnson
Keyword(s):  
Flow Cytometry ◽  
Genetic Factors ◽  
Fruit Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Clonal Plants ◽  
Pollen Deposition ◽  
Sexual And Asexual Reproduction ◽  
Challenging Question

The balance between sexual and asexual reproduction can vary markedly in clonal plants. At one extreme, plants are sexually infertile and reproduction is solely clonal. Infertility can be caused by environmental and/or genetic factors, but the role of each is often unknown. Here we determine variation in sexual reproduction and explore the underlying factors causing sexual infertility in Cyrtanthus breviflorus Harv. We examined open- and cross-pollinated fruit set, ploidy using flow cytometry, pollen viability, pollinator visits to flowers and pollen deposition onto stigmas. One population was sexually infertile; no plants produced fruit. Three populations were sexually fertile; >98% of plants produced fruit. Percent pollen viability differed between infertile (18%) and fertile (97%) populations. The most likely cause of infertility was unequal ploidy. Plants in the infertile population were triploid, whereas those in fertile populations were diploid. Pollination factors were not related to infertility. In infertile and fertile populations, pollen-collecting insects visited flowers frequently, depositing 4-fold more pollen grains onto stigmas than the number of ovules per flower. Our study is the first to demonstrate infertility and triploidy in C. breviflorus. How triploidy became established despite high levels of pollinator activity remains a challenging question.

scholarly journals A Duplicated Copy of the Meiotic Gene ZIP4 Preserves up to 50% Pollen Viability and Grain Number in Polyploid Wheat

Biology ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 290
Author(s):  
Abdul Kader Alabdullah ◽  
Graham Moore ◽  
Azahara C. Martín
Keyword(s):  
Pollen Viability ◽  
Pollen Grains ◽  
Wheat Chromosome ◽  
Grain Number ◽  
Meiotic Gene ◽  
Chromosome 5B ◽  
Mutant Pollen ◽  
Female Gametogenesis ◽  
Chromosome 3B

Although most flowering plants are polyploid, little is known of how the meiotic process evolves after polyploidisation to stabilise and preserve fertility. On wheat polyploidisation, the major meiotic gene ZIP4 on chromosome 3B duplicated onto 5B and diverged (TaZIP4-B2). TaZIP4-B2 was recently shown to promote homologous pairing, synapsis and crossover, and suppress homoeologous crossover. We therefore suspected that these meiotic stabilising effects could be important for preserving wheat fertility. A CRISPR Tazip4-B2 mutant was exploited to assess the contribution of the 5B duplicated ZIP4 copy in maintaining pollen viability and grain setting. Analysis demonstrated abnormalities in 56% of meiocytes in the Tazip4-B2 mutant, with micronuclei in 50% of tetrads, reduced size in 48% of pollen grains and a near 50% reduction in grain number. Further studies showed that most of the reduced grain number occurred when Tazip4-B2 mutant plants were pollinated with the less viable Tazip4-B2 mutant pollen rather than with wild type pollen, suggesting that the stabilising effect of TaZIP4-B2 on meiosis has a greater consequence in subsequent male, rather than female gametogenesis. These studies reveal the extraordinary value of the wheat chromosome 5B TaZIP4-B2 duplication to agriculture and human nutrition. Future studies should further investigate the role of TaZIP4-B2 on female fertility and assess whether different TaZIP4-B2 alleles exhibit variable effects on meiotic stabilisation and/or resistance to temperature change.

The importance of fruit set, fruit abortion, and pollination success in fruit production of teak (Tectona grandis)

2010 ◽  
Vol 40 (11) ◽  
pp. 2204-2214 ◽  
Author(s):  
E. R. Palupi ◽  
J. N. Owens ◽  
S. Sadjad ◽  
Sudarsono ◽  
D. D. Solihin
Keyword(s):  
Fruit Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Tectona Grandis ◽  
Seed Orchard ◽  
Fruit Production ◽  
Time Of Day ◽  
Natural Forests ◽  
Pollination Success ◽  
Fruit Abortion

Teak ( Tectona grandis L.) is believed to have been introduced from India 400–500 years ago and there appear to be no old-growth natural forests. However, Indonesia has many teak plantation forests and 40%–50% of seeds for reforestation come from seed orchards and the remainder from plantations. In both, flower and fruit abortion results in low fruit set and thus seed production. We investigated flower and fruit development in a clonal seed orchard in East Java in 1999 and 2001 using cross- and open-pollinated trees. The rates of abortion using cross-pollinations showed a similar pattern but were lower than for open-pollinations. The highest rate of abortion in cross- and open-pollinations was during pollination and fertilization, ranging 11%–23% and 31%–32%/day, respectively, less during fruit initiation (5%–6% and 6%–8%/day) and the lowest was during fruit maturation (<0.5%/day). Cross-pollinations increased fruit production by 10-fold compared with open-pollinations. About 30% of flowers were pollinated with an average of five pollen grains per stigma in open-pollinations. Pollen viability varied among clones and time of day but was not affected by position of flowers in an inflorescence. We conclude that low pollination success and low pollen viability are major causes for low fruit production in teak and are related to insect pollinators.

scholarly journals Sensitivity of commercial pumpkin yield to potential decline among different groups of pollinating bees

2017 ◽  
Vol 4 (5) ◽  
pp. 170102 ◽  
Author(s):  
Sonja C. Pfister ◽  
Philipp W. Eckerter ◽  
Jens Schirmel ◽  
James E. Cresswell ◽  
Martin H. Entling
Keyword(s):  
Crop Yield ◽  
Fruit Set ◽  
Pollen Grains ◽  
Pollen Deposition ◽  
Insect Pollination ◽  
Study Region ◽  
Flower Visitation ◽  
Pollen Receipt ◽  
The Relationship ◽  
Pollinator Fauna

The yield of animal-pollinated crops is threatened by bee declines, but its precise sensitivity is poorly known. We therefore determined the yield dependence of Hokkaido pumpkin in Germany on insect pollination by quantifying: (i) the relationship between pollen receipt and fruit set and (ii) the cumulative pollen deposition of each pollinator group. We found that approximately 2500 pollen grains per flower were needed to maximize fruit set. At the measured rates of flower visitation, we estimated that bumblebees (21 visits/flower lifetime, 864 grains/visit) or honeybees (123 visits, 260 grains) could individually achieve maximum crop yield, whereas halictid bees are ineffective (11 visits, 16 grains). The pollinator fauna was capable of delivering 20 times the necessary amount of pollen. We therefore estimate that pumpkin yield was not pollination-limited in our study region and that it is currently fairly resilient to single declines of honeybees or wild bumblebees.

scholarly journals Metabolite profiling in Mango (Mangifera indica L.) pollen grains in relation to viability

2019 ◽  
Vol 14 (1) ◽  
pp. 33-42
Author(s):  
K S Shivashankara ◽  
G A Geetha ◽  
T K Roy
Keyword(s):  
Amino Acids ◽  
Fruit Set ◽  
Mangifera Indica ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Free Sugars ◽  
Fruit Drop ◽  
Fruit Setting ◽  
Viability Percentage ◽  
Pollination And Fertilization

Mango productivity is affected mainly by irregular flowering, proportion of bisexual flowers, poor pollination and fertilization and fruit drop. Poor fruit set in some of the varieties may be associated with the lower pollen viability. The present experiment was initiated to assess the viability of pollen grains and their metabolites in three mango cultivars Amrapali, Alphonso and Totapuri which are differing in their fruit set intensity. The profiling of sugars, amino acids and some of the phytohormones were analysed using Liquid Chromatography-Mass Spectrometry (LC-MS/MS). Assessment of pollen grains in three mango cultivars indicated that free sugars such as fructose and glucose, and available amino acids including serine, proline, lysine, phenylalanine, alanine and glutamic acid were predominantly higher in all the cultivars. Phytohormones like IAA, IBA, ABA, GA,zeatin, jasmonic acid and salicylic acid were significantly different in low fruit setting cultivars Alphonso and Totapuri compared to high fruit setting cultivar Amrapali. In cv. Alphonso all the metabolites were higher at anthesis but later decreased drastically compared to cvs. Totapuri and Amrapali. Pollen viability percentage was significantly higher in cv. Amrapali than in cvs. Totapuri, Alphonso. Among all the cultivars, Amrapali maintained better chemical composition at anthesis and also at two hours after anthesis compared to cvs. Totapuri and Alphonso.

scholarly journals Floral herbivory does not reduce pollination-mediated fitness in shelter rewarding Royal Irises

2017 ◽  
Author(s):  
Mahua Ghara ◽  
Christina Ewerhardy ◽  
Gil Yardeni ◽  
Mor Matzliach ◽  
Yuval Sapir
Keyword(s):  
Fruit Set ◽  
Seed Set ◽  
Pollen Grains ◽  
Reproductive Organs ◽  
Pollen Grain ◽  
Lower Number ◽  
Pollen Deposition ◽  
Pollination Services ◽  
Pollinator Visitation ◽  
Direct Damage

ABSTRACTFlorivory, the damage to flowers by herbivores can affect fitness both directly and indirectly. Flowers consumed by florivores may fail to produce fruit or produce lower seed set because of direct damage to reproductive organs. In addition, eaten flowers are less attractive to pollinators because of reduced or modified advertisement, which reduces pollination services. While observational data are abundant, experimental evidence is scarce and results are contrasting. We tested experimentally the effect of florivory on both pollinator visitation and reproductive success in three species of the Royal Irises, which have large flowers that are attractive to pollinators, and potentially also for florivores. We hypothesized that florivory will reduce pollen deposition due to reduced attractiveness to pollinators, while fruit set and seed set will depend on the extent of florivory. We performed artificial florivory in two experiments over two years. In the first experiment, each of the three floral units of a single Iris flower was subject to either low or high artificial florivory, or left un-touched as control. We counted the number of pollen grains deposited on each of the three stigmas as a measure of pollinator visitation. In the second experiment, three flowers of the same plant received low, high, or no artificial florivory and were further recorded for fruit and seed production. In 2016, high artificial florivory revealed lower number of pollen grains on stigmas of Iris atropurpurea, but in 2017 there was no difference. Similarly, number of pollen grains in high artificial was lower than low florivory in 2017 in I. petrana. No significant effect of florivory was found on pollen grain deposition, fruit set or seed set. The results remained consistent across species and across years. The results undermine the assumption that flower herbivory is necessarily antagonistic interaction and suggests that florivores may not be strong selection agents on floral reproductive biology in the Oncocyclus irises.

scholarly journals Electrostatic Processes Underlying Natural and Mechanized Transfer of Pollen

1998 ◽  
Author(s):  
Edward Law ◽  
Samuel Gan-Mor ◽  
Hazel Wetzstein ◽  
Dan Eisikowitch
Keyword(s):  
Electric Fields ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Basic Knowledge ◽  
Pollen Deposition ◽  
Average Charge ◽  
Pollen Transfer ◽  
Transfer Vectors ◽  
Pollination Systems ◽  
Relaxation Characteristics

The project objective was to more fully understand how the motion of pollen grains may be controlled by electrostatic forces, and to develop a reliable mechanized pollination system based upon sound electrostatic and aerodynamic principles. Theoretical and experimental analyses and computer simulation methods which investigated electrostatic aspects of natural pollen transfer by insects found that: a) actively flying honeybees accumulate ~ 23 pC average charge (93 pC max.) which elevates their bodies to ~ 47 V likely by triboelectrification, inducing ~ 10 fC of opposite charge onto nearby pollen grains, and overcoming their typically 0.3-3.9 nN detachment force resulting in non-contact electrostatic pollen transfer across a 5 mm or greater air gap from anther-to-bee, thus providing a theoretical basis for earlier experimental observations and "buzz pollination" events; b) charge-relaxation characteristics measured for flower structural components (viz., 3 ns and 25 ns time constants, respectively, for the stigma-style vs. waxy petal surfaces) ensure them to be electrically appropriate targets for electrodeposition of charged pollen grains but not differing sufficiently to facilitate electrodynamic focusing onto the stigma; c) conventional electrostatic focusing beneficially concentrates pollen-deposition electric fields onto the pistill tip by 3-fold as compared to that onto underlying flower structures; and d) pollen viability is adequately maintained following exposure to particulate charging/management fields exceeding 2 MV/m. Laboratory- and field-scale processes/prototype machines for electrostatic application of pollen were successfully developed to dispense pollen in both a dry-powder phase and in a liquid-carried phase utilizing corona, triboelectric, and induction particulate-charging methods; pollen-charge levels attained (~ 1-10 mC/kg) provide pollen-deposition forces 10-, 77-, and 100-fold greater than gravity, respectively, for such charged pollen grains subjected to a 1 kV/cm electric field. Lab and field evaluations have documented charged vs. ukncharged pollen deposition to be significantly (a = 0.01-0.05) increased by 3.9-5.6 times. Orchard trials showed initial fruit set on branches individually treated with electrostatically applied pollen to typically increase up to ~ 2-fold vs. uncharged pollen applications; however, whole-tree applications have not significantly shown similar levels of benefit and corrective measures continue. Project results thus contribute important basic knowledge and applied electrostatics technology which will provide agriculture with alternative/supplemental mechanized pollination systems as tranditional pollen-transfer vectors are further endangered by natural and man-fade factors.

scholarly journals Fruit Set in Avocado: Pollen Limitation, Pollen Load Size, and Selective Fruit Abortion

Agronomy ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1603
Author(s):  
María L. Alcaraz ◽  
José I. Hormaza
Keyword(s):  
Fruit Set ◽  
Pollen Limitation ◽  
Pollen Grains ◽  
Endosperm Development ◽  
Pollen Deposition ◽  
Woody Perennial ◽  
Flowering Season ◽  
Fruit Abortion ◽  
Load Size ◽  
Competition For Resources

Avocado is a woody perennial fruit crop originating in Central America and Mexico domesticated and cultivated in the Americas since pre-Columbian times, currently cultivated in subtropical, tropical, and Mediterranean climates worldwide, with increasing importance in international trade. Avocado shows an exuberant flower production that, however, results in a very low fruit set reflected in a massive abscission of flowers and fruitlets. Several factors are involved in this behavior, and, in this work, we have focused on pollination limitation. The results obtained show that pollen deposition takes place at the female and male stages during the avocado flowering season and that the percentage of flowers with pollen on the stigma varies along the flowering season, probably due to changes in temperature that affect not only the floral behavior but also pollinator activity. However, no embryo or endosperm development took place when pollination occurred during the male flowering phase. Thus, the low number of pollen grains landing on the stigmas of female stage flowers observed under natural pollination conditions might not be enough to ensure a good yield. The production of an excess of flowers and subsequent flower drop of most of the flowers provides the opportunity of a selective fruitlet drop depending on the genotype of the embryo since fruits derived from outcrossing showed higher chances of reaching maturity. Moreover, an important competition for resources occurs among developing fruits and new vegetative growth, conferring importance to the time of flower fertilization for effective fruit set.

scholarly journals On the reproductive biology of Salacia fruticosa Wall. ex M.A. Lawson - an endemic medicinal plant of the Western Ghats, india

2018 ◽  
Vol 10 (15) ◽  
pp. 13002-13005
Author(s):  
K. Subin ◽  
P. A. Jose ◽  
T. V. Sarath
Keyword(s):  
Reproductive Biology ◽  
Fruit Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Seedling Bank ◽  
The Poor ◽  
Short Period ◽  
Poor Seed ◽  
Endemic Medicinal Plant ◽  
The Western Ghats

Salacia fruticosa Wall. ex M.A. Lawson, an endemic species was studied for the reproductive biology as this species showed reduced fruit set and natural regeneration.  The stigma-anther proximity, an extremely low number of pollen grains, a short period of pollen viability, a sparse incidence of pollinators, protandrous and facultative autogamous nature of the flowers and a low percent in fruit set were identified as biological constraints for the species.  The incidence of seed pest was added to the poor seed and seedling bank and accelerated rarity process of the species.

scholarly journals Determination of Blooming, Pollen and Fruit Set Characteristics in Punica granatum

2019 ◽  
Vol 47 (4) ◽  
pp. 1258-1263
Author(s):  
Deniz AKSOY ◽  
Zeynel DALKILIC
Keyword(s):  
Fruit Set ◽  
Pollen Viability ◽  
Pollen Grains ◽  
Punica Granatum ◽  
Digital Object Identifier ◽  
Self Pollination ◽  
Beginning Of Flowering ◽  
Male Flowers ◽  
In The Beginning

The objective of this study was to investigate flowering, pollen, and fruit set characteristics of locally registered pomegranate cultivars between two consecutive years. ‘Dr. Ercan 35’, ‘Efenar 35’, ‘Kamilbey 35’, and ‘Tezeren 35’ cultivars have been developed by cross-breeding programs. Open-, cross-, and self-pollination studies were performed with these cultivars using three trees in each replicate in the field. Number of anthers per flower, number of pollen grains per anther, viability, and germination tests were conducted in the laboratory. Fruit set ratio of self-pollinated combinations were lower than open-pollination. The fruit set ratio from self-pollination was obtained from ‘Dr. Ercan’ (60.3%), ‘Efenar 35’ (62.4%), ‘Kamilbey 35’ (50.5%), and ‘Tezeren 35’ (25.2%). The highest fruit set ratio (49.7%) was obtained from ‘Kamilbey 35’ × ‘Dr. Ercan 35’ combination. The highest number of characteristics was as follows: ‘Tezeren 35’ (402 anthers/hermaphrodite flowers), ‘Kamilbey 35’ (8550 pollen/anther, male flowers in the beginning of flowering), ‘Efenar 35’ (84.7% pollen viability, hermaphrodite flowers), ‘Kamilbey 35’ (71.2%, pollen germination, hermaphrodite flowers). In conclusion, at least one, two or more, pollinator cultivars are necessary for commercial plantations using with these recently released pomegranate cultivars.   ********* In press - Online First. Article has been peer reviewed, accepted for publication and published online without pagination. It will receive pagination when the issue will be ready for publishing as a complete number (Volume 47, Issue 4, 2019). The article is searchable and citable by Digital Object Identifier (DOI). DOI link will become active after the article will be included in the complete issue. *********

Self-compatibility, autonomous self-pollination, and insect-mediated pollination in the clonal species Iris versicolor

1993 ◽  
Vol 71 (11) ◽  
pp. 1503-1509 ◽  
Author(s):  
Paul Kron ◽  
Steven C. Stewart ◽  
Allison Back
Keyword(s):  
Reproductive Biology ◽  
Fruit Set ◽  
Pollen Grains ◽  
Clonal Plants ◽  
Pollinator Behaviour ◽  
Self Pollination ◽  
Self Compatibility ◽  
Three Stages ◽  
Pass Through ◽  
Clonal Species

In clonal species, sexual and asexual systems interact to create a hierarchy of reproduction. For example, self-pollination can occur within pollination units, flowers, ramets, or clones. We investigated the reproductive biology of a natural population of Iris versicolor using pollination manipulations and observations of pollinator behaviour. We found that (i) individuals were completely self-compatible, (ii) selfing rates were close to 100%, (iii) autonomous self-pollination can occur through stigma–anther contact or wind action, (iv) most seed and fruit set can be accounted for by insect pollination, and (v) facilitated self-pollination likely occurs because pollinators frequently visit more than one pollination unit within a flower. Our observations showed that flowers pass through three stages: (i) a male stage (in which pollen is freely available, but stigmas are inaccessible, preventing autogamy); (ii) a female stage (in which stigma flaps have reflexed and are receptive, but pollinators may have already removed most pollen grains, structuring opportunities for geitonogamy); and (iii) a strongly autogamous stage (in which stigma flaps have curled back to contact anthers, leading to delayed autonomous self-pollination). This hierarchy of relatedness among mates determines the genetic consequences of vegetative and sexual reproduction in clonal plants and influences their evolution. Key words: Iris, self-incompatibility, reproductive biology, clonal, pollination.

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