The International Journal of Plant Reproductive Biology
(Indexed by CABI)
ISSN Print : 0975-4296; ISSN Online : 2249-7390
 
Volume-2, Number-1, January 2010
  Diatom Reproductive Biology: Living in a Crystal Cage 

Alberto Amato
ENS/CNRS UMR 8186, Biologie Moleculaire des Organismes Photosynthetiques 46, rue d’Ulm 75230 CEDEX 05,
Paris, France

e-mail : amato@biologie.ens.fr; Fax : +33 1 44 32 39 35

  ABSTRACT


Diatoms are unicellular heterokonts characterised by a bipartite cell wall made of amorphous silica. Their ecological importance is proved by the fact that they yearly produce one fifth of the oxygen on Earth, while their economic interest resides in that they are used in filters for water and beer and for biofuel production. This class of algae has been studied for long time but our knowledge about their reproductive biology is still a new field and needs more intense investigation, especially from a molecular point of view. Here I review what is known about sexual reproduction in pennate and centric diatoms from both a
morphologic/behavioural and an ecologic standpoint.
 

Keywords : Auxospore, anisogamy, diatoms, heterothally, homothally, isogamy, oogamy, sexual reproduction

 

 

Gametangial Ontogeny in Intertidal Green Alga: Monostroma latissimum (Kützing) Wittrock

Felix Bast* & Kazuo Okuda
Graduate School of Kuroshio Science, Kochi University, 2-5-1 Akebono, Kochi 780-8520, Japan

*
e-mail : felix.bast@gmail.com

  ABSTRACT

The gametangial ontogeny in dioecious green alga Monostroma latissimum as studied by lightmicroscopy has been described for the first time. Mature gametophytes were collected from the Pacificcoast of Japan. Two morphotypes were observed and both were confirmed to be of one panmictic population. Gametangial maturation occurred in discontinuous patches along the frondal apex. During maturation, each gametangial mother cell (GMC) was transformed into one gametangium. The gametangial plastids divided and cell volume increased. Fully mature GMCs were large, loosely arranged and numerous gametes with chromatic eyespots present in them. Gametes were released by the dehiscence of gametangial sheath in a posterior faced linear fashion by disintegration of thalli. This was brought about by providing an intense illumination at the end of dark period.
 The release was synchronous within each mature patch.

Keywords : “Gametangial dehiscence”; Gametophyte; GMC; Morphotype; Plastid; Seaweed
 
 

Sexual Reproduction in Water Moulds - I: General Aspects related to family Saprolegniaceae

S.K. Prabhuji
Biotechnology and Molecular Biology Centre, M.G. Post Graduate College, Gorakhpur – 273 001, India

e-mail : shaktiprabhuji@rediffmail.com

  ABSTRACT

The preliminary considerations on the generic identification and sexual reproduction in Saprolegniaceae have been critically dealt with in the present paper. Various aspects of the development of sexual reproductive structures, effects of different physico-chemical and nutritional factors and certain specific features have also been reviewed.

Keywords : Sexual reproduction, Saprolegniaceae, Physico-chemical factors, Nutritional requirements
 

In Vitro Study on Micropropagation and Reproductive Behaviour of Moss Bryoerythrophyllum recurvirostrum (Hedw.) Chen.

Vishal Awasthi, Virendra Nath* & A.K. Asthana
Bryology Laboratory, National Botanical Research Institute
(Council of Scientific and Industrial Research, New Delhi), Lucknow – 226 001, India

*e-mail : drvirendranath2001@rediffmail.com

  ABSTRACT

In vitro propagation of Bryoerythrophyllum recurvirostrum (Hedw.) Chen. has been carried out by using spores as explants. A full differentiation of protonema into well developed gametophytes has been achieved by inoculating spores into a range of concentrations of inorganic media with and without sucrose under laboratory conditions. Effect of sucrose and light conditions,production and behaviour of protonema, globular cells, protonemal gemmae etc. were also observed. In vitro raised plants were acclimatized and transferred to soil in order to their further proliferation.

Keywords : Bryoerythrophyllum recurvirostrum (Hedw.) Chen., culture, propagation, protonemal gemmae, spores
  The Development of Male and Female Flowers in Actinidia deliciosa

Lara Reale* & Francesco Ferranti
Department of Applied Biology, Borgo XX Giugno 74, 06121 Perugia, Italy

*
e-mail : citolabo@unipg.it; Fax : 075 5856407

  ABSTRACT

The timing of male and female flower development, in Actinidia deliciosa, was studied through observations using light and scanning electron microscopes. The data confirmed the presence of hermaphroditic flowers at the initial developmental phases which become successively unisexual. In the male flowers the stop of pistil development was observed six weeks before anthesis, when archesporial cells in anthers are observed; in these flowers the ovary is characterised by a loculus with vacuolated placental tissue, without ovules. In the female flowers, at anthesis, the stamens are completely differentiated but there are no viable pollen grains in the anthers. Pollen degeneration starts a few days after microsporogenesis; at this stage microspores have a thin wall, a poor cytoplasm and a degenerating nucleus.

Keywords : Actinidia deliciosa, flower development, dioecism
  Biotic Pollination in Aerides odorata Lour. (Orchidaceae)

S.K. Chaturvedi*  & Shonali Chaturvedi
Department of Botany, Nagaland University, Lumami, Mokokchung - 798 601, P.B. 53, India

Department of Botany, Ewing Christian College, Allahabad - 211 00, India

*e-mail : sunchat1@rediffmail.com

  ABSTRACT

Flowers of Aerides odorata Lour., an indigenous orchid of Nagaland, have been investigated for their modes of pollination. The flowers exhibit biotic mode of pollination through the agency of bees which belong to genus Bombus (Bumble bees) and Xylocopa (Carpenter bees). The earliest foragers of these flowers are Xylocopa or Carpenter bees which start foraging spree as early as 4.30 A.M. in the months of May- June at the investigated localities in the state of Nagaland whereas the bumble bees (Bombus sp.) are late foragers. However, the butterflies Papilio iswara iswara White, commonly known as “Great Helen” and black ants of genus Crematogastor have also been observed to visit the flowers for its sucrose rich nectar but have never been found as pollinators. The lemony fragrance emitted by the flowers functions as the primary attractant and the nectar secreted inside the spur has been identified as secondary attractant for visitors/ pollinators. Anthecological studies exhibit attachment of pollinaria on the fore- head of Bombus and Xylocopa and their subsequent transfer to the rostellum takes place during the process of nectar licking. This type of biotic mode of pollination where pollinaria are transferred to the rostellum through the fore
head of visitors has been assigned a new term“Frontotriby”.

Keywords : Aerides odorata, pollination, Bombus, Xylocopa, Papilio iswara iswara, Crematogastor, frontotriby
 

Assessment of Ovule Receptivity as a Function of Expected Brood Size in Flowering Plants

Shinjinee Sengupta* & Rajesh Tandon2*
Biotechnology Division, Indian Institute of Chemical Biology, 4 Raja SC, Mullick Road - 700 032, Kolkata
Department of Botany, University of Delhi, Delhi – 110 007
e-mail :
shin86@gmail.com; *rjtnd@rediffmail.com

  ABSTRACT

In order to get sexual seeds, viable pollen must land on a receptive stigma to effect fertilization. Thus, the receptive period of a stigma is considered to be a crucial period for achieving fertilization. In practice, it has been noticed that even when the receptive period has been successfully used for controlled pollinations; all the ovules do not become seeds. It has been shown that the readiness of the ovules is related to their ability to attract pollen tubes by means of the signals produced from the synergids of a mature embryo sac. Also the mature ovules produce micropylar exudates to facilitate directionality to pollen tubes before fertilization. Whether or not the ability of ovules to produce micropylar exudates (MEx) has any correlation with their readiness to get fertilized can be ascertained from average brood size in a fruit irrespective of the regulatory mechanisms that operate during postfertilization events. In the present investigation, an attempt was made to statistically analyze the relation between the extent of average number of receptive ovules and seed formation in some leguminous plants. Ovule receptivity was ascertained by localizing the exudates with toluidine blue O’ stain at different developmental stages of flower. As it was impelling to decouple the role of pollen limitation as the proximate cause of low seed-set, the amount of pollen load was determined. Because in nature it is possible that the entire amount of pollen deposited onto a conspecific stigma may not be viable enough to sire all the seeds, the viable pollen proportion of the pollen load was also determined. The work established that ovules successfully respond to the test and all the ovules in an ovary do not show MEx. The proportion of receptive ovules in a flower reached a plateau at the receptive stages of the stigma or at anthesis. A positive linear correlation between percent receptive ovules and percent seed-set indicated that low seed to ovule ratios were due to low number of receptive ovules present in ovary which remained unfertilized. Statistical analyses indicated that ovule receptivity is highly significant than the pollen load in determining the proportion of seed set and pattern of seed development in a fruit.

Keywords : Legumes, micropylar exudates, pollen to ovule ratio, reproductive biology, stigma receptivity
 
 

Intra-inflorescence Pattern of the Opening of Apple (Malus domestica Borkh.) Flowers

József Racskó* & Diane D. Miller
Department of Horticulture and Crop Science, The Ohio State University, Ohio Agricultural Research
and Development Center, 1680 Madison Avenue, Wooster, OH 44691, USA

*
e-mail : racsko.1@osu.edu.

  ABSTRACT

Domestic apple usually bears four to seven flowers on an inflorescence from which the central initiates first followed by the laterals. The order in which the flowers open corresponds to the order in which they are developed, thus starting with the uppermost (terminal) flower and proceeding downwards through laterals. This characteristic is very important as flowers which open first, have usually the greater chance to be pollinated, set fruit and reach maturity than flowers which open later. The results of this study pointed out that the opening time of the selected ’Gala’, ’Elstar’, ’Golden Delicious’, ’Granny Smith’ and ’Fuji’ apple flowers was greatly influenced by their position on the inflorescence. It was shown that in natural conditions, the terminal flower opens first, followed by the third or fourth and more basal flowers, and lastly by the subterminal flower. The difference in the opening day of the individual flowers is the greatest between the terminal flower and any of the lateral flowers. Even among the lateral flowers, a ranking of dominance exists, although not as great as between the terminal and laterals. Results of individual flower removal treatments supported the hormonal hypothesis regarding the flower opening, thus an hypothetical hormonal signal produced by the terminal flower seems to play the major role in the opening pattern of the cluster. Therefore, the removal of the terminal flower, i.e. the absence of the source of the regulating signal, causes no temporal pattern in the opening of the remaining lateral flowers. Lateral flowers seem to not play any role in the flowering order of the inflorescence. Years seemed to have a greater impact than cultivars on the occurrence of the beginning and the duration of the flowering.

Keywords : Flower number per cluster, terminal flower, lateral flower, flowering, opening sequence
 

Floral Traits in Relation to Breeding System in Murraya koenigii (L.) Spreng.

Renu Bala* & Veenu Kaul
Department of Botany, University of Jammu, Jammu - 180 006

*e-mail : renuverma39@gmail.com

  ABSTRACT

Murraya koenigii (L.) Spreng. belonging to family Rutaceae is a semi-deciduous aromatic shrub or tree let. Known for its medicinal and culinary properties, it is widespread in distribution. Plants are prolific flower producers but moderate seed setters. Individual flowers are small, hermaphrodite, dull coloured, odouri-, nectari- and polleni-ferous. These features help in attracting a variety of insects. Floral structure, events of floral biology and phenology suggest a mixed mating system in the plant. Anthesis is immediately followed by anther dehiscence which is sequential and overlaps with stigma receptivity. Stamens borne in two whorls are at two levels; outer long reaching the level of stigma and dehiscing first while inner ones are short much below the stigma. The former facilitate selfing and the latter can mediate both selfing and outcrossing with the help of insects. High P/O and male-biased sex-allocation ratios, and results of pollination experiments support mixed mating system in the plant. This type of mating system can help in the production of a superior genotype of the species having desirable traits of different parents.

tKeywords : Fruit set, mixed mating system, P/O ratio, seed set, sex allocation
 

Sexual Polymorphism in the Dioecious Plant species of Eastern Saudi Arabia

 

Mohammed A. Al-Fredan
College of Science, King Faisal University, P.O. Box 5234, Al-Hassa – 31982 Kingdom of Saudi Arabia

e-mail: malfredan@kfu.edu.sa; Tel.: 00966506924500

  ABSTRACT

Flowering plants exhibit a great diversity of sexual systems, covering almost every imaginable combination of sex conditions. Dioecy, the occurrence of male and female individuals in natural plant populations, has evolved many times in the angiosperms. Although dioecy has clearly evolved as an outcrossing mechanism, in many species it appears to have evolved as a mechanism to increase the efficiency of resource allocation. Eastern region of Saudi Arabia consists of a broad, flat, low coastal plain that is covered with sand and gravel. This region is covered with grasses and steppe vegetation that supports nomadic and semi-nomadic herding population. A study has been conducted on the dioecious plant species of Eastern Saudi Arabia for the presence of various kinds of sexual polymorphism and divergence in the 1:1 male female ratio in the populations. The relationship between sexual systems and herkogamy was statistically significant. Most monoecious species were herkogamous. Sexual systems were also associated with dichogamy, and most of the dichogamous plants were dioecious. Monoecy was associated with both protandry and protogyny. Herkogamy was statistically associated with dichogamy. The results also indicated that all dioecious species were herkogamous.

Keywords : Aconitum chasmanthum, endemic, critically endangered medicinal herb, diploid (2n = 2x = 16), translocation hetrozygosity, protandry, outbreeding, self-incompatible
 

Sodium Arsenate-A Metabolic inhibitor used as a Chemical Hybridizing Agent for
Brassica juncea
(l.) Czern & Coss.

S.V.S. Chauhan*, H.K. Gupta & Vandana Singh
Academy of Life Science, 8/13 I Kaushalpur Bye Pass Road, Agra - 282 005, India
*
e-mail : svsc07@gmail.com; svs350@rediffmail.com

  ABSTRACT

Foliar sprays with various concentrations (0.1, 0.25, 0.5, 1.0 & 1.5%) of sodium arsenate (SA) at two different developmental stages induced pollen sterility ranging between 25-100% in Brassica juncea (L.) Var. Pusa Bold. The single or double treatments with higher concentrations (1.0 & 1.5%) caused 90-100% pollen sterility lasting throughout flowering. However, these plants exhibited a significant reduction in the number of siliqua/plant, siliqua size, number of seeds/siliqua, total yield and 100 seed weight and the days taken to first flowering were significantly increased. These plants showed marked changes in their floral morphology. The size of the flowers was reduced, colour of the petals and anthers changed, anthers were non-dehiscent. Another interesting feature observed in the floral buds of plants showing 100% pollen sterility was elongation of style due to which the slightly enlarged stigma protruded out of the buds. These stigmas were receptive and facilitated germination of pollen brought by honey bees from the beehive kept in the filed. On the other hand, single treatment before floral bud initiation with 0.5% sodium arsenate induced 94.6% pollen sterility. Interestingly in these treated plants, the reduction in siliqua size, number of seeds/siliqua and 100 seed weight was not significant. Thus, one or two treatments with 0.5, 1.0 and 1.5% SA are useful for inducing high degree of pollen sterility and these plants can be exploited for hybrid seed production.

Keywords : Brassica juncea, sodium arsenate, floral morphology, male sterility, yield parameters
 

Sexual Reproductive Effort (SRE) and Resource Partitioning in Three Species of Phyllanthus L.

Harjeet Kour, Indu Sharma & Namrata Sharma*
Department of Botany, University of Jammu, Jammu - 180 006

*e-mail : phyllanthus@rediffmail.com

  ABSTRACT

The communication describes the results of a few experimental manipulations done in three monoecious species of Phyllanthus L. namely P. fraternus, P. urinaria and P. simplex. Sexual Reproductive Effort (SRE) was first estimated in natural populations of these three species. Later the plants of each species were selectively chosen for removal of male or female buds and these were made to behave as unisexual plants. SRE was estimated in these plants also. Results indicated a trade-off between vegetative growth and female function in P. fraternus and P. urinaria and between male and female functions in P. simplex.

Keywords : P. fraternus, P. urinaria, P. simplex, Sexual reproductive effort (SRE), trade-offs
  Phenological Information Service

Phenology of Arnebia benthamii in Kashmir Himalayas
Khursheed Ahmad Ganaiea & Shabana Aslamb

Department of Botany Islamia College of Science and Commerce Srinagar J&K
Department of Botany, University of Kashmir Srinagar J&K

  ABSTRACT

Alpines are characterized by low temperatures, snow cover and short growing seasons which compel the inhabiting species to complete their life cycles in these short periods. Arnebia benthamii coming over expectations completes the cycle well within this period, stretching its seasonal onset and senescence to over 4- 4 ˝ months. Up to May the higher altitude zones remain under white cover- the snow sheath with very low temperatures. The plants of Arnebia benthamii over winter in the form of seeds and perrenating rhizomes. Soon after snow melt the seasonal dawn of sprouting is set in 3rd and 4th week of May with cessation and completion executed/witnessed up to the end of first week of June. This phenophase is followed by elongation of floral stalk and bud formation, which experiences a partial overlap with the sprouting phenophase, witnessing initiation in the 4th week of May, lasting of bud formation up to 2nd week of June mid June. After bud formation, the anthesis, which acts as a gate way to the play ground of floral biology is switched on. Anthesis slightly overlaps with the previous phenophase extending up to 2nd week of July. The full bloom is witnessed in the last week of June and first week of July. Fruit formation starts from 2nd week of July and maturation materialized in by last week of August to first week of September. Then the seasonal dusk of senescence starts its business of snatching and fading the green dress turning it goldish.

 
 
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