Polyploid breeding in Portulaca grandiflora L.

Singh, Amrita

doi:10.1508/cytologia.44.167

Cited by 7 publications

(12 citation statements)

References 6 publications

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“…It is generally assumed that the number of quadrivalents is governed by the size of the chromosomes, chiasma frequency and excess of chromosomes within the cell which interfere with normal pairing. The less number of quad rivalents have been also reported in sunflower (Dhesi and Saini 1973) , Verbena (Arora 1975), Portulaca (Singh 1979), Helianthus annuus (Gupta and Roy 1983), Petunia hybrida (Singh and Roy 1988). A high degree of reversion from other chromosome associations to bivalents in second generation in the present experiment confirm the opinion of Bhatt (1977) and Singh (1979) and complete bivalent formation may take place in subsequent generations in tetraploids with low multivalent frequency.…”

Section: Discussionsupporting

confidence: 87%

“…Such autotetraploid plants with preponderance of bivalents have been recorded by other workers (Forbes and Burton 1963, Malik and Tripathi 1968, Harlan and de Wet 1969, Harlan et al 1970). Gupta andRoy (1983, 1986) and Singh andRoy (1987, 1988) confirmed that remarkable recovery of pollen fertility in subsequent generation due to the chromosome associations tended to change to normal pattern having lesser number of uni and tetravalents. Pollen sterility in autotetraploid Phlox causes less fruit and seed formation.…”

Section: Discussionmentioning

confidence: 87%

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Meiotic behaviour and pollen fertiity in C1 and C2 generation of autotetraploid Phlox.

Singh

1991

CYTOLOGIA

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Induced polyploidy is known to enhance the production potential of plants where veg etative organs and their biomass constitute the economic product (Lavania 1986). It is well known that experimentally produced autotetraploids show a reduced fertility as related to their diploid initial lines. This is true for the pollen as well as the seed fertility. With regard to the seed fertility, the situation is considerably worse. In the family Polemoniaceae, genus Phlox (2n=14) has mainly horticultural plants in which ploidy was induced to increase flower size as well as seed out put, with a hope that enough variability could be created by the induc tion of polyploidy and selection from segregation generation which would yield better genotype for the improvement of the plant. In the present study chromosome pairing behaviour and pollen fertility were investigated up to second (C2) generation. Materials and methodsThe seeds of Phlox drummondii Hook., family polemoniaceae, were collected from the healthy plants of botanical garden of the University. Seeds were tested for their diploid character and normal feature of meiosis. The colchicine solution was applied to the apical buds of the plant (see Singh and Roy 1984). First generation (C1)The effects induced by colchicine were measured by following parameters:Meiotic abnormalities For meiotic studies, flower buds were fixed in acetic-alcohol (1:3) with a few drop of ferric chloride in it to facilitate staining.Squashes were made permanent by t-butyl alcohol schedule and microphotographs were taken for every important observation and present whenever possible. Pollen fertilityHeating the pollen grains in a drop of 1% aceto-carmine solution, those which suitably stained were observed as fertile and the empty, shrunken ones as sterile. Fertility percentage was scored on the average of 200 pollen grains. Second generation (C2)The seeds were collected from C1 generation and sown for the study of C2 generation.Meiotic abnormalities Second generation meiocytes were examined on the lines of first generation (C1).

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Section: Discussionsupporting

confidence: 87%

Section: Discussionmentioning

confidence: 87%

Meiotic behaviour and pollen fertiity in C1 and C2 generation of autotetraploid Phlox.

Singh

1991

CYTOLOGIA

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“…Myers (1943, '45) said that frequencies of quadrivalents are of minor importance in meiotic regularity, while several others (Plarre 1954, Hilpert 1957, McCollum 1958, Aastveit 1968 claimed that the frequency of bivalents and not quadrivalents lead to the formation of balanced gametes. A high degree of reversion from other chromosome associations to bivalents in second generation in the present investigation, confirm the opinion of Bhatt (1977) and Singh (1979) that complete bivalent formation may take place in subsequent generations in tetraploids having a low multivalent frequency. For the reversion to the diploid initial situation, a double reduction is necessary in that way so that haploid microspores are formed from the tetraploid PMC's (Gottschalk 1978).…”

Section: Observationssupporting

confidence: 90%

“…The pre sent plant showed low frequency of multivalents. The occurrence of less number of quadri valents than the expected number of autotetraploids have been also reported in maize (Giles and Randolph 1951), Brassica (Swaminathan and Sulba 1959), Sunflower (Dhesi and Saini 1973), Verbena (Arora 1975), Portulaca (Singh 1979). Myers (1943, '45) said that frequencies of quadrivalents are of minor importance in meiotic regularity, while several others (Plarre 1954, Hilpert 1957, McCollum 1958, Aastveit 1968 claimed that the frequency of bivalents and not quadrivalents lead to the formation of balanced gametes.…”

Section: Observationsmentioning

confidence: 67%

“…Hazarika and Rees (1967) reported that univalents and multivalents due to segregational errors lower the fertility in autotetraploids. Singh (1979) in Portulaca grandiflora holds the view that higher pollen sterility and variation in number of spores per sporad may have resulted from disturbed meiosis in C1 which is evident by unequal separation of chromosomes at anaphase I and stray bivalent at metaphase I. The observations suggested that a greater frequency of bivalent chromosome associations does help in giving higher pollen fertility.…”

Section: Observationsmentioning

confidence: 95%

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Induced colchiploidy in Petunia hybrida Hort. Morphocytogenetical studies.

Singh

Roy

1988

CYTOLOGIA

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Increase in the productivity or improvement in the quality of a plant by the use of fertilizers has limitations while these aspects can be achieved with greater assertion and to a long range advantage by genetical means. Of these the application of the methods of selection, hybridi zation and polyploidy had been most fruitful in bringing about all round betterment in many cases of agricultural, horticultural or even wild plants. Petunia hybrida Hort. is a common ornamental plants grown for its beautiful flowers which range in colur from white to deep red or purple (Bailey 1958). With the increase of the ploidy level all or most of these can be achieved although they may be associated with some disadvantage such as poor seed setting. However, reduce seed setting or such disabilities may assume lesser importance in this orna mental because the plant has too many seeds per capsule. In the present experiment, P. hybrida (pink) has been selected to induce autoploidy to observe the following objectives: Lengthening of flowering period, increasing the colour diversity and improving the size and keeping quality of flowers. Materials and methodsThe seeds of Petunia hybrida Hort. (pink) Vilm. has been utilized in the present study and collected from the plants grown for several successive generations in the botanical graden of the university. Tested for their diploid character and normal feature of meiosis. The col chicine treatment was applied on apical portion of the plant (See Singh and Roy 1984).After treatment, the dimension of the plant parts changed and these were documented after measuring the plant height, internodal length, leaf (L/W), stomatal size, flower size and seed setting (Average of 10 plants in each case).For meiotic studies, flower buds of different treatment plants were fixed in acetic-alcohol (1:3) with a few drop of ferric chloride in it to improve staining. Squashes were made per manent by t-butyl alcohol schedule.Heating the pollen grains in a drop of 1% acetocarmine solution, those which suitably stained were taken as fertile and the empty shrunken ones as sterile. Fertility percentage was scored on the average of 200 pollen grains. ObservationsVarious concentration of colchicine (0.20-0.50%) was applied on the apical bud and the 0.25% concentration was found effective in inducing the maximum number of tetraploid plants. Out of thirty plants were treated with above solution, 63.33% plants were survived and only 30% turned out as tetraploid (Table 1). Seeds obtained from induced tetraploids by selfing were sown in the field and plants of C2 generation were also found to be tetraploid on being cytologically investigated. Observations on induced autotetraploidy in P. hybrida was extended over first (C1) and second (C2) generation using suitable parameters.

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Reproductive biology and intergeneric breeding compatibility of ornamental Portulaca and Calandrinia (Portulacaceae)

2009

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Portulaca grandiflora Hook and P. umbraticola Kunth (Portulacaceae) are popular garden annuals, and have been bred for improved ornamental value. However, limited research has been published on hybridisation of Portulaca, with no reports on intergeneric hybridisation. Calandrinia balonensis Lindley and Calandrinia sp. nov. (not yet fully classified) are floriferous Australian Portulacaceae species, with potential as novel flowering pot plants, and are potential candidates for breeding with ornamental Portulaca. We studied the reproductive biology of these four species and breeding compatibility for reciprocal crosses of P. grandiflora × C. balonensis (2n = 18) and P. umbraticola × C. sp. nov. (2n = 24). All four species produced seeds for intraspecific outcrosses. P. grandiflora and C. sp. nov. are partially self-compatible whereas P. umbraticola and C. balonensis are highly self-incompatible. Autogamy was detected only for P. grandiflora. Reciprocal crosses of P. grandiflora × C. balonensis and P. umbraticola × C. sp. nov. with similar chromosome numbers did not produce seeds, primarily because of pollen–pistil incompatibility that prevents pollen-tube growth within the stigmata. Methods to overcome hybridisation barriers of these species combinations need to be established to create novel products for ornamental horticulture.

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Polyploid breeding in Portulaca grandiflora L.

Cited by 7 publications

References 6 publications

Meiotic behaviour and pollen fertiity in C1 and C2 generation of autotetraploid Phlox.

Meiotic behaviour and pollen fertiity in C1 and C2 generation of autotetraploid Phlox.

Induced colchiploidy in Petunia hybrida Hort. Morphocytogenetical studies.

Reproductive biology and intergeneric breeding compatibility of ornamental Portulaca and Calandrinia (Portulacaceae)

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