scholarly journals Ploidy Mosaics - Does Endopolyploidy in Explants Affects the Cytogenetic Stability of Orchids Regenerated From PLBs?

Author(s):  
Yohan Fritsche ◽  
Thiago Sanches Ornellas ◽  
Valdir Marcos Stefenon ◽  
Miguel Pedro Guerra

Abstract The induction and regeneration of protocorm-like bodies (PLBs) is a morphogenetic pathway widely used for orchid micropropagation. As endopolyploidy, i.e., the coexistence of cells with different ploidy levels, is a common feature in orchid tissues, a natural question arises when using somatic tissues as explants for orchid micropropagation: does endopolyploidy in explants affect the cytogenetic stability of regenerated plantlets? To answer this question, Epidendrum fulgens was used as a model plant, and flow cytometry (FC) was used to analyze endopolyploidy in pollinia, petals, labella, leaf bases, leaf tips, root tips, protocorms bases and protocorms apexes, which were subsequently used as explants for PLB induction and plant regeneration. The ploidy screening showed contrasting ploidy patterns in the samples. Endopolyploidy was detected in all tissues, with C-values ranging from 1C to 16C. Protocorm bases and root tips presented the highest proportion of endopolyploidy, while petals and protocorm apexes showed the lowest proportion. Flower parts presented high oxidation for PLB induction and pollinia failed to produce PLB or callus. The highest induction rate was observed at 10 µM TDZ, with 92%, 22%, and 0.92% for protocorm bases, leaves, and root tips, respectively. Plantlets were more easily regenerated from PLBs induced from protocorm bases than from leaves and roots. Doubled ploidy levels were registered in a proportion of 11% and 33% for PLB-regenerated plantlets obtained from protocorm bases and leaf bases, respectively, which was not directly associated with the proportion of endopolyploid cells or cycle value of explants.

Genes ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1950
Author(s):  
Guadalupe Palomino ◽  
Javier Martínez-Ramón ◽  
Verónica Cepeda-Cornejo ◽  
Miriam Ladd-Otero ◽  
Patricia Romero ◽  
...  

Echeveria is a polyploid genus with a wide diversity of species and morphologies. The number of species registered for Echeveria is approximately 170; many of them are native to Mexico. This genus is of special interest in cytogenetic research because it has a variety of chromosome numbers and ploidy levels. Additionally, there are no studies concerning nuclear DNA content and the extent of endopolyploidy. This work aims to investigate the cytogenetic characteristics of 23 species of Echeveria collected in 9 states of Mexico, analyzing 2n chromosome numbers, ploidy level, nuclear DNA content, and endopolyploidy levels. Chromosome numbers were obtained from root tips. DNA content was obtained from the leaf parenchyma, which was processed according to the two-step protocol with Otto solutions and propidium iodide as fluorochrome, and then analyzed by flow cytometry. From the 23 species of Echeveria analyzed, 16 species lacked previous reports of 2n chromosome numbers. The 2n chromosome numbers found and analyzed in this research for Echeveria species ranged from 24 to 270. The range of 2C nuclear DNA amounts ranged from 1.26 pg in E. catorce to 7.70 pg in E. roseiflora, while the 1C values were 616 Mbp and 753 Mbp, respectively, for the same species. However, differences in the level of endopolyploidy nuclei were found, corresponding to 4 endocycles (8C, 16C, 32C and 64C) in E. olivacea, E. catorce, E. juarezensis and E. perezcalixii. In contrast, E. longiflora presented 3 endocycles (8C, 16C and 32C) and E. roseiflora presented 2 endocycles (8C and 16C). It has been suggested that polyploidization and diploidization processes, together with the presence of endopolyploidy, allowed Echeveria species to adapt and colonize new adverse environments.


Genes ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 27
Author(s):  
Marianna Paľová ◽  
Dajana Ručová ◽  
Michal Goga ◽  
Vladislav Kolarčik

Somatic polyploidy or endopolyploidy is common in the plant kingdom; it ensures growth and allows adaptation to the environment. It is present in the majority of plant groups, including mosses. Endopolyploidy had only been previously studied in about 65 moss species, which represents less than 1% of known mosses. We analyzed 11 selected moss species to determine the spatial and temporal distribution of endopolyploidy using flow cytometry to identify patterns in ploidy levels among gametophytes and sporophytes. All of the studied mosses possessed cells with various ploidy levels in gametophytes, and four of six species investigated in sporophytic stage had endopolyploid sporophytes. The proportion of endopolyploid cells varied among organs, parts of gametophytes and sporophytes, and ontogenetic stages. Higher ploidy levels were seen in basal parts of gametophytes and sporophytes than in apical parts. Slight changes in ploidy levels were observed during ontogenesis in cultivated mosses; the youngest (apical) parts of thalli tend to have lower levels of endopolyploidy. Differences between parts of cauloid and phylloids of Plagiomnium ellipticum and Polytrichum formosum were also documented; proximal parts had higher levels of endopolyploidy than distal parts. Endopolyploidy is spatially and temporally differentiated in the gametophytes of endopolyploid mosses and follows a pattern similar to that seen in angiosperms.


1998 ◽  
Vol 123 (1) ◽  
pp. 73-77 ◽  
Author(s):  
Mark W. Farnham

Using anther culture to generate doubled-haploid (DH) homozygous lines for use as parents in F1 hybrid crosses has become a common practice in breeding broccoli (Brassica oleracea L. Italica Group). During anther culture and subsequent embryogenesis and plant regeneration, polyploidization of microspore-derived embryos may not occur or it may occur accompanied by a doubling, tripling, quadrupling, octupling, or irregular polyploidization of the genome. Thus regenerants from the process can be haploids, diploids, triploids, tetraploids, octaploids, or aneuploids. The objectives of this research were to 1) conduct repeat cycles of broccoli anther culture using a group of F1 hybrids as anther donors and develop populations of regenerants; 2) analyze resulting populations using DNA flow cytometry and determine the influence of F1 source on frequency of different ploidy levels among regenerants; and 3) compare seed set in broccoli inbreds developed in a traditional selfing program compared to seed set in DH broccoli derived from anther culture. In two cycles (1994 and 1995) of anther culture, anther-derived populations of regenerants were developed using the F1 hybrids `Marathon', `Everest', `High Sierra', and `Futura' as sources of anthers. In 1994, `Everest', `High Sierra', and `Futura' yielded populations that included 2% to 7% haploids, 53% to 56% diploids, 32% to 38% tetraploids, and 5% to 6% other types. `Marathon'-derived regenerants were 5% haploid, 78% diploid, 15% tetraploid, and 2% other, showing significantly more diploids. In 1995, `Marathon' regenerants again included significantly more diploids and fewer tetraploids than those derived from other F1 sources, confirming that the genotype of the anther source affects the frequency of a particular ploidy level among regenerants derived from culture. In manual self-pollinations of 1994 regenerants, only diploids and rare tetraploids set seed. When plants that set no seed were discounted, seed production following manual self pollinations of 1995 regenerants was not significantly different from that of traditional inbreds derived from the same F1 sources.


Genome ◽  
1989 ◽  
Vol 32 (6) ◽  
pp. 1048-1053 ◽  
Author(s):  
Margaret J. Beaton ◽  
Paul D. N. Hebert

The haploid genome sizes (0.37 and 0.47 pg) of two members of the cladoceran crustacean genus Daphnia rank among the smallest known for Crustacea. An examination of cladoceran somatic tissues by scanning microdensitometry revealed abundant endopolyploidy in both species. Although cells in the labrum possessed the highest DNA content (1024C), endopolyploid cells (4–512C) were widely distributed throughout the body. Daphnia pulex and D. magna exhibited similar ploidy levels in most tissues, but differences between the two species were noted in the epidermis and labrum. The prevalence of polyploid nuclei suggests that endopolyploidy is an important process in organisms whose genomes have been miniaturized by nucleotypic selection.Key words: somatic polyploidy, genome size, Daphnia, ploidy shifts, macroevolution.


HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 612g-613
Author(s):  
Mark W. Farnham

Broccoli (Brassica oleracea L. Italica group) breeders are increasingly using anther or microspore culture to produce dihaploid (diploid), homozygous lines for use in making hybrids. During the process of anther culture and subsequent plant regeneration, wherein embryos develop from microspores and plants are regenerated from the embryos, polyploidization occurs and diploid regenerants can result. However, polyploidization may not occur at all, or it may involve a tripling or quadrupling of the chromosome complement, instead of a doubling. Thus, populations may contain haploids, triploids, or tetraploids, in addition to diploids. In two cycles (1994-95 and 1995-96) of anther culture, regenerated populations from different broccoli hybrid sources were evaluated using flow cytometry to facilitate efficient identification of diploids vs. haploids, tetraploids, or others and to determine if anther donor genotype has an effect on the frequency of different ploidy levels among regenerants. In the first cycle, five broccoli hybrids had anther-derived populations in which ≈33% were haploid, 55% diploid, 37% tetraploid, and 5% aneuploid or abherent types. The hybrid, `Marathon', was different; it's regenerants were 78% diploid and only 15% tetraploid. In the second cycle, anther-derived populations had a significantly different makeup with a most hybrids giving 30% to 40% diploids and 50% to 60% tetraploids. However, consistent with the previous cycle, `Marathon' gave significantly more diploids (68%) and fewer tetraploids (25%) than other hybrids. These results indicate that anther donor genotype affects ploidy frequency among regenerants. Genotypes producing a high frequency (>60%) of diploids may be relatively uncommon.


Genes ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 957
Author(s):  
Paulina Tomaszewska ◽  
Till K. Pellny ◽  
Luis M. Hernández ◽  
Rowan A. C. Mitchell ◽  
Valheria Castiblanco ◽  
...  

Urochloa (including Brachiaria, Megathyrus and some Panicum) tropical grasses are native to Africa and are now, after selection and breeding, planted worldwide, particularly in South America, as important forages with huge potential for further sustainable improvement and conservation of grasslands. We aimed to develop an optimized approach to determine ploidy of germplasm collection of this tropical forage grass group using dried leaf material, including approaches to collect, dry and preserve plant samples for flow cytometry analysis. Our methods enable robust identification of ploidy levels (coefficient of variation of G0/G1 peaks, CV, typically <5%). Ploidy of some 348 forage grass accessions (ploidy range from 2x to 9x), from international genetic resource collections, showing variation in basic chromosome numbers and reproduction modes (apomixis and sexual), were determined using our defined standard protocol. Two major Urochloa agamic complexes are used in the current breeding programs at CIAT and EMBRAPA: the ’brizantha’ and ’humidicola’ agamic complexes are variable, with multiple ploidy levels. Some U. brizantha accessions have odd level of ploidy (5x), and the relative differences in fluorescence values of the peak positions between adjacent cytotypes is reduced, thus more precise examination of this species is required. Ploidy measurement of U. humidicola revealed aneuploidy.


2021 ◽  
Vol 50 (1) ◽  
pp. 29-35
Author(s):  
Shu-Gen Wei ◽  
Ling-Yun Wan ◽  
Ying Wei ◽  
Li-Li He ◽  
Jin-E Fu ◽  
...  

Eighty nine Artemisia samples treated with different concentrations of colchicine were used as breeding samples, with diploid Artemisia as the control. The ploidy levels of samples were determined by flow cytometry and confocal laser scanning microscopy (CLSM). An analysis of the flow cytometry results identified three suspected tetraploid plants and seven suspected triploid plants. The results of this study may be useful for breeding new Artemisia lines.


HortScience ◽  
1997 ◽  
Vol 32 (3) ◽  
pp. 439D-439 ◽  
Author(s):  
Mary Ann Start ◽  
James Luby ◽  
Robert Guthrie ◽  
Debby Filler

The hardy Actinidia species represent a source of genetic diversity for improving A. deliciosa (kiwifruit) as well as for creating new economically important cultivars through intra- and interspecific crosses. Attempts at breeding in Actinidia have been complicated by the existence of intraspecific as well as interspecific variation in ploidy. The haploid chromosome number in Actinidia is 29 and diploid (2n=2x=58), tetraploid (2n=4x=116), and hexaploid (2n=6x=174) levels have been identified. Because of the problems encountered when crossing parents differing in ploidy level, it is desirable to know the ploidy levels of plants to be used in breeding. We determined the ploidy levels of 61 Actinidia accessions currently available in the U.S., including primarily accessions of relatively winter-hardy species. The 61 accessions, representing eight species and three interspecific hybrids, were screened for ploidy using flow cytometry. Mitotic root tip cells from one plant from each putative ploidy level were examined microscopically to confirm the ploidy level derived from flow cytometry. There were 17 diploids, 40 tetraploids, and 4 hexaploids. Intraspecific variation was not found among accessions of the species arguta, callosa, deliciosa, kolomikta, melanandra, polygama, or purpurea. All kolomikta and polygama accessions were diploid. All arguta, callosa, melanandra, and purpurea accessions were tetraploid. Actinidia deliciosa was hexaploid. One chinensis accession was tetraploid. Two accessions (NGPR 0021.14 and 0021.3), acquired as chinensis, were hexaploid and may, in fact, be A. deliciosa based on their morphology. `Issai' (arguta × polygama) was hexaploid and `Ken's Red' and `Red Princess' (both melanandra × arguta) were tetraploid.


2011 ◽  
Vol 21 (2) ◽  
pp. 135-141 ◽  
Author(s):  
A.K. M. Sayeed Hassan ◽  
Nadira Begum ◽  
Rebeka Sultana ◽  
Rahima Khatun

An efficient protocol was developed for shoot proliferation and plant regeneration of Phlogacanthus thyrsiflorus Nees. (Acanthaceae) - a rare medicinal shrub of Bangladesh, through in vitro culture using shoot tip and nodal explants. Best shoot induction was observed on MS with 1.0 mg/l BAP + 0.5 mg/l NAA, in which 84.2% of nodal explants responded to produce maximum number (12.4 ± 0.66) of shoots per culture. In vitro raised shoots rooted on half-strength MS with 0.5 mg/l IBA + 0.5 mg/l NAA. For acclimation and transplantation, the plantlets in the rooting culture tubes were kept in normal room temperature for 7 days before transplanting in pots where plantlets were reared for three weeks. The survival rate of regenerated plantlets was 85%. Key words: Phlogacanthus thyrsiflorus, Shoot proliferation, Plant regeneration   D. O. I. 10.3329/ptcb.v21i2.10236   Plant Tissue Cult. & Biotech. 21(2): 135-141, 2011 (December)


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