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Islam-Faridi N, Hodnett GL, Zhebentyayeva T, Georgi LL, Sisco PH, Hebard FV, Nelson CD. Cyto-molecular characterization of rDNA and chromatin composition in the NOR-associated satellite in Chestnut (Castanea spp.). Sci Rep 2024; 14:980. [PMID: 38225361 PMCID: PMC10789788 DOI: 10.1038/s41598-023-45879-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Accepted: 10/25/2023] [Indexed: 01/17/2024] Open
Abstract
The American chestnut (Castanea dentata, 2n = 2x = 24), once known as the "King of the Appalachian Forest", was decimated by chestnut blight during the first half of the twentieth century by an invasive fungus (Cryphonectria parasitica). The Chinese chestnut (C. mollissima, 2n = 2x = 24), in contrast to American chestnut, is resistant to this blight. Efforts are being made to transfer this resistance to American chestnut through backcross breeding and genetic engineering. Both chestnut genomes have been genetically mapped and recently sequenced to facilitate gene discovery efforts aimed at assisting molecular breeding and genetic engineering. To complement and extend this genomic work, we analyzed the distribution and organization of their ribosomal DNAs (35S and 5S rDNA), and the chromatin composition of the nucleolus organizing region (NOR)-associated satellites. Using fluorescent in situ hybridization (FISH), we have identified two 35S (one major and one minor) and one 5S rDNA sites. The major 35S rDNA sites are terminal and sub-terminal in American and Chinese chestnuts, respectively, originating at the end of the short arm of the chromosome, extending through the secondary constriction and into the satellites. An additional 5S locus was identified in certain Chinese chestnut accessions, and it was linked distally to the major 35S site. The NOR-associated satellite in Chinese chestnut was found to comprise a proximal region packed with 35S rDNA and a distinct distal heterochromatic region. In contrast, the American chestnut satellite was relatively small and devoid of the distal heterochromatic region.
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Affiliation(s)
- Nurul Islam-Faridi
- Forest Tree Molecular Cytogenetics Laboratory, Southern Institute of Forest Genetics, USDA Forest Service, Southern Research Station, Texas A&M University, College Station, TX, 77843, USA.
| | - George L Hodnett
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843, USA
| | - Tetyana Zhebentyayeva
- The Schatz Center for Tree Molecular Genetics, Department of Ecosystem Science and Management, The Pennsylvania State University, University Park, PA, 16802, USA
- Department of Forestry and Natural Resources, University of Kentucky, Lexington, KY, 40546, USA
| | - Laura L Georgi
- Meadowview Research Farms, The American Chestnut Foundation, 29010 Hawthorne Drive, Meadowview, VA, 24361, USA
| | - Paul H Sisco
- The American Chestnut Foundation, 50 North Merrimon Ave., Suite 115, Asheville, NC, 28804, USA
| | - Frederick V Hebard
- Meadowview Research Farms, The American Chestnut Foundation, 29010 Hawthorne Drive, Meadowview, VA, 24361, USA
| | - C Dana Nelson
- USDA Forest Service, Southern Research Station, Forest Health Research and Education Center, Lexington, KY, 40546, USA
- USDA Forest Service, Southern Institute of Forest Genetics, Harrison Experimental Forest, 23332 Success Road, Saucier, MS, 39574, USA
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Hodnett GL, Ohadi S, Pugh NA, Bagavathiannan MV, Rooney WL. Sorghum bicolor x S. halepense interspecific hybridization is influenced by the frequency of 2n gametes in S. bicolor. Sci Rep 2019; 9:17901. [PMID: 31784572 PMCID: PMC6884547 DOI: 10.1038/s41598-019-53193-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 10/26/2019] [Indexed: 11/20/2022] Open
Abstract
Tetraploid johnsongrass [Sorghum halepense (L.) Pers.] is a sexually-compatible weedy relative of diploid sorghum [Sorghum bicolor (L.) Moench]. To determine the extent of interspecific hybridization between male sterile grain sorghum and johnsongrass and the ploidy of their progeny, cytoplasmic (CMS), genetic (GMS) and chemically induced male sterile lines of Tx623 and Tx631 were pollinated with johnsongrass pollen. At maturity 1% and 0.07% of the developing seeds of Tx623 and Tx631 respectively were recovered. Ninety-one percent of recovered hybrids were tetraploid and two percent were triploid, the tetraploids resulting from 2n gametes present in the sorghum female parent. Their formation appears to be genotype dependent as more tetraploids were recovered from Tx623 than Tx631. Because a tetraploid sorghum x johnsongrass hybrid has a balanced genome, they are male and female fertile providing opportunities for gene flow between the two species. Given the differences in 2n gamete formation among Tx623 and Tx631, seed parent selection may be one way of reducing the likelihood of gene flow. These studies were conducted in controlled and optimum conditions; the actual outcrossing rate in natural conditions is expected to be much lower. More studies are needed to assess the rates of hybridization, fitness, and fertility of the progeny under field conditions.
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Affiliation(s)
- George L Hodnett
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843-2474, USA.
| | - Sara Ohadi
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843-2474, USA.,Department of Plant Sciences, University of California, Davis, CA, 95616, USA
| | - N Ace Pugh
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843-2474, USA.,School of Plant Sciences, University of Arizona, Tucson, AZ, 85721, USA
| | | | - William L Rooney
- Department of Soil and Crop Sciences, Texas A&M University, College Station, TX, 77843-2474, USA
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Zwick MS, Islam-Faridi MN, Zhang HB, Hodnett GL, Gomez MI, Kim JS, Price HJ, Stelly DM. Distribution and sequence analysis of the centromere-associated repetitive element CEN38 of Sorghum bicolor (Poaceae). Am J Bot 2000; 87:1757-1764. [PMID: 11118410 DOI: 10.2307/2656825] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Fluorescence in situ hybridization (FISH) of a large-insert genomic clone, BAC 22B2, previously suggested that Sorghum bicolor (2n = 20) has the tetraploid architecture A(b)A(b)B(b)B(b). Here, we report on BAC 22B2 subclone pCEN38 (1047-bp insert) as related to sorghum and sugarcane. Mitotic FISH of six different subclones of BAC 22B2 showed that pCEN38 produced the strongest specificity to the A(b) subgenome and signal occurred primarily near centromeres. Southern blots of pCEN38 to 21 crop plants revealed a narrow taxonomic distribution. Meiotic metaphase I FISH positioned pCEN38 sequences near active centromeres. Pachytene FISH revealed that the distributions are trimodal in several B(b) and possibly all sorghum chromosomes. DNA sequencing revealed that the pCEN38 fragment contains three tandemly repeated dimers (<280 bp) of the same sequence family found in sorghum clone pSau3A10, and that each dimer consists of two divergent monomers (<140 bp). Sequence comparisons revealed homology between the pCEN38 monomers and the SCEN 140 bp tandem repeat family of sugarcane. FISH of pCEN38 yielded signal in centromere regions of most but not all sugarcane chromosomes. Results suggest that sugarcane and sorghum share at least one ancestor harboring elements similar to pCEN38 and SCEN and that each species had an ancestor in which the repetitive element was weakly present or lacking.
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Affiliation(s)
- M S Zwick
- Investigen Inc., 851 West Midway Ave., Alameda, California 94501 USA
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Hodnett GL, Crane CF, Stelly DM. A rapid stain-clearing method for video based cytological analysis of cotton megagametophytes. Biotech Histochem 1997; 72:16-21. [PMID: 9062705 DOI: 10.3109/10520299709082206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Optical "clearing" is a cost saving method for preparing large numbers of whole, dissected or thickly sectioned cytological specimens such as plant ovules and ovaries. Minimal labor is required and specimens retain three-dimensional integrity. Previous development of high contrast stain-clearing methods using hemalum to impart contrast has facilitated analysis and photography under bright field illumination for small ovules. The deep stain intensity of hemalum, however, often precludes adequate light transmission and contrast within internal focal planes, limiting the applicability of hemalum-based stain-clearing to small specimens. Having encountered this problem for nucelli of cotton (Gossypium barbadense L.), which are roughly 300 microns thick at fertilization, we have developed a modified stain-clearing system. The two key features of these new methods are the use of azure, C, which allows the intensity of staining to be readily regulated, and contrast manipulation via video signal and image processing. Intensity of azure C stain was readily controlled by modifying the staining and/or dehydration media to produce relatively low contrast specimens. Analysis was facilitated by indirect viewing on a video monitor using adjustments of sensitivity, exposure, and contrast of the charge-coupled device (CCD) camera. Digital processing provided further enhancement. Acceptable images were obtained from virtually all specimens. These methods, which combine low contrast (high transmittance) specimens with high contrast imaging, should facilitate data acquisition on reproduction, thus the developmental and genetic characterization of reproductive mutants. Other applications, e.g., in pathology and embryology, are readily envisioned.
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Affiliation(s)
- G L Hodnett
- Department of Soil and Crop Sciences, Texas A & M University, College Station 77843-2474, USA
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