Genome Size Variation in Maize Populations Selected for Cold Tolerance

Abstract

Previous studies have indicated a relationship between genome size and cold tolerance in plants. Many species adapted to growth in cool environments have large genome sizes. These studies are based on interspecific DNA content variation. In this study, the nuclear DNA content of eight maize populations was determined. These populations were obtained from the University of Nebraska and represent populations selected for cold tolerance and their respective unselected original populations. Intraspecific DNA content variation was observed between the selected and unselected popolations. Upon assessing the data based solely on cold tolerance, no clear relationship between genome size and cold tolerance was apparent. When both freeze tolerance and cold tolerance were considered, populations which were cold tolerant and exhibited a certain degree of freeze tolerance were observed to have significantly larger genomes relative to the unselected populations. Thus, it appears that the relationship between intraspecific genome size variation and cold tolerance is similar to the relationship between interspecific genome size variation and growth at cooler temperatures in plants.

Genetic variation in Miscanthus × giganteus and the importance of estimating genetic distance thresholds for differentiating clones

“…Nuclei were analyzed using a flow cytometer Model LSRII (BD Biosciences, San Jose, CA, USA; Flow Cytometry Facility at the University of Illinois‐Keck Biotechnology Center). To estimate pg of DNA per 2C nucleus, mean fluorescence of the analyzed sample G1 peak was divided by the fluorescence reading of the G0/G1 peak of sorghum, multiplied by 1.74 pg/2C (McMurphy & Rayburn, ).…”

Synthetic polyploid production of Miscanthus sacchariflorus,Miscanthus sinensis, and Miscanthus x giganteus

“…The protocol is the same as described above with the replacement of the progenitor control with sorghum as the internal standard being cochopped with the Miscanthus lines. The 2C value of nDNA content of the sorghum line was calibrated at 1.74 pg using the maize genotype W‐22 as a calibration standard which is reported to have 5.35 pg DNA/2C (McMurphy & Rayburn, ). Mean fluorescence of the Miscanthus G1 peak is divided by the fluorescence reading of the internal standard, multiplied by 1.74 pg/2C, and expressed in pg/2C nucleus.…”

“…The 2C values of nDNA in five genome doubled lines for each of M. sinensis 'Grosse fontaine,' M. sacchariflorus 'Golf course,' and M. x giganteus 'Illinois' and their diploid or triploid progenitors (Table 2) were measured by flow cytometry with sorghum as an internal standard using the modified protocol of Rayburn et al (2009). The protocol is the same as described above with the replacement of the progenitor control with Rayburn, 1991). Mean fluorescence of the Miscanthus G1 peak is divided by the fluorescence reading of the internal standard, multiplied by 1.74 pg/2C, and expressed in pg/2C nucleus.…”

Dioscorea

“…For this purpose, flow cytometry has been recently used to determine ploidy levels in yams (Gamiette et al 1999). The method is non-destructive (one sample can be prepared from a few milligrams of leaf tissues), exceptionally rapid, sensitive and convenient, does not require dividing cells, and can detect both mixoploidy and aneuploidy (Galbraith et al 1983;De Laat et al 1987;Arumuganathan and Earle 1991a, b;McMurphy and Rayburn 1991;Dolezel 1997). Ploidy determination of D. alata, D. cayensis-rotundata and some wild yam species by flow cytometry and conventional chromosomes counting revealed variable ploidy levels of 4x, 6x, and 8x in the species (Gamiette et al 1999) with majority being tetraploid (Dansi et al 2000a).…”