Genome size and environmental factors in the genus Pinus

Abstract

Nuclear 1C DNA content in haploid megagametophyte tissue of 18 North American and one exotic Pinus species was determined using scanning microspectrophotometry. The nuclear DNA content in root meristematic cells of Zea mays L. ssp. mays, inbred line Va35 (4C = 10.31 pg) was used as a standard. DNA content measured by microspectrophotometry was verified using laser flow cytometry with two additional standards, Hordeum vulgare cv. Sultan (2C = 11.12 pg) and P. eldarica (2C = 47.30 pg). DNA values obtained by both methods were significantly correlated (r = 0.987). The 1C nuclear DNA content ranged from 21 pg to 31 pg. The ratio of DNA content in embryo tissue of P. eldarica to that in megagametophyte tissue was 1.72 by scanning microspectrophotometry and 1.74 by laser flow cytometry. To date, this is the most comprehensive data set available for North American Pinus species. Relationships between genome size of 18 North American Pinus species and climatic factors and indices of growth were investigated using regression and correlation analyses. Positive correlations were observed between nuclear DNA content and growth indices, minimum seed‐bearing age, and seed dimensions. Strong negative correlations were observed between nuclear DNA content and two climatic factors, the lowest mean annual and monthly precipitation (excluding January) and the highest mean monthly spring air temperature. These correlations suggest that the large genome size and its variation in Pinus are adapted responses to the habitats of these species.

The ten cytological races of the Scilla autumnalis species complex

“…5 it has been observed that in some plant species increases in nuclear DNA content are correlated positively or negatively with such parameters as seed mass, yield, growth indices, frost resistance, maturation and climatic factors (Wakamiya et a!., 1993;Fig. 6 Geographical distribution of the chromosomal races of the Scilla autumnalis species complex.…”

Genomic mapping in Pinus pinaster (maritime pine) using RAPD and protein markers

“…Pine genome organization Gynmosperm species are characterized by: (i) their antiquity (conifers appeared 140 millions years before the first angiosperm) and their longevity, (ii) the absence of ploidy level and chromosome number evolution (reviewed by Neale & Williams, 1991), and (iii) the very high and consistent amount of DNA per nucleus (Ohri & Khoshoo, 1986;Wakamiya et a!., 1993). The technique of DNA reassociation kinetics applied to Pinus species (Miksche & Hotta, 1973;Rake et at., 1980;Kriebel, 1985) showed that 25 per cent of total DNA is low-to single-copy, 75 per cent being middle to highly repetitive.…”

“…RAPDs have been used for genomic mapping in several conifer species (Neale & Sederoff, 1991;Tulsieram et a!., 1992;Nelson et a!., 1993;Bineffi & Bucci, 1994). Pinus species have a large genome (Ohri & Khoshoo, 1986;Wakamiya et a!., 1993) characterized by a high proportion of repetitive DNA (Miksche & Hotta, 1973;Rake et a!., 1980;Kriebel, 1985). Therefore, RAPDs and markers that are based on coding sequences could provide different coverage of the genome in pine.…”

Selfing and sibship structure in a two-cohort stand of maritime pine (Pinus pinaster Ait.) using nuclear SSR markers

“…The development of microsatellites in Pinus species has been reported to be difficult due to the size and complexity of their genome [23,50]. In Pinus pinaster, screening of a library enriched with CA and GA repeats and cross-species amplification were quite unsuccessful and only three primer pairs produced single variable bands segregating in a Mendelian manner ( [27], our unpublished results).…”