Somatic stability of microsatellite loci in Eastern white pine, Pinus strobus L.

Abstract

Variation at nuclear-and chloroplast-encoded microsatellite loci was studied among and within clonally propagated individuals of Eastern white pine. Total DNA was extracted and assayed from gamete-bearing tissue (megagametophytes) located on six different branch positions on each of 12 individual genets. No within-individual variation was observed among 12 loci studied. Estimates of numbers of mitotic cell divisions required to produce the tissue used as the source of genomic DNA were obtained by combining tree growth and anatomical data. This allowed for the calculation of upper bound estimates of numbers of mutations per locus per somatic cell division. The estimated somatic mutation rate was found to be substantially lower than those published for genomic microsatellite mutation rates in other plant species.

Microsatellite analysis of Rosa damascena Mill. accessions reveals genetic similarity between genotypes used for rose oil production and old Damask rose varieties

“…Red Damask used as an outgroup. The dendrogram was constructed after analysis with a set of 11 microsatellite markers derived from R. wichuraiana -No somatic mutations were detected after analysis of rametes and megagametophytes of Pinus strobes L. at eight microsatellite loci (Cloutier et al 2003). -A single hyper-mutable locus, out of eight loci, was identified in rametes of Robina pseudoacacia (Lian et al 2004) -Variation in the alleles of two out of ten microsatellite loci was detected among the plantlets derived from the single donor tree of Populus tremuloides (Rahman and Rajora 2001) -A high rate of intra-cultivar microsatellite variability was observed after analysis of 25 and 22 clones of the old grape cultivars Pinot noir and Chardonnay, where, respectively, 15 and 9 microsatellite loci out of the 100 analyzed possess mutated alleles in at least one clone (Riaz et al 2002) The modes of multiplication, cultivation, and selection of the oil rose very much resemble these of grape cultivars and clones, where plants of widely used cultivars are subject of intensive vegetative multiplication and cultivation, often followed by selection of the best performing plants and development of supposedly new clones from the same genotype.…”

Somatic deleterious mutation rate in a woody plant: estimation from phenotypic data

“…In some plant species, it has been estimated that there are fewer than a hundred somatic cell divisions, separating zygote formation from gamete formation, whereas, in others, there may be many thousands of such divisions. The actual number is difficult to determine with accuracy (Otto and Walbot, 1990;Cloutier et al, 2003;Scofield, 2006). In the case of long-lived plants, it has been argued that because of the large numbers of somatic cell divisions separating zygote from gamete formation, significant numbers of somatic mutations in theory can accumulate within the cell lineages that eventually differentiate into gametogenic tissue, and that this, in turn, should lead to a higher overall per-generation rate of mutation than observed in annual plants (Klekowski, 1988).…”

“…Rates of somatic mutation have been estimated by direct assay of marker locus genotypes in long-lived plants (for example, Cloutier et al, 2003;O'Connell and Ritland, 2004), but the fitness consequences of marker mutations are difficult to determine. In contrast, a more direct approach involves assaying the phenotypic effects of somatic mutation by measuring fitness of progeny (or gametophytes) produced by different portions of the plant (Schultz and Scofield, 2009).…”

Germline replications and somatic mutation accumulation are independent of vegetative life span in Arabidopsis

“…An important consequence of this developmental strategy is that somatic mutations acquired during vegetative growth can be transmitted to the next generation (2). Numerous studies have been conducted in attempts to understand whether and how somatic mutations contribute to fitness and evolution in plants (3)(4)(5)(6)(7)(8). DNA replication during cell division is hypothesized to be a leading cause of genetic mutation (9)(10)(11), and mutation rates are highly correlated with genome duplications in many taxa (12)(13)(14)(15)(16).…”

“…Thus, a critical impediment to the studies examining the role of somatic mutation in plant genome evolution is the lack of knowledge on the number of cell divisions separating a zygote from its gametes, a characteristic termed "cell depth" (17), and how that number changes with vegetative growth. To our knowledge, estimates of gametic cell depth in plants are limited to calculations based on mitotic index and growth rates (5,18) or total cell numbers and DNA content (19), which provide no information on correlations between cell depth and development.…”