Genome size and plant development in hexaploid Festuca arundinacea

Abstract

The development of plants belonging to natural populations of hexaploid Festuca arundinacea with different basic amounts of nuclear DNA was studied. A previous investigation showed that the genome sizes of the populations correlate positively with the mean temperature during the year and with that of the coldest month at the stations. Mitotic cycle time is affected by nuclear DNA content; in a population with a C-value of 6.05 pg, it is 3 h shorter than in a population with a Cvalue of 8.28 pg. In contrast, the genome size affects neither the proportion of cells entering mitosis in the meristems, nor the enlargement of cells in differentiated leaf tissues. By studying plant development in 30 populations, it was found that their genome size correlates negatively with the seed germination power (P= 0.036) and the early growth of both the seminal root (P= 0.009) and the first foliage leaf (P= 0.099). By contrast, the genome size correlates positively with the height of the highest culm (P 0.014) and other quantitative characters of the plants at anthesis, as well as with their flowering time (P 0.037). It is suggested that the variations in the basic amount of nuclear DNA within F. arundinacea have a role in improving the fitness of plants in environments differing in climatic factors such as temperature.

Developmental and environmental variation in genomes

“…A significant inverse correlation between genome size and developmental rate has been found in five freshwater cyclopoid species at three temperatures, that is, species with smaller genomes developed faster (Wyngaard et al, 2005). In hexaploid F. arundinacea, DNA content is positively correlated with mitotic time and flowering time (Ceccarelli et al, 1993). The genome sizes of F. arundinacea natural populations correlate positively with the mean temperature during the year and with that of the coldest month at the stations (Ceccarelli et al, 1993).…”

“…In hexaploid F. arundinacea, DNA content is positively correlated with mitotic time and flowering time (Ceccarelli et al, 1993). The genome sizes of F. arundinacea natural populations correlate positively with the mean temperature during the year and with that of the coldest month at the stations (Ceccarelli et al, 1993). Both cell proliferation in the shoot meristems and cell enlargement in differentiated tissues are affected by the genome size; for example, the basic amount of nuclear DNA is negatively correlated with the height of the main stem of the Vicia faba plants at anthesis (Minelli et al, 1996).…”

Nucleotype and phenotype in Vicia faba

“…Thus, these DNA changes have been suggested to play a role in development and/or in environmental adaptation. This view has recently found confirmation in the observation that intraspecific alterations of the genome size may affect certain characters of the cellular and/or organismal phenotype (Karp et al, 1982;Cavallini et al, 1993;Ceccarelli et al, 1993;Natali Ct a!., 1993;Frediani et al, 1994 Repeated DNA sequences, and particularly noncoding highly repeated sequences, are involved as a rule in intraspecific genome size alterations.…”

“…the nuclear mass and volume; Bennett, 1985) rather than by producing more qualitative changes in the genotype. The significant correlations between genome size and phenotypic characters which have been found by studying a number of plants in certain species back this idea Ceccarelli et a!., 1993;Natali et a!., 1993). It may also find support in the observation that certain effects on the phenotype of intraspecific genome size variations are quite similar to those produced by the presence of supernumerary chromosomes in the nucleus (Ceccarelli et al, 1993). Changes in the basic amount of nuclear DNA do not affect the same phenotypic characters, or do not affect them in the same way, in the few plant species studied so far in this respect, probably on account of the genetic diversity occurring between them.…”

“…sativum and nonexistent in H. annuus. The generation time is correlated positively with the genome size in F arundinacea and H. annuus, whereas no such correlation exists in P sativum (data in Ceccarelli et a!., 1993;Natali et a!., 1993). On account of the preceding, the effects of changes in the basic genome size on developmental dynamics and phenotypic characters at the cellular and organismal level seem to be worth studying in other plant species.…”