Plant DNA flow cytometry and estimation of nuclear genome size.

Two new nuclear isolation buffers for plant DNA flow cytometry: a test with 37 species.

This article provides an up-to-date review concerning from basic issues of polyploidy to aspects regarding the relevance and role of both natural and artificial polyploids in plant breeding programs. Polyploidy is a major force in the evolution of both wild and cultivated plants. Polyploid organisms often exhibit increased vigor and, in some cases, outperform their diploid relatives in several aspects. This remarkable superiority of polyploids has been the target of many plant breeders in the last century, who have induced polyploidy and/or used natural polyploids in many ways to obtain increasingly improved plant cultivars. Some of the most important consequences of polyploidy for plant breeding are the increment in plant organs ("gigas" effect), buffering of deleterious mutations, increased heterozygosity, and heterosis (hybrid vigor). Regarding such features as tools, cultivars have been generated with higher yield levels, improving the product quality and increasing the tolerance to both biotic and abiotic stresses. In some cases, when the crossing between two species is not possible because of differences in ploidy level, polyploids can be used as a bridge for gene transferring between them. In addition, polyploidy often results in reduced fertility due to meiotic errors, allowing the production of seedless varieties. On the other hand, the genome doubling in a newly formed sterile hybrid allows the restoration of its fertility. Based on these aspects, the present review initially concerns the origin, frequency and classification of the polyploids, progressing to show the revolution promoted by the discovery of natural polyploids and polyploidization induction in the breeding program status of distinct crops.

The polyploidy and its key role in plant breeding.

Nuclear DNA Amounts in Angiosperms and their Modern Uses—807 New Estimates

Nuclear DNA Amounts in Angiosperms: Progress, Problems and Prospects

Nuclear DNA Amounts in Roses

Summary Colonies of Diplocarpon rosae derived from single conidia were isolated on malt extract agar, multiplied (at 23°C) and stored (at -20°C) on surface-sterilised leaf discs of a universally susceptible rose, ‘Frensham’. The resistance of 16 species and cultivars of Rosa to different isolates ofD. rosae was assessed using surface-sterilised leaf discs. Four pathotypes of D. vosae were distinguished on the basis of host range. One species and one hybrid were resistant to all pathotypes. Two species and two cultivars were susceptible to all pathotypes. Four species and six cultivars were interpreted as having vertical resistance because they were strongly resistant to some but not all pathotypes. Only species and hybrids of the section Cinnamomeae were resistant to the pathotype identified as CW1 whereas only roses of other origins were resistant to the pathotype DA2.

Resistance of roses to pathotypes of Diplocarpon rosae

The genus Rosa includes over 100 species, distributed throughout the temperate and subtropical regions of the Northern Hemisphere. According to Rehder (1960) the genus consists of 4 subgenera; 3 are monotypic and the fourth, Eurosa, includes all the remaining species grouped into 10 sections.The genus exhibits a typical polyploid series with a basic chromosome number of 7. Euploids range from 2n = 2x = 14, to 2n = 8x = 56 (Darlington and Wylie, 1955) and aneuploids are rare (Rowley, 1960).

Somatic embryogenesis in Rosa spp.

The genus Rosa includes more than 100 species which are distributed naturally in the Northern Hemisphere only (Rehder 1960). Most modern cultivated roses fall into two classes: the Hybrid Teas and the Floribundas. Hybrid Tea roses have large single flowers and are used primarily for cut flowers. The Floribunda roses have an inflorescence with several rather smaller flowers and are used primarily as garden roses.

Regeneration of Plants from Protoplasts of Rosa Species (Roses)

Protoplasts of three Rosa cultivars were fused with each other, with protoplasts of Prunus `Colt' and with protoplasts of Rubus laciniatus, using polyethylene glycol 4000 as a fusogen. Protoplasts of Prunus were incapable of cell division and those of Rosa and Rubus were disabled by treatments with metabolic inhibitors, either iodoacetate (IOA) or rhodamine 6-G (R6G). Parental protoplasts were then fused in combinations that required complementation for their survival. RAPD analysis of 41 fusion-derived cell lines showed that two lines resulting from fusions of Rosa + Rosa and one from a fusion of Rosa + Prunus, contained some DNA markers from both fusion partners. The others contained markers of only one fusion parent. This showed that after protoplast fusion, the heterokaryons did not develop into cell lines with stable hybrid nuclei. Plants regenerated from cell lines derived from Rosa + Prunus and Rosa + Rubus fusions contained DNA markers of only Rosa and their DNA amounts were no greater than that of the Rosa parent. However, they differed morphologically from the Rosa parent to a remarkable degree, possibly because they inherited undetected genes of Prunus or Rubus, or because they were somaclonal variants of the Rosa parent. Alternative strategies for the production of somatic hybrids are discussed.

https://link.springer.com/content/pdf/10.1007%2Fs10681-005-9011-5.pdf

K. Yokoya

Papers

Nuclear DNA Amounts in Roses

Resistance of roses to pathotypes of Diplocarpon rosae

Somatic embryogenesis in Rosa spp.

Regeneration of Plants from Protoplasts of Rosa Species (Roses)

Cell lines and plants obtained after protoplast fusions of Rosa + Rosa , Rosa + Prunus and Rosa + Rubus