We have developed a diagnostic method to screen rapidly for plant species potentially capable of biparental inheritance ofplastid DNA using the DNA fluorochrome 4',6-diamidino-2-phenylindole (DAPI) in conjunction with epifluorescence microscopy. Pollen shed from 235 plant species (including about 50 of agronomic importance) representing 80 families were screened. Putative plastid DNA was detected in the generative and/or sperm cells of pollen from 26 genera (43 species) representing 15 families. Plastid DNA was not detected in the generative or sperm cells of pollen from 192 plant species, thereby strongly suggesting that these species have only maternal inheritance. Our cytological diagnosis corroborated the known genetic evidence in 42 plant species and conflicted with the genetic reports in five species, which are discussed. The data suggest that biparental inheritance of plastids is rare; overall, it may occur in about 14% of flowering plant genera, examples of which are scattered among 19% of the families examined. This methodology also readily reveals whether pollen is bi- or trinucleate.

Rapid screening method to detect potential biparental inheritance of plastid DNA and results for over 200 angiosperm species

B chromosomes are extra chromosomes to the standard complement that occur in many organisms They can originate in a number of ways including derivation from autosomes and sex chromosomes in intraa

/pdf/b-chromosome-evolution-25cmhcd0kp.pdf

B-chromosome evolution.

Remains of barley (Hordeum vulgare) grains found at archaeological sites in the Fertile Crescent indicate that about 10,000 years ago the crop was domesticated there from its wild relative Hordeum spontaneum. The domestication history of barley is revisited based on the assumptions that DNA markers effectively measure genetic distances and that wild populations are genetically different and they have not undergone significant change since domestication. The monophyletic nature of barley domestication is demonstrated based on allelic frequencies at 400 AFLP polymorphic loci studied in 317 wild and 57 cultivated lines. The wild populations from Israel-Jordan are molecularly more similar than are any others to the cultivated gene pool. The results provided support for the hypothesis that the Israel-Jordan area is the region in which barley was brought into culture. Moreover, the diagnostic allele I of the homeobox gene BKn-3, rarely but almost exclusively found in Israel H. spontaneum, is pervasive in western landraces and modern cultivated varieties. In landraces from the Himalayas and India, the BKn-3 allele IIIa prevails, indicating that an allelic substitution has taken place during the migration of barley from the Near East to South Asia. Thus, the Himalayas can be considered a region of domesticated barley diversification.

/pdf/on-the-origin-and-domestication-history-of-barley-hordeum-2f8kuc8z2v.pdf

On the Origin and Domestication History of Barley (Hordeum vulgare)

The exploration, conservation and use of the genetic resources of plants is a contemporary issue which requires a multidisciplinary approach. Here the role of population genetic data, particularly those derived from electrophoretic analysis of protein variation, is reviewed. Measures of the geographic structure of genetic variation are used to check on sampling theory. Current estimates justify the contention that alleles which have a highly localised distribution, yet are in high frequency in some neighbourhoods, represent a substantial fraction of the variation. This class, which is the most important class in the framing of sampling strategies, accounts for about 20–30% of variants found in 12 plant species. The importance of documenting possible coadapted complexes and gene-environment relationships is discussed. Furthermore, the genetic structure of natural populations of crop relatives might suggest the best structure to use in the breeding of crops for reduced vulnerability to pest and disease attack, or for adaptation to inferior environments. The studies reported to date show that whilst monomorphic natural populations do occur, particularly in inbreeding colonisers, or at the extreme margins of the distribution, polymorphism seems to be the more common mode. It is stressed here that the genetic resources of the wild relatives of crop plants should be systematically evaluated. These sources will supplement, and might even rival, the primitive land races in their effectiveness in breeding programmes. We may look forward to a wider application of gel electrophoresis in the evaluation of plant genetic resources because this technique is currently the best available for detecting genetic differences close to the DNA level on samples of reasonable size.

Isozymes, plant population genetic structure and genetic conservation.

Polyploidy in populations of well-differentiated plant species is now widely recognized (1,2). Most reports, however, are limited to a few individuals from one or several populations and thereby illustrate only a fraction of the extant genomic diversity in most species. They rarely purport populational dynamics involving Polyploidy as an evolutionary process. Nevertheless, there are recent notable exceptions and these will be utilized freely in this review of Polyploidy within species populations.

Polyploidy in species populations.

The geographical distribution of accessory chromosomes in centaurea scabiosa

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1601-5223.1956.tb03026.x

The cytological behaviour of accessory chromosomes in centaurea scabiosa

The cytological behaviour and mode of transmission of accessory chromosomes in plantago serraria

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1601-5223.1958.tb03474.x

Studies of the genetical effects of accessory chromosomes in centaurea scabiosa

By means of thin-layer chromatography, 1424 local varieties of barley were investigated. Two collections of Hordeum spontaneum and one of H. agriocrithon were also analysed. In H. vulgare three distinctly different flavonoid patterns were found, designated A, B and C. The B pattern could be divided into two types: B1 and B2. The flavonoid pattern of H. spontaneum deviates sharply from those of H. vulgare. Hordeum agriocrithon has the same flavonoid pattern as the A pattern in H. vulgare. The flavonoid patterns A and B occur throughout the cultivated area of H. vulgare. However, differences in frequency between the A and B patterns were revealed when different areas were compared. Flavonoid pattern C is, with a few exceptions, found only in varieties of barley from Ethiopia. Controlled crossing experiments between the different flavonoid types of H. vulgare were performed on a limited scale. The phylogeny of H. vulgare in relation to H. spontaneum and H. agriocrithon is discussed. The flavone glycosides that constitute these differences are briefly reviewed.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1601-5223.1975.tb01469.x

Sune Fröst

Papers

The geographical distribution of accessory chromosomes in centaurea scabiosa

The cytological behaviour of accessory chromosomes in centaurea scabiosa

The cytological behaviour and mode of transmission of accessory chromosomes in plantago serraria

Studies of the genetical effects of accessory chromosomes in centaurea scabiosa

Flavonoid patterns and the phytogeny of barley