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Typus
Verschleierung
Bearbeiter
SleepyHollow02
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Untersuchte Arbeit:
Seite: 5, Zeilen: 1 ff. (komplett)
Quelle: Mohamed 2009
Seite(n): 3 f., Zeilen: 3: 7 ff.; 4: 1 ff.
[Studies with wild and cultivated barley have reported that there is more variation within the wild than in the] cultivated barley (Saghai Maroof et al. 1995), although in some cases the opposite has been reported for some isozymes and mitochondrial DNA (Nevo, 1992). The larger genetic variation within wild barley gives good opportunity to use this variation for breeding purposes like drought, salinity and diseases resistance.

1.3.3 Wild barley (H. vulgare ssp. spontaneum)

Wild barley represents an important genetic resource for cultivated barley, which has a narrowed gene pool due to intensive breeding. Therefore, it is inevitably to study the genetics of different traits in wild barley, if it can use for cultivars improvement. Hordeum vulgar ssp. spontaneum (wild barley) is the ancestor of cultivated barley. It belongs to the Poaceae-family of grasses and within it to the Triticeae-tribe. Triticeae is a temperate plant group mainly concentrated around central and South-eastern Asia, although the species belonging to it are distributed around the world. Triticeae includes many economically important cultivated cereals and forages but also about 350 wild species. The wild species are of great interest as potential gene donors for commercial breeding (Vanhala 2004).

Wild ancestry: The wild ancestor of the cultivated barley is well known. The crop shows close affinities to a group of wild and weedy barley forms which are traditionally grouped in Hordeum spontaneous C. Koch, but which are in fact, the wild race or subspecies of the cultivated crop. The correct name for this wild is therefore H. vulgare L. ssp. spontaneum (C. Koch). These are annual, brittle, two-rowed, diploid (2n = 14), predominantly self-pollinated barley forms and the only wild Hordeum stock that is cross compatible and fully interceptive with the cultivated barley, spontaneum X vulgare hybrids show normal chromosome pairing in meiosis (Bothmer 1992). Morphologically, the similarity between wild spontaneous and cultivated two-rowed distichal varieties is rather striking. They differ mainly in their modes of seed dispersal. Wild barley ears are brittle and maturity disarticulates into individual arrow-like triplets. These are highly specialized organs, which ensure the survival of the plant under wild conditions. Under cultivation this specialization broke down and non-brittle mutants were automatically selected for in the man-made system of sowing, reaping and threshing (Harlan and Zohary 1966, Zohary 1969).

The development of new barley cultivars tolerant of abiotic and biotic stress is an essential part of the continued improvement of the crop. The domestication of barley, as in many crops, resulted in a marked truncation of the genetic variation present in wild populations. This process is significant to agronomists and scientists because a lack of allelic variation will prevent the development of adapted cultivars and hinder the investigation of the genetic [mechanisms underlying performance.]

Studies with wild and cultivated barley have shown that there is more variation within

the wild than in the cultivated barley (Saghai Maroof et al. 1995), although in some cases the opposite has been reported for some isozymes and mitochondrial DNA (Nevo, 1992). The larger genetic variation within wild barley gives the opportunity to use this variation for breeding purposes.

1.2.3 Wild barley

Wild barley represents an important genetic resource for cultivated barley, which has a narrowed gene pool due to intensive breeding. Therefore, it is imperative to study the genetics of different traits in wild barley, if it is to be used for cultivar improvement. Hordeum vulgare ssp. spontaneum (wild barley) is the ancestor of cultivated barley. It belongs to the poaceae-family of grasses and within it to the triticeae-tribe. Triticeae is a temperate plant group mainly concentrated around central and South-eastern Asia, although the species belonging to it are distributed around the world. Triticeae includes many economically important cultivated cereals and forages but also about 350 wild species. The wild species are of great interest as potential gene donors for commercial breeding (Vanhala 2004).

Wild ancestry: The wild ancestor of the cultivated barley is well known. The crop shows close affinities to a group of wild and weedy barley forms which are traditionally grouped in Hordeum spontaneous C. Koch, but which are in fact, the wild race or subspecies of the cultivated crop. The correct name for this wild is therefore H. vulgare L. ssp. spontaneum (C. Koch). These are annual, brittle, two-rowed, diploid (2n = 14), predominantly self-pollinated barley forms and the only wild Hordeum stock that is cross compatible and fully interceptive with the cultivated barley, vulgare x spontaneum hybrids show normal chromosome pairing in meiosis (von Bothmer 1992). Also

[p.4:] morphologically, the similarity between wild spontaneous and cultivated two-rowed distichal varieties is rather striking. They differ mainly in their modes of seed dispersal. Spontaneous ears are brittle and maturity disarticulates into individual arrow-like triplets. These are highly specialized devices, which ensure the survival of the plant under wild conditions. Under cultivation this specialization broke down and non-brittle mutants were automatically selected for in the man-made system of sowing, reaping and threshing (Harlan and Zohary 1966, Zohary 1969).

The development of new barleys tolerant of abiotic and biotic stress is an essential part of the continued improvement of the crop. The domestication of barley, as in many crops, resulted in a marked truncation of the genetic variation present in wild populations. This process is significant to agronomists and scientists because a lack of allelic variation will prevent the development of adapted cultivars and hinder the investigation of the genetic mechanisms underlying performance.

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