Cytogenetic analysis of interspecific hybrids and amphiploids between two diploid crested wheatgrasses, Agropyron mongolicum and A. cristatum
19
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
Agropyron mongolicum Keng, the narrow linear-spiked diploid species (2n = 14), was hybridized with the broad pectinate-spiked diploid (2n = 14), A. cristatum (L.) Gaertner. The F 1 hybrids were all diploids and morphologically intermediate to their parents. Chromosome pairing at metaphase I in the hybrids averaged 1.40 I, 5.59 II, 0.35 III, and 0.09 IV per cell, demonstrating that the two parental genomes are very similar. The F 1 hybrids were partially fertile. The F 2 progeny showed a broad array of variations in spike morphology and chromosome pairing behavior. Cytological data of the F 1 hybrids and the F 2 progeny revealed that these two diploid species contain the same basic P genome but differ by structural rearrangements of some chromosomes. The patterns of multivalent associations were the result of a heterozygous reciprocal translocation between a long and a very short chromosome segment. The colchicine-induced C 0 amphiploids were fully fertile with regular chromosome pairing behavior. These two diploid species are the likely source of morphological variation in the tetraploid crested wheatgrasses.Key words: Agropyron, cytogenetics, chromosome pairing, interspecific hybrids.Keywords:
Agropyron cristatum
Agropyron
Chromosome pairing
Polyploid
Cite
Agropyron cristatum
Agropyron
Cite
Citations (28)
Agropyron cristatum, Agropyron intermedium, Agropyron riparium, Elymus junceus and Stipa viridula were studied in relation to clipping effects on productivity and longevity. All species, except Elymus junceus, produced progressively less as number of clippings increased. Agropyron intermedium yielded the most forage, especially when harvested only once per season, followed closely by Agropyron cristatum. Crude protein yield was less variable under various frequencies of clipping than forage yield, and differences between species were also smaller. Elymus junceus and Agropyron cristatum displayed the strongest competitive ability, especially under frequent clipping and Stipa viridula the lowest. The amount of root produced varied significantly between species. Agropyron cristatum and Elymus junceus produced the most root and Stipa viridula the least. Fertilizer applied in the fourth and fifth crop years increased the yield by 30 to 200 per cent. It was concluded that Agropyron cristatum and Elymus junceus were about equally persistent under frequent clipping and should be more useful long-term pasture grasses than the other three in dry cold climates.
Agropyron cristatum
Agropyron
Elymus
Stipa
Clipping (morphology)
Leymus
Agrostis
Cite
Citations (25)
Dewey, Douglas R. (Utah State U., Logan.) Morphology and (cytology of synthetic hybrids of Agropyron trichophorum X Agropyron cristatum. Amer. Jour. Bot. 50(10): 1028–1034. Illus 1963.—Three hybrids were obtained from controlled crosses of pubescent wheatgrass, A. trichophorum (2 n = 42), and hexaploid crested wheatgrass, A. cristatum (211 = 42). The hybrids were intermediate between the parent plants for all vegetative and spike characteristics observed. Under open pollination, 2 of the hybrids set 2 seeds each, and the other hybrid produced 60 seeds. Meiosis in the parent plants was basically regular. Average motaphase‐I chromosome associations were 0.09 I, 20.56 II, 0.05 III, and 0.16 IV per cell in the A. trichophorum parent, which was described as a segmental autoallohexaploid. The hexaploid A. cristatum parent averaged 0.18 I, 7.44 II, 0.81 III, 2.86 IV, 0.08 V, and 2.11 VI per cell at diakinesis and was described as an autohexaploid. Chromosome pairing in the hexaploid hybrid averaged 5.08 I, 8.94 II, 4.33 III, 1.11 IV, 0.27 V, and 0.05 VI per cell. On the basis of chromosome pairing in the parent species and their hybrids, it was concluded that 1 of the A. trichophorum genomes was partially homologous with the 3 genomes of hexaploid A. cristatum . Genome formulae for hexaploid A. cristatum , A. trichophorum , and their hybrids were represented as AAAAAA, A 1 A 1 B 1 B 1 B 2 B 2 , and AAAA 1 B 1 B 2 respectively.
Agropyron cristatum
Agropyron
Chromosome pairing
Chromosome number
Cite
Citations (6)
Hexaploid A. repens, 2n = 42, and diploid A. cristatum, 2n = 14, were hybridized and gave rise to two 28-chromosome reciprocal hybrids. Approximately 1% of hand-emasculated florets of both parent species produced viable hybrid seed following controlled pollination. Early embryo abortion prevented greater hybrid seed set on A. repens, whereas failure of fertilization appeared to be the major cause of poor hybrid seed set on A. cristatum. Reciprocal differences in hybrid vegetative and spike morphology were striking. The A. repens × A. cristatum hybrid was vigorous, highly rhizomatous, and bore abundant spikes whose morphology was intermediate between that of the parent species. A. cristatum × A. repens hybrids were weak, non-rhizomatous with frequently-malformed spikes. Mean chromosome associations of 0.10 I, 20.10 II, and 0.43 IV were observed in 134 metaphase-I cells of A. repens. Subsequent meiotic stages were regular except for occasional laggards and bridges at anaphase I and II. Metaphase-I chromosome associations averaged 0.07 I and 6.97 II in 124 A. cristatum cells. Chromosome pairing in the hybrids was highly variable and averaged 11.45 I, 7.58 II, 0.44 III, and 0.02 IV per cell in 187 cells interpreted. From 5 to 14 laggards appeared in every hybrid cell at anaphase I. Bridges were observed in approximately 25% of the anaphase-I cells. Similar irregularities were observed at anaphase II. Pollen viability was estimated as 3%, and the hybrids failed to set viable seed. On the basis of chromosome pairing in the species itself and in the hybrids, A. repens was designated as a segmental autoallohexaploid with a genome formula of the type A1A1A2A2BB. Although A. repens and A. cristatum chromosomes paired occasionally, the genomes of the 2 species were essentially non-homologous. Some of the interpretational difficulties of genome analysis were discussed.
Agropyron cristatum
Repens
Agropyron
Cite
Citations (3)
Agropyron cristatum
Agropyron
Morphology
Cite
Citations (2)
Agropyron cristatum L. Gaertner (2n = 14) and Agropyron desertorum (Fisch. ex Link) Schultes (2n = 28) cultivars were crossed with common wheat (Triticum aestivum L. em. Thell. 2n = 42, ABD genomes) in an attempt to bring the P genome of Agropyron into a wheat background for future genetic exploitation and to evaluate possible homoeology with the wheat genomes. Interspecific hybrid plants were obtained from crosses using both Agropyron species. Chromosome doubled amphiploids (2n = 56, AABBDDPP) were successfully produced by colchicine treatment of hybrid plants from the T. aestivum – A. cristatum cross. Meiotic cells of the amphiploid contained the expected 28 chromosome pairs but also exhibited a considerable amount of chromosome pairing disturbance, resulting in an average of 3.55 univalents per cell. Consequently, fertility was reduced in the amphiploid and the progeny were frequently aneuploid. Homoeologous pairing in the T. aestivum – A. cristatum hybrid was low, but the pairing disruption exhibited in the amphiploid suggested that homoeologous relationships may have been masked in the hybrid.Key words: Triticum aestivum, Agropyron cristatum, chiasma frequency, intergeneric hybrid, amphiploid.
Agropyron cristatum
Agropyron
Chromosome pairing
Common wheat
Cite
Citations (51)
Agropyron cristatum (2n = 4x = 28, PPPP) possesses potentially valuable traits that could be used in wheat (Triticum aestivum) improvement through interspecific hybridization. Homoeologous pairing between wheat chromosomes and P chromosomes added to wheat in a set of wheat - A. cristatum addition lines was assessed. First, the Ph-suppressing effect of P chromosomes (except 7P) was analyzed. It was concluded that this system is polygenic with no major gene, and consequently, has no prospect in the transfer of alien genes from wild relatives. In a second step, the potential of the deletion ph1b of the Ph1 gene for inducing P-ABD pairing was evaluated. Allosyndetic associations between P and ABD genomes are very rare. This very low level of pairing is likely due to divergence in the repeated sequences between Agropyron and wheat genomes. Development of translocation lines using ionizing radiation seems to be a more suitable technique than homoeologous recombination to exploit the A. cristatum genome in wheat improvement.
Agropyron cristatum
Agropyron
Chromosome pairing
Common wheat
Triticeae
Cite
Citations (21)
تحقیق حاضر به منظور بررسی و مقایسه مقاومت به خشکی در سه گونه مرتعی انجام گردید. گونه هایی که در این تحقیق مورد بررسی قرار گرفتند عبارت بودن از: Ag. Cristanum Agropyron desertorum و Stipa barbata. این گونه ها چندساله، در مرحله ای از رشد خوشخوراک و از نظر مقاومت به خشکی نیز مهم می باشند. تحقیق در گلخانه دانشکده منابع طبیعی دانشگاه تهران انجام شد. طرح آماری که در این تحقیق مورد استفاده قرار گرفت به صورت طرح کاملا تصادفی بود و با انتخاب 3 گونه گیاهی، 3 تیمار دور آبیاری (3، 6 و 12روزه) و 4 تکرار انجام گردید. ویژگی های گیاهی گونه های مورد بررسی در سه مرحله مورد ارزیابی و اندازه گیری قرار گرفت. در مرحله نخست میزان پژمردگی گونه ها، پتانسیل آب برگ، مقدار وزن خشک اندام های هوایی، مقدار وزن خشک ریشه، مقدار وزن خشک کل (مجموع وزن ریشه و اندام های هوایی) و نسبت ریشه به اندام های هوایی مورد بررسی قرار گرفت. در مرحله دوم مقدار کربوهیدرات محلول گونه ها با استفاده از ماده خشک آنها اندازه گیری شد. نتایج بدست آمده از تحقیق نشان داد که با افزایش زمان تنش میزان پژمردگی گونه ها افزایش یافته است. گونه Stipa barbata دارای بیشترین میزان پژمردگی بوده، دو گونه Agropyron desertorum و cristatum Ag. دارای میزان پژمردگی یکسانی بودند. با افزایش زمان تنش از مقدار وزن خشک اندام های هوایی و وزن خشک کل گونه ها کاسته شده و بر وزن خشک ریشه و نسبت ریشه به اندام های هوایی در گونه Sripa barbata نسبت به دو گونه Agropyron desertorum وAgropyron cristatum تفاوت معنی داری داشته در سطح پایین تری قرار داشت. دو گونه Agropyron در هیچ کدام از خصوصیات فوق با یکدیگر تفاوت معنی دار نداشتند. پتانسیل آب برگ گونه ها در دوره های مختلف آبیاری در هیچ یک از گونه ها تفاوت معنی دار نشان نداد. تغییرات ساختاری بوجود آمده در اجزاء برگ جهت مقابله با خشکی در دو گونه Agropyron شبیه به هم بوده و نسبت به گونه Sti[pa barbata سازگاری بیشتری برای مقابله با خشکی نشان دادند. با افزایش زمان تنش بر مقدار کربوهیدرات محلول گونه ها افزوده شد اما در مقایسه سه گونه از نظر مقدار کربوهیدرات محلول، بین سه گونه تفاوت معنی دار وجود نداشت
Agropyron cristatum
Agropyron
Stipa
Cite
Citations (0)
Four interspecific hybrids of tetraploid A. spicatum × diploid A. cristatum ‘Fairway’ were obtained by controlled pollinations of emasculated and unemasculated spikes of A. spicatum. Most vegetative and spike characteristics of the hybrids were intermediate between those of the parent species. Tetraploid A. spicatum behaved cytologically as an autotetraploid, with mean chromosome associations of 0.09 I, 7.95 II, 0.03 III, and 2.98 IV being observed in 103 cells interpreted. The diploid A. cristatum was cytologically regular and formed 7 bivalents in 160 of 163 cells examined. Meiosis in the triploid hybrids was highly irregular, and these plants were completely sterile. Chromosomes of A. spicatum and A. cristatum differed sufficiently in size so that they could be distinguished in the hybrids. Seven bivalents and 7 univalents were formed in 90.5% of 262 cells interpreted at metaphase I. Mean chromosome associations of 6.87 I, 6.98 II, and 0.05 III were observed in the hybrids. Most chromosome pairing was due to autosyndesis of A. spicatum chromosomes, but A. cristatum chromosomes occasionally paired among themselves and with A. spicatum chromosomes. Tetraploid A. spicatum was considered to be an autotetraploid. On the basis of cytological evidence, A. cristatum, A. spicatum, and their interspecific hybrids were represented by genome formulae of AA, BBBB, and ABB, respectively.
Agropyron cristatum
Agropyron
Cite
Citations (3)