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Vernalization Requirement (vernalization + requirement)
Selected AbstractsThe Characterization and Geographical Distribution of the Genes Responsible for Vernalization Requirement in Chinese Bread WheatJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 4 2009Qing-Ming Sun Abstract The frequency and distribution of the major vernalization requirement genes and their effects on growth habits were studied. Of the 551 bread wheat genotypes tested, seven allelic combinations of the three Vrn-1 genes were found to be responsible for the spring habit, three for the facultative habit and one for the winter habit. The three Vrn-1 genes behaved additively with the dominant allele of Vrn-A1 exerting the strongest effect. The allele combinations of the facultative genotypes and the discovery of spring genotypes with "winter" allele of Vrn-1 implied the presence of as yet unidentified alleles/genes for vernalization response. The dominant alleles of the three Vrn-1 genes were found in all ten ecological regions where wheat is cultivated in China, with Vrn-D1 as the most common allele in nine and Vrn-A1 in one. The combination of vrn-A1vrn-B1Vrn-D1 was the predominant genotype in seven of the regions. Compared with landraces, improved varieties contain a higher proportion of the spring type. This was attributed by a higher frequency of the dominant Vrn-A1 and Vrn-B1 alleles in the latter. Correlations between Vrn-1 allelic constitutions and heading date, spike length, plant type as well as cold tolerance were established. [source] Vernalization requirement of wild beet Beta vulgaris ssp. maritima: among population variation and its adaptive significanceJOURNAL OF ECOLOGY, Issue 4 2002Pierre Boudry Summary 1Seven populations of Beta vulgaris ssp. maritima (wild beet) situated along a latitudinal cline were studied for their vernalization requirement and its consequences for fitness. 2Various cold regimes were applied in glasshouses and experimental gardens with plants of different ages. Three additional experimental sites (on the French Mediterranean, Atlantic and North Sea coasts) situated near three of the sampled populations, and thus including a reciprocal transplant design, were used to evaluate the influence of latitude under natural conditions. Survival and plant size were measured over 3 years. 3The vernalization requirement was greater in plants from more northern origins. The level of cold required to allow flowering overcompensated for the colder springs, so that northern plants in northern sites flowered less than southern plants in southern sites. 4Young seedlings were more difficult to vernalize than plants that had already developed vegetative rosettes. 5Differences in vernalization requirement seem to be an adaptive response to spring temperatures and season length in a particular latitude. A whole winter vernalization almost always led to flowering in the subsequent year whatever the latitude or geographical origin. 6Plants from the Atlantic and Channel coasts showed the highest lifetime reproductive success at all sites. Southern populations were better adapted to disturbed habitats as shown by their higher first-year reproductive success. The North Sea population had a lower reproductive success than the Atlantic populations, even in its native environment. [source] Transgenic weed beets: possible, probable, avoidable?JOURNAL OF APPLIED ECOLOGY, Issue 4 2002Benoît Desplanque Summary 1Weed beets pose a serious problem for sugar beet Beta vulgaris crops. Traditionally, the only efficient method of weed control has been manual removal, but the introduction of transgenic herbicide-tolerant sugar beets may provide an alternative solution because non-tolerant weed beets can be destroyed by herbicide. We evaluated the possibility that new, transgenic, weed beets may arise by gene flow between wild and crop plants. 2In a study area in northern France, weed beets were present in variable densities in sugar beet fields of up to 80 weed beet plants m,2. Weed beets arise from a long-lived seed bank, with seeds germinating from depths of 5 cm or less. In addition, diploid F1 crop,wild hybrids and triploid variety bolters (individuals with a low vernalization requirement) were present in low densities in virtually all sugar beet fields. We found gene flow to be possible between all forms, illustrated by both overlapping flowering periods in the field and successful controlled cross-pollinations. 3The F1 crop,wild hybrids result from pollination in the seed-production region by wild plants possessing the dominant bolting allele B for flowering without experiencing a period of cold. In the case of a transgene for herbicide tolerance incorporated into male-sterile seed-bearer plants, such hybrids will contain both the herbicide-tolerance and the bolting allele. Contamination of the fields by transgenic weed beets will be the result unless bolters are removed manually. The same will apply in the case of a cytoplasmically inherited transgene. 4Incorporation of the transgene into the pollinator plants will prevent the immediate formation of transgenic weed beets. However, in sugar beet fields, variety bolters may successfully cross-pollinate with weed beets in neighbouring fields. The use of diploid pollinator plants instead of tetraploids will considerably enhance gene flow towards wild beets, and is not, therefore, an attractive option. 5In conclusion, the appearance of transgenic weed beets is possible but can best be retarded if the transgene for herbicide tolerance is incorporated into the tetraploid pollinator breeding line. [source] Vernalization requirement of wild beet Beta vulgaris ssp. maritima: among population variation and its adaptive significanceJOURNAL OF ECOLOGY, Issue 4 2002Pierre Boudry Summary 1Seven populations of Beta vulgaris ssp. maritima (wild beet) situated along a latitudinal cline were studied for their vernalization requirement and its consequences for fitness. 2Various cold regimes were applied in glasshouses and experimental gardens with plants of different ages. Three additional experimental sites (on the French Mediterranean, Atlantic and North Sea coasts) situated near three of the sampled populations, and thus including a reciprocal transplant design, were used to evaluate the influence of latitude under natural conditions. Survival and plant size were measured over 3 years. 3The vernalization requirement was greater in plants from more northern origins. The level of cold required to allow flowering overcompensated for the colder springs, so that northern plants in northern sites flowered less than southern plants in southern sites. 4Young seedlings were more difficult to vernalize than plants that had already developed vegetative rosettes. 5Differences in vernalization requirement seem to be an adaptive response to spring temperatures and season length in a particular latitude. A whole winter vernalization almost always led to flowering in the subsequent year whatever the latitude or geographical origin. 6Plants from the Atlantic and Channel coasts showed the highest lifetime reproductive success at all sites. Southern populations were better adapted to disturbed habitats as shown by their higher first-year reproductive success. The North Sea population had a lower reproductive success than the Atlantic populations, even in its native environment. [source] Variation of freezing tolerance, Cor/Lea gene expression and vernalization requirement in Japanese common wheatPLANT BREEDING, Issue 5 2007M. Ishibashi Abstract Freezing tolerance and vernalization requirement are important traits for adaptation of wheat to growing in a high-latitude area. Fr-1 and Vrn-1, tightly linked on homoeologous group 5 chromosomes, are major loci for controlling the freezing tolerance and vernalization requirement, respectively. It was previously supposed that winter-habit wheat should possess a winter-type Fr-1 allele guaranteeing winter survival, but that such allele is unnecessary for spring-habit cultivars. To clarify such allelic linkage between the Vrn-1 and Fr-1 loci in the D genome, we studied freezing tolerance and vernalization requirement, and compared cold-responsive expression patterns of Cor (cold responsive)/Lea (late-embryogenesis-abundant), their putative transcription factor genes and three Vrn-1 homoeologs in Japanese common wheat cultivars. Wide variation of freezing tolerance and two alleles of Vrn-D1 were observed in the Japanese cultivars, whereas the accumulation levels of the Cor/Lea transcripts were not be correlated with the levels of freezing tolerance. The allelic linkage between Vrn-1 and Fr-1 loci well known in the A genome was not observed in the D genome of Japanese cultivars possessing Vrn-D1 or vrn-D1 allele. [source] The influence of a spring habit gene, Vrn-D1, on heading time in wheatPLANT BREEDING, Issue 2 2001H. Kato Abstract The adaptability of wheat cultivars to environmental conditions is known to be associated with a vernalization requirement, that is, spring/winter habit. To clarify the genetic effect of the spring habit gene, Vrn-D1, on heading time in the field, recombinant inbred lines (RILs) with or without the Vrn-D1 gene were produced from F2 plants of the cross between ,Nanbukomugi' and ,Nishikazekomugi', non-carrier and carrier cultivars of this gene, respectively. Using growth chambers with a controlled temperature and photoperiod, three components of heading time, i.e. vernalization requirement, photoperiodic sensitivity and narrow-sense earliness (earliness per se), were evaluated in each RIL. RILs with the Vrn-D1 gene (E lines) showed greatly reduced vernalization requirements and slightly shorter narrow-sense earliness than RILs without Vrn-D1 (L lines), although no difference in photoperiodic sensitivity was observed between the two groups. RILs were planted at four different sites in Japan and examined for their heading time in the field. E lines headed significantly earlier than L lines at all locations, indicating that the earliness of E lines is stable in various environmental conditions. These results indicated that spring habit caused by Vrn-D1 gene, as well as narrow-sense earliness, was responsible for heading time in the field. [source] | ||||||||||