Vernalization Treatment Research Articles

487 Strategies to Enhance Production of Annual Globe Artichoke

Annual production of globe artichokes (Cynara scolymus L.) requires vernalization of the plants, either through cold treatment of transplants or from natural temperature conditions in the spring. Studies were conducted in upstate New York to determine if artificial vernalization treatments could be achieved by earlier planting dates. Initial trials evaluated two cultivars used for annual production in other parts of the country—'Imperial Star' and `Green Globe Improved'. Transplants were set in the field with or without a vernalizing cool treatment, to determine the extent of natural vernalization achieved under New York conditions. `Imperial Star' produced slightly higher marketable yields than `Green Globe Improved' in 2 years of trials. Vernalization treatment increased the number of plants producing buds and the marketable yields, when transplants were set after 15 May. Natural vernalization was achieved and cold treatment prior to transplanting did not improve yields of plants established in early May. At later planting dates, vernalizing transplants increased the number of plants producing apical buds (largest) by about 20%, yet, >57% of non-vernalized plants of each variety produced buds within the season. Average bud sizes did not vary with vernalization treatment. A similar number of days from transplanting to first bud harvest (69 to 75) was noted regardless of planting date and size of transplant.

FKF1, a Clock-Controlled Gene that Regulates the Transition to Flowering in Arabidopsis

Plant reproduction requires precise control of flowering in response to environmental cues. We isolated a late-flowering Arabidopsis mutant, fkf1, that is rescued by vernalization or gibberellin treatment. We positionally cloned FKF1, which encodes a novel protein with a PAS domain similar to the flavin-binding region of certain photoreceptors, an F box characteristic of proteins that direct ubiquitin-mediated degradation, and six kelch repeats predicted to fold into a β propeller. FKF1 mRNA levels oscillate with a circadian rhythm, and deletion of FKF1 alters the waveform of rhythmic expression of two clock-controlled genes, implicating FKF1 in modulating the Arabidopsis circadian clock.

Vernalization Strategies to Enhance Production of Annual Globe Artichoke

Annual production of globe artichokes (Cynara scolymus L.) requires vernalization of the plants, either through cold treatment of transplants or from natural temperature conditions in the spring. Studies were conducted in upstate New York, to determine if artificial vernalization treatments could be achieved by earlier planting dates. Initial trials evaluated two varieties used for annual production in other parts of the country—`Imperial Star' and `Green Globe' Improved. Transplants were set in the field with or without a vernalizing cool treatment, to determine the extent of natural vernalization achieved under New York conditions. `Imperial Star' produced slightly higher marketable yields than `Green Globe Improved' in 2 years of trials. Vernalization treatment increased the number of plants producing buds and the marketable yields, when transplants were set after 15 May. Natural vernalization was achieved and cold treatment before transplanting did not improve yields of plants established in early May. At later planting dates, vernalizing transplants increased the number of plants producing apical buds (largest) by about 20%, yet over 57% of nonvernalized plants of each variety produced buds within the season. Average bud sizes did not vary with vernalization treatment. A similar number of days from transplanting to first bud harvest (69 to 75 days) was noted regardless of planting date and size of tran.

The early-flowering mutant efs is involved in the autonomous promotion pathway of Arabidopsis thaliana.

The transition to flowering is a crucial moment in a plant's life cycle of which the mechanism has only been partly revealed. In a screen for early flowering, after mutagenesis of the late-flowering fwa mutant of Arabidopsis thaliana, the early flowering in short days (efs) mutant was identified. Under long-day light conditions, the recessive monogenic efs mutant flowers at the same time as wild type but, under short-day conditions, the mutant flowers much earlier. In addition to its early-flowering phenotype, efs has several pleiotropic effects such as a reduction in plant size, fertility and apical dominance. Double mutant analysis with several late-flowering mutants from the autonomous promotion (fca and fve) and the photoperiod promotion (co, fwa and gi) pathways of flowering showed that efs reduces the flowering time of all these mutants. However, efs is completely epistatic to fca and fve but additive to co, fwa and gi, indicating that EFS is an inhibitor of flowering specifically involved in the autonomous promotion pathway. A vernalisation treatment does not further reduce the flowering time of the efs mutant, suggesting that vernalisation promotes flowering through EFS. By comparing the length of the juvenile and adult phases of vegetative growth for wild-type, efs and the double mutant plants, it is apparent that efs mainly reduces the length of the adult phase.

Effect of Temperature and Photoperiod on the Development of Lupinus albus L. in a Controlled Environment

An experiment to determine the effect of temperature and photoperiod on Lupinus albus under controlled environmental conditions was carried out, using the three Lupinus albus genotypes ‘Tifwhite’, ‘Esta’ and ‘Kiev’, and three temperature (10/20, 18/28 and 20 °C continuously) and two photoperiod (8 and 16 h daylength) regimes, in all combinations. Half of the seeds were vernalized for 21 days at 4 °C to alleviate the obligate vernalization requirement of Tifwhite. Although Esta and Kiev do not have obligate vernalization requirements, they were influenced by this vernalization period. Observations included the duration of the period from planting to seedling emergence, the duration of the period from planting to the beginning of flowering and the duration of flowering. The vernalization treatment accelerated plant development in all genotypes. The period from planting to emergence was shorter under the higher temperature regime. For all genotypes, the period from planting to flowering was shorter under the longer photoperiod, the same trend as would be expected for long‐day plants. Duration of flowering periods were, in contrast to pre‐flowering periods, shorter for all genotypes at cooler temperatures. The results of this study confirm that photoperiod does contribute to the growth period from planting to flowering in L. albus and that this species does behave as a long‐day plant.

Detection of an earliness per se quantitative trait locus in the proximal region of wheat chromosome 5AL

AbstractA homoeologous quantitative trait locus to that of eps5L on barley chromosome 5H was identified in a syntenic region of wheat chromosome 5A. Wheat single chromosome recombinant lines (SCRs) were developed from a cross between ‘Chinese Spring’(‘Cappelle‐Desprez’ 5A) and ‘Chinese Spring’(Triticum spelta 5A), these were grown together with the parental controls under different vernalization and photoperiod regimes. The variation for ear emergence time accelerated heading induced by the T. spelta segment indicated an effect associated with the Xcdo412‐Xbcd9 interval. Since no differences between the SCRs and controls in responses to vernalization and photoperiod treatments were detected, this effect was identified as an earliness per se gene, Q Eetocs‐5 A.2, which may be homoeologous to the eps5L quantitative trait locus of barley. Xbcd926 has been found to be closely linked to the rice flowering time quantitative trait loci, QHd9a or FLTQ2, on chromosome 9, suggesting possible relationships among the quantitative trait loci across wheat, barley and rice genomes.

Cloning and characterization of vernalization-related gene (ver203F) cDNA 3′ end

Based on the cDNA fragment sequence of vernalization-related geneverc203 cloned by differential screening in our lab, the 5′ primer has been designed. The cDNA 3′ end ofver203 gene (1 197 bp) has been cloned by the RACE method. And it is identified by Northern blotting that its expression is special in vernalization treatment. After comparing the sequence in the nucleotide sequence databases of Genbank, EMBL and DDBJ, the gene has homology withHordeum vulgare jesmonate-induced protein gene. It is suggested that this gene might be related to the signal transduction mediated by jamonate.

粒状セラミックスを利用した水処理システムと処理水の植物に及ぼす影響について （第２報） 処理水の種子バーナリゼーションへの応用

In order to apply wheat (Triticum vulgare VILL.) seeds of winter habit to the late-summer sowing culture, the vernalization treatment method was carried out using water treated with ceramics.The plant height and the growing speed were promoted with the low temperature treatment using water treated with ceramics instead of tap water, and the maximum tillering stage was faster than that using tap water in the pot test. On the other hand, in the field test, the tiller was promoted, and the number of stems increased with low temperature treatment using water treated with ceramics instead of tap water.The heading period was accelerated by performing low temperature treatment using water on seeds. However, the difference of the heading date between the low temperature treatment using tap water and the low temperature treatment using water treated with ceramics was 2-3days.The effect of treated water with ceramics on the yield component was observed to be greater than the control and treatment using tap water in the pot test, however, the difference of the yield of the treatment using water treated with ceramics and other treatments was not clear in the field test.

Inheritance of the Vernalization Response Determined by Doubled Haploids in Spring Oilseed Rape (Brassica napus L.)

The presence of a vernalization requirement can delay floral initiation until the cold requirement of the plant has been satisfied. Breeders attempting to develop early‐maturing cultivars should be aware and have an understanding of the genetic basis of factors such as vernalization response to assess potential impact on their programs. The ability to generate doubled haploid (DH) lines from oilseed rape (Brassica napus) has led to the use of DH populations in genetic studies. The objective of this study was to determine the mode of inheritance of the vernalization response in spring B. napus with DH lines. A set of Fl‐derived DH lines from crosses between spring oilseed rape parent lines were evaluated for their response to vernalization. The use of DH lines allowed the exposure of the individuals of identical genotype to two differentreatments, vernalization and no vernalization. The vernalization treatment consisted of exposure of germinated seeds for 2 wk at 4°C. Seeds of the non‐vernalized treatment were germinated at 22°C. Comparison between treatments of the final leaf number on the main raceme (FLN) was used to assess the vernalization response. The results indicated that there is a gene for nonresponse to vernalization in the spring oilseed rape cultivar Karat. FLN offers a direct measure of vernalization response, since leaf initiation ceases when floral initiation begins.

FLD interacts with genes that affect different developmental phase transitions to regulate Arabidopsis shoot development.

A new fld mutant allele, fld-2, which significantly delayed flowering, was isolated and characterized in Arabidopsis thaliana. Even under long-day conditions after more than 100 days in the greenhouse, the majority of fld-2 mutant plants had not bolted. In addition, mutant inflorescences produced more than 10 co-florescences that were subtended by a high number of rosette-like leaves before giving rise to flowers. The late-flowering phenotype of the fld-2 mutation could be partially overcome by both vernalization and GA treatment but it was not influenced by 5-azaC treatment. Phenotypic analyses of double mutants indicated that fld-2 is epistatic to early flowering mutants elf1, elf2 and elf3. In addition, fld-2 could enhance vegetative characteristics in embryonic flower 1 (emf1) mutants by causing many small sessile leaves in fld-2 emf1 double mutants. The relief of the terminal flower 1 (tfl1) mutant phenotype in fld-2 tfl1 double mutants, and the enhancement of leafy (lfy) and apetala1 (ap1) mutant phenotypes in fld-2 lfy and fld-2 ap1 double mutants, suggest that FLD is also likely to be involved in the floral transition. Our results strongly suggest that the FLD gene plays a key role in regulating the reproductive competence of the shoot and results in different developmental phase transitions in Arabidopsis.

Analysis of natural allelic variation at flowering time loci in the Landsberg erecta and Cape Verde Islands ecotypes of Arabidopsis thaliana.

We have analyzed the flowering behavior of two Arabidopsis ecotypes: the laboratory strain Landsberg erecta (Ler) and an ecotype from the tropical Cape Verde Islands (Cvi). They differ little in their flowering phenotypes and in their responses to photoperiod length changes and to vernalization treatment. However, segregating populations derived from crosses between them showed a much larger variation. An approach of quantitative trait locus (QTL) mapping in recombinant inbred lines (RILs) grown under three environments differing in day-length and/or vernalization treatment has been used to detect and locate flowering loci. Four main QTLs were identified, designated early day-length insensitive (EDI), flowering F, G, and H (FLF, FLG, and FLH, respectively), to which most of the flowering behavior differences could be attributed. To further characterize the individual loci, near isogenic lines were constructed by introgressing Cvi early alleles of EDI and FLH into the Ler genetic background. EDI-Cvi alleles produce earliness under both long- and short-day photoperiods, rendering Ler plants almost day-length neutral. In addition, RILs were selected to analyze FLF and FLG. These loci interact epistatically and RILs carrying late alleles at FLF and FLG were very responsive to vernalization and showed an increased response to photoperiod length changes. The possible role of these loci for the control of flowering is discussed in the context of the current Arabidopsis model.

Influence of Simulated Shipping and Rooting Temperature and Production Year On Easter Lily (Lilium longiflorum Thunb.) Development

Interaction between simulated shipping and rooting temperature and harvest year was studied on Lilium longiflorum. Bulb dormancy and maturity appear to be separate phenomenon and are affected by temperature differently. Shoot emergence (an indicator of release from dormancy) was hastened by 10 °C shipping and 10 to 20 °C rooting temperatures in both years. Flower induction was affected differently by simulated shipping and rooting temperatures during 1992 and 1993, indicating that bulb maturity differed between the 2 years. Final leaf and flower number decreased because of shipping or rooting temperature, but only when bulbs were mature and received cool temperatures (<16 °C) before a 6-week vernalization treatment. Immature bulbs (at harvest) are unresponsive to vernalizing shipping and rooting temperatures. Prevernalization handling temperature and vernalization treatment length should vary with year based on degree of bulb maturity to achieve consistency in final morphology. Internode length is associated more with the time elongation is suppressed after dormancy is broken than with flower induction (where internode length increases as the length of time elongation is suppressed after breaking of dormancy increases).

Vernalization Requirements among Selected Genotypes of Annual Bluegrass (Poa annua L.)

Poa annua L. is a common turfgrass species in golf turf. The species is usually considered to be annual because of characteristics including continuous flowering throughout a growing season. In reality, the species exhibits a wide diversity of flowering habits from continual to seasonal, or only in spring. In efforts to study the flowering physiology of the species and to improve hybridization work, we initiated experiments to determine environmental conditions for floral induction in one P. annua var. annua and four P. annua var. reptans genotypes. Growth chamber and greenhouse environments were used to test (i) the minimum length of time needed for vernalization, (ii) the effective temperature for vernalization, and (iii) whether juvenility exists with regard to vernalization. Poa annua var. reptans genotypes were vernalized after 10 to 12 wk at 4 and 8C, but not at 12C. Poa annua var. annua did not respond to vernalization treatments, Poa annua var. reptans also exhibited variation in juvenile period ranging from 25 d to greater than 35 d after germination. Incomplete vernalization resulted in inflorescence development, but flowers were deformed. Vernalization requirements differed between var. annua and var. reptans genotypes, as well as among var. reptans. This information can be used to improve P. annua breeding, as well as to investigate the diversity within this species.

QTLs and Epistasis Associated with Vernalization Responses in Oat

Oat (Avena sativa L.) genotypes differ in their patterns of growth and development in response to vernalization (cold temperatures applied to germinating seeds). Genomic regions controlling vernalization response in heading date, plant height, and tiller number were mapped in a recombinant inbred (RI) population derived from the cross of oat cultivars ‘Kanota’ (vernalization‐responsive) and ‘Ogle’ (vernalization‐insensitive).Seventy‐one F6‐derived RI lines were subjected to vernalization and no‐vernalization treatments, and then grown in growth chambers. A genetic linkage map of 561 (primarily RFLP) loci was used to identify quantitativet rait loci (QTLs) affecting the traits in vernalized and non‐vernalized plants. Nine to 16 linkage groups and unlinked loci were associated with each trait assessed herein. Individual loci explained up to 37% of the phenotypic variation. Three to five significant loci were included in multiple locus linear models which explained up to 66% of phenotypic variation for each trait. One to 14 interactions between loci were found for each trait. The interactions explained up to 30% of the phenotypic variation not accounted for by the main effects of loci involved in the interactions. Inclusion of epistatic interactions tended to improve the fit of multiple locus models. As much as 83% of phenotypic variation was explained by multiple locus models including epistasis. Numerous epistatic interactions involving at least one locus with no significant main effect were detected.

Cumulative Effects of Vernalization Treatment in Successive Generations of Wheat

Cumulative after-effects of successive vernalization treatments for 20 to 30 generations lvere observed using three wheat varieties; Danchi-komugi, Norin 61 and Lutescens 62. The results are summarized as follolws: 1. Heading date was advanced by the successive treatments by a maximum of 1.7 days in the 4th generation in the case of Danchi-komugi and 6.5 days in the 17th generation in Norin 61. Thereafter the advancement gradually decreased. In this experiment, it appears that the cumulative after-effects did not convertge to a particular level, and that they lvere not significantly larger than those in the Ist generation. In contrast to these varieties, the heading date was not significantl\* affected bv the vernalization treatment in Lutescens 62. 2. In Danchi-komugi, the culm length decreased until the 4th generation and tended to increase up to the 8th generatlon, and then decreased again. Remarkable cumulative after-effect on culm length was observed in Norin 61. Culm became shortest in the 12th generation and the length recovered by the 16th generation, and decreased gradually thereafter. Culm length of Lutescens 62 rather increased until the 4th generation and then decreased. 3. Ear length tended to increase for all the varieties, though the changes were not conspicuous after the 12th generation in Danchi-komugi, the 8th generation in Norin 61 and the 16th generationin Lutescens 62, respectively. 4. Plant height at the internode elongation stage in Danchi-komugi had shown a periodicity covering eight genelations, with reversed cumulative and non-cumulative effects every four years in both the successive treatment lines (D1-D30) and the non-treatment lines after successive treatment (D5-0-D24-0). This periodicity suggested that Danchi-komugi developed a dynamic homeostasis over generations for the sensibility to low temperature.

Vernalization in wheat II. Genetic variability for the interchangeability of plant age and vernalization duration

Differences in response to vernalization in wheat ( Triticum aestivum L.) were quantified through controlled environment experiments with 26 lines with diverse geographical origins. Vernalization treatments of 0 to 56 d were applied to plants at their first leaf stage. All plants headed irrespective of duration of vernalization treatment. Vernalization response was assessed through the change of final leaf number (FLN) on the main stem at heading. Five lines did not respond to vernalization. FLN for vernalization-sensitive lines generally decreased to a minimum as days of vernalization treatment increased. Plants at and after the stage where additional vernalization did not reduce FLN were vernalization insensitive. The quantitative features of this vernalization response, up to the point of insensitivity, were characterized with a linear regression: ( F i − 6) = α − βT v, where F i is FLN observed for a particular vernalization treatment, T v is the time in days of that vernalization treatment, and α and β are the Y-intercept and the slope of the regression, respectively. This model fitted the experimental results well. The parameters α and β varied among lines, and are useful for quantifying vernalization response in wheat. The implication of each parameter can be interpreted biologically: α is the “changeable number of leaves”, i.e., how many leaves can be potentially decreased by vernalization treatment, and β represents the “exchange rate” between leaf numbers and vernalization days, i.e., how many leaves can be reduced by one day of vernalization treatment.

Environmental Control of Floral Induction and Development in Kentucky Bluegrass

Kentucky bluegrass (Poa pratensis L.) floral induction requires a lengthy, uninterrupted period of cold temperature with a short photoperiod. Our objective was to develop an deficient artificial vernalization procedure to facilitate breeding experiments. The stage of plant development and length of vernalization period necessary for floral induction was determined for six cultivars: Abbey, Aspen, Midnight, Park, Rugby, and Trenton. Plants were exposed progressively to three temperature and light‐controlled environments: (i) seedlings were grown in a 12‐h photo‐ and thermal period with a 20°C day/14°C night temperature regime and high irradiance of 30 W m−2 from germination until 3, 5, 9, or 13 wk after emergence (approx. 8, 26, 145, and 198 leaf stage, respectively); (ii) plants were then vernalized for an 8‐h photoperiod at 5°C constant temperature and low irradiance of 7 W‐2 for 4, 8, or 12 wks; and (iii) plants were transferred panicle development conditions of 18‐h photoperiod and 12‐h thermal period with a 18°C day/15°C night temperature regime and high irradiance of 30 W−1 for 16 wk. No panicles were observed on plants with the 4‐wk vernalization treatment. For all cultivars except Midnight, the 9‐wk plant development and 12‐wk vernalization treatment resulted in floral induction of all plants. The same four cultivars responded to this treatment with a mean panicle number greater than five panicles per plant and the time from seedling emergence to 75% of the panicles emerged was approximately 28 wk. This study has demonstrated that an artificial vernalization procedure could be developed that would make reproductive material of Kentucky bluegrass available throughout the year independent of season or climate.

Vernalization and Gibberellin Physiology of Winter Canola (Endogenous Gibberellin (GA) Content and Metabolism of [3H]GA1 and [3H]GA20.

Winter canola (Brassica napus cv Crystal) is an oilseed crop that requires vernalization (chilling treatment) for the induction of stem elongation and flowering. To investigate the role of gibberellins (GAs) in vernalization-induced events, endogenous GA content and the metabolism of [3H]GAs were examined in 10-week vernalized and nonvernalized plants. Shoot tips were harvested 0, 8, and 18 d postvernalization (DPV), and GAs were purified and quantified using 2H2-internal standards and gas chromatography-selected ion monitoring. Concentrations of GA1, GA3, GA8, GA19, and GA20 were 3.1-, 2.3-, 7.8-, 12.0-, and 24.5-fold higher, respectively, in the vernalized plants at the end of the vernalization treatment (0 DPV) relative to the nonvernalized plants. Thermoregulation apparently occurs prior to GA19 biosynthesis, since vernalization elevated the concentration of all of the monitored GAs. [3H]GA20 or [3H]GA1 was applied to the shoot tips of vernalized and nonvernalized plants, and after 24 h, plants were harvested at 6, 12, and 15 DPV. Following high-performance liquid chromatography analyses, vernalized plants showed increased conversion of [3H]GA20 to a [3H]GA1-like metabolite and reduced conversion of [3H]GA1 or [3H]GA20 to polar 3H-metabolites, putative glucosyl conjugates. These results demonstrate that vernalization influences GA content and GA metabolism, with GAs serving as probable regulatory intermediaries between chilling treatment and subsequent stem growth.

Vernalization in wheat I. A model based on the interchangeability of plant age and vernalization duration

Vernalization treatments of 0 to 70 d initiated when 0 to 8 leaf tips were visible were applied to plants of the winter wheat ( Triticum aestivum L.) cultivars Pioneer 2548 and Augusta. All plants headed irrespective of duration of vernalization. Unvernalized plants of Pioneer 2548 and Augusta had mean final leaf numbers (FLN) of 20.8 ± 1.3 and 21.7 ± 1.0, respectively. Increased duration of vernalization generally reduced FLN within an age treatment until an age-dependent point of vernalization insensitivity was reached. Estimates of the minimum days of vernalization required to reach vernalization insensitivity decreased in a linear fashion as plant age at the onset of vernalization treatment increased. The number of leaves appearing after the onset of vernalization insensitivity averaged 6.3 ± 0.5. FLN minus six appears to be a valid estimate in our experimental conditions for the onset of vernalization insensitivity, at least for plants that had six or more leaves appearing after the end of vernalization treatment. Linear regressions of FLN minus six against days of vernalization were significant for both cultivars (for treatments with six or more leaves emerging after vernalization). The Y-intercepts of the fitted regressions were close to values obtained by subtracting six from FLN of unvernalized plants. Both intercept and slope were controlled genetically. Accumulated plant age, expressed as leaf stage, enables attainment of vernalization insensitivity, independent of, or in combination with vernalization treatment.

Phyllochron Response to Vernalization and Photeperiod in Spring Wheat

An understanding of how environment controls the initiation and development of the leaf is required to construct dynamic crop simulation models. The aim of this study was to determine the effect of vernalization and photoperiod on total number of leaves at anthesis, leaf emergence rate, and phyllochron in 20 spring wheat genotypes (Triticum aestivum L.). An experiment was conducted under greenhouse conditions during spring 1992 at ICARDA, Tel Hadya, Syria, with all combinations of three photoperiods (8‐, 12‐, and 16‐h daylength) and two vernalization treatments (vernalized and nonvernalized). Total number of leaves on the main stem at anthesis decreased with increasing photoperiod. Vernalization reduced the total number of leaves on main stem at anthesis in the eight vernalization‐sensitive genotypes. Leaf number on the main stem was linearly (r = 0.99) related to accumulated growing degree days (°C d). Genotypes differed in leaf emergence rates. Leaf‐emergence rate increased with increasing photoperiod. Phyllochron decreased with increased daylength from 124 °C d leaf−1 at 8 h to 97 °C d leaf−1 at 16‐h photoperiod. These results suggests that, to model leaf appearance and canopy development in wheat, genotypic coefficients of phyllochron need to be determined in relation to photoperiod. Additionally, the effect of vernalization at inductive photoperiods on the phyllochron in genotypes adapted to heat‐prone tropical environments needs further study.