The control of boron accumulation by two genotypes of wheat

The mechanism of boron (B) uptake in wheat was studied using two genotypes with known differences in their ability to accumulate B. Influx and efflux of B was measured in the roots of intact 21 d old plants.Roots grown in 15 M B, when transferred to solutions containing 1mM B showed a rapid increase in B content for up to 60 min, after which no further increase was evident up to 4 h. No genotypic difference in B influx was apparent over these time periods. Roots grown in 1mM B for 7 d and then rinsed in B-free solutions quickly lost most of B that they contained within 1 hour; little further efflux was observed over the following three hours. As with the influx, no genotypic difference in B flux was evident.It is suggested that the lack of genotypic difference in the short-term B fluxes could be due to a masking effect of extracellular B bound in the cell walls of the roots.Department of Botany, University of Adelaide     

Differential response of oilseed rape (Brassica napus L.) cultivars to low boron supply

Three experiments were carried out on an alluvial sandy loam (Udifluvent) at Tonglu, Zhejiang Province, P.R. China from 1992 to 1995, to determine the genotypic range in boron (B) efficiency of 16 oilseed rape (Brassica napus L.) cultivars, to identify the B-efficient cultivars and to identify specific responses which can be utilised for selection in a breeding program. The 16 cultivars which included high-quality and conventional types differed significantly in survival, plant height, leaf area, shoot dry weight and seed yield; however, the ranking of the cultivars for their seed yield or other plant traits differed with B treatment. With severe B deficiency (CaCl2 extractable B < 0.26 mg/kg) and no boron applied, none of the cultivars exhibited significant B efficiency, with seed yield <300 kg/ha. With moderate B deficiency (CaCl2 extractable B 0.34 mg/kg or 0.17 kg B/ha applied), seed yield varied significantly among the cultivars from 397 to 1889 kg/ha in year 1 and from 616 to 1260 kg/ha in year 3. Zhongyou 821 and 92-13 were the most B-efficient and Wanyou 324, Huashuang 2 and Su 2051 were the most B-inefficient cultivars under moderate B deficiency. Significant differences were found among the cultivars in leaf B concentration; however, there was no close relationship between leaf B concentration and seed yield responses to B of oilseed cultivars. Of all the growth parameters measured, leaf area was the early indicator best correlated with subsequent seed yield and may be useful for evaluating the response of cultivars to low B supply. Contrary to current opinion, it was also found that high-quality oilseed rape cultivars were not all sensitive to low B supply nor were all conventional cultivars B-efficient.     

Selection of Brassica rapa genotypes for tolerance to boron toxicity

Although boron (B) is a micronutrient essential for the growth of vascular plants, it reduces growth and seed yield when present in excessive amounts. A hydroponic assay of nineteen Brassica rapa genotypes resulted in the identification of two tolerant genotypes, WWY Sarson and Local at a range of boron concentrations (15–165 μM). The most tolerant and sensitive genotypes were assessed for shoot boron concentrations in a soil assay with 4, 29 and 54 mg B kg⁻¹ soil. The soil assay confirmed the results of the hydroponic screening. Shoot boron uptake was at least three times lower and shoot boron concentrations about 10 times lower in the tolerant than sensitive genotypes, indicating that boron tolerance involved boron exclusion from the shoot.     

Resistance of wheat genotypes to boron toxicity is expressed at the cellular level

The effects of toxic boron (B) concentrations on the growth of wheat genotypes at organ level and cellular level were investigated using excised root culture techniques. At the organ level, wheat genotypes differed for root elongation and lateral root development in response to toxic B concentrations. Genotypes classified as resistant from field studies had longer root axes and more lateral roots than sensitive or moderately sensitive genotypes, but there was no difference in axis elongation between sensitive and moderately sensitive genotypes. At the cellular level, callus production of root explants among genotypes still different at toxic B concentrations: resistant genotypes could produce more callus than sensitive or moderately sensitive genotypes. These results suggest that differences among genotypes in resistance to toxic B concentrations may be related to cell membrane permeability to B since they were also expressed in undifferentiated callus cells. The distinct and consistent differences among genotypes in response to B toxicity both at the organ level and at the cellular level could serve as a basis for selection in a breeding program. The methods were precise and efficient.     

Tolerance of peanut to excess boron

The tolerance ofArachis hypogaea cv. Shulamit to high concentrations of B in nutrient solution, [B]o, was determined under greenhouse conditions that promoted the production of vegetative dry matter. Plants grew in large containers in which a root zone of nutrient solution was separated from a pod zone of soil. Grain yield was reduced at a calculated [B]o-threshold of 0.29 mM, which was associated with a concentration of B in the vegetative shoots that was approximately four times larger than the control. Symptoms of B toxicity occurred on leaves as young as the third unfolded leaf from the shoot apex before the [B]o-threshold. Excess B caused a relatively larger decrease in pod number than in vegetative shoot weight, which was high in all treatments (78 g d.wt/plant) and it did not decrease single grain weight. It was suggested that the tolerance of grain development to excess B was a consequence of the high ratio of vegetative matter to pod number.     

Intergeneric Somatic Hybridization Between Brassica napus L. and Sinapis alba L.

Electrically induced protoplast fusion was used to produce somatic hybrids between Brassica napus L. and Sinapis alba L. Seven hybrids were obtained and verified by the simple sequence repeat and cleaved amplified polymorphic sequence analysis of the genefael, indicating that the characteristic bands from S. alba were present in the hybrids. The hybridity was also confirmed by chromosome number counting because the hybrids possessed 62 chromosomes, corresponding to the sum of fusion-parent chromosomes. Chromosome pairing at meiosis was predominantly normal, which led to high pollen fertility,ranging from 66% to 77%. All hybrids were grown to full maturity and could be fertilized and set seed after self-pollination or back-crosses with B. napus. The morphology of the hybrids resembled characteristics from both parental species. An analysis of the fatty acid composition in the seeds of F1 plants was conducted and the seeds were found to contain different amounts of erucic acid, ranging from 11.0% to 52.1%.     

Changes in protein profile of pigeonpea genotypes in response to NaCl and boron stress

Two pigeonpea [Cajanus cajan (L.) Millsp.] genotypes, a salt tolerant Manak and a salt sensitive ICPL 88039 were subjected to stress treatment of 3 mM boron, 60 mM NaCl and boron + NaCl at the seedling stage. Radicle and plumule proteins were analyzed by SDS-PAGE. Boron treatment increased 28.3 kDa proteins in plumule and 38.3 and 51.9 kDa proteins in radicle of Manak, however, there was no specific protein in ICPL 88039 either in plumule or in radicle. In NaCl treatment 95.6 kDa proteins appeared in plumule and 67.5 kDa proteins in radicle of Manak. Conversely content of some proteins decreased by boron treatment alone or in combination with NaCl although they were present in the controls. Thus, 54.3 kDa protein disappeared in ICPL 88039 plumule, 68.4 kDa in Manak radicle and 28.1 kDa in ICPL 88039 radicle.     

甘蓝型油菜芥酸含量的主基因＋多基因遗传

应用植物数量性状主基因＋多基因混合遗传模型对甘蓝型油菜无芥酸品种HSTC     

Intergeneric Somatic Hybridization Between Brassica napus L. And Sinapis alba L.

Electrically induced protoplast fusion was used to produce somatic hybrids between Brassica napus L. and Sinapis alba L. Seven hybrids were obtained and verified by the simple sequence repeat and cleaved amplified polymorphic sequence analysis of the genefael, indicating that the characteristic bands from S. alba were present in the hybrids. The hybridity was also confirmed by chromosome number counting because the hybrids possessed 62 chromosomes, corresponding to the sum of fusion-parent chromosomes. Chromosome pairing at meiosis was predominantly normal, which led to high pollen fertility,ranging from 66% to 77%. All hybrids were grown to full maturity and could be fertilized and set seed after self-pollination or back-crosses with B. napus. The morphology of the hybrids resembled characteristics from both parental species. An analysis of the fatty acid composition in the seeds of F1 plants was conducted and the seeds were found to contain different amounts of erucic acid, ranging from 11.0% to 52.1%.     

Comparison of boron uptake and translocation in two vetiver genotypes and evaluation of boron removal efficiency of vetiver floating islands

The objectives of this study were to identify genotypic differences in the uptake and translocation of boron (B) in vetiver (Chrysopogon zizanioides L.), a promising species in B phytoremediation, and to determine the efficiency of vetiver floating island system in B phytoremediation. Changes in plant biomass and B uptake and translocation were determined in two vetiver genotypes, Sierra and Sunshine, cultured hydroponically in a nutrient solution and exposed to six different B concentrations for 7 d and 14 d. The efficiency of B removal by Sierra (a high B accumulative genotype) grown in floating islands was also determined. Shoot B concentration differed significantly between the two genotypes but differences in root concentration were not significant. Root to shoot B transfer and B uptake ability were higher in Sierra than in Sunshine. The uptake and translocation of B was affected by B concentration and time of exposure. Sierra plants grown in floating islands were more efficient in B removal at lower B concentrations. Most of the B removed accumulated in the middle-upper sections of old leaves. Sierra is more suitable for the removal of B from wastewaters than Sunshine, especially in vetiver floating island system.     

Variation in the growth of lupin species and genotypes on alkaline soil

Commercial lupins grow poorly on alkaline and neutral fine-textured soils. Genotypic variation exists among lupins. The present study compared the growth of 13 lupin genotypes, including introduced cultivars and wild types, in an alkaline loamy soil and an acid loamy soil.Plants grown in the alkaline and acid soils did not show obvious symptoms of iron deficiency at any stage. There was however a large variation of shoot fresh weight among genotypes in response to the alkaline soil with L. atlanticus and L. pilosus being more tolerant than L. luteus, L. cosentinii, L. albus and L. angustifolius. Some variation also existed among genotypes of L. angustifolius. In addition, root growth was retarded on the alkaline soil except for L. atlanticus, L. pilosus P20955 and L. albus Kiev mutant. In the alkaline soil, root growth at week 2 correlated well with the shoot fresh weight at week 12. The results suggest that early root elongation may be useful for screening tolerant genotypes for alkaline soils.     

Response of soybean genotypes to boron,zinc and manganese deficiency in tissue culture

The effect of boron (B), zinc (Zn), and manganese (Mn) deficiency in the medium on eight soybean genotypes was evaluated using friable callus after a 21 day growth period. Of the three micronutrients evaluated, Zn and B deficiencies had the greatest effect on callus weight, while Mn had only a slight effect. Despite this, significant differences in callus weight reduction of the eight genotypes tested were observed on the three different media. These results indicate that genotypic variation for response to B, Zn, and Mn deficiency is present in soybean at the cellular level. If the resistant genotypes identified in this study are also resistant at the whole plant level, then they could be used in soils which are deficient in the above micronutrients.     

An integrated approach to oilseed rape cultivar selection using phenotypic stability

Summary Various methods of evaluating phenotypic stability have been proposed; however, no single method can adequately describe cultivar performance. The objectives of this study were to integrate a number of methods of evaluating stability and to use this approach for cultivar selection. These objectives were considered in the context of the broad-based oilseed rape cultivar (Brassica napus spp. oleifera) evaluation system currently used in western Canada. Regression analysis was used to assess cultivar response to environments. Cluster analysis was used to assemble cultivars into groups with similar regression coefficients (b _i ) and mean yield. Three parametric stability parameters, years within locations mean square (MS; Y/L), Shukla's stability variance ( _i ² ), and Francis and Kannenberg's coefficient of variability (CV _i ), were compared to determine which method would be most suitable for selection of oilseed rape cultivars from within clustered groups. Yield data from three cultivars and six breeding lines that had been tested for 2 years at 26 locations in the Western Canola Cooperative Test A were used for all calculations. The cluster analysis was successful in identifying commercially acceptable breeding lines. The parameter MS _i Y/L was considered to be more appropriate than either CV _i or _i ² , because it measured only the unpredictable portion of the genotype x environment interaction and was independent of the other cultivars in the test. The use of cluster analysis to group entries with similar b _i values and mean yields, followed by selection for stability within groups, was advocated.Contribution No. 846 of the Plant Science Department, University of Manitoba     

Low temperature effects on growth and actin cytoskeleton organisation in suspension cells of winter oilseed rape

Rhodamine-phalloidin staining of winter oilseed rape suspension cells revealed that the structure of actin cytoskeleton changes with the phase of cell growth. In small, 4-day-old cells, entering the exponential phase of growth, a dense and uniformly distributed cortical microfilament networks was seen. In six-day-old vacuolated cells, which reached the stationary phase of growth, the actin cytoskeleton was composed of thicker microfilament cables in irregular arrangements. In cells acclimated in cold for 7 days a dense, uniformly distributed and cortical microfilament network was still seen. The fine microfilament network was sensitive to extracellular freezing since the structures underwent depolymerization at −3 °C (in the presence of extracellular ice), both in non-acclimated and cold-acclimated cells. The thicker transvacuolar cables in cells of the stationary growth phase resisted freezing to −7 °C. Acclimation of suspensions at 2 °C resulted in slowing down growth of cells and in the increased freezing tolerance of cells as indicated by a decrease of LT₅₀ from −11 °C to −17.5^o or to −25 °C when determined 7 or 20 days after the beginning of the cold treatment, respectively. Freezing tolerance of non-acclimated cells decreased from −11 °C to −8 °C during subculture, showing a transient increase to −17 °C on the day 6. Results indicate that the arrangement of actin microfilaments and their sensitivity to freezing-induced depolymerization depends on the phase of cell growth rather than on cell acclimation status. Possible mechanisms involved in the freezing-induced depolymerization of actin microfilaments are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Physiological and yield effects of uniconazole on winter rape (Brassica napus L.)

Uniconazole at various concentrations on rape, at the three-leaf stage, was examined for physiologic and yield effects. Foliar sprays of 10, 25, and 50 mg/liter significantly reduced seedling height, and increased shoot width (stem width before elongation), number of green leaves, and total dry weight at transplanting. Chlorophyll content, superoxide dismutase and catalase activities, root oxidizability (capacity for root oxidation), and ethylene production were also increased. Additionally, the number of branches and pods/plant were increased; and a 7.4, 8.5, and 4.3% increase of seed yield over the controls was observed with treatments at 10, 25, and 50 mg/liter uniconazole, respectively. No significant effects were observed on plant maturity, the seed oil content, or the erucic acid and glucosinolate content. Total oil production significantly increased with 10, 25, and 50 mg/liter by 9.9, 10.6, and 6.8%, respectively, over the controls. These results suggested that uniconazole-induced high productivity was accompanied by increased levels of activities of various antioxidants, including superoxide dismutase and catalase, and by the improvement of root oxidizability and plant vigor.Abbreviations SOD superoxide dismutase - CAT catalase - NBT nitro blue tetrazolium - TTC red tetrazolium - IAA indoleacetic acid     

Response to soil aluminium of two white clover (Trifolium repens L.) genotypes

An aluminium (Al) tolerant genotype of white clover was compared with an Al susceptible genotype in artificial soil profiles in which exchangeable Al increased with depth. The tolerant genotype had a greater proportion of its root mass deeper in the soil than the susceptible genotype. Nitrogenase activity showed a similar pattern. Shoot Al concentration did not vary between the genotypes but root Al in the susceptible line was twice that in the tolerant genotype. Plant potassium content in the susceptible line was relatively less, probably in response to higher aluminium content.     

Photosynthetic characteristics and productivity of spring rape plants as related to crop density

Optimal density of spring rape (Brassica napus L.) crop stand was determined by plant photosynthetic characteristics at the beginning of flowering. As crop density increased from 100 to 350 plants/m², leaf surface index (LSI) of the crop was found to increase by 18.2–80.2%, and LSI decreased by 38.8–67.3% as compared with the sparsest crop (50–100 plants/m²). LSI depended on the rate of incident PAR reaching 0.5 and 0.25 heights of the crop stand and to the soil surface. When crop density increased from 100 to 350 plants/m², the photosynthetic potential (PP) of the crop increased 1.8 times as compared with the sparsest crop. PP of the densest rape crop stand was 3 times lower than in the sparsest crop. When the crop density increased from 100 to 250 plants/m², the daily increment in biomass calculated per leaf surface unit increased by 27.0% as compared with the sparsest crop and depended on LSI. When leaf area decreased, the daily increment in biomass calculated per leaf surface unit declined; in the densest stand, this characteristic was by 58.3% lower than in the sparsest crop. Rape productivity at the flowering stage depended on the crop density, LSI of plants, rate of PAR reaching 0.5 and 0.25 heights of the crop stand and to the soil surface, PP, and the daily increment in biomass calculated per leaf surface unit. Crop productivity at the flowering stage and the rape seed yield were associated by a significant parabolic relationship. When crop density increased from 100 to 350 plants/m², seed yield per plant considerably decreased (by 33.1–78.5%) as compared with the sparsest crop. The greatest influence on seed yield per plant was exerted by LSI and the daily increment in biomass calculated per leaf surface unit. When crop density increased to 250–300 plants/m², the seed yield considerably rose (by 28.6–58.8%) as compared with the sparsest crop; when this index reached 300–350 plants/m², the seed yield decreased because plant growth was suppressed, with the productivity reduced. The results thus obtained suggest that the photometric characteristics of spring rape were at optimum at crop density of 100–250 plants/m². The agroclimatic conditions of Lithuania ensure potential for rapid accumulation of total biomass and high seed yield.     

Boron efficiency in oilseed rape: II. Development of a rapid lab-based screening technique

The level of genotypic variation in tolerance to low boron (B) supply was investigated in solution culture grown, 10 day old (D10) oilseed rape (Brassica napus L.) plants, by using a rapid screening technique whereby root length, root elongation rate and total root dry weight were used to indicate plant response to B. Root length proved more reliable in determining genotype responses, and was used to characterise a total of 61 genotypes, of which Huashuang 2, Nangchang rape, Huashuang 1 and Zhongyou 821, and to a lesser extent, Zheyou 2, Dunkeld, Xinza 2, Nangjin 2051, 92-58, 92-13, and Awassa 115 exhibited some form of tolerance to low B supply. The genotypic rankings based on this early vegetative response corroborated with field based B-efficiency. The results demonstrate the expression of the B-efficiency mechanism in the early vegetative stages of plant growth, and establish the value of root length as a selection criterion for B-efficiency in oilseed rape. This revised version was published online in June 2006 with corrections to the Cover Date.     

人工合成甘蓝型油菜中花色与芥酸含量的遗传连锁分析

利用人工合成的甘蓝型油菜品系．No．2127-17(白花、有芥酸)与加拿大双低甘蓝型油菜品种Quantum(黄花、低芥酸)配制杂交组合。对亲本、F1、BC1、F2和DH(doubled haploid)5个世代的花色及芥酸含量进行分析,结果表明：花色受单基因控制,且白花对黄花为显性;芥酸含量仅表现出一对基因的差异且具有加性效应的遗传模式。花色和芥酸含量的连锁分析表明：白花与高芥酸紧密连锁．在DH群体中重组频率为5．8％。采用集团分离分析法(Bulked Segregant Analysis,BSA),从685条10个碱基的随机引物筛选到一个与黄花和低芥酸含量紧密连锁的RAPD标记S92-1400。在遗传图谱上黄花基因和低芥酸基因距离S92-1400标记的图距分别为2．2cM和5．4cM。     

Resistance to boron toxicity amongst several barley and wheat cultivars: A preliminary examination of the resistance mechanism

The mechanism of resistance toB toxicity in barley and wheat was studied in a solution culture experiment using several cultivars displaying a large range of sensitivity to excessB supply. Plants were cultured for 35 d atB concentrations ranging from normal to excessive (15 to 5000 M, respectively) then examined for dry matter production and theB distribution between roots and shoots.In both species, increasedB supply was accompanied by increased tissueB concentrations, development ofB toxicity symptoms and depressed growth. At each level ofB supply, however, resistant cultivars accumulated considerably lessB than did sensitive cultivars, in both roots and shoots. Even at the lowestB supply, at which noB toxicity symptoms developed and growth was not affected, resistant cultivars maintained relatively low tissueB concentrations. No cultivar displayed an ability to tolerate high tissueB concentrations.These results indicate that sensitivity toB toxicity in barley and wheat is governed by the ability of cultivars to excludeB. If theB concentrations of tissues is used to indicate resistance toB toxicity, then cultivars have the same ranking whether cultured at a normal or excessB supply.