Culture selected somaclonal variation in five Triticum aestivum L. genotypes

Somaclones (R₃ and R₄ generations) regenerated from five winter wheat (Triticum aestivum L.) genotypes were evaluated for variation in agronomic and morphological characters. Immature embryos were used as initial explant material. Comparisons for plant height, top internode length, spike length, number of seeds per spike and 100 seed weight were made between the somaclones and their parents. Some morphological variations of stem and spike characteristics were registered which demonstrate that plant height and spike length can be changed by using immature embryo culture. The results obtained may be considered a biotechnological contribution to wheat plant improvement. This revised version was published online in August 2006 with corrections to the Cover Date.     

Frost Resistance of Somaclones Derived from Triticum aestivum L. Winter Wheat Calli

Frost resistance was studied in SC₄ seedlings generated by self pollination from 31 (SC₄) plants of ‘GK Csongor’ winter wheat variety derived from resistance than ‘GK Csongor’. With respect to percentage survival, one family possessed significantly higher frost resistance as compared to the control at a temperature of -13°C In the case of regrowth analysis, 22 of the 31 families showed less growing capacity and 5 proved to be significantly better than ‘GK Csongor’. According to both testing methods, one family showed significantly higher frost resistance than the control.     

Somaclonal Variation in Tissue Culture of Triticum aestivum×Agropyron desertorum F1 Hybrid

Callus induced from immature inflorescences of the partially self-fertile hybrids (2 n = 35; ABDPP) between Triticum aestivum (2n = 42; AABBDD) and Agropyron desertorum (2n = 28; PPPP) led to the regeneration of 88 plants on MS medium supplemented with 2 mg/l of 2,4-D. These regenerants were used to investigate somaclonal variation and to obtain more selfed derivatives. Immature inflorescences at the stage of developing floral primordia gave the best response in terms of callus induction and plant regeneration. The regenerants exhibited great variability for most morphological traits. Although the regenerants did not exhibit variation in chromosome number, they did show a higher degree of meiotic instability than the initial hybrid. In particular, the regenerants gave much higher selfed seed-set (5.49 %) than the donor hybrid (0.46 %), so that a total of 484 selfed seeds were obtained.     

An assessment of somaclonal variation as a breeding tool for generating herbicide tolerant genotypes in wheat (Triticum aestivum L.)

The present work was initiated to assess tissue culture techniques as a means of generating and selecting herbicide tolerant genotypes of wheat through exploiting somaclonal variation. Callus was initiated from immature embryos of genetically defined varieties and subcultured onto selective media containing 5 μm, 10 μm and 50 μm concentrations of difenzoquat and atrazine. Plants were regenerated from all the selective media except that media containing the highest herbicide concentration. The progenies of the regenerated plants were tested as whole plants for their response to spray application of the herbicides. For difenzoquat, variation in response from extreme susceptibility to tolerance was observed. However, genetic characterization by progeny testing tolerant lines revealed that the induced variation was not heritable. No plants tolerant to atrazine were obtained. Overall, no clear evidence of heritable mutations was obtained. Alternative strategies to obtain herbicide tolerant genotypes using cell culture techniques are discussed. This revised version was published online in July 2006 with corrections to the Cover Date.     

Studies on somaclonal variants for resistance to scab in bread wheat (Triticum aestivum L.) through in vitro selection for tolerance to deoxynivalenol

This study was conducted to develop an efficient in vitro selection system for scab resistance by using in vitro screening for tolerance to deoxynivalenol (DON). Immature embryos of two wheat varieties, a scab-resistant variety Sumai 3 and a susceptible variety Mianyang 11, and their reciprocal F₁ hybrids were cultured on MS medium supplemented with 2,4-D 2 mg/l and 0.6 × 10^-4 M DON for callus induction. The responses of callus induction and plant regeneration to 0.6 × 10^-4 M DON differed significantly between resistant and susceptible varieties, according to observed scab resistance levels at the plant level in the field. The percentage of callus formation of resistant variety Sumai 3 on induction medium containing DON was higher than that of susceptible variety Mianyang 11. Regeneration of DON-tolerant calli on DON-containing differentiation medium differed significantly between Sumai 3 and Mianyang 11. Averaged across the DON-tolerant calli of two varieties and their reciprocals, regeneration of DON-tolerant calli was decreased 3-fold on DON-containing medium. By an inoculation test with conidiospores of Fusarium graminearum Schw, we obtained several resistant lines from progenies of regenerated plants from DON-tolerant calli. These somaclonal lines had lower disease scoring (reaction index, infected spikelets and disease incidence), shorter plants and better yield components than Sumai 3, a famous Chinese resistant variety. This revised version was published online in July 2006 with corrections to the Cover Date.     

Somaclonal variation in three Argentinean varieties of Triticum aestivum with different karyotypic instability*

Three cultivars of wheat showing different levels of spontaneous karyotypic instability were studied regarding their stability in vitro for a number of characters, i.e. chromosome structure, gliadin pattern, glume and grain colour, awn type, chlorophyll pigmentation and plant morphology. The progenies of somaclones derived from immature embryos of both aneuploid and euploid plants were used in this study along with foundation seeds and a large number of their sexual progeny in order to discriminate between pre-existent variability and any novel variation induced by the in vitro culture. Only one translocation not described before and a new gliadin pattern were detected which could be ascribed to the effects of tissue culture, suggesting that this technique is not effective for inducing novel variation for breeding purposes in wheat.     

花药培养在小麦耐盐育种上的应用研究

在小麦花药培养中，采用加入一定浓度ＮａＣｌ（０．１％、０．３％、０．５％）的筛选培养基，用恒定浓度筛选法和逐渐增加浓度筛选法，可筛选出耐盐变异体，获得耐盐花培株系。两种筛选方法比较，逐渐增加浓度筛选法可以明显提高筛选效率。经５个有性世代的鉴定表明，耐盐变异体的耐盐特性可以稳定遗传给后代。经筛选的花培株系中，耐盐特性能够稳定遗传的株系比例约占１／４。在育种实践中，经多点试验鉴定，已选育出一批有实用价     

Agronomic and Physiological Study of Cold and Flooding Tolerance of Spelt (Triticum spelta L.) and Wheat (Triticum aestivum L.)

Flooding of soil occurs all over the world in areas of crop production. The resulting lack of available oxygen in the soil can hinder the establishment of field crops such as wheat ( Triticum aestivum L.) and thus lead to a decrease in yield. The current study compares the tolerance of spelt ( Triticum spelta L.) and wheat to wet and cold stress during germination and early growth. Two specific traits seem to be related to the superior early flooding tolerance of spelt: (1) fast growth of the coleoptile, which reaches the soil surface rapidly, thus reducing the time span of hypoxia sensitivity, independent of temperatures between 10 and 20 °C; (2) the improved physiological adaptation for coleoptile growth under hypoxia is probably due to lower oxygen consumption between germination and emergence. Because of this high level of flooding tolerance, spelt would also be a good source for breeding for stress tolerance in wheat. These findings will help to detect quantitative trait loci (QTL) for characters such as growth rate, flooding tolerance and oxygen consumption in future studies. A marker-assisted introgression of spelt into wheat is necessary to avoid combination with undesirable agronomic traits of spelt.     

The Response of Anther Culture in a Genetically Wide Material of Winter Wheat (Triticum aestivum L.)

In a screening experiment with 215 different winter cultivars of Triticum aestivum L. for response in anther culture, pollen embryos or callus were obtained from 200 different cultivars and green plants from 93 different cultivars. On average, from the whole material, 1.3 green plants were obtained per 100 anthers cultured. Variance components estimated from replicates with selected parts of the plant material indicated that for the formation of pollen embryos from anthers, interactions between genotypes and replications were dominating, accounting for 45 to 50 per cent of the variation. Main effects from genotypes were less prominent, accounting for 25 to 30 per cent of the variation, and the replications showed relatively little effect, accounting, for about 4 to 12 per cent of total variation. Regeneration of plants from pollen embryos or callus was not significantly influenced by either genotype or replicates. The frequencies of plants regenerated being green, however, were influenced from both genotype and environments contributing 42.5 and 34.9 per cent of the total variation respectively, while only minor interactions between genotype and environments were indicated for this character.     

小麦品种无性系变异改良技术研究

针对晋阳345和晋麦73两个定型品种存在抗寒性较差的缺点,对其幼胚愈伤组织进行了4种处理:1、愈伤组织在MD培养基上继代2～3次;2、愈伤组织在紫外灯下约10cm照射2h;3、愈伤组织在低温2℃和常温25℃下交替培养30d;4、愈伤组织在紫外灯下照射2h后,再在低温2℃和常温25℃下交替培养30d。结果表明,4个处理后代R2主要农艺性状的变异率差异显著,且紫外灯照射幼胚愈伤组织的变异率比低温2℃和常温25℃交替处理幼胚愈伤组织高,其后代各种农艺性状的变异范围较大,变异率较高。但后者有利于改良抗寒性较差的定型小麦品种。     

小麦供锌状况对叶片结构及叶绿体超微结构的影响

锌缺乏或过量使小麦叶肉细胞变小,多环复式细胞显著减少。缺锌植株的叶绿体中基粒垛数少,基粒垛叠片层少,基质片层少,部分片层膨胀;叶绿体内包含较大的液泡和淀粉“泡”;叶绿体被膜模糊,甚至消失.锌过量则使小麦的叶绿体变小,基粒和基质片层明显减少,部分片层膨胀,亲锇颗粒多;在叶绿体周围线粒体出现较多.     

Distribution and Origin of Hybrid Necrosis Genes in German Winter Wheat (Triticum aestivum L.) Cultivars

Hybrid necrosis in Triticum is known to be caused by the interaction of two complementary dominant genes. In the present paper, the genotypes for hybrid necrosis of 64 winter wheat cultivars are presented. 41 cultivars were found to possess the Ne₂ necrosis gene, whereas 23 cultivars were non-carriers. The Ne₁ gene was not found in any of the cultivars analyzed.     

Nitrate Assimilation and Nitrogen Harvest in Uniculm 'Gigas' Wheat (Triticum aestivum L.)

Contribution of the upper laminae designated as 7, 8 and 9 (flag), to the total reduced nitrogen was determined by two different methods; integration of nitrate reductase activity over the entire growing season of individual laminae, and laminae removal at ear emergence. The values obtained by these methods were: 20, 14, and 12 %, and 23, 15, 12 %, respectively. The in vivo nitrate reductase activity was relatively higher in the lamina 9, which contributed an extra 8 % towards total reduced nitrogen when the other laminae were removed from the shoot. No such compensatory response was observed when either lamina 7 or 8 was retained.     

The Growth in Culture of Detached Ovaries of Wheat (Triticum aestivum L. em. Thell)

Viable embryos have been recovered from fertilized wheat (Triticum aestivum) ovaries detached on the day of, or up to 7 days post-, anthesis and cultured aseptically fur up to 18 days. The most significant factors in determining the yield of embryos was the plating density, age and complexity of the explants. 26% of ovaries excised on the day of anthesis produced viable embryos if cultured as pairs of florets. The potential use of detached ovary cultures in gametophyte microinjection experiments, rescuing embryos from wide crosses and in chemically manipulating the early stages of embryo development are discussed.     

Identification of Powdery Mildew Resistance Genes in Common Wheat (Triticum aestivum L.)

Major genes for resistance to powdery mildew were analysed in 24 Czechoslovakian wheat cultivars and, in part, in their parents. For this purpose individual isolates of the pathogen, able to differentiate host lines with known resistance genes, were selected. Eight of nineteen winter wheat cultivars do not possess any major resistance gene. Three cultivars have one and seven have two genes. One cultivar carries a combination of three genes (Pm2, Pm4b, Pm8). The most common resistance genes are Pm4b, Pm5 and Pm8. Pm2 is once combined with Pm6. Only one of five spring cultivars lacked a major resistance gene. Mlk is once present alone and twice combined with Pm5. There is one spring cultivar with a novel combination of three genes: Pm1, Pm5 and another gene needing further characterization. The observations are discussed with additional results of parent lines and further information on pedigrees.     

小麦株高近等基因系的RAPD标记研究

采用ＲＡＰＤ技术,以４个小麦株市基因近等基因系（分别含有rht、Ｒht1、Rht2、Rht3)为材料,对２９６个单一随机引物（１０个核苷酸）进行了筛选。发现２５个引我的扩增产物的近等基因系间表现出特异性,在６次重复试验中,有１８个引物的特异护增片段不能重复,６个引物可以重复２－３资,唯有ＯＰＡＭ０１在全部试验中均能稳定重复,其特异扩增版段ＯＰＡＭ０１１８６０可以作为rht基因的ＲＡＰＤ标记。     

小麦株高近等基因系的RAPD标记研究

采用RAPD技术, 以4个小麦株高近等基因系(分别含有rht、 Rht1、 Rht2、 Rht3基因)为材料, 筛选了296个单一随机引物(10个核苷酸)。 发现25个引物的扩增产物在近等基因 系间表现出特异性。 在6次重复试验中, 有18个引物的特异扩增片段不能重复, 6个引物 可以重复2～3次, 唯有OPAM01在全部试验中均能稳定重复, 其特异扩增     

Performance of Spelt (Triticum spelta L.) and Wheat (Triticum aestivum L.) at two Different Seeding Rates and Nitrogen Levels under Contrasting Environmental Conditions

The aim of this investigation was to obtain information about differences between spelt and wheat in relation to their performance under low-input conditions. Two spelt varieties ( Oberkulmer, Hercule ) and two wheat varieties ( Anna, Iend ) were grown at two different seeding rates (S1 = 200; S2 = 400 kernels/m²) and two nitrogen levels (Nl = 80 kg N/ha; N2 = 110 kg N/ha) at two contrasting locations (Muri; altitude 459 m asl; Oberwallestalden: altitude 1011 m asl). No growth regulators and fungicides were applied.
The overall mean for the "husked" yield (grains and glumes) of spelt was not significantly different from the grain yield of wheat. At the higher site Oberwallestalden however, the "husked" yield of spelt was 10.5 % higher than the grain yield of wheat. Although the number of ears per m² was higher at S2 than at S1, spelt and wheat produced a similar yield at both seeding rates (spelt: S1 = 96 % of S2; wheat: S1 = 95 % of S2) due to the higher single ear weight at S1.
The reaction of spelt and wheat to nitrogen was similar. The yield was 10 % higher at N2 than at Nl for both species. The performance of spelt under low-input conditions was better than for wheat in marginal areas for cereal production only.