Comparison of doubled haploid lines and F2 bulks for the improvement of barley in the dry areas of North Syria

Drought stress is the main factor limiting barley yields in West Asia and North Africa. This study compares the utility of doubled haploid lines (DHLs) and conventional F₂ plant-derived bulks (F₂Bs) in improving barley in stress environments. Double crosses were made, DHLs were developed by anther culture from double-cross F₁ plants, and F₂Bs were produced by bulking the offspring of F₂ plants. Field tests were conducted in three drought-stressed environments. No major differences were observed in the mean performance of DHLs and F₂Bs. For most traits, both the genotypic and the genotype × location interaction variances were higher in the DHL group, whereas heritabilities were similar. Higher gains from selection were predicted for the DHL group. Regression analysis of yield stability indicated a lower predictability of the DHL performance. The haploid technique can improve breeding populations from which varieties with stable yields can be developed. The costs involved are determined by the DHL production rate, which needs to be improved in many developing countries.     

Genetics of multiple disease resistance in a doubled-haploid population of barley

The barley accession Q21861 possesses resistance to the stem-rust (Puccinia graminis f.sp. tritici), leaf-rust (P. hordei), and powdery-mildew (Blumeria graminis f.sp. hordei) pathogens. An anther-culture-derived doubled-haploid population was produced from F₁ plants from a cross of this accession and the susceptible breeding line SM89010 as a means of rapidly and efficiently determining the genetics of multiple disease resistance. The doubled-haploid population segregated 1:1 (resistant:susceptible) for resistance to the stem rust pathotype QCC indicating the involvement of a single resistance gene, rpg4. Two-gene (3:1) and one-gene (1:1) segregation ratios were observed for resistance to the stem-rust pathotype MCC at low (23–25°c) and high (27–29°C) temperature, respectively. These different segregation patterns were due to a pathotype × temperature interaction exhibited by rpg4 and Rpg1. another stem-rust-resistance gene present in Q21861. One-gene and two-gene segregation ratios were observed in reaction to the leaf rust and powdery mildew pathogens. These data demonstrate the utility of doubled haploid populations for determining the genetics of multiple disease resistance in barley.     

Regeneration of fertile doubled haploid plants from colchicine-supplemented media in wheat anther culture

The effect of colchicine added to induction medium for the production of fertile doubled haploid plants after in‐vitro anther culture was studied in wheat, Triticum aestivum L. For this, one winter and two spring wheat varieties were used. Anther cultures of the three genotypes were treated with 0.03% colchicine for 3 days at the beginning of microspore induction. Colchicine had no significant effect on anther response and embryoid production of the genotypes examined. However, in the winter wheat genotype ‘Mv Szigma’, colchicine caused a significant reduction in microspore‐derived structures. A significant decrease was also observed in plant regeneration ability of two genotypes (‘Vergina’ and ‘Acheloos’) after colchicine treatment. In addition, a significant reduction of the albinos produced was observed in all genotypes after olchicine treatment. In contrast, the regenerants obtained from the colchicine‐supplemented induction media produced significantly higher percentages of fertile plants in all genotypes. However, the level of fertility, was significantly different among the fertile plants obtained. This, together with the observation that in the case of the winter wheat variety the colchicine treatment resulted in 100% completely fertile plants with a high seed‐setting ability indicate that there is space for further improvement of the method when it is applied to spring cultivars. Finally, the increased number of seeds per 100 plated anthers obtained from all three genotypes after colchicine treatment, clearly demonstrates that the addition of colchicine to induction medium was superior to the conventional anther culture method and it could therefore be introduced into wheat breeding programmes.     

小孢子培养获得松花型花椰菜DH再生植株

对5个松花型花椰菜(Brassica oleraceavar.botrytisL.)杂种一代的小孢子培养研究表明,小孢子胎胚发生主要依赖于基因型,庆农65天的每花蕾胚状体产量最高,平均达15.5个。松花菜的胚状体萌发率一般在30%左右,并有效地获得了大量的DH再生植株。冷激预处理能显著地影响花椰菜小孢子的胚胎发生,但供体材料间存在不同的结果。结球期和开花结角期再生植株的生育期与育性出现较大分离,可育且能正常结角的比例约占全部小孢子再生植株的50%以上,因而不再需要加倍处理。     

Plant Regeneration Through Anther Culture of Three Wild Species of Hordeum (H. murinum, H. marinum and H. bulbosum)

Plant regeneration was achieved through anther culture of three wild species of Hordeum (H. murinum, H. marinum and H, bulbosum). Calli or embryoids were formed from microspores in anthers cultured on a medium containing 6-benzylammopurine (BAP) and ficoll. These calli or embryoids regenerated green or albino shoots and roots after transfer to regeneration media. Green plantlets which developed on regeneration media were transferred to soil where they showed further growth.     

Triploid and Hexaploid Regenerants from Hexaploid Timothy (Phleum pratense L.) via Anther Culture

Pollen embryos were obtained from eight genotypes and viable green plants were regenerated from four genotypes in an anther-culture experiment with 165 genotypes of Phleum pratense L. Formation of proembryos inside the cultured anthers during the first 10—12 days was significantly influenced by genotypes and by the type of nutrient media. Primary embryos developed into multiple secondary embryos before regeneration of plants. Among a total of 62 plants regenerated, only 13 were albinos. Of the green regenerants, 11 were triploid while 35 were hexaploid when DNA-content was measured by flow cytometry. Eight plants with a triploid DNA-content did possess the triploid chromosome number of 21. Triploid and hexaploid regenerants from two different parents showed simplified isozyme (GPI and PGD) banding patterns relative to that of their parents.     

预热处理对甘薯蛋白酶解特性的影响

以碱性蛋白酶（Alcalase）为水解酶,研究了不同预热处理温度和时间对甘薯蛋白酶解特性的影响。采用单因素试验及响应面分析法,对Alcalase水解预热处理条件进行了研究,建立了水解度（DH）及三氯乙酸氮溶解指数（TCA-NSI）与预热处理的回归模型,分析了模型的有效性及因子间的交互作用。结果表明,预热处理对Alcalase酶解甘薯蛋白的DH和TCA-NSI的影响显著（P＜0.05）;甘薯蛋白预热处理的最优工艺参数为：温度92℃,时间13?min。在此条件下,DH与TCA-NSI分别为26.32%和84.33%。与直接酶解天然甘薯蛋白相比,在预热处理的最佳工艺条件下所得到的DH和TCA-NSI分别提高了15.89%和53.37%。     

Retrospect on in vitro androgenesis of sorghum (Sorghum bicolor)

Development of sorghum hybrids can immensely benefit from an enhanced anther culture protocol since the resultant doubled haploids would accelerate, as in other major cereal crops, the attainment of homozygosity and fixation of alleles. Production of the hybrids that have got high yielding, stress tolerance and other traits of industrial significance in a shorter time as compared to the current trend can hence be realized. This review presents the advances that have been made in the development of such a protocol, with closer attention to androgenic induction components of pre-treatment, culture media composition and conditions as well as ploidy determination and eventual chromosome doubling. From the findings of this review, it is clear that further work is desired to ensure a protocol, that to a large degree, breaks the genotype dependency trend that has been widely cited to impede the usability of the tested protocols.     

QTL mapping and associated marker selection for the efficacy of green plant regeneration in anther culture of rice

Anther culturability of rice is a quantitative trait controlled by nuclear‐encoded genes. The identification of quantitative trait loci (QTL) and associated marker selection for anther culturability is important for increasing the efficiency of green plant regeneration from microspores. QTL associated with the capacity for green plant regeneration in anther culture of rice were mapped on chromosomes 3 and 10 using 164 recombinant inbred (RI) lines from a cross between ‘Milyang 23’ and ‘Gihobyeo’. The quantitative trait locus located on chromosome 10 was detected repeatedly when three anther culture methods were applied and was tightly linked to the markers, RG323, RG241 and RZ400. Associations between these markers and the efficacy of green plant regeneration in 43 rice cultivars and two F₂ populations, ‘MG RI036’/‘Milyang 23’, and ‘MG RI036’;/‘IR 36’ were analysed. One of these markers, RZ400, was able to identify effectively genotypes with good (> 10.0%) and poor (< 3.0%) regenerability, based on the marker genotypes in the cultivars and two F₂ populations. This marker enables the screening of rice germplasm for anther culturability and introgression into elite lines in breeding programmes.     

Wide mapping of a T-DNA insertion site in oilseed rape using bulk segregant analysis and comparative mapping

Doubled haploid oilseed rape lines segregating for a transgene inducing herbicide resistance (bar gene) were investigated for the wide mapping of the T-DNA insertion site. Bulk segregant analysis using presence/absence and intensity polymorphisms between the bulks, as well as comparative mapping with a linkage group deriving from another cross, led to the identification of 11 random amplified polymorphic DNA (RAPD) markers tightly or loosely linked to the bar gene. Ten RAPD loci out of 11 were located on the same side of the bar locus, strongly suggesting that the T-DNA integrated in a telomeric or subtelomeric position. The eleventh RAPD marker exhibited a strong segregation distortion, which could be the result of a heteroduplex formation. Comparison of the linkage groups obtained from the two crosses showed different recombination rates between markers, possibly reflecting differences in parental genetic backgrounds. Consequences and potential applications in transgene dispersal safety assessment studies are discussed.