General combining ability of six genotypes of spring wheat (Triticum aestivum) for biscuit-making quality characteristics

The first South African soft wheat breeding programme was initiated in 19 90 , consequently almost no information is available on soft wheat quality characteristics. The aim of this study was to determine general combining ability (GCA) of several spring wheats for biscuit-making quality characteristics. A full dialled cross was made with five spring wheats with good biscuit-making quality and a sixth hard wheat with poor biscuit-making quality. Seventeen quality characteristics were measured. When the GCA to specific combining ability (SCA) ratios were calculated, strong additive gene action was shown for all characteristics, excluding flour colour and biscuit diameter, which suggested high heritabilities for most characteristics. None of the characteristics showed more non-additive than additive gene action. Three of the soft wheat cultivars combined well for the characteristics important for biscuit-making quality.     

Nuclear DNA content and in vitro induced somatic polyploidization cassava (Manihot esculenta Crantz) breeding

Summary The diploid (2C) amount of DNA in cassava (Manihot esculenta Crantz) is 1.67 picograms (pg) per cell nucleus. This value corresponds to 772 mega-base pairs in the haploid genome. The size of the nuclear genome in cassava is very small in comparison with other Angiosperms. Flow cytometry techniques were used to screen ploidy levels in a large population of in vitro plantlets treated with colchicine and oryzalin (3,5-dinitro-N⁴,N-dipropylsulphate). Culture of axillary node cuttings for 48 hours in liquid medium supplemented with 2.5 to 5.0 mM colchicine in combination with 2% dimethyl sulfoxide (DMSO) resulted in a high frequency (23 to 42%) of non-chimeric tetraploids in the V₃ generation. Although mixoploidy may persist in as many as four cycles of vegetative propagation of node cuttings, solid (non-chimeric) tetraploids can be identified by flow cytometry among in vitro plantlets and then rapidly propagated for field testing. A somatic polyploidization system is proposed for implementation in cassava breeding programmes.Dedicated to the memory of the late Dr. Novak. Correspondence to M. van Duren     

Resistance to powdery mildew (Erisyphe polygoni D.C.) in peas (Pisum sativum L.)

Summary In certain years the fungus Erisyphe polygoni D.C., which is responsible for powdery mildew may heavily effect peas, especially dry peas.Some lines from Peru, Hawaii, and Geneva, U.S.A. as well as the varieties Mexique 4 and Stratagem show resistance to this disease. The resistance of the progenies from Peruvian material is confined to the leaves.The results of the investigations show that one recessive gene er ₁ can bring about full resistance in the field and in the glasshouse under Dutch conditions.The leaf resistance of the Peruvian lines is caused by a second recessive gene er ₂.The Dutch breeder could use in his resistance breeding work chiefly the variety Stratagem or the line SVP 942, which already possess the desirable straw length and seed colour.     

农村沼气-秸秆气-太阳能"三能合一"综合运行模式探讨——以天津市邦均镇示范工程为例

介绍了农村沼气-秸秆气-太阳能"三能合一"综合运行模式,以邦均镇为例对"三能合一"模式进行了经济、生态和社会效益分析。分析表明,"三能合一"综合运行模式可以改善农村环境卫生状况,还能生产可再生能源,同时沼渣和沼液可以作为优质有机肥循环利用,该模式的技术和产品还可商业化,能取得良好的经济、生态和社会效益。     

玉米BEL1-like基因家族的鉴定、表达和调控分析

BEL1-like(BELL)家族蛋白是植物中普遍存在的一类具有同源异型结构域的转录因子。拟南芥中BELL家族蛋白能与KNOTTED1-like蛋白互作形成异源二聚体,并结合到特异顺式作用元件来调控基因的表达,从而影响植物生长发育进程。本文采用隐马可夫(HMM)模型,在玉米基因组中鉴定到15个BELL家族基因(Zm BELL),分布于7条玉米染色体。通过与拟南芥BELL基因的序列比较将这些基因分为两大类。在玉米8种组织中Zm BELL有不同的表达模式,具有明显的组织表达特异性。基于基因共表达分析及BELL-like蛋白特异结合的顺式元件分析,预测到86个可能受Zm BELL调控的下游靶标基因。这86个基因和12个Zm BELL表达模式相同,并且在基因启动子区存在与BEL1-like蛋白结合的顺式元件。这些结果为进一步解析玉米BELL家族基因的功能和作用机制积累了有价值的资料。     

Gibberellins as gametocides for the common onion (Allium cepa L.). III. GA4+7 and pollen viability

Summary The gametocidal effect of GA₄₊₇ in onion is strong in respect of pollen production but very weak or absent in respect of pollen viability. Large scale application of GA₄₊₇ for the production of onion hybrid seed is still impossible because of low seed yield and high costsof required chemicals. On a small scale, however. GA₄₊₇ can be used very well to emasculate breeding material.Because of switching over to the gibberellin terminology of plant physiologists, this title slightly deviates from that of the two previous articles.     

Gibberellic acid as a gametocide for the common onion (Allium cepa L.)

Summary A high concentration of gibberellic acid (GA₃, 2%) was found to act as a gametocide for the common onion, Allium cepa L., when sprayed in the beginning of the bolting process.This technique is suggested as a possible substitute for hand emasculation, since it would greatly facilitate interspecific and intervarietal crosses, recurrent backcrosses and the selection of good B lines.     

Molecular mapping of powdery mildew resistance genes in wheat: A review

Powdery mildew, caused by Blumeria graminis f. sp. tritici (syn. Erysiphe graminis f. sp. tritici), is one of the most important diseases of common wheat (Triticum aestivum L.) worldwide. Molecular mapping and cloning of genes for resistance to powdery mildew in hexaploid wheat will facilitate the study of molecular mechanisms underlying resistance to powdery mildew diseases and help understand the structure and function of powdery mildew resistance genes, and permit marker-assisted selection in breeding programs. So far, 48 genes/alleles for resistance to powdery mildew at 32 loci have been identified and located on 16 different chromosomes, of which 21 resistance genes/alleles have been tagged by restriction fragment length polymorphisms (RFLPs), random-amplified polymorphic DNAs (RAPDs), amplified fragment length polymorphisms (AFLPs), sequence characterized amplified regions (SCARs), sequence-tagged sites (STS) or simple sequence repeats (SSRs). Several quantitative trait loci (QTLs) for adult plant resistance (APR) to powdery mildew have been associated with molecular markers. The detailed information on chromosomal location and molecular mapping of these genes has been reviewed. Isolation of powdery mildew resistance genes and development of valid molecular markers for pyramiding resistance genes in breeding programs is also discussed.     

CIMMYT's approach to breeding for wide adaptation

Summary The wheat area in developing countries, including China, is around 100 million ha. To address the needs of these very diverse wheat growing areas, CIMMYT has defined 12 wheat mega-environments (ME). A ME is defined as broad, not necessarily continuous often transcontinental area with similar biotic and abiotic stresses, cropping systems and consumer preferences. The factors describing each ME are presented.CIMMYT's breeding methodology is centered around the development of widely adapted germplasm with high and stable yield across a wide range of environments. Segregating populations are alternating screened in two diverse environments in Mexico. One key requirement is that all germplasm is tested under near optimum conditions for its yield potential. The second one is multi-locational testing of advanced lines at sites that represent a given ME (key locations) and careful screening of germplasm for tolerance to abiotic and biotic stresses specific to that environment. This methodology has permitted the pyramiding of a large number of multiple resistance genes for use against a wide spectrum of diseases and tolerance to abiotic stresses within each ME. In addition, the widespread testing of lines allows the identification of traits which are beneficial in several environments. Data from international nurseries are used to further delineate environments within an ME. This approach has proven to be successful since around 70% of the spring wheat area in developing countries (excluding China) is planted to varieties derived directly or indirectly from CIMMYT germplasm. The performance of the bread wheat cultivar Pastor in international trials is given as an example for a wide adaptation.