Isoenzymes and their Importance for Breeding Autopolyploids

Isoenzyme analyses have been carried out in polyploid rye. Taking into consideration zymograms at the diploid level, conclusions can be drawn concerning the genetics of band positions and band intensity. This is rather clear with the aspartate aminotransferase and the NAD-specific aromatic alcohol dehydrogenase. For both isoenzymes one gene locus with two alleles is responsible in the zones analyzed. In both cases a superdominance is assumed. Thereby nulliplex-, simplex-, duplex-, triplex- and quadru-plex types can be distinguished. For the banding pattern with the leucine aminopeptidase two gene loci with two alleles each are responsible. With allelic interaction codominance is supposed. On this base it is possible to differentiate between homozygosity and heterozygosity. Difficulties in autopolyploid breeding can be overcome by means of genetically-analyzed isoenzymes as markers. This is demonstrated by examples.     

Plant Regeneration and Genetic Variability from Tissue Cultures of Sunflower (Helianthus annuus L.)

Adventitious buds were induced from in vitro culture of sunflower (Helianthus annuus L.) cotyledons. Four inbred lines (G1, G2, G3 and HA89), an open pollinated variety (‘Argentario’) and two hybrids with specific genetic markers were used. Cotyledons were cultured in vitro on MS medium (Murashlge and Skoog 1962) containing various concentrations of kinetin and indole 3-acetic acid (IAA). The quantitative interactions between auxin and cytokinin, the age of the cotyledons and the 2,3,5-triiodobenzoic acid (TIBA) treatments have been found to influence shoot regeneration. The plantlets, after rooting, were successfully established on soil. Qualitative variation was noted in self-pollinated progeny of plants regenerated from culture of two inbreds. Chimerism in regenerated plants was indicated by sectoring of the genetic markers. Some culture-induced variant phenotypes were similar to known spontaneous mutation in sunflower but others have been not yet described. Preliminary data indicate that most of them may have single-gene recessive inheritance.     

Mapping genes for resistance to sprouting damage in wheat

A series of experiments to investigate the genetic basis of pre-harvest sprouting are reported. The results are combined with previously published studies in a composite genetic map for sprout resistance in hexaploid wheat. Different studies, using classical genetics, aneuploids, chromosome substitutions, or QTL mapping, have identified various regions of the A, B, and D genomes affecting dormancy. Comparisons between the available studies lead to the following conclusions: • Different studies often identify different genetic loci, in part reflecting different sampling from the available gene pool. This implies that many loci are involved in determining resistance, and that new loci may be discovered as the number of mapping studies increases.• There are, however, examples where similar map locations are implicated over different crosses. These may reflect the detection of key resistance genes. • Finally, (genotype × environment) interactions are frequently observed. The implications of these observations for crop improvement and research programmes are discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Combining different linkage maps in sugar beet (Beta vulgaris L.) to make one map

Several genetic maps for sugar beet (Beta vulgaris L.), from different German research groups, have been published and it is now possible to consider combining them with the aid of the common markers. The computer program JOINMAP (versions 1.3 and 2.0) was used for pair-wise combination of three populations. Several problems arose: the genetic background of the populations, different population structures (F₂ versus F₁× F₁), different number of polymorphic loci for common probes in the populations to be combined, different estimates of the recombination rates between the same markers and differences between the Join Map versions. The maps from two F₂ populations could be integrated into a single map, but it was more appropriate to construct separate maps for the F₂ populations and the F₁× F₁ population using common markers as reference points only.     

Molecular markers and protein quantities as genetic descriptors in maize. II. Prediction of performance of hybrids for forage traits

As it is related to the variability in genome expression, variability in protein quantities revealed by two-dimensional electrophoresis was proposed for describing phenotypic diversity. The objective of this study was to compare the predictive power of different genetic distances derived from molecular markers and from protein quantitative variations in a diallel of 210 hybrids among 21 maize inbred lines (Zea mays L.) of various origin. The lines were characterized for: 1. 142 markers resulting from the analysis of enzyme, RFLP, and protein-structure polymorphism; and 2. The variation in relative quantities of 190 proteins. The hybrids were evaluated for six forage traits in four environments. Correlations between the genetic distances computed for 142 marker loci and hybrid performances were moderate to high in diallels using crosses between related lines. Genetic distances based on protein quantities showed, in most cases, similar or lower correlations. Distance measures were not useful as predictors of hybrid performance for crosses between unrelated lines. Protein quantities were better for revealing specific genotypes.     

Doubled Haploids of Cocoa (Theobroma cacao L.) 2. Observations of Monogenic and Polygenic Characters

The expression of monogenic and polygenic characters has been studied in families of spontaneous haploids of cocoa which nave been doubled with colchicine. Segregation of six enzyme markers, heterozygous in the various parent clones, has been analysed in the doubled haploids for alcohol dehydrogsnase (ADH), malate dehydrogenase locus B (MDH-B), isocitrate dehydrogenase (IDH), acid phosphatase (ACP), phosphoglucomutase (PGM) and phosphoglucose isomerase (PGI). Nine of the eleven families showed a Mendelian-type segregation, two presented distortions but all alleles were found in the haploid progenies. Polygenic characters were expressed with great variability: A few DHs showed similar or even higher values than their parents for individual characters, but the majority were lower, and large depressions could be seen for the group of characters studied. These results have consequences for the use of doubled haploids of cocoa which must both give a sure production of hybrid seeds and be good progenitors; no prediction of their value as progenitors seems possible after observation of their own characteristics and the only selection made from these plants will be a propos their characters directly involved in seed production. These selected doubled haploids will subsequently have to be tested as progenitors.     

ISSR profiling of Indian cultivars of mulberry (Morus spp.) and its relevance to breeding programs

Mulberry, Morus spp. has a wide range of use, the chief among them is to feed the silk producing caterpillar Bombyx mori L. (Bombycidae; Bombycoidea). As a homeland of mulberry, India has a number of indigenous mulberry species, of which a few are widely cultivated. In the present investigation genetic distance among such eleven mulberry cultivars originated from six different states of India covering a wide geographic area extending from 15^° N to 32^° N latitude and 72^°E to 89^°E longitude was studied using inter-simple sequence repeat primers. Out of the 20primers tested, 13 primers, viz, nine di-nucleotide, three tri-nucleotide and one penta-nucleotide repeats, gave clear and reproducible band profiles. While the (AT)_n rich primers could not amplify the DNA, the (GA)n, (AC)n and (AG)n rich primers gave excellent amplification profiles. The genetic distance among the cultivars varied from a minimum of 0.053, between Punjab local and Bombay local, to a maximum of 0.431, between Almora local andSujanpur-5. Clustering of the cultivars according to nearest neighbor method created three groups. The north-Indian cultivars made a separate and distinct group while the cultivars originated from eastern and southern India occupied a distinct position. Almora local was found quite different from others. The first two canonical functions identified through discriminant function analysis accounted for 91.2% of the total variability. Distribution of cultivars belonging to six different zones on canonical matrix realized from Discriminant Function Analysis (DFA) revealed wider variability for West Bengal, Karnataka and Punjab which reaches the group centroids of Uttar Pradesh and Himachal Pradesh. This attests to the past contribution of West Bengal in east and Karnataka in south towards development of mulberry cultivars indifferent parts of India. Step-wise linear regression analysis, further, identified two markers (825.₁₄₀₀ and835.₇₅₀) associated with leaf yield, which also satisfied the Beta estimation, thereby testifying strong association of these two markers with leaf yield. This finding along with the classification of the eleven cultivars bear strong relevance to mulberry breeding for different agro climatic areas. This revised version was published online in August 2006 with corrections to the Cover Date.     

柱花草花粉不育基因连锁的SCAR标记研究

本研究以圭亚那柱花草‘1979’（Stylosanthes guianensis ‘1979’,母本,花粉不育）和‘热研2号’柱花草（轮回父本）的BC₁F₁代群体为材料,利用简单序列重复区间扩增多态性（Inter-simple Sequence Repeat,ISSR）技术,结合集群分组分析法（Bulked Segregate Analysis,BSA）构建花粉育性基因池。结果表明：利用100条ISSR引物筛选出在不育基因池中有特异条带的引物共11条;经BC₁F₁群体单株验证,有8个标记仅在花粉不育个体中出现,表明其与花粉不育基因连锁;将这8个特异性片段回收、克隆、测序,并分别设计8对特异序列特异扩增区域（Sequenced Charaeterized Amplified Region,SCAR）引物,对BC₁F₁单株进行验证,发现这8条片段仅在不育个体中扩增出目标条带,表明8 ISSR特异片段成功转化为8个SCAR标记。本研究结果为建立柱花草稳定的雄性不育系提供新的理论基础,为柱花草杂交育种奠定基础。