Inheritance and linkage study of isozyme loci and morphological traits in red clover
Information on inheritance of isozymes and linkage maps in Trifolium pratense L is limited. Genetic analysis of 18 isozyme systems and three morphological traits (white vs. pink flower, present vs. absent leaf marker and green vs. sun-red stem) was conducted. Six loci of four isozymes had simple Mendelian inheritance. Joint segregation analyses among 8 isozyme loci and 3 morphological gene markers (55 pair-wise combinations) resulted in the assignment of one linkage group. Two morphological markers coding for flower (c) and stem (gs) color were found to be in the same linkage group based on the analyses of two segregating families. The recombination values of the two progenies for c-gs were 0.079 and 0.113. No linkage was found between any of the isozyme loci and the morphological traits.
Molecular breeding for animal, human and environmental welfare
Since farmers started to cultivate land and deliberately sow seed, selection has led to the development of domesticated crops suitable for a wide range of agro-ecological and socio-cultural conditions. Based on increasing understanding of genetics and genes, new prospects for molecular breeding have emerged. Both forward and reverse genetic approaches and techniques such as marker-assisted selection and introgression, mutation breeding and transformation are now available. Increased precision in genetic manipulation promotes the application of more targeted breeding strategies to a wider range of traits serving a broader range of objectives. These include enhanced prospects for multifunctional land-use with improvements in the efficient use of inputs such as nitrogen, phosphate and water; in soil quality and protection against erosion; in pest and disease resistance; in enhanced animal nutrition and improved livestock product quality; in reduced pollution risks and health problems; and in potential for alternative use of grassland such as for amenity purposes, industrial processing and pharmaceuticals.
Alcohol dehydrogenase in the desert species Acacia erioloba: ontogeny during germination and induction in seedling roots
Dry seeds of Acacia erioloba, a southern African desert tree species, contain high levels of ADH which separate into six electrophoretic (PAGE) bands in axes and five bands in cotyledons. It is proposed that ADH in this species is coded for by three genes and that the isoenzymes arise from intergenic and intragenic dimerization of protomers. The number of ADH isoenzymes and activity decreases after germination, this change being more rapid in axes than in cotyledons. Decline in activity appears to require active protein synthesis. Cycloheximide and nitrogen prevent, but oxygen enhances loss of ADH activity. An ADH inactivator was shown to be present in developing axes and may be involved in the regulation of ADH activity. Anoxia, in contrast to hypoxia and 2,4-D, is largely ineffective in inducing ADH activity in seedling roots. Roots of well-aerated plants show one ADH electrophoretic band. Induction causes increase in activity in five ADH isoenzymes with most activity occurring in two isoenzymes.