Latest Research News on Germplasm : May 2020

EXOTIC MAIZE GERMPLASM: STATUS, PROSPECTS, AND REMEDIES

In the United States and Canada, exotic maize germplasm can be domestic unadapted germplasm, temperate foreign germplasm, or tropical or semitropical germplasm. U.S. and Canadian plant breeders have made extensive use of elite but unadapted domestic germplasm. This paper documents the extent of usage of temperate, semitropical, and tropical sources of exotic maize germplasm currently in use in the U.S. It also describes a successful attempt to adapt specific elite sources of tropical germ plasm to U.S. growing conditions and a systematic way to choose promising sources of exotic germplasm from the broad array of tropical and semitropical maize germplasm represented by the various Latin American collections. While attempts to use exotic maize germplasm have thus far been limited, ineffective, and rather static, an example presented demonstrates that barriers to use of elite tropical maize germplasm can largely be broken within six years if breeding materials are chosen appropriately. Choice of breeding materials, indeed, is critical to the success of an exotic maize breeding program, yet it is an area that receives very little attention in current programs. [1]

The comparison of RFLP, RAPD, AFLP and SSR (microsatellite) markers for germplasm analysis

The utility of RFLP (restriction fragment length polymorphism), RAPD (random-amplified polymorphic DNA), AFLP (amplified fragment length polymorphism) and SSR (simple sequence repeat, microsatellite) markers in soybean germplasm analysis was determined by evaluating information content (expected heterozygosity), number of loci simultaneously analyzed per experiment (multiplex ratio) and effectiveness in assessing relationships between accessions. SSR markers have the highest expected heterozygosity (0.60), while AFLP markers have the highest effective multiplex ratio (19).  [2]

Drought Tolerant Sorghum and Cotton Germplasm

Rosenow, D.T., Quisenberry, J.E., Wendt, C.W. and Clark, L.E., 1983. Drought tolerant sorghum and cotton germplasm. Agric. Water Manage., 7: 207–222.

Sorghum (Sorghum bicolor (L.) Moench) and cotton (Gossypium hirsutum L.) are the summer crops traditionally grown in the rainfed or supplementary irrigated areas of the semi-arid southern Great Plains. Both crops have the ability to withstand periods of water deficit and to yield an economic return to the farmer.

Numerous traits contribute to drought tolerance in both sorghum and cotton. Only limited breeding effort has been expended on identifying or combining such traits. Drought tolerance has seldom been a primary breeding objective, usually addressed indirectly under major objectives such as improved yield, pest resistance, and adaptation. [3]

Molecular Genetic Markers for Assessing the Genetic Variation and Relationships in Lactuca Germplasm

The genus Lactuca L. belonging to the Asteraceae family, is widely distributed in different geographical and ecological areas. Lettuce and most of the other species of the genus Lactuca L. have been cultivated for their economic and medicinal importance. This review summarizes recent knowledge of the application of biochemical (isozymes) and molecular technologies (restriction fragment length polymorphism; random amplified polymorphic DNA; amplified fragment length polymorphism; microsatellites or simple sequence repeats; single nucleotide polymorphism) in Lactuca germplasm in order to better understand the genetic variation, interspecific relationships, taxonomy and breeding as a basis for further research studies. Undoubtedly, this would in turn provide a better platform for germplasm improvement, utilization and conservation. [4]

Taxonomic Relationships and Biochemical Genetic Characterization of Brassica Resources: Towards a Recent Platform for Germplasm Improvement and Utilization

The genus Brassica L. is one of the most economically important genera in the family Brassicaceae. It has an essential role in agriculture and horticulture, as well as contributing to the economy and populations health. This genus includes numerous species comprising major vegetable and oilseed crops with various agronomic traits that need to be further characterized. The present paper highlights the current knowledge of taxonomy, chromosome number, genomic relationships, geographical distribution, origin, domestication, and breeding technologies of the six economically important Brassica species grown in Egypt, as well as describing their genetic diversity and relationships at the level of biochemical markers, including storage proteins and isozymes. This information would help developing new and more productive crops of disease resistant and highly agronomic traits, resulting in a recent platform for crop improvement and conservation. [5]

Reference
[1] Goodman, M.M., 1985. Exotic maize germplasm: Status, prospects, and remedies. Iowa State J. Res, 59(4), pp.497-527.
[2] Powell, W., Morgante, M., Andre, C., Hanafey, M., Vogel, J., Tingey, S. and Rafalski, A., 1996. The comparison of RFLP, RAPD, AFLP and SSR (microsatellite) markers for germplasm analysis. Molecular breeding, 2(3), pp.225-238.

[3]  Rosenow, D.T., Quisenberry, J.E., Wendt, C.W. and Clark, L.E., 1983. Drought tolerant sorghum and cotton germplasm. In Developments in agricultural and managed forest ecology (Vol. 12, pp. 207-222). Elsevier.

[4] El-Esawi, M.A., 2015. Molecular genetic markers for assessing the genetic variation and relationships in Lactuca germplasm. Annual Research & Review in Biology, pp.1-13.

[5] Taxonomic Relationships and Biochemical Genetic Characterization of Brassica Resources: Towards a Recent Platform for Germplasm Improvement and Utilization

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