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Full-Text Articles in Plant Sciences

Effects Of Elevated Co2 And Defoliation On Grasses: A Comparative Ecosystem Approach, Brian J. Wilsey, James S. Coleman, Samuel J. Mcnaughton Jan 1997

Effects Of Elevated Co2 And Defoliation On Grasses: A Comparative Ecosystem Approach, Brian J. Wilsey, James S. Coleman, Samuel J. Mcnaughton

Brian J. Wilsey

Three plant species from each of three grassland ecosystems were grown under elevated (700 mL/m3) and ambient (350 mL/m3) CO2 and were defoliated or left undefoliated to test whether species response to elevated CO2 and grazing is related to evolutionary grazing history or to mode of photosynthesis. The three ecosystems represented a tropical grassland dominated by C4 species (the Serengeti of Africa), a temperate grassland dominated by a mixture of C3 and C4 species (Flooding Pampa of South America), and a northern temperate grassland dominated by C3 species (Yellowstone National Park of North America). Plants were grown in growth chambers …


Evolutionary Implications Of Meiotic Chromosome Behavior, Reproductive Biology, And Hybridization In 6x And 9x Cytotypes Of Andropogon Gerardii (Poaceae), Guillermo A. Norrmann, Camilo L. Quarín, Kathleen H. Keeler Jan 1997

Evolutionary Implications Of Meiotic Chromosome Behavior, Reproductive Biology, And Hybridization In 6x And 9x Cytotypes Of Andropogon Gerardii (Poaceae), Guillermo A. Norrmann, Camilo L. Quarín, Kathleen H. Keeler

School of Biological Sciences: Faculty Publications

Andropogon gerardii, big bluestem, has 60 and 90 chromosome cytotypes. Meiosis in the hexaploid was shown to be regular, although some secondary associations of bivalents form. Meiosis in the enneaploid (2n = 9x = 90) is irregular, leading to most gametes having unbalanced chromosome complements. Both cytotypes show considerable self-incompatibility. Cytotypes crossed freely, forming a variety of fertile euploids and aneuploids. Indistinguishable exomorphology, intermixing in natural populations, and compatibility suggest that A. gerardii is best understood as a cytotypically complex single species.


Effect Of Media Constituents On In Vitro Culturing Of Cowpea (Vigna Unguiculata) Shoot Tip And Leaf Disk Explants, Mohanjeet S. Brar, Edwin J. Anderson, Teddy E. Morelock, Ronald W. Mcnew Jan 1997

Effect Of Media Constituents On In Vitro Culturing Of Cowpea (Vigna Unguiculata) Shoot Tip And Leaf Disk Explants, Mohanjeet S. Brar, Edwin J. Anderson, Teddy E. Morelock, Ronald W. Mcnew

Journal of the Arkansas Academy of Science

Cowpea is an important legume food crop that is commonly grown in Arkansas and numerous other southern states. The application of biotechnological approaches for the improvement of U.S. cowpea genotypes is currently not possible due to the lack of a regeneration and transformation system. Therefore, the first priority of our research efforts is the development of a plant regeneration system that will facilitate plant transformation studies. In an effort to optimize the media requirements for tissue culturing cowpea, we evaluated the in vitro response of shoot tip and leaf disk explants to various levels of Murashige and Skoog (MS) macro …


Factors Affecting Transformation Efficiency Of Poplar Hybrid Line Nc5331 By Agrobacterium Tumefaciens, Xin Y. Li, Feng H. Huang, Edward E. Gbur Jr. Jan 1997

Factors Affecting Transformation Efficiency Of Poplar Hybrid Line Nc5331 By Agrobacterium Tumefaciens, Xin Y. Li, Feng H. Huang, Edward E. Gbur Jr.

Journal of the Arkansas Academy of Science

Acetosyringone, pH, and glucose, which may affect Agrobacterium-mediated gene transformation to poplar hybrid line NC5331, were investigated in an attempt to raise the gene transfer efficiency. The Agrobacterium tumefaciens strain used harbored disarmed vector (pMON9749) carrying a bet-glucuronidase gene and a kanamycin resistant marker. With the addition of acetosyringone at 25 to 75 MuM, the transformation efficiency was significantly enhanced, but dependent on pH. Acetosyringone required a pH above 5.8 to achieve an efficient gene transfer and failed to enhance the transformation at lower pH. However, with addition of both acetosyringone and glucose, the transformation was not affected by pH. …