Effect of Thidiazuron and Benzylaminopurine on In Vitro Shoot Proliferation of Carnation (Dianthus caryophyllus L.)

Carnations (Dianthus caryophyllus L.) are among the most widely used cut flowers in the world. Tissue culture techniques offer an efficient method for the micropropagation of carnations. This study was conducted to test the effect of thidiazuron (TDZ) and benzylaminopurine (BAP), artificial cytokinins, on shoot multiplication of two carnation cultivars, Barlo II Nora and Raggio di Sole. Isolated axillary buds were cultured on Gamborg\u27s (B-5) basal medium supplemented with 30 g/L sucrose and 8 g/L agar. The cultures were maintained at a 10-h photoperiod (40 (mu-Em2s-1) and 23°C±2C°. Number of multiple shoots produced was dependent upon the genotype and was also influenced by the cytokinin type and concentration. Barlo II Nora produced the highest shoot number with 14 shoots per explant on a medium containing 20 mg/L BAP. The cultivar Raggio di Sole cultured on BAP-containing media produced a maximum of 4 shoots per explant. Barlo II Nora cultured on TDZ-containing media produced a maximum of 8 shoots per explant, however, large amounts of calli were associated with these shoots. Increasing the concentration of cytokinin was associated with an increase in shoot number and a decrease inshoot height. Shoots were rooted on Gamborg\u27s medium containing 2 mg/L of 3-indole-butyric acid (IBA) and then transferred to pots. Once acclimatized the carnations were transferred to a greenhouse where they exhibited normal growth. This method could be useful for the rapid propagation of carnations in commercial production

Effect of Media Constituents on In Vitro Culturing of Cowpea (Vigna unguiculata) Shoot Tip and Leaf Disk Explants

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 and micro nutrients, vitamins, and iron. One commercial cultivar, Early Scarlet (formerly 91-135), and one advanced Arkansas breeding line, 91-245, were used as tissue sources. Shoot tips were cultured on media augmented with 5 mg/L kinetin and 0.01 mg/L naphthaleneacetic acid (NAA). Multiple shoots were produced from shoot tips, and these grew well when cultured on full strength MS. However, increasing MS levels to 1.5 times the standard concentration induced taller shoots from both genotypes. Leaf disks were cultured on MS media supplemented with 0.5 mg/L benzylaminopurine (BAP) and 1mg/L 2,4 dichlorophenoxyacetic acid (2,4-D). Callus proliferation was greatest on media containing full strength MS supplemented with 0.5 mg/L BAP and 1 mg/L 2,4-D. The effects of the media constituents were genotype dependent, with Early Scarlet generally producing larger shoots and greater amounts of calli. The results obtained from this study demonstrate that the plant genotype and growth hormones have the greatest influence on cowpea growth in vitro. Therefore, in developing a cowpea regeneration system, it will be necessary to test numerous genotypes in combination with various growth regulators. To improve regeneration frequencies the media components can be optimized for the genotypes of interest