Osmolarity, conductivity, buffer capacity, and solubility of oxygen of plant cell culture media

66-69Osmolarity, conductivity, buffer capacity, and solubility of oxygen of twelve commonly used plant tissue and cell culture media were investigated. Osmolarity and conductivity of different nutrient media showed considerable difference. Buffer capacity of culture medium measured from acid-base titration value indicated that plant cell culture media had moderate buffer strength. It varied from 82 µmole/L of White's medium to 1564 µmole/L of Eriksson's medium at pH 5.5. Solubility of oxygen in various cell culture media ranged from 7.01 - 7.79 mg/L. The present data would be useful in bioprocessing and in the selection of nutrient medium for in vitro culture of plant tissue and cells. </span

Biocontrol of Bacillus subtilis against Infection of Arabidopsis Roots by Pseudomonas syringae Is Facilitated by Biofilm Formation and Surfactin Production

Relatively little is known about the exact mechanisms used by Bacillus subtilis in its behavior as a biocontrol agent on plants. Here, we report the development of a sensitive plant infection model demonstrating that the bacterial pathogen Pseudomonas syringae pv tomato DC3000 is capable of infecting Arabidopsis roots both in vitro and in soil. Using this infection model, we demonstrated the biocontrol ability of a wild-type B. subtilis strain 6051 against P. syringae. Arabidopsis root surfaces treated with B. subtilis were analyzed with confocal scanning laser microscopy to reveal a three-dimensional B. subtilis biofilm. It is known that formation of biofilms by B. subtilis is a complex process that includes secretion of surfactin, a lipopeptide antimicrobial agent. To determine the role of surfactin in biocontrol by B. subtilis, we tested a mutant strain, M1, with a deletion in a surfactin synthase gene and, thus, deficient in surfactin production. B. subtilis M1 was ineffective as a biocontrol agent against P. syringae infectivity in Arabidopsis and also failed to form robust biofilms on either roots or inert surfaces. The antibacterial activity of surfactin against P. syringae was determined in both broth and agar cultures and also by live-dead staining methods. Although the minimum inhibitory concentrations determined were relatively high (25 μg mL(-1)), the levels of the lipopeptide in roots colonized by B. subtilis are likely to be sufficient to kill P. syringae. Our results collectively indicate that upon root colonization, B. subtilis 6051 forms a stable, extensive biofilm and secretes surfactin, which act together to protect plants against attack by pathogenic bacteria

<span style="font-size: 19.0pt;mso-bidi-font-size:14.0pt;font-family:"Times New Roman","serif"; color:black">Permeabilization and <i><span style="font-size:19.5pt; mso-bidi-font-size:14.5pt;font-family:"Times New Roman","serif";color:black">in situ </span></i><span style="font-size:19.0pt;mso-bidi-font-size:14.0pt; font-family:"Times New Roman","serif";color:black">adsorption studies during growth and coumarin production <span style="font-size:20.0pt;mso-bidi-font-size: 15.0pt;font-family:"Times New Roman","serif";color:black;mso-bidi-font-weight: bold">in<b> </b><span style="font-size:19.0pt;mso-bidi-font-size:14.0pt; font-family:"Times New Roman","serif";color:black">hairy root cultures of <i><span style="font-size:19.5pt;mso-bidi-font-size:14.5pt;font-family:"Times New Roman","serif"; color:black">Cichorium intybus </span></i><span style="font-size:19.0pt; mso-bidi-font-size:14.0pt;font-family:"Arial","sans-serif";color:black; mso-bidi-font-weight:bold">L. </span></span></span></span></span>

564-571<span style="font-size: 13.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";="" color:black"="">Effect of addition of a penneabilizing agent dimethyl sulfoxide (DMSO) and a solid adsorbent, XAD -7, on growth and coumarin production in hairy root cultures of <span style="font-size:13.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif";color:black"="">C. intybus was studied. Continuous permeabilization of the hairy root cultures <span style="font-size: 13.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";="" color:black"="">of  C. <span style="font-size:13.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif";color:black"="">intybus with DMSO has been shown to be an effective strategy for enhanced release of coumarins while preserving the root viability. DMSO at 0.2 % <span style="font-size:13.0pt;mso-bidi-font-size:8.0pt; font-family:" times="" new="" roman","serif";color:black"="">(v/v) level showed the maximum growth and coumarin production but was less as compared to control on day 28. Treatment of cells with increasing concentrations of DMSO (0.3 - 0.6 % <span style="font-size:13.0pt;mso-bidi-font-size:8.0pt; font-family:" times="" new="" roman","serif";color:black"="">v/v) to hairy root cultures of <span style="font-size:14.0pt;mso-bidi-font-size:9.0pt;font-family: " times="" new="" roman","serif";color:black"="">C. <span style="font-size: 13.5pt;mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif";="" color:black"="">intybus, <span style="font-size:13.0pt;mso-bidi-font-size: 8.0pt;font-family:" times="" new="" roman","serif";color:black"="">showed an inverse relationship with growth and coumarin production. Growth and production of coumarins increased with 1 <span style="font-size:13.0pt;mso-bidi-font-size: 8.0pt;font-family:" arial","sans-serif";color:black"="">% media filtrate (MF) of cultures of Phytopthora parasirica <span style="font-size:13.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";color:black"="">var. <span style="font-size:13.5pt;mso-bidi-font-size:8.5pt;font-family: " times="" new="" roman","serif";color:black"="">nicotiana treatment. It was observed that treatment with DMSO (0.2 % <span style="font-size:13.0pt;mso-bidi-font-size:8.0pt; font-family:" times="" new="" roman","serif";color:black"="">v/v) and 1 % <span style="font-size:13.0pt;mso-bidi-font-size:8.0pt; font-family:" times="" new="" roman","serif";color:black"="">MF of P. parasitica <span style="font-size:13.0pt;mso-bidi-font-size: 8.0pt;font-family:" times="" new="" roman","serif";color:black"="">showed the better growth and coumarin production with an increased release of coumarins as compared to the control and other treatments. It was observed that treatment of hairy root cultures with XAD -7 resulted in lesser growth and coumarin production as compared to control during the culture period. Addition of XAD -7 along with 1 <span style="font-size:13.0pt;mso-bidi-font-size:8.0pt; font-family:" arial","sans-serif";color:black"="">% <span style="font-size: 13.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif";="" color:black"="">MF of <span style="font-size:13.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif";color:black"="">P. parasitica showed enhanced growth , coumarin production and increased adsorption as compared to control and lone XAD-7 treatment. Combined addition of DMSO I <span style="font-size:13.0pt;mso-bidi-font-size: 8.0pt;font-family:" times="" new="" roman","serif";color:black"="">XAD-7 with fungal elicitor showed synergistic response in terms of biomass and coumarin production. Excretion of coumarins in both the cases was dependent on the presence of DMSO I <span style="font-size:13.0pt;mso-bidi-font-size: 8.0pt;font-family:" times="" new="" roman","serif";color:black"="">XAD-7. These result s showed that continuous permeabilization of hairy root cultures of C. <span style="font-size:13.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif";color:black"="">intybus by using DMSO at 0.2 <span style="font-size:13.0pt; mso-bidi-font-size:8.0pt;font-family:" arial","sans-serif";color:black"="">% (v/v) level coupled with 1 <span style="font-size:13.0pt; mso-bidi-font-size:8.0pt;font-family:" arial","sans-serif";color:black"="">% MF of <span style="font-size:13.5pt;mso-bidi-font-size: 8.5pt;font-family:" times="" new="" roman","serif";color:black"="">P. parasitica maintained viability of tissues and produced coumarins at higher level. </span