Production location of the gelling agent Phytagel has a significant impact on Arabidopsis thaliana seedling phenotypic analysis

BackgroundRecently, it was found that 1% Phytagel plates used to conduct Arabidopsis thaliana seedling phenotypic analysis no longer reproduced previously published results. This Phytagel, which is produced in China (Phytagel C), has replace American-made Phytagel (Phytagel), which is no longer commercially available. In this study, we present the impact of Phytagel produced in the United States vs. China on seedling phenotypic analysis. As a part of this study, an alternative gelling agent has been identified that is capable of reproducing previously published seedling morphometrics.ResultsPhytagel and Phytagel C were investigated based on their ability to reproduce the subtle phenotype of the sob3-4 esc-8 double mutant. Fluence-rate-response analysis of seedlings grown on 1% Phytagel C plates failed to replicate the sob3-4 esc-8 subtle phenotype seen on 1% Phytagel. Furthermore, root penetrance analysis showed a significant difference between sob3-4 esc-8 seedlings grown on 1% Phytagel and 1% Phytagel C. It was also found that 1% Phytagel C was significantly harder than 1% Phytagel. As a replacement for Phytagel C, Gellan was tested. 1% Gellan was able to reproduce the subtle phenotype of sob3-4 esc-8. Furthermore, there was no significant difference in root penetration of the wild type or sob3-4 esc-8 seedlings between 1% Phytagel and 1% Gellan. This may be due to the significant reduction in hardness in 1% Gellan plates compared to 1% Phytagel plates. Finally, we tested additional concentrations of Gellan and found that seedlings on 0.6% Gellan looked more uniform while also being able to reproduce previously published results.ConclusionsPhytagel has been the standard gelling agent for several studies involving the characterization of subtle seedling phenotypes. After production was moved to China, Phytagel C was no longer capable of reproducing these previously published results. An alternative gelling agent, Gellan, was able to reproduce previously published seedling phenotypes at both 1% and 0.6% concentrations. The information provided in this manuscript is beneficial to the scientific community as whole, specifically phenomics labs, as it details key problematic differences between gelling agents that should be performing identically (Phytagel and Phytagel C).

Low Acyl Gellan Gum as a Gelling Agent in Medium of Saccharomyces Yeasts

Commercial agar used in microbiological culture has a disadvantage of impurity and opacity. This work aimed to provide an alternative gelling agent to agar and the function of low acyl gellan gum in microbiological culture media was studied. The results showed the texture and water activity of GYGs (glucose-YNB medium containing low acyl gellan gum at different concentrations of 0.3%, 0.6%, 0.9%, 1.2%, 1.5%) were suitable for cultivation of Saccharomyces yeasts. The gelling temperature of GYGs was enhanced with the increased concentration of low acyl gellan gum, while clarity of medium and colony diameter decreased. Scanning electron microscope showed that GYG09 (glucose-YNB medium containing 0.9% low acyl gellan gum) possessed homogeneous porous structures, which was superior to GYA20 with respect to higher clarity and lower dosage of gelling agent when surface plating method was used; however, GYG09 was not suitable for pour plating method.