Project description:Martian regolith (unconsolidated surface material) is a potential medium for plant growth in bioregenerative life support systems during manned missions on Mars. However, hydrated magnesium sulfate mineral levels in the regolith of Mars can reach as high as 10 wt%, and would be expected to be highly inhibitory to plant growth. A global approach was used to identify novel genes with potential to enhance tolerance to high MgSO4 stress. The early Arabidopsis root transcriptome response to elevated concentrations of magnesium sulfate was characterized in col-0, and also between col-0 and the mutant line cax1-1 – a mutant relatively tolerant of high levels of MgSO4•7H2O in soil solution.
Project description:Martian regolith (unconsolidated surface material) is a potential medium for plant growth in bioregenerative life support systems during manned missions on Mars. However, hydrated magnesium sulfate mineral levels in the regolith of Mars can reach as high as 10 wt%, and would be expected to be highly inhibitory to plant growth. A global approach was used to identify novel genes with potential to enhance tolerance to high MgSO4 stress. The early Arabidopsis root transcriptome response to elevated concentrations of magnesium sulfate was characterized in col-0, and also between col-0 and the mutant line cax1-1 – a mutant relatively tolerant of high levels of MgSO4•7H2O in soil solution. After 3 weeks of growth under hydroponic conditions, Arabidopsis thaliana col-0 roots were exposed to a basic nutrient solution (0.25 g/L MES, 1/16x MS, pH 5.7) with an additional 2.08 mM magnesium sulfate (total Ca:Mg ratio = 1:15) for 45 min., 90 min., or 180 min., while a col-0 control set was exposed to the basic nutrient solution without additional magnesium sulfate for 45 minutes. Arabidopsis thaliana cax1-1 roots were exposed to the basic nutrient solution with additional magnesium sulfate for 180 min. only. Four replicate containers were harvested for the control and each of the treatment sets, resulting in a total of 20 samples. Gene expression of the col-0 sets exposed to magnesium sulfate treatment for 45 min., 90 min., or 180 min. was compared to gene expression of the col-0 control set. Gene expression of the cax1-1 set exposed to magnesium sulfate treatment for 180 min. was compared to gene expression of the col-0 set exposed to magnesium sulfate treatment for 180 minutes.
Project description:Root hairs are frequently reported to be plastic in response to nutrient supply, but relatively little is known about their development in response to magnesium (Mg) availability, and evidence is scarce about the signals involved in this process. Here, we showed that both density and length of root hairs of Arabidopsis decreased logarithmically with increasing Mg supply in the media , which correlated with the initiation of new trichoblast files and likelihood of trichoblasts to form hairs. Low Mg resulted in greater concentrations of reactive oxygen species (ROS) and Ca2+ in the roots and displayed a stronger tip-focused gradient of ROS and cytosolic Ca2+ concentration ([Ca2+]c) during initiation and elongation of root hairs. This gradient could be eliminated by DPI or BAPTA. Application of either DPI or BAPTA to low Mg treatment blocked the enhanced development of root hairs. The opposite was true when the plants under high Mg were supplied with Ca2+ or PMS. Whole-genome transcriptome data revealed that the maximum differential expressed genes involved in ‘stress’, ‘oxidation reduction’, ‘ion transport and homeostasis’ and ‘cell wall organization’. A greater fraction of morphogenetic H-genes and root hair -specific genes as well as genes involved in ‘cell wall structure’ were up-regulated by 7-d treatment of 0.5 μM Mg but down-regulated by 7-d treatment of 10,000 μM Mg. It is concluded that a distinct and previously poorly characterized response of root hair development to Mg availability is presented in Arabidopsis where ROS and Ca2+ are the signaling molecules that control this response.
Project description:Physiological mechanisms involved in root hair development in response to magnesium (Mg) availability are unclear. This study investigated the influence of Mg availability on root hair development in arabidopsis grown in different Mg concentrations ranging from 0.5 μM to 10 mM. After 7-d treatment, root hair development was enhanced in roots exposed to low Mg but was inhibited severely in roots grown in high Mg. Low Mg (0.5 µM) enhanced many genes like LRX1, COW1, EXP7 and ROP2 that control root hair development. Low Mg supply also increased concentrations of total Ca2+ and ROS in roots, but application of either BAPTA or DPI to low Mg treatment blocked the enhanced development of root hairs. The opposite was true when the plants under high Mg (3 mM) were supplied with Ca2+ or PMS. Besides, in roots under low Mg and high Mg, the most significant biological function enrichment were in the ‘oxidation reduction’, ‘cell wall organization’, ‘ion response’. This study demonstrated that Ca2+ and ROS played critically in controlling the Mg-induced development of root hairs. Meanwhile, transcriptome analysis associated with Mg supply contributed to a better understanding of molecular events responsible for sensing Mg status. Roots were sampled from five-week-cultivated Arabidopsis after 7 d treatment of low Mg (supplied with 0.5 μM Mg2+) and high Mg (supplied with 10 mM Mg2+).
Project description:This study contributes large-scale genes expression data of molecular function for a plant system under combined of two CO2 concentration and three Mg levels. It provides an additional example of the power of integrated analyses for the comprehensive study of the molecular physiology of complex biological systems. Moreover, taking into consideration the particular interest of the two investigated perturbations in plant biotechnology, enhanced understanding of the molecular physiology of the plants under climate change conditions could lead to the design of novel metabolic engineering strategies to copy with crops to magnesium problems. Examination of two CO2 concentration and three Mg levels of shoot and root Arabidopsis