Expression analysis of Jatropha curcas L. almt genes under low pH and aluminum stress

In the previous study, the six populations of Jatropha curcas L. were grown on an acid Al-toxic subsoil (pH 4.3) media in the greenhouse and drained with nutrient solutions containing 3.2 mM AlCl₃ to characterize their differences in response to Al toxicity. The Al treatment significantly affected all growth parameters. Statistical analysis on Al tolerance growth parameters showed a grouping pattern among the six Jatropha populations. They can be grouped into two clusters based on similar sensitivity to Al toxicity; those two groups represent the slightly tolerant and sensitive population to 3.2 mM AlCl₃ following treatment for a month. Although grouped as Al-sensitive population, IP-2P has superior traits in productivity and those become the reason to use it as plant material to develop transgenic Jatropha plant. For the preliminary analysis, in this study IP-2P population was selected to subjected to gene expression analysis by qRT PCR. Quantitative real-time RT PCR analysis verified almt gene is preferentially expressed in the root tip, although transcript accumulate both in roots and leaves. Expression was highest at 24 h exposure rather than 7 days. Not all the transcripts are up-regulated by exposure to Al. Low pH (pH 4.0) treatment alone can also induce transcript accumulation both in the root apices and leaves but at significantly lower rates than observed for Al. In conclusion, it was found that Al stress in Jatropha root and leaf is not a specific response. Nonetheless, the Jatropha plants were relatively sensitive to Al stress. Therefore, this J. curcas L. IP-2P can be used for improving Al tolerance in plant by constructing transgenic plant carrying almt gene.