|YANG, LIMING - University Of Georgia|
|FOUNTAIN, JAKE - University Of Georgia|
|JIANG, TINGBO - University Of Georgia|
|LEE, R - University Of Georgia|
|CHEN, SIXUE - University Of Florida|
|KEMERAIT, ROBERT - University Of Georgia|
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/21/2017
Publication Date: 2/21/2017
Citation: Yang, L., Fountain, J., Jiang, T., Ni, X., Lee, R.D., Scully, B.T., Chen, S., Kemerait, R.C., Guo, B. 2017. Deciphering drought-induced response patterns at the biochemical and molecular level in maize related to aflatoxin contamination resistance [abstract]. Meeting Abstract.
Technical Abstract: Drought stress influences crop growth, decreases yield, and exacerbates Aspergillus flavus infection and pre-harvest aflatoxin contamination. In order to dissect drought stress-induced responses in maize, genotypes with contrasting levels of drought tolerance were used to investigate the physiological, biochemical, and molecular changes in seedlings and kernels under drought stress. Seedlings of drought-sensitive genotypes (B73 and Lo1016) exhibited higher production of reactive oxygen species (ROS) and nitric oxide levels, and rapid increases in stress-responsive enzyme activities compared to the tolerant lines (Lo964, Va35 and Grace E-5). Kernel proteomic analyses revealed that B73 exhibited a vigorous, induced response to stress while Lo964 displayed stable, constitutive expression of defense proteins. Comprehensive metabolomics analyses of developing kernels also found that drought stress induced higher sugar accumulation, and energy and unsaturated fatty acid metabolism in B73. Contrarily, Lo964 had higher sphingolipid metabolite accumulation, a higher glycolysis rate, and a lower TCA cycle rate in response to drought stress. In addition, pre-incubation of kernels in high humidity prior to inoculation during A. flavus-kernel screening assays resulted in enhanced visible sporulation and reduced aflatoxin production. Biochemical investigation showed that pre-incubation resulted in increases in ROS content at 2-3 days after inoculation (DAI) while kernels lacking pre-incubation exhibited increases at 3-4 DAI. Given that aflatoxin production is most active 3-4 DAI, reduced ROS exposure during this key period following pre-incubation may contribute to reduced contamination. These results indicate that drought sensitivity is associated with diverse metabolic processes in maize, and that ROS production may contribute to the exacerbated aflatoxin contamination during drought stress.