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ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #240104
Title: Monitoring the expression of maize genes in developing kernels under drought stress using oligo-microarray

Author
item LUO, MENG - Louisiana State University
item LIU, JIA - J Craig Venter Institute
item LEE, DEWEY - University Of Georgia
item Scully, Brian
item Guo, Baozhu

Submitted to: Journal of Integrative Plant Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/19/2010
Publication Date: 10/5/2010
Citation: Luo, M., Liu, J., Lee, R.D., Scully, B.T., Guo, B. 2010. Monitoring the expression of maize genes in developing kernels under drought stress using oligo-microarray. Journal of Integrative Plant Biology. 52(12):1059-1074.

Interpretive Summary: Aflatoxin contamination caused by Aspergillus flavus is a serious food and feed safety issue in maize production world-wide. The objectives of this study were to study gene expressions under drought stress and to identify genes, affected by drought stress, for future possible utilization as molecular tool for germplasm assessment and assisted breeding. The maize inbred line Tex6, reported to have reduced preharvest aflatoxin contamination, was used in this study. The standard maize inbred B73 as susceptible control was included in real-time gene expression study. Tex6 kernel gene expression profiles at the 25, 30, 35, 40, 45 day after pollination (DAP) were analyzed under drought stress verse well-watered condition using maize oligonucleotide microarrays. A total of 9573 positive array spots were detected with unique gene identification number (ID), and 7988 positive array spots were common in both stressed and not stressed samples. The total numbers of expressed genes reached a peak at 35 DAP in drought stressed samples. Expression patterns of some genes in several stress response-related pathways were tracked, and some genes in these pathways were responding to drought stress positively, which could reflect the resistance traits in Tex6. The comparison between Tex6 and B73 in response to drought stress revealed significant differences in specific gene expression patterns and relative gene expression levels. The data suggest that these down-regulated and/or the up-regulated genes might have played important roles in the later stage of enhanced susceptibility or resistance to A. flavus and aflatoxin contamination in preharvest maize grains.

Technical Abstract: Preharvest A. flavus infection is usually exacerbated when maize plants suffer drought stress in the late grain-fill stage. However, the field observation suggests that drought-tolerant maize lines displayed less aflatoxin contamination under the stress in comparison with the drought-sensitive maize lines. The molecular and genetic mechanisms underlying drought tolerant maize lines with reduced preharvest aflatoxin contamination is still unclear. The objectives of this study were to study gene expression profiles under drought stress and to identify genes, affected by drought stress, for future possible utilization as genomic tool for germplasm assessment and breeding. The maize inbred line Tex6, reported to have reduced preharvest aflatoxin contamination, was subjected to microarray analysis under drought stress. The standard maize inbred B73 as susceptible control was included in real-time qPCR study of genes selected from microarray. Tex6 kernel gene expression profiles at the 25, 30, 35, 40, 45 day after pollination (DAP) were analyzed in developing kernels under drought stress verse well-watered condition using the 70-mer maize oligonucleotide microarrays. A total of 9573 positive array spots were detected with unique IDs, and 7988 positive array spots were common in both stressed and not stressed samples. The total numbers of expressed genes reached a peak at 35 DAP in drought stressed samples. Expression patterns of some genes in several stress response-related pathways, including ABA (abscisic acid), JA (jasmonic acid) and PAL (phenylalanine ammonia-lyase), were tracked, and some genes in these pathways were responding to drought stress positively, which could reflect the resistance traits in Tex6. The real-time qRT-PCR validated microarray expression data in Tex6. The comparison between Tex6 and B73 in response to drought stress revealed significant differences in specific gene expression patterns and relative gene expression levels.