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Currently, the molecular regulation mechanisms involved in the early development of maize brace root are poorly known. To gain insight into the transcriptome dynamics that are associated with its development, genome-wide gene expression profiling was conducted by Solexa sequencing (Illumina Inc., San Diego, CA, USA). More than five million tags were generated from the stem node tissues without and with just-emerged brace roots, including 149 524 and 178 131 clean tags in the two libraries, respectively. Of these, 82 864 (55.4%) and 91 678 (51.5%) tags were matched to the reference genes. The most differentially expressed tags with a log ratio > 2 or < −2 ( P < 0.001) were analyzed further, representing 143 up-regulated and 152 down-regulated genes, except for unknown transcripts, which were classified into 11 functional categories. The most enriched categories were those of metabolism, signal transduction and cellular transport. Many genes or biological pathways were found to be commonly shared between brace root and lateral or adventitious root development, such as genes participating in cell wall degradation and synthesis, auxin transport and signaling, ethylene signaling, etc. Next, the expression patterns of 20 genes were assessed by quantitative real-time PCR, and the results obtained showed general agreement with the Solexa analysis. Furthermore, a comparison of the brace root transcriptome with that of maize primary root revealed substantial differences in the categories and abundances of expressed transcripts. In conclusion, we first reveal the complex changes in the transcriptome during the early development of maize brace root and provide a comprehensive set of data that are essential for understanding its molecular regulation. [ABSTRACT FROM AUTHOR]

Enzymatic and non-enzymatic antioxidants play important roles in the tolerance of abiotic stress. To increase the resistance of seeds to oxidative stress, At2S3 promoter from Arabidopsis was used to achieve overexpression of the antioxidants in a seed-specific manner. This promoter was shown to be capable of driving the target gene to have a high level of expression in seed-related organs, including siliques, mature seeds, and early seedlings, thus making its molecular farming applications in plants possible. Subsequently, genes encoding Mn-superoxide dismutase ( MSD1), catalase ( CAT1), and homogentisate phytyltransferase ( HPT1, responsible for the first committed reaction in the tocopherol biosynthesis pathway) were overexpressed in Arabidopsis under the control of the At2S3 promoter. Double overexpressers co-expressing two enzymes and triple overexpressers were produced by cross pollination. Mn-SOD and total CAT activities, as well as γ-tocopherol content, significantly increased in the corresponding overproduction lines. Moreover, single MSD1-transgene, double, and triple overexpressers displayed remarkably enhanced oxidative stress tolerance compared to wild type during seed germination and early seedling growth. Interestingly, an increase in the total CAT activity was also observed in the single MSD1-transgenic lines as a result of MSD1 overexpression. Together, the combined increase in Mn-SOD and CAT activities in seeds plays an essential role in the improvement of antioxidant capacity at early developmental stage in Arabidopsis. [ABSTRACT FROM AUTHOR]