Project description:Abiotic stress causes disturbances in the cellular homeostasis. Re-adjustment of balance in carbon, nitrogen and phosphorus metabolism therefore plays a central role in stress adaptation. However, it is currently unknown which parts of the primary cell metabolism follow common patterns under different stress conditions and which represent specific responses. To address these questions, changes in transcriptome, metabolome and ionome were analyzed in maize source leaves from plants suffering low temperature, low nitrogen (N) and low phosphorus (P) stress. The selection of maize as study object provided data directly from an important crop species and the so far underexplored C4 metabolism. Growth retardation was comparable under all tested stress conditions. The only primary metabolic pathway responding similar to all stresses was nitrate assimilation, which was down-regulated. The largest group of commonly regulated transcripts followed the expression pattern: down under low temperature and low N, but up under low P. Several members of this transcript cluster could be connected to P metabolism and correlated negatively to different phosphate concentration in the leaf tissue. Accumulation of starch under low temperature and low N stress, but decrease in starch levels under low under low P conditions indicated that only low P treated leaves suffered carbon starvation. In conclusion, maize employs very different strategies for management of nitrogen and phosphorus metabolism under stress. While nitrate assimilation was regulated depending on demand by growth processes, phosphate concentrations changed depending on availability, thus building up reserves under excess conditions. Carbon and energy metabolism of the C4 maize leaves were particularly sensitive to P starvation. Responses of maize source leaves to low temperature, low nitrogen and low phosphorus conditions were tested in independent single-stress experiments. Seedlings were cultivated in pots containing nutrient-poor peat soil under the controlled conditions of a growth chamber. The plants were fertilized with modified Hoagland solutions, containing 15mM KNO3 and 0.5mM KH2PO4 for control conditions; for low N and low P treatment, the nutrient concentrations were reduced to 0.15mM KNO3 and 0.1mM KH2PO4, respectively. Low temperature treated plants were always supplied with control nutrient solution. Plants from the nitrogen and phosphorus experiment as well as the control temperature plants were exposed to 28°C during the day and 20°C during the night. Low temperature treatment was limited to the night period and was reduced to 4°C for the 10h dark period. Source leaf lamina were harvested at day 20 (low temperature experiment) or day 30 after start of germination (low nitrogen and low phosphorus experiment) for parallel analysis of transcriptome, metabolome and ion profiles. The molecular data is further supplemented by phenotypic characterization of the maize seedlings under investigation.
Project description:Rapid and uniform seed germination is required for modern cropping system. Thus, it is important to optimize germination performance through breeding strategies in maize, in which identification for key regulators is needed. Here, we characterized an AP2/ERF transcription factor, ZmEREB92, as a negative regulator of seed germination in maize. Enhanced germination in ereb92 mutants is contributed by elevated ethylene signaling and starch degradation. Consistently, an ethylene signaling gene ZmEIL7 and an α-amylase gene ZmAMYa2 are identified as direct targets repressed by ZmEREB92. OsERF74, the rice ortholog of ZmEREB92, shows conserved function in negatively regulating seed germination in rice. Importantly, this orthologous gene pair is likely experienced convergently selection during maize and rice domestication. Besides, mutation of ZmEREB92 and OsERF74 both lead to enhanced germination under cold condition, suggesting their regulation on seed germination might be coupled with temperature sensitivity. Collectively, our findings uncovered the ZmEREB92-mediated regulatory mechanism of seed germination in maize and provide breeding targets for maize and rice to optimize seed germination performance towards changing climates.
Project description:Abiotic stress causes disturbances in the cellular homeostasis. Re-adjustment of balance in carbon, nitrogen and phosphorus metabolism therefore plays a central role in stress adaptation. However, it is currently unknown which parts of the primary cell metabolism follow common patterns under different stress conditions and which represent specific responses. To address these questions, changes in transcriptome, metabolome and ionome were analyzed in maize source leaves from plants suffering low temperature, low nitrogen (N) and low phosphorus (P) stress. The selection of maize as study object provided data directly from an important crop species and the so far underexplored C4 metabolism. Growth retardation was comparable under all tested stress conditions. The only primary metabolic pathway responding similar to all stresses was nitrate assimilation, which was down-regulated. The largest group of commonly regulated transcripts followed the expression pattern: down under low temperature and low N, but up under low P. Several members of this transcript cluster could be connected to P metabolism and correlated negatively to different phosphate concentration in the leaf tissue. Accumulation of starch under low temperature and low N stress, but decrease in starch levels under low under low P conditions indicated that only low P treated leaves suffered carbon starvation. In conclusion, maize employs very different strategies for management of nitrogen and phosphorus metabolism under stress. While nitrate assimilation was regulated depending on demand by growth processes, phosphate concentrations changed depending on availability, thus building up reserves under excess conditions. Carbon and energy metabolism of the C4 maize leaves were particularly sensitive to P starvation.
Project description:Transcriptional profiling of 4 maize varieties comparing genetic root response under control temperature conditions with genetic root response under low temperature conditions
Project description:To provide a more detailed insight into molecular changes in seeds exposed to the accelerated ageing process, we excised embryos and compared the differences in the proteome composition. Seeds collected from four contrasting locations were exposed to accelerated ageing. Next, embryos were dissected and analyzed in five biological replicates [1-5]. Sample description:CAS [1-5] - location n. 5 - (Caslav) - high yield, above average temperature and high rainfall; a significant decrease in germination energy after the accelerated ageing test. UHO [1-5] - location n. 11 (Uhersky Ostroh) - low yield, high temperature and low rainfall; very low decrease in germination energy after the accelerated ageing test.CH [1-5] - location n. 2 (Chrastava) - average yield, low temperature, very high rainfall; a significant decrease in germination energy after the accelerated ageing test.K [1-5] - location n. 8 (Krasne Udoli) - average yield, low temperature, average rainfall; a significant decrease in germination energy after the accelerated ageing test.
Project description:Purpose: To identify the potential genes that regulate seed germination speed in maize, we performed a time-series transcriptome analysis with two inbred maize lines (72-3 fast germination, F9721 slow germination) during the seed germination and compared the differentially expressed genes (DEGs) in transcriptome with genes identified by GWAS Methods: Methods: mRNA profiles of two maize inbred lines 72-3 and F9721 showing divergent seed germination at six stages during germination were generated by deep sequencing, in triplicate, using Illumina Hiseq2500. The sequence reads that passed quality filters were analyzed at the gene level. Hisat2 was used to align clean reads to maize B73 reference genome, and HTSeq was used to count transcript abundance. DESeq2 models were used to compare DEGs at each germination stage within or between samples Results: Comparative transcriptome study identified 12 hours after imbibition (HAI) as the critical stage responsible for the variation of germination speed. The DEGs between 72-3 and F9721 were mainly enriched in metabolic pathways, biosynthesis of secondary metabolites, oxidoreductase activity pathways, hormone signal transduction, and amino acid transporter activity pathways Conclusions: Combined with evidence from gene expression data, GWAS, and gene synteny with other model species, we finally anchored three genes as the likely candidate genes regulating germination speed in maize