Project description:Post-transcriptional mechanisms, including alternative splicing (AS) and alternative translation initiation (ATI), have been used to explain the protein diversity involved in plant developmental processes and stress responses. Rice germination under hypoxia conditions is a classical model system for the study of low oxygen stress. It is known that there is transcriptional regulation during rice hypoxic germination, but the potential roles of AS and ATI in this process are not well understood. In this study, a proteogenomic approach was used to integrate the data from RNA sequencing, qualitative and quantitative proteomics to discover new players or pathways in the response to hypoxia stress. The improved analytical pipeline of proteogenomics led to the identification of 10,253 intron-containing genes, 1,729 of which were not present in the current annotation. Approximately 1,741 differentially expressed AS (DAS) events from 811 genes were identified in hypoxia-treated seeds in comparison to controls. Over 95% of these were not present in the list of differentially expressed genes (DEG). In particular, regulatory pathways such as spliceosome, ribosome, ER protein processing and export, proteasome, phagosome, oxidative phosphorylation and mRNA surveillance showed substantial AS changes under hypoxia, suggesting that AS responses are largely independent of traditional transcriptional regulation. Massive AS changes were identified, including the preference usage of certain non-conventional splice sites and enrichment of splicing factors in the DAS datasets. In addition, using self-constructed protein libraries by 6-frame translation, thousands of novel proteins/peptides contributed by ATI were identified. In summary, these results provide deeper insights towards understanding the underlying mechanisms of AS and ATI during rice hypoxic germination.
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:Melatonin plays a potential role in multiple plant developmental processes and stress response. However, there are no reports regarding exogenous melatonin promoting rice seed germination under salinity and nor about the underlying molecular mechanisms at genome-wide. Here, we revealed that exogenous application of melatonin conferred roles in promoting rice seed germination under salinity. The putative molecular mechanisms of exogenous melatonin in promoting rice seed germination under high salinity were further investigated through metabolomic and transcriptomic analyses. The results state clearly that the phytohormone contents were reprogrammed, the activities of SOD, CAT, POD were enhanced, and the total antioxidant capacity was activated under salinity by exogenous melatonin. Additionally, melatonin-pre-treated seeds exhibited higher concentrations of glycosides than non-treated seeds under salinity. Furthermore, exogenous melatonin alleviated the accumulation of fatty acids induced by salinity. Genome-wide transcriptomic profiling identified 7160 transcripts that were differentially expressed in NaCl, MT100 and control. Pathway and GO term enrichment analysis revealed that genes involved in the response to oxidative stress, hormone metabolism, heme building, mitochondrion, tricarboxylic acid transformation were altered after melatonin pre-treatment under salinity. This study provides the first evidence of the protective roles of exogenous melatonin in increasing rice seed germination under salt stress, mainly via activation of antioxidants and modulation of metabolic homeostasis.
Project description:RNAseq profiling of seeds and 7 time points during germination in rice under aerobic and anerobic conditions, as well as following re-oxygenation.
Project description:Sucrose non-fermenting-1-related protein kinase 1 (SnRK1) is a central regulator of metabolism and developmental transition in plant. Compound 991 is a well-known 5′-adenosine monophosphate activated protein kinase (AMPK) activator in mammals. SnRK1 and AMPK are highly conserved. However, whether 991 could also act as a SnRK1 activator is unknown. Adding 991 significantly increased the activity of SnRK1 in desalted extracts from germinating rice seeds in vitro. To determine whether 991 has biological activity in plant, rice seeds were treated with different concentrations of 991. Low concentration of 991 promoted rice seed germination, while high concentration of 991 inhibited rice germination. The effect of 991 on rice germination is similar to the effect of OsSnRK1a overexpression on germination. To explore whether 991 affects germination by specifically affecting SnRK1, the germination status of the snrk1a mutant and WT under 1 μM 991 treatment were compared. The snrk1a mutant exhibited insensitivity to 991. Through phosphoproteomic analysis, we found that the differential phosphopeptides caused by 991 treatments and overexpression of OsSnRK1a are largely overlapped. Phosphoproteomic analysis also revealed that SnRK1 might affect rice germination by regulating the phosphorylation levels of S285-PIP2;4, S1013-SOS1 and S110-ABI5. These results showed that 991 is a specific and workable SnRK1 activator in rice. The promotion and inhibition of 991 treatments on germination also exist in wheat seeds. 991 is expected to be used for exploring the function of SnRK1 in more detail and depth and chemical regulation of growth and development in crops.
Project description:affy_rice_2011_03 - affy_compartimentation_rice_albumen_embryon - During germination, the rice seed goes from a dry quiescent state to an active metabolism. As with all cereals, the rice seed is highly differentiated between the embryo (that will give rise to the future plantlet) and the endosperm (that contains the seed storage compounds and that will degenerate). The molecular mechanisms operating in the rice seed embryo have begun to be described. Yet, very few studies have focused specifically on the endosperm during the germination process. In particular, the endosperm is mostly addressed with regards to its storage proteins but we have detected a large protein diversity by two-dimensional electrophoresis. Similarly, the endosperm is rich in total RNA which suggest that gene expression coming from seed maturation could play a role during the germination process. In this context, we want to compare the transcriptome of the embryo and the endosperm during rice seed germination. -We germinate rice seeds of the first sequenced rice cultivar i.e. Nipponbare during 0, 4, 8, 12, 16 and 24h of imbibition in sterile distilled water. Germination occurs under constant air bubbling, in the dark at 30°C. These rice seeds are then manually dissected into embryo and endosperm fractions. -The embryo-derived samples are abbreviated in “E” while the endosperm samples are abbreviated “A”. The germination time-point is indicated after the letter (e.g. E8 for embryo samples harvested after 8 hours of germination). Finally, the biological repetition number is indicated before the letter and the time digit (e.g. 1-E8 for an embryo sample from the first repetition at 8 hours of imbibition).
Project description:Transcript abundance profiles were examined over the first 24 hours of germination in rice grown under anaerobic conditions. Transcript abundance profiles were also examined for rice grown under aerobic conditions for 24 h and then switched to anaerobic conditions and vice versa.
Project description:To explore the molecular mechanisms of rice seed germination under salt stress mediated by OsMFT1, we established osmft1 mutant lines, and then examined the gene expression profiles in seeds of WT and osmft1.
Project description:affy_rice_2011_03 - affy_compartimentation_rice_albumen_embryon - During germination, the rice seed goes from a dry quiescent state to an active metabolism. As with all cereals, the rice seed is highly differentiated between the embryo (that will give rise to the future plantlet) and the endosperm (that contains the seed storage compounds and that will degenerate). The molecular mechanisms operating in the rice seed embryo have begun to be described. Yet, very few studies have focused specifically on the endosperm during the germination process. In particular, the endosperm is mostly addressed with regards to its storage proteins but we have detected a large protein diversity by two-dimensional electrophoresis. Similarly, the endosperm is rich in total RNA which suggest that gene expression coming from seed maturation could play a role during the germination process. In this context, we want to compare the transcriptome of the embryo and the endosperm during rice seed germination. -We germinate rice seeds of the first sequenced rice cultivar i.e. Nipponbare during 0, 4, 8, 12, 16 and 24h of imbibition in sterile distilled water. Germination occurs under constant air bubbling, in the dark at 30M-BM-0C. These rice seeds are then manually dissected into embryo and endosperm fractions. -The embryo-derived samples are abbreviated in M-bM-^@M-^\EM-bM-^@M-^] while the endosperm samples are abbreviated M-bM-^@M-^\AM-bM-^@M-^]. The germination time-point is indicated after the letter (e.g. E8 for embryo samples harvested after 8 hours of germination). Finally, the biological repetition number is indicated before the letter and the time digit (e.g. 1-E8 for an embryo sample from the first repetition at 8 hours of imbibition). 36 arrays - rice; organ comparison,time course