RESUMO
The objective of the study is to reveal the freezing tolerance mechanisms of wheat by combining the emerging single-molecule real-time (SMRT) sequencing technology PacBio Sequel and Illumina sequencing. Commercial semiwinter wheat Zhoumai 18 was exposed to -6°C for 4 h at the four-leave stage. Leaves of the control group and freezing-treated group were used to perform cDNA library construction. PacBio SMRT sequencing yielded 51,570 high-quality isoforms from leaves of control sample of Zhoumai 18, encoded by 20,366 gene loci. In total, 73,695 transcript isoforms, corresponding to 23,039 genes, were identified from the freezing-treated leaves. Compared with transcripts from the International Wheat Genome Sequencing Consortium RefSeq v1.1, 57,667 novel isoforms were discovered, which were annotated 21,672 known gene loci, as well as 3,399 novel gene loci. Transcriptome characterization including alterative spliced events, alternative polydenylation sites, transcription factors, and fusion transcripts were also analyzed. Freezing-responsive genes and signals were uncovered and proved that the ICE-ERF-COR pathway and ABA signal transduction play a vital role in the freezing response of wheat. In this study, PacBio sequencing and Illumina sequencing were applied to investigate the freezing tolerance in common wheat, and the transcriptome results provide insights into the molecular regulation mechanisms under freezing treatment.
RESUMO
Microbial mechanisms associated with soil organic carbon (SOC) decomposition are poorly understood. We aim to determine the effects of inorganic and organic fertilizers on soil labile carbon (C) pools, microbial community structure and C mineralization rate under an intensive wheat-maize double cropping system in Northern China. Soil samples in 0-10 cm layer were collected from a nine-year field trial involved four treatments: no fertilizer, CK; nitrogen (N) and phosphorus (P) fertilizers, NP; maize straw combined with NP fertilizers, NPS; and manure plus straw and NP fertilizers, NPSM. Soil samples were analyzed to determine labile C pools (including dissolved organic C, DOC; light free organic C, LFOC; and microbial biomass C, MBC), microbial community composition (using phospholipid fatty acid (PLFA) profiles) and SOC mineralization rate (from a 124-day incubation experiment). This study demonstrated that the application of chemical fertilizers (NP) alone did not alter labile C fractions, soil microbial communities and SOC mineralization rate from those observed in the CK treatment. Whereas the use of straw in conjunction with chemical fertilizers (NPS) became an additional labile substrate supply that decreased C limitation, stimulated growth of all PLFA-related microbial communities, and resulted in 53% higher cumulative mineralization of C compared to that of CK. The SOC and its labile fractions explained 78.7% of the variance of microbial community structure. Further addition of manure on the top of straw in the NPSM treatment did not significantly increase microbial community abundances, but it did alter microbial community structure by increasing G+/G- ratio compared to that of NPS. The cumulative mineralization of C was 85% higher under NPSM fertilization compared to that of CK. Particularly, the NPSM treatment increased the mineralization rate of the resistant pool. This has to be carefully taken into account when setting realistic and effective goals for long-term soil C stabilization.