Water‐saving breeding and cultivation of winter wheat (Triticum aestivum L.) have always been among the important missions in North China. But there is still a dispute on the regulation of water use in winter wheat. A pot experiment was conducted to investigate the physiological and morphological mechanisms of water use in two cultivars of winter wheat (KN9204 and drought‐tolerant LH2) via partial root‐zone drying (PRD). The results indicated that the weight of 1000 grains was higher under PRD conditions for both cultivars. Total water consumption per plant significantly decreased by 11.6 and 17.3% for KN9204 and LH2, respectively, and water‐use efficiency (WUE) significantly increased by 17.2 and 20.3% under PRD. The net photosynthetic rate did not differ between PRD and full irrigation (FI) for either cultivar; however, transpiration rate was lower under PRD than FI, which improved WUE at the leaf level. Flag leaf water potential was significantly lower under PRD than FI for both cultivars, while water content was similar for both treatments. The soluble sugars content of leaves of KN9204 was higher under PRD than FI, while the proline content was 45.9% (KN9204) and 15% (LH2) higher under PRD. Stomatal density increased under PRD, but stomatal width and area declined. Overall, the two types of winter wheat had both common and individual means of improving WUE under PRD conditions. The results would further improve the theoretical underpinning of water‐saving breeding and cultivation in winter wheat.
SUMMARY
In rice (Oryza sativa), the lemma and palea protect the internal organs of the floret,provide nutrients for seed development, and determine grain size. We previously revealed that a trans‐acting small interfering RNA targeting AUXIN RESPONSE FACTORS (tasiR‐ARF) regulates lemma polarity establishment via post‐transcriptional repression of AUXIN RESPONSE FACTORS (ARFs) in rice. TasiR‐ARF formation requires RNA‐DEPENDENT RNA POLYMERASE 6 (RDR6). However, the underlying molecular mechanism of the tasiR‐ARF–ARF regulon in lemma development remains unclear. Here, by genetic screening for suppressors of the thermosensitive mutant osrdr6‐1, we identified three suppressors, huifu 1 (hf1), hf9, and hf17. Mapping‐by‐sequencing revealed that HF1 encodes a MYB transcription factor belonging to the KANADI1 family. The hf1 mutation partially rescued the osrdr6‐1 lemma defect but not the defect in tasiR‐ARF levels. DNA affinity purification sequencing analysis identified 17 725 OsKANADI1‐associated sites, most of which contain the SPBP‐box binding motif (RGAATAWW) and are located in the promoter, protein‐coding, intron, and intergenic regions. Moreover, we found that OsKANADI1 could directly bind to the intron of OsARF3a in vitro and in vivo and promote OsARF3a expression at the transcriptional level. In addition, hf9 and hf17 are intragenic suppressors containing mutations in OsRDR6 that partially rescue tasiR‐ARF levels by restoring OsRDR6 protein levels. Collectively, our results demonstrate that OsKANADI1 and tasiR‐ARFs synergistically maintain the proper expression of OsARF3a and thus contribute to rice lemma development.
Evidence is mounting that RNA modifications play essential roles in posttranscriptional regulation of gene expression. So far, over 150 RNA modifications catalyzed by distinct enzymes have been documented. In plants, genome-wide identification of RNA modifications is largely limited to the model species Arabidopsis thaliana, while lacking in diverse non-model plants. Here, we present PRMdb, a plant RNA modification database, based on the analysis of thousands of RNA-seq, degradome-seq and small RNA-seq data from a wide range of plant species using the well-documented tool HAMR (high-throughput analysis of modified ribonucleotide). PRMdb provides a user-friendly interface that enables easy browsing and searching of the tRNA and mRNA modification data. We show that PRMdb collects high-confidence RNA modifications including novel RNA modification sites that can be validated by genomic PCR and reverse transcription PCR. In summary, PRMdb provides a valuable web resource for deciphering the epitranscriptomes in diverse plant species and will facilitate functional studies of RNA modifications in plants. RPMdb is available via http://www.biosequencing.cn/PRMdb/.
Precursor RNAs undergo extensive processing to become mature RNAs. RNA transcripts are subjected to 5′ capping, 3′-end processing, splicing, and modification; they also form dynamic secondary structures during co-transcriptional and post-transcriptional processing. Like coding RNAs, non-coding RNAs (ncRNAs) undergo extensive processing. For example, secondary small interfering RNA (siRNA) transcripts undergo RNA processing, followed by further cleavage to become mature siRNAs. Transcriptome studies have revealed roles for co-transcriptional and post-transcriptional RNA processing in the regulation of gene expression and the coordination of plant development and plant–environment interactions. In this review, we present the latest progress on RNA processing in gene expression and discuss phased siRNAs (phasiRNAs), a kind of germ cell-specific secondary small RNA (sRNA), focusing on their functions in plant development and environmental responses.
Under the changing climate, asymmetric warming pattern would be more likely during day and night time, instead of symmetric one. Concurrently, the growth responses and water use of plants may be different compared with those estimated based on symmetric warming. In this work, it was compared with the effects of symmetric (ETs) and asymmetric (ETa) elevation of temperature alone, and in interaction with elevated carbon dioxide concentration (EC), on the grain yield (GY) and evapotranspiration in winter wheat (Triticum aestivum L.) based on pot experiment in the North China Plain (NCP). The experiment was carried out in six enclosed-top chambers with following climate treatments: (1) ambient temperature and ambient CO2 (CON), (2) ambient temperature and elevated CO2 (EC), (3) elevated temperature and ambient CO2 (ETs; ETa), and (4) elevated temperature and elevated CO2 (ECETs, ECETa). In symmetric warming, temperature was increased by 3°C and in asymmetric one by 3.5°C during night and 2.5°C during daytime, respectively. As a result, GY was in ETa and ETs 15.6 (P < 0.05) and 10.3% (P < 0.05) lower than that in CON. In ECETs and ECETa treatments, GY was 14.9 (P < 0.05) and 9.1% (P < 0.05) higher than that in CON. Opposite to GY, evapotranspiration was 7.8 (P < 0.05) and 17.9% (P < 0.05) higher in ETa and ETs treatments and 7.2 (P < 0.05) and 2.1% (P > 0.05) lower in ECETs and ECETa treatments compared with CON. Thus, GY of wheat could be expected to increase under the changing climate with concurrent elevation of CO2 and temperature as a result of increased WUE under the elevated CO2. However, the gain would be lower under ETa than that estimated based on ETs due to higher evapotranspiration.
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