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Summary: MiRNAs have been reported to be the key regulators involving a wide range of biological processes in diverse plant species, but their functions in switchgrass, an important biofuel and forage crop, are largely unknown. Here, we reported the novel function of miR528, which has expanded to four copies in switchgrass, in controlling biomass trait of tillering number and regrowth rate after mowing. Blocking miR528 activity by expressing short tandem target mimic (STTM) increased tiller number and regrowth rate after mowing. The quadruple pvmir528 mutant lines derived from genome editing also showed such improved traits. Degradome and RNA‐seq analysis, combined with in situ hybridization assay revealed that up‐regulation of two miR528 targets coding for Cu/Zn‐SOD enzymes, might be responsible for the improved traits of tillering and regrowth in pvmir528 mutant. Additionally, natural variations in the miR528‐SOD interaction exist in C3 and C4 monocot species, implying the distinct regulatory strength of the miR528‐SOD module during monocot evolution. Overall, our data illuminated a novel role of miR528 in controlling biomass traits and provided a new target for genetic manipulation‐mediated crop improvement. [ABSTRACT FROM AUTHOR]

The lack of genome editing platforms has hampered efforts to study and improve forage crops that can be grown on lands not suited to other crops. Here, we established efficient Agrobacterium‐mediated clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR‐associated nuclease 9 (Cas9) genome editing in a perennial, stress‐tolerant forage grass, sheepgrass (Leymus chinensis). By screening for active single‐guide RNAs (sgRNAs), accessions that regenerate well, suitable Agrobacterium strains, and optimal culture media, and co‐expressing the morphogenic factor TaWOX5, we achieved 11% transformation and 5.83% editing efficiency in sheepgrass. Knocking out Teosinte Branched1 (TB1) significantly increased tiller number and biomass. This study opens avenues for studying gene function and breeding in sheepgrass. [ABSTRACT FROM AUTHOR]

In cases where a client suffers from completely unlabeled data, unsupervised learning has difficulty achieving an accurate fault diagnosis. Semi-supervised federated learning with the ability for interaction between a labeled client and an unlabeled client has been developed to overcome this difficulty. However, the existing semi-supervised federated learning methods may lead to a negative transfer problem since they fail to filter out unreliable model information from the unlabeled client. Therefore, in this study, a dynamic semi-supervised federated learning fault diagnosis method with an attention mechanism (SSFL-ATT) is proposed to prevent the federation model from experiencing negative transfer. A federation strategy driven by an attention mechanism was designed to filter out the unreliable information hidden in the local model. SSFL-ATT can ensure the federation model's performance as well as render the unlabeled client capable of fault classification. In cases where there is an unlabeled client, compared to the existing semi-supervised federated learning methods, SSFL-ATT can achieve increments of 9.06% and 12.53% in fault diagnosis accuracy when datasets provided by Case Western Reserve University and Shanghai Maritime University, respectively, are used for verification. [ABSTRACT FROM AUTHOR]

Low temperatures occurring at the booting stage in rice (Oryza sativa L.) often result in yield loss by impeding male reproductive development. However, the underlying mechanisms by which rice responds to cold at this stage remain largely unknown. Here, we identified MITOCHONDRIAL ACYL CARRIER PROTEIN 2 (OsMTACP2), the encoded protein of which mediates lipid metabolism involved in the cold response at the booting stage. Loss of OsMTACP2 function compromised cold tolerance, hindering anther cuticle and pollen wall development, resulting in abnormal anther morphology, lower pollen fertility, and seed setting. OsMTACP2 was highly expressed in tapetal cells and microspores during anther development, with the encoded protein localizing to both mitochondria and the cytoplasm. Comparative transcriptomic analysis revealed differential expression of genes related to lipid metabolism between the wild type and the Osmtacp2-1 mutant in response to cold. Through a lipidomic analysis, we demonstrated that wax esters, which are the primary lipid components of the anther cuticle and pollen walls, function as cold-responsive lipids. Their levels increased dramatically in the wild type but not in Osmtacp2-1 when exposed to cold. Additionally, mutants of two cold-induced genes of wax ester biosynthesis, ECERIFERUM1 and WAX CRYSTAL-SPARSE LEAF2, showed decreased cold tolerance. These results suggest that OsMTACP2-mediated wax ester biosynthesis is essential for cold tolerance in rice at the booting stage. An acyl carrier protein promotes wax ester biosynthesis at low temperatures to support anther cuticle formation and pollen grain maturation. [ABSTRACT FROM AUTHOR]

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. Significance Statement: The lemma and palea are unique and important organs for rice, providing nutrients and protection for floret and seed development, and directly affecting grain size. Our findings show that the expression of OsARF3a was controlled by both OsKANADI1 and via RDR6 at the transcription and post‐transcription levels, thus ensuring the normal development of glumes in rice. [ABSTRACT FROM AUTHOR]