Cellulose, which can be converted into numerous industrial products, has important impacts on the global economy. It has long been known that cellulose synthesis in plants is tightly regulated by various phytohormones. However, the underlying mechanism of cellulose synthesis regulation remains elusive. Here, we show that in rice (Oryza sativa), gibberellin (GA) signals promote cellulose synthesis by relieving the interaction between SLENDER RICE1 (SLR1), a DELLA repressor of GA signaling, and NACs, the top-layer transcription factors for secondary wall formation. Mutations in GA-related genes and physiological treatments altered the transcription of CELLULOSE SYNTHASE genes (CESAs) and the cellulose level. Multiple experiments demonstrated that transcription factors NAC29/31 and MYB61 are CESA regulators in rice; NAC29/31 directly regulates MYB61, which in turn activates CESA expression. This hierarchical regulation pathway is blocked by SLR1-NAC29/31 interactions. Based on the results of anatomical analysis and GA content examination in developing rice internodes, this signaling cascade was found to be modulated by varied endogenous GA levels and to be required for internode development. Genetic and gene expression analyses were further performed in Arabidopsis thalianaGA-related mutants. Altogether, our findings reveal a conserved mechanism by which GA regulates secondary wall cellulose synthesis in land plants and provide a strategy for manipulating cellulose production and plant growth.

Cotton produces natural fiber for the textile industry. The genetic effects of genomic structural variations underlying agronomic traits remain unclear. Here, we generate two high-quality genomes of Gossypium hirsutum cv. NDM8 and Gossypium barbadense acc. Pima90, and identify large-scale structural variations in the two species and 1,081 G. hirsutum accessions. The density of structural variations is higher in the D-subgenome than in the A-subgenome, indicating that the D-subgenome undergoes stronger selection during species formation and variety development. Many structural variations in genes and/or regulatory regions potentially influencing agronomic traits were discovered. Of 446 significantly associated structural variations, those for fiber quality and Verticillium wilt resistance are located mainly in the D-subgenome and those for yield mainly in the A-subgenome. Our research provides insight into the role of structural variations in genotype-to-phenotype relationships and their potential utility in crop improvement.

Upland rice is a distinct ecotype that grows in aerobic environments and tolerates drought stress. However, the genetic basis of its drought resistance is unclear. Here, using an integrative approach combining a genome-wide association study with analyses of introgression lines and transcriptomic profiles, we identify a gene, DROUGHT1 (DROT1), encoding a COBRA-like protein that confers drought resistance in rice. DROT1 is specifically expressed in vascular bundles and is directly repressed by ERF3 and activated by ERF71, both drought-responsive transcription factors. DROT1 improves drought resistance by adjusting cell wall structure by increasing cellulose content and maintaining cellulose crystallinity. A C-to-T single-nucleotide variation in the promoter increases DROT1 expression and drought resistance in upland rice. The potential elite haplotype of DROT1 in upland rice could originate in wild rice (O. rufipogon) and may be beneficial for breeding upland rice varieties.

OsTBL1 and OsTBL2 represent xylan acetyltransferases, which catalyze addition of acetyl groups onto the 2-O and 3-O position of xylosyl residues and is essentia

Acetylation, a prevalent modification of cell-wall polymers, is a tightly controlled regulatory process that orchestrates plant growth and environmental adaptation. However, due to limited characterization of the enzymes involved, it is unclear how plants establish and dynamically regulate the acetylation pattern in response to growth requirements. In this study, we identified a rice (Oryza sativa) GDSL esterase that deacetylates the side chain of the major rice hemicellulose, arabinoxylan. Acetyl esterases involved in arabinoxylan modification were screened using enzymatic assays combined with mass spectrometry analysis. One candidate, DEACETYLASE ON ARABINOSYL SIDECHAIN OF XYLAN1 (DARX1), is specific for arabinosyl residues. Disruption of DARX1 via Tos17 insertion and CRISPR/Cas9 approaches resulted in the accumulation of acetates on the xylan arabinosyl side chains. Recombinant DARX1 abolished the excess acetyl groups on arabinoxylan-derived oligosaccharides of the darx1 mutants in vitro. Moreover, DARX1 is localized to the Golgi apparatus. Two-dimensional ¹³C-¹³C correlation spectroscopy and atomic force microscopy further revealed that the abnormal acetylation pattern observed in darx1 interrupts arabinoxylan conformation and cellulose microfibril orientation, resulting in compromised secondary wall patterning and reduced mechanical strength. This study provides insight into the mechanism controlling the acetylation pattern on arabinoxylan side chains and suggests a strategy to breed robust elite crops.

Cotton Verticillium wilt (VW) is often a destructive disease that results in significant fibre yield and quality losses in Gossypium hirsutum . Transferring the resistance trait of Gossypium barbadense to G. hirsutum is optional but challenging in traditional breeding due to limited molecular dissections of resistance genes. Here, we discovered a species‐diversified structural variation (SV) in the promoter of receptor‐like protein 6 (RLP6) that caused distinctly higher expression level of RLP6 in G. barbadense with the SV than G. hirsutum without the SV. Functional experiments showed that RLP6 is an important regulator in mediating VW resistance. Overexpressing RLP6 significantly enhanced resistance and root growth, whereas the opposite phenotype appeared in RLP6 ‐silenced cotton. A series of experiments indicated that RLP6 regulated reactive oxygen species (ROS) and salicylic acid (SA) signalling, which induced diversified defence‐related gene expression with pathogenesis‐related (PR) proteins and cell wall proteins enrichments for resistance improvement. These findings could be valuable for the transfer of the G. barbadense SV locus to improve G. hirsutum VW resistance in future crop disease resistance breeding.