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. 2003 Sep;15(9):2020-31.
doi: 10.1105/tpc.011775.

BRITTLE CULM1, which encodes a COBRA-like protein, affects the mechanical properties of rice plants

Yunhai Li  1 , Qian Qian, Yihua Zhou, Meixian Yan, Lei Sun, Mu Zhang, Zhiming Fu, Yonghong Wang, Bin Han, Xiaoming Pang, Mingsheng Chen, Jiayang Li
Affiliations

BRITTLE CULM1, which encodes a COBRA-like protein, affects the mechanical properties of rice plants

Yunhai Li et al. Plant Cell. 2003 Sep.

Abstract

Plant mechanical strength is an important agronomic trait. To understand the molecular mechanism that controls the plant mechanical strength of crops, we characterized the classic rice mutant brittle culm1 (bc1) and isolated BC1 using a map-based cloning approach. BC1, which encodes a COBRA-like protein, is expressed mainly in developing sclerenchyma cells and in vascular bundles of rice. In these types of cells, mutations in BC1 cause not only a reduction in cell wall thickness and cellulose content but also an increase in lignin level, suggesting that BC1, a gene that controls the mechanical strength of monocots, plays an important role in the biosynthesis of the cell walls of mechanical tissues.

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Figures

Figure 1.
Figure 1.
Phenotypes and Physical Properties of Wild-Type and bc1-2 Mutant Plants. (A) A wild-type culm. (B) An easily broken bc1-2 culm, as indicated by the arrow. (C) The force required to break culms. (D) The force required to break flag leaves. (E) The elongation ratios of leaves. Error bars were obtained from 10 measurements for (C) and from 22 measurements for (D) and (E). WT, wild type.
Figure 2.
Figure 2.
Scanning Electron Micrographs Showing the Differences between Sclerenchyma Cells and Vascular Bundles in Wild-Type and bc1-2 Plants. (A) Cross-section of a wild-type culm. (B) Cross-section of a bc1-2 mutant culm. (C) Cross-section of a wild-type leaf. (D) Cross-section of a bc1-2 leaf. Sc, sclerenchyma cells; V, vascular bundles. Bars = 12.5 μm.
Figure 3.
Figure 3.
Measurement and Staining of Cellulose and Lignin in Wild-Type and bc1-2 Plants. (A) and (B) Cellulose (A) and lignin (B) contents (milligrams per gram of total cell wall residues) of the culm segments from wild-type (WT) and bc1-2 plants. The error bars were obtained from five measurements. (C) to (H) Wiesner's staining of the transverse culm sections of wild-type (C) and bc1-2 (D) plants, and magnified sections ([E] and [F]), showing the increased level of lignin in the walls of sclerenchyma cells and vascular bundles in the mutant culm. (G) and (H) Magnified sections of (E) and (F), showing the irregular thin and defective walls of sclerenchyma cells in the mutant culm. (I) to (L) Calcofluor staining of the transverse culm sections of wild-type (I) and bc1-2 (J) plants, and magnified sections (K) and (L), showing the decreased level of cellulose in the cell walls of sclerenchyma cells and vascular bundles in the mutant culm. Bars = 160 μm in (C), (D), (I), and (J), 40 μm in (E) and (F), 10 μm in (G) and (H), and 80 μm in (K) and (L).
Figure 4.
Figure 4.
Cloning and Confirmation of the BC1 Gene. (A) The BC1 locus was mapped in the chromosome 3 (Chr 3) centromeric region between markers C524a and RM16. (B) A BAC contig covering the BC1 locus. The numerals indicate the number of recombinants identified from 7068 bc1-2 F2 plants. BAC1, OSJNBa0006H20; BAC2, OSJNBa0052G19; BAC3, OSJNBa0007B10; BAC4, OSJNBa0057M10; BAC5, OSJNBa0036N23. (C) Fine mapping of the BC1 locus with the markers (P1 to P7) developed based on the OSJNBa0036N23 sequence. The BC1 locus was narrowed to a 3.3-kb genomic DNA region between CAPS markers P2 and P4 and cosegregated with marker P3. (D) BC1 gene structure, showing the mutated sites of the two bc1 alleles. The start codon (ATG) and the stop codon (TGA) are indicated. Closed boxes indicate the coding sequence, open boxes indicate the 5′ and 3′ untranslated regions, and lines between boxes indicate introns. Mutation sites in bc1-1 and bc1-2 also are shown. (E) Complementation constructs. The construct pCna18 contains the entire BC1 gene, including a 2795-bp upstream sequence and a 1459-bp downstream sequence. The plasmid pCna181T contains a partial BC1 gene that encodes the first 173 amino acid residues. (F) Identification of transgenic plants. The deletion of 4 bp in bc1-2 destroys a BstNI site that is used for the CAPS marker P3. Lane 1, wild type; lane 2, bc1-2; lane 3, the pCna18-transformed rice line 1; lane M, 1-kb marker.
Figure 5.
Figure 5.
BC1 cDNA and Predicted Amino Acid Sequences. Numbers at left refer to the positions of nucleotides. Red letters indicate the 4-bp deletion in bc1-2 and the 1-bp insertion in bc1-1; blue letters indicate different nucleotides between indica and japonica subspecies; purple letters indicate the N-terminal signal; orange letters indicate the conserved CCVS motif; and green letters indicate the C terminus, including the predicted ω-site and the hydrophobic tail.
Figure 6.
Figure 6.
BC1 Expression Analysis. (A) RT-PCR analysis of BC1. Total RNA was isolated from leaves (L), leaf sheaths (S), culms (C), and roots (R) of wild-type plants. Amplification of actin cDNA was used to ensure that approximately equal amounts of cDNA were loaded. (B) Comparison of BC1 transcripts between bc1 mutant (m) and wild-type (w) plants with RT-PCR.
Figure 7.
Figure 7.
Expression Patterns of the BC1 Gene Revealed by in Situ Hybridization in Transverse Sections of Wild-Type Rice Plants. (A) Young stem and leaf sheath. (B) A magnified section from (A), showing the strong expression of BC1 in the developing vascular bundles. (C) Leaves and leaf sheath, showing the intense expression of BC1 in young leaves and sheaths. (D) A magnified section from (C), showing strong signals in the developing vascular and other mechanical tissues. (E) Tiller bud, showing strong signals in vascular bundles. (F) Mature vascular bundles, showing the sharply decreased expression level of BC1 compared with that shown in (E). (G) Background control, in situ hybridization of a young leaf sheath with a sense probe. L, leaf; Ls, leaf sheath; P, phloem; S, stem; Sc, sclerenchyma cells; V, vascular bundles; X, xylem. Bars = 70 μm in (E) and (G), 450 μm in (A) and (C), and 35 μm in (B), (D), and (F).
Figure 8.
Figure 8.
The BC1 Gene Family in Rice. (A) Intron/exon structure of rice BC1 family genes. Exons are indicated with gray boxes, and introns are indicated with white boxes. (B) Expression of rice BC1 family genes in aerial parts of rice seedlings revealed by RT-PCR. Amplification of actin (ACT) transcript was used as an internal control. L1 to L9, BC1L1 to BC1L9. (C) Chromosomal positions of BC1 family genes. The chromosomes are labeled with roman numerals. The number below the gene symbol represents the genetic position of each putative gene (centimorgans). (D) Neighbor-joining tree of rice BC1L proteins and Arabidopsis AtCOBRA family members. The numbers at each node represent the bootstrap support (percentage). The scale bar is an indicator of genetic distance based on branch length.
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References

    1. Arioli, T., et al. (1998). Molecular analysis of cellulose biosynthesis in Arabidopsis. Science 279, 717–720. - PubMed
    1. Burk, D.H., Liu, B., Zhong, R., Morrison, W.H., and Ye, Z.H. (2001). A katanin-like protein regulates normal cell wall biosynthesis and cell elongation. Plant Cell 13, 807–827. - PMC - PubMed
    1. Burk, D.H., and Ye, Z.H. (2002). Alteration of oriented deposition of cellulose microfibrils by mutation of a katanin-like microtubule-severing protein. Plant Cell 14, 2145–2160. - PMC - PubMed
    1. Carpita, N., and McCann, M. (2000). The cell wall. In Biochemistry and Molecular Biology of Plants, B.B. Buchanan, W. Gruissem, and R.L. Jones, eds (Rockville, MD: American Society of Plant Physiologists), pp. 52–108.
    1. Chen, M., et al. (2002). An integrated physical and genetic map of the rice genome. Plant Cell 14, 537–545. - PMC - PubMed

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