中文摘要：

脆秆突变体是一类研究植物机械强度的重要材料。利用EMS（甲基磺酸乙酯）诱变粳稻品种日本晴,筛选获得一个脆秆突变体,命名为bc16（brittle culm16）。与野生型植株相比,bc16茎秆、叶片和根明显变脆,而株高、穗粒数降低,穗长和主根长变短。茎秆细胞壁成分分析表明,bc16纤维素含量显著低于野生型植株,半纤维素含量则显著增加,而木质素含量差异不显著。突变体bc16薄壁细胞形状无规则、排列紊乱,表皮层下厚壁细胞次生壁和薄壁细胞壁变薄。遗传分析表明bc16突变体由隐性单基因控制,位于水稻第2染色体长臂端InDel标记2-F和2-H间66.6kb的区间内。该区间共有7个候选基因,其中Os02g0738900是bc3脆秆基因的等位基因。测序结果表明,bc16突变体中的Os02g0738900基因从ATG开始第5113位,在第13内含子近末端发生了T→A的置换,导致转录过程中该内含子末端6个核苷酸被剪切到mRNA中,最终导致翻译提前终止。实时荧光定量PCR结果表明Os02g0738900基因在bc16脆秆突变体根、茎、叶中的表达量降低。bc16基因可能通过调控厚壁组织次生细胞壁和薄壁细胞初生壁的合成来影响水稻茎秆机械强度。

英文摘要：

Brittle culm mutants are one of the important materials to study plant mechanical strength.A brittle culm mutant named as bc16（brittle culm 16）was isolated from Nipponbare through EMS（Ethyl Methane Sulphonate）treatment.Compared with wild type,bc16 featured fragile and easily broken stems,leaves,roots,lower plant height and filled grains per panicle,shorter panicle length and main root length.The components analysis of stem cell wall showed that the cellulose content in bc16 mutant was sharply decreased,while hemi-cellulose content was evidently increased and no significant difference had been found in the lignin content between bc16 mutant and wild type.The cell shape and arrangement of parenchyma cells in bc16 mutant became irregular and disordered.Moreover,the parenchyma cell walls and the secondary cell walls of sclerenchyma cells in bc16 mutant under the epidermis layer were thinner than those in wild type.The results of genetic analysis revealed that the mutant trait was controlled by a single recessive gene,which was mapped in a 66.6-kb region between InDel（insertion-deletion）markers 2-F and 2-H on chromosome2 with 7candidate genes.Among these genes,Os02g0738900,which is allelic to BC3 gene,was specially focused on.There was a T to A substitution at the very end of the 13 th intron of Os02g0738900 which was at the 5113 th base location from initiation codon by sequencing,which led an splicing forward mutation in the process of transcription,and six nucleotides were cut into mRNA as a result,which finally cause the stop of translation.Additionally,in the mutant,there were significant decrease in the expression of bc16 gene in roots,culms and leaves by real-time PCR method.The bc16 might affect the synthesis of sclerenchyma secondary cell wall and parenchyma primary cells wall,which could affect the mechanical strength of rice stem.