It has been reported that Arabidopsis chloroplast accD transcripts undergo RNA editing and that loss of accD-C794 RNA editing does not affect plant growth under normal conditions.To date,the exact biological role of accD-C794 editing has remained elusive.Here,we reveal an unexpected role for accD-C794 editing in response to heat stress.Loss of accD-C794 editing results in a yellow and dwarf phenotype with decreased chloroplast gene expression under heat stress,and artificial improvement of C794-edited accD gene expression enhances heat tolerance in Arabidopsis.These data suggest that accD-C794 editing confers heat tolerance in planta.We also found that treatment with the product of acetyl coenzyme A carboxylase(ACCase)could allay mutant phenotypic characteristics and showed that a mutation in the CAC3 gene for the a-subunit of ACCase was associated with dwarfism under heat stress.These observations indicate that defective accD-C794 editing may be intrinsic to reduced ACCase activity,thereby contributing to heat sensitivity.ACCase catalyzes the committed step of de novo fatty acid(FA)biosynthesis.FA content analysis revealed that unsaturated oleic(C18:1)and linoleic acids(C18:2)were low in the accD-C794 editing-defective mutant but high in the C794-edited accD-overexpressing plants compared with the wild type.Supplying exogenous C18:1 and C18:2 could rescue the mutant phenotype,suggesting that these FAs play an essential role in tolerance to heat stress.Transmission electron microscopy observations showed that heat stress seriously affected the membrane architecture in accD editing-defective mutants but not in accD-overexpressing plants.These results provide the first evidence that accD-C794 editing regulates FA biosynthesis for maintenance of membrane structural homeostasis under heat stress.
以小球藻及莱茵衣藻原生质体为受体细胞,利用电击法将质粒p CAMBIA1301转入小球藻和莱茵衣藻,摸索电击转化条件并进行分子检测。结果表明:两类藻都对潮霉素敏感,小球藻及莱茵衣藻分别在含25 mg/L和100 mg/L潮霉素的固体培养基上的生长被完全抑制;小球藻和莱茵衣藻原生质体电击转化的最佳电击场强分别为0.8 k V/cm和0.6 k V/cm,最佳脉冲时间均为10 ms;制备原生质体和通过2-脱氧-D-葡萄糖处理可明显提高转化效率;分子检测说明GUS报告基因成功转入两种藻并可稳定遗传。
Plant architecture is an important factor for crop production. Some members of micro RNA156(mi R156) and their target genes SQUAMOSA Promoter-Binding Protein-Like(SPL) were identi fi ed to play essential roles in the establishment of plant architecture. However, the roles and regulation of mi R156 is not well understood yet. Here, we identi fi ed a T-DNA insertion mutant Osmtd1(Oryza sativa multi-tillering and dwarf mutant). Osmtd1 produced more tillers and displayed short stature phenotype. We determined that the dramatic morphological changes were caused by a single T-DNA insertion in Osmtd1. Further analysis revealed that the T-DNA insertion was located in the gene Os08g34258 encoding a putative inhibitor I family protein. Os08g34258 was knocked out and Osmi R156 f was signi fi cantly upregulated in Osmtd1. Overexpression of Os08g34258 in Osmtd1 complemented the defects of the mutant architecture, while overexpression of Osmi R156 f in wild-type rice phenocopied Osmtd1. We showed that the expression of Os SPL3, Os SPL12,and Os SPL14 were signi fi cantly downregulated in Osmtd1 or Osmi R156 f overexpressed lines, indicating that Os SPL3,Os SPL12, and Os SPL14 were possibly direct target genes of Osmi R156 f. Our results suggested that Osmi R156 f controlledplant architecture by mediating plant stature and tiller outgrowth and may be regulated by an unknown protease inhibitor I family protein.
