Leaf cells undergo two main developmental events;i.e., cell proliferation and cell differentiation, before maturation. These events occur sequentially at specific positions and with specific timing during leaf develop...Leaf cells undergo two main developmental events;i.e., cell proliferation and cell differentiation, before maturation. These events occur sequentially at specific positions and with specific timing during leaf development. To understand the transition from cell proliferation to cell differentiation of rice leaves, we analyzed rice leaves from both morphological and molecular viewpoints. The results of anatomical, morphological, and histochemical analyses indicated that P4 leaf primordium is the stage when dynamic transition of the cellular state from immature to mature along the proximal-distal axis of the leaf occurs. We screened for marker genes showing a dynamic expression pattern along the proximal-distal axis of the P4 leaf, and applied them to expression analysis in wild-type and various morphogenetic mutants. The changes in expression pattern of the marker genes varied between developmental stages and between mutants. Our analysis reinforced previous data regarding the developmental transition of wild-type rice leaves and indicated that the transition can be monitored using our molecular markers. The results of this study indicate that expression analysis using these molecular markers would be valuable for understanding the genetic effects on leaf development in various leaf morphogenetic mutants.展开更多
Understanding the genetic mechanism underlying rice leaf-shape development is crucial for optimizing rice configuration and achieving high yields; however, little is known about leaf abaxial curling. We isolated a ric...Understanding the genetic mechanism underlying rice leaf-shape development is crucial for optimizing rice configuration and achieving high yields; however, little is known about leaf abaxial curling. We isolated a rice transferred DNA （T-DNA） insertion mutant, BY240, which exhibited an abaxial leaf curling phenotype that co-segregated with the inserted T-DNA. The T-DNA was inserted in the promoter of a novel gene, ACL1 （Abaxially Curled Leaf 1）, and led to overexpression of this gene in BY240. Overexpression of ACL1 in wild-type rice also resulted in abaxial leaf curling. ACL1 encodes a protein of 116 amino acids with no known conserved functional domains. Overexpression of ACL2, the only homolog of ACL1 in rice, also induced abaxial leaf curling. RT-PCR analysis revealed high expressions of ACLs in leaf sheaths and leaf blades, suggesting a role for these genes in leaf development. In situ hybridization revealed non-tissue-specific expression of the ACLs in the shoot apical meristem, leaf primordium, and young leaf. Histological analysis showed increased number and exaggeration of bulliform cells and expansion of epidermal cells in the leaves of BY240, which caused developmental discoordination of the abaxial and adaxial sides, resulting in abaxially curled leaves. These results revealed an important mechanism in rice leaf development and provided the genetic basis for agricultural improvement.展开更多
Sphingosine-1-phosphate lyase （SPL） is involved in degrading the conserved sphingolipid signaling molecule sphingosine-1-phosphate. However, molecular studies on plant SPL have not been reported to date. Here, we pr...Sphingosine-1-phosphate lyase （SPL） is involved in degrading the conserved sphingolipid signaling molecule sphingosine-1-phosphate. However, molecular studies on plant SPL have not been reported to date. Here, we present bioinformatic, molecular and functional analyses of putative SPL proteins from Arabidopsis thaliana and rice （designated as AtSPL and OsSPL, respectively）. Amino acid sequence comparison revealed that plant SPL contalned the pyridoxal-dependent decarboxylase domain and the conserved residue that may be involved in substrate catalysis. When expressed in Saccharomyces cerevisiae, AtSPL and OsSPL corrected the hypersensitive phenotype of the yeast dpl1 deletion strain, which is deficient in endogenous SPL activity, to exogenous supplied sphingolipid long chain bases （LCBs）, suggesting that plant SPL protein is functional In vivo in degrading phosphorylated LCBs. In Arabidopsis, AtSPL transcripts were detected in roots, stems, leaves, flowers and siliques. In pAtSPL-AtSPL∷GUS transgenic lines, the AtSPL∷GUS fusion protein was found in a variety of vegetative and reproductive tissues. AtSPL expression level was dynamically regulated during leaf development and senescence, and was steadily and significantly increased in Arabidopsis seedlings treated with the cell death-inducing fungal toxin fumonisin B1. The potential function of SPL in Arabidopsis is discussed.展开更多
文摘Leaf cells undergo two main developmental events;i.e., cell proliferation and cell differentiation, before maturation. These events occur sequentially at specific positions and with specific timing during leaf development. To understand the transition from cell proliferation to cell differentiation of rice leaves, we analyzed rice leaves from both morphological and molecular viewpoints. The results of anatomical, morphological, and histochemical analyses indicated that P4 leaf primordium is the stage when dynamic transition of the cellular state from immature to mature along the proximal-distal axis of the leaf occurs. We screened for marker genes showing a dynamic expression pattern along the proximal-distal axis of the P4 leaf, and applied them to expression analysis in wild-type and various morphogenetic mutants. The changes in expression pattern of the marker genes varied between developmental stages and between mutants. Our analysis reinforced previous data regarding the developmental transition of wild-type rice leaves and indicated that the transition can be monitored using our molecular markers. The results of this study indicate that expression analysis using these molecular markers would be valuable for understanding the genetic effects on leaf development in various leaf morphogenetic mutants.
文摘Understanding the genetic mechanism underlying rice leaf-shape development is crucial for optimizing rice configuration and achieving high yields; however, little is known about leaf abaxial curling. We isolated a rice transferred DNA （T-DNA） insertion mutant, BY240, which exhibited an abaxial leaf curling phenotype that co-segregated with the inserted T-DNA. The T-DNA was inserted in the promoter of a novel gene, ACL1 （Abaxially Curled Leaf 1）, and led to overexpression of this gene in BY240. Overexpression of ACL1 in wild-type rice also resulted in abaxial leaf curling. ACL1 encodes a protein of 116 amino acids with no known conserved functional domains. Overexpression of ACL2, the only homolog of ACL1 in rice, also induced abaxial leaf curling. RT-PCR analysis revealed high expressions of ACLs in leaf sheaths and leaf blades, suggesting a role for these genes in leaf development. In situ hybridization revealed non-tissue-specific expression of the ACLs in the shoot apical meristem, leaf primordium, and young leaf. Histological analysis showed increased number and exaggeration of bulliform cells and expansion of epidermal cells in the leaves of BY240, which caused developmental discoordination of the abaxial and adaxial sides, resulting in abaxially curled leaves. These results revealed an important mechanism in rice leaf development and provided the genetic basis for agricultural improvement.
基金Supported by the National Natural Science Foundation of China （30521001） and the Chinese Academy of Sciences （KSCX2-SW-304）.Acknowledgments The authors are grateful to Drs Lu Liang and Yiping Tong for helpful discussion on this work and the writing of the manuscript.
文摘Sphingosine-1-phosphate lyase （SPL） is involved in degrading the conserved sphingolipid signaling molecule sphingosine-1-phosphate. However, molecular studies on plant SPL have not been reported to date. Here, we present bioinformatic, molecular and functional analyses of putative SPL proteins from Arabidopsis thaliana and rice （designated as AtSPL and OsSPL, respectively）. Amino acid sequence comparison revealed that plant SPL contalned the pyridoxal-dependent decarboxylase domain and the conserved residue that may be involved in substrate catalysis. When expressed in Saccharomyces cerevisiae, AtSPL and OsSPL corrected the hypersensitive phenotype of the yeast dpl1 deletion strain, which is deficient in endogenous SPL activity, to exogenous supplied sphingolipid long chain bases （LCBs）, suggesting that plant SPL protein is functional In vivo in degrading phosphorylated LCBs. In Arabidopsis, AtSPL transcripts were detected in roots, stems, leaves, flowers and siliques. In pAtSPL-AtSPL∷GUS transgenic lines, the AtSPL∷GUS fusion protein was found in a variety of vegetative and reproductive tissues. AtSPL expression level was dynamically regulated during leaf development and senescence, and was steadily and significantly increased in Arabidopsis seedlings treated with the cell death-inducing fungal toxin fumonisin B1. The potential function of SPL in Arabidopsis is discussed.
