RESUMO
The molecular mechanisms underlying spontaneous bud mutations, which provide an important breeding tool in carnation, are poorly understood. Here we describe a new active hAT type transposable element, designated Tdic101, the movement of which caused a bud mutation in carnation that led to a change of flower color from purple to deep pink. The color change was attributed to Tdic101 insertion into the second intron of F3'H, the gene for flavonoid 3'-hydroxylase responsible for purple pigment production. Regions on the deep pink flowers of the mutant can revert to purple, a visible phenotype of, as we show, excision of the transposable element. Sequence analysis revealed that Tdic101 has the characteristics of an autonomous element encoding a transposase. A related, but non-autonomous element dTdic102 was found to move in the genome of the bud mutant as well. Its mobilization might be the result of transposase activities provided by other elements such as Tdic101. In carnation, therefore, the movement of transposable elements plays an important role in the emergence of a bud mutation.
Assuntos
Sistema Enzimático do Citocromo P-450/genética , Elementos de DNA Transponíveis/genética , Dianthus/genética , Flores/genética , Mutagênese Insercional , Proteínas de Plantas/genética , Antocianinas/metabolismo , Sequência de Bases , Sistema Enzimático do Citocromo P-450/metabolismo , DNA de Plantas/química , DNA de Plantas/genética , Dianthus/metabolismo , Flores/metabolismo , Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Genoma de Planta/genética , Íntrons/genética , Dados de Sequência Molecular , Pigmentação/genética , Proteínas de Plantas/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNARESUMO
Stromal glycerol-3-phosphate acyltransferases (GPAT) are responsible for the selective incorporation of saturated and unsaturated fatty-acyl chains into chloroplast membranes, which is an important determinant of a plant's ability to tolerate chilling temperatures. The molecular mechanisms of plant chilling tolerance were elucidated by creating chimeric GPATs between squash (Cucurbita moscata, chilling-sensitive) and spinach (Spinacea oleracea, chilling-tolerant) and the results were interpreted using structural information on squash GPAT determined by X-ray crystallography at 1.55 A resolution. Enzymatic analysis of the chimeric GPATs showed that the chimeric GPATs containing the spinach region from residues 128 to 187 prefer the 18:1 unsaturated fatty acid rather than 16:0 saturated fatty acid. Structure analysis suggests that the size and character of the cavity that is formed from this region determines the specific recognition of acyl chains.
Assuntos
Cucurbita/enzimologia , Glicerol-3-Fosfato O-Aciltransferase/química , Proteínas de Plantas/química , Spinacia oleracea/enzimologia , Sequência de Aminoácidos , Cristalografia por Raios X , DNA de Plantas/química , DNA de Plantas/genética , Escherichia coli/genética , Ácidos Graxos/metabolismo , Glicerol-3-Fosfato O-Aciltransferase/genética , Glicerol-3-Fosfato O-Aciltransferase/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Conformação Proteica , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/genética , Selenometionina/metabolismoRESUMO
Many pathogenic plant viruses are RNA viruses, which initiate production of double-stranded RNA intermediates when they replicate in host plant cells. Introduction of double-stranded RNA-specific ribonucleases such as the Schizosaccharomyces pombe derived pac I protein and animal cell derived interferon-induced 2',5'-oligoadenylate synthetase (2-5 Aase)/ribonuclease L (RNase L) system into various plants may make plants resistant to various pathogenic viruses and viroids. We have demonstrated that pac I and 2-5 Aase/RNase L transgenic tobacco plants are resistant to various viruses including tobacco mosaic virus, cucumber mosaic virus and potato virus Y. In addition, pac I transgenic potato plants are resistant to potato spindle tuber viroid. Using Agrobacterium-mediated transformation, we have established a transformation system for chrysanthemum plants and have recently developed pac I transgenic chrysanthemum (Dendranthema grandiflora cv Reagan) resistant to chrysanthemum stunt viroid and have grown them in isolated fields for an evaluation of their effects.
