RESUMO
Aroma-related volatiles, together with sugars and acids, play an important role in determining fruit flavor quality. Characteristic volatiles of peach fruit are mainly derived from fatty acids such as linoleic acid (18:2) and linolenic acid (18:3). In the present study, six genes encoding fatty acid desaturases (FAD) were cloned, including two ω-6 FAD genes (PpFAD2, PpFAD6) and four ω-3 FAD genes (PpFAD3-1, PpFAD3-2, PpFAD7 and PpFAD8). Heterologous expression of peach FADs in tobacco plants showed that PpFAD3-1, and PpFAD3-2 significantly reduced contents of 18:2, and accumulated significant higher levels of 18:3. In the case of volatiles, transgenic plants produced lower concentrations of hexanal and higher levels of (E)-2-hexenal. Consequently, the ratio of the (E)-2-hexenal and hexanal was about 5- and 3-fold higher than that of wild type (WT) in PpFAD3-1 and PpFAD3-2 transformants, respectively. No significant changes in volatile profiles were observed in transgenic plants overexpressing the four other peach FAD genes. Real-time quantitative polymerase chain reaction (qPCR) analysis showed that ripe fruit had high PpFAD3-1 and low PpFAD3-2 transcript levels. In contrast, high PpFAD3-2 and low PpFAD3-1 transcript levels were observed in young fruit. These results indicate a temporal regulation of these two ω-3 FADs during development and ripening, influencing peach fruit volatile formation.
Assuntos
Ácidos Graxos Dessaturases/metabolismo , Frutas/enzimologia , Proteínas de Plantas/metabolismo , Prunus persica/enzimologia , Compostos Orgânicos Voláteis/metabolismo , Análise por Conglomerados , Ácidos Graxos Dessaturases/genética , Ácidos Graxos Ômega-3/metabolismo , Frutas/química , Frutas/metabolismo , Cromatografia Gasosa-Espectrometria de Massas , Ácido Linoleico/metabolismo , Proteínas de Plantas/genética , Plantas Geneticamente Modificadas/metabolismo , Prunus persica/química , Prunus persica/metabolismo , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de DNA , Nicotiana/genética , Nicotiana/metabolismo , Compostos Orgânicos Voláteis/análise , Ácido alfa-Linolênico/metabolismoRESUMO
OBJECTIVE: To explore the genetic diversity of germplasm resources of Baphicacanthus cusia on molecular leve. METHODS: The molecular biological technique-random amplified polymorphic DNA (RAPD) were used. RESULTS: 104 random decamer primers were screened for RAPD fragments of Baphicacanthus cusia. 422 DNA bands were amplified by 12 primers, 55.69% products were found to be polymorphic. Base on UPGMA cluster analysis, a DNA molecular dendrogram was established to discuss the genetic diversity of the germplasm resources of Baphicacanthus cusia. The genetic differences are related to morphological differences on a certain extant, but not to geographic regions. CONCLUSION: There actually existed much genetic diversity on molecular level among different natural populations of Baphicacanthus cusia.
