RESUMO
Tapping panel dryness (TPD) is a complex physiological syndrome found widely in rubber tree (Hevea brasiliensis) plantations that causes severe yield loss in natural rubber-producing countries. In an earlier study, we confirmed that there is a negative correlation between HbMyb1 expression and TPD severity. To further investigate the function of HbMyb1 in TPD, HbMyb1 was over-expressed in tobacco controlled by a CaMV 35S promoter. In transgenic plants expressing HbMyb1, cell death induced by UV-B irradiation, paraquat and the hypersensitive reaction to necrotrophic fungal infection (Botrytis cinerea) was suppressed with a close correlation between HbMyb1 protein levels and the extent of suppression. In addition the nuclear condensation and degradation were observed in laticifer cells of TPD trees, while the nucleus of laticifer cells of healthy trees was morphologically normal. On the basis of the results described above, we propose that HbMyb1 maybe suppress stress induced cell death in rubber trees.
Assuntos
Adaptação Fisiológica/genética , Morte Celular/genética , Hevea/fisiologia , Nicotiana/fisiologia , Doenças das Plantas/genética , Estresse Fisiológico/genética , Fatores de Transcrição/metabolismo , Botrytis , Núcleo Celular , Expressão Gênica , Genes de Plantas , Hevea/genética , Hevea/metabolismo , Paraquat , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Plantas Geneticamente Modificadas , Valores de Referência , Nicotiana/genética , Nicotiana/metabolismo , Fatores de Transcrição/genética , Árvores , Raios UltravioletaRESUMO
TPD (tapping panel dryness) is a complex physiological syndrome widely found in rubber tree (Hevea brasiliensis) plantations, which causes severe yield and crop losses in natural rubber-producing countries. The molecular mechanism underlying TPD is not known and there is presently no effective prevention or treatment for this serious disease. To investigate the molecular mechanism of TPD, we isolated and characterized genes for which the change of expression is associated with TPD. We report here the identification and characterization of a Myb transcription factor HbMyb1. HbMyb1 is expressed in leaves, barks, and latex of rubber trees, but its expression is significantly decreased in barks of TPD trees. Our results suggest that the expression of HbMyb1 is likely associated with TPD and that the function of HbMyb1 is associated with the integrity of bark tissue of rubber trees.