Functional Analysis of the promoter region of mannose-binding lectins (MBLs) form Oncidium Gower Ramsey
Date Issued
2006
Date
2006
Author(s)
Huang, Li-Ru
DOI
zh-TW
Abstract
The monocot mannose-binding lectins are an extended superfamily of structurally and evolutionarily related proteins, which until now have been isolated from species of the Amaryllidaceae, Alliaceae, Araceae, Bromeliaceae, Lilliaceae, and Orchidaceae. Monocot mannose-binding lectins have been found in most vegetative tissues such as leaves, flowers, ovaries, bulbs, tubers, rhizomes, and roots. Previous study showed that monocot mannose-binding lectins are believed to play a role in the plant’s defense against sucking insects, nematodes, other invertebrates and even fungi. A mannose-binding lectin (MBL) has been isolated from Oncidium Gower Ramsey. It is an abundant storage protein in Oncidium pseudobulb.
In order to understand the role of the promoter region of MBL in the regulating of gene expression, the 2Kb 5’-flanking region of MBL was further cloned and sequenced by PCR-based genomic walking method. A number of putative regulatory motifs were identified, including two ABRE, two WUN-motifs, three W-boxes, three TGA-boxes, four MYBs and six MYC protein binding sequences. The promoter of MBL was fused to the GUS and GFP sequences, then the resulting constructs were used to transform Arabidopsis, rice and tobacco. In Arabidopsis transgenic plants, the histochemical analysis revealed the expression of MBL promoter::GUS was detected at high level in shoot apical meristems, hypocotyls and roots at different stages of development. In RT-PCR analysis, we found that the GUS expression in roots and stems were higher than that in leaves. Besides, we found that the GUS activity was induced by IAA, JA and SA, but especially by ABA and Blumeria gramini f.sp. hordei. In rice transgenic calli and plants, the histochemical and RT-PCR analysis indicated that the GUS activity was prominantly induced by JA, ABA, SA and Blumeria gramini f.sp. hordei, but suppressed by IAA. This expression pattern was similar to that of the MBL gene in Oncidium. In addition, histochemical analysis of GUS activity in rice seedlings revealed that the GUS activity was also induced by mechanical wounding treatment. Otherwise, In tobacco calli, the RT-PCR analysis revealed that the GFP activity was induced by ABA, SA and Blumeria gramini f.sp. hordei. This result in tobacco was similar to that in Arabidopsis. In summary, the data suggest that the regulation of the MBL gene may be not the same in monocots and dicots. Moreover, it also suggested that the MBL genes in Oncidium maybe play a role in the plant’s defense against fungi.
Subjects
甘露糖結合型凝集素
mannose-binding lectins
Type
other
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