The characterization of GmTIP, a root-specific gene from soybean, and the expression analysis of its promoter

The soybean encounters severe root-related biotic and abiotic stresses causing extensive yield losses annually. The use of a root-specific promoter to confer expression of genes in a targeted manner has the potential to benefit the genetic improvement of the soybean. Several tonoplast intrinsic protein genes (TIPs) in plants like tobacco, strawberry, tomato, maize, pine, have been identified exhibiting root-specific expression. To explore the possibility of root-specific gene and promoter utilizations in soybean, we cloned soybean GmTIP and the upstream promoter sequence from soybean, and examined the expression patterns and promoter activity. Fluorometric GUS assays revealed that the GUS activity was obviously higher in roots than in leaves in transgenic Arabidopsis, regardless of the length of the promoter fragment. Weak GUS expression was found in other organs except root in transgenic Arabidopsis with the GmTIPp-2054 construct. Deletion analysis of the GmTIP promoter displayed that it still keep root-specific expression and can also be induced by various factors, such as methyl jasmonate, salicylic acid, abscisic acid, gibberellins acid, indole-3-acetic acid, NaCl, and PEG6000. This study provides a useful tool for soybean root improvement by genetic engineering.