Ubiquitous urease affects soybean susceptibility to fungi

Abstract

The soybean ubiquitous urease (encoded by GmEu4) is responsible for recycling metabolically derived urea. Additional biological roles have been demonstrated for plant ureases, notably in toxicity to other organisms. However, urease enzymatic activity is not related to its toxicity. The role of GmEu4 in soybean susceptibility to fungi was investigated in this study. A differential expression pattern of GmEu4 was observed in susceptible and resistant genotypes of soybeans over the course of a Phakopsora pachyrhizi infection, especially 24 h after infection. Twenty-nine adult, transgenic soybean plants, representing six independently transformed lines, were obtained. Although the initial aim of this study was to overexpress GmEu4, the transgenic plants exhibited GmEu4 co-suppression and decreased ureolytic activity. The growth of Rhizoctonia solani, Phomopsis sp., and Penicillium herguei in media containing a crude protein extract from either transgenic or non-transgenic leaves was evaluated. The fungal growth was higher in the protein extracts from transgenic urease-deprived plants than in extracts from non-transgenic controls. When infected by P. pachyrhizi uredospores, detached leaves of urease-deprived plants developed a significantly higher number of lesions, pustules and erupted pustules than leaves of non-transgenic plants containing normal levels of the enzyme. The results of the present work show that the soybean plants were more susceptible to fungi in the absence of urease. It was not possible to overexpress active GmEu4. For future work, overexpression of urease fungitoxic peptides could be attempted as an alternative approach.Electronic supplementary materialThe online version of this article (doi:10.1007/s11103-012-9894-1) contains supplementary material, which is available to authorized users.

Soybean Urease: Over a Hundred Years of Knowledge

“…Soybeans mutants, lacking ub-SBU, were more susceptible to necrotrophic fungi, such as Penicillium herguei, Phomopsis sp and Rhizoctonia solani, and to the biotrophic pathogen Phakopsora pachyrhizi, responsible for the Asian soybean rust disease. In accordance to a defense role of ub-SBU against fungi infection, a rust-resistant soybean cultivar (PI561356) had a higher level of expression of ub-SBU after infection with P. pachyrhizi, in comparison with a susceptible cultivar (Embrapa-48) [93].…”

“…Recently, evidences of the participation of ub-SBU in soybean resistance to fungi were reported [93]. Soybeans mutants, lacking ub-SBU, were more susceptible to necrotrophic fungi, such as Penicillium herguei, Phomopsis sp and Rhizoctonia solani, and to the biotrophic pathogen Phakopsora pachyrhizi, responsible for the Asian soybean rust disease.…”

“…Since JBU, es-SBU and the derived peptide Jaburetox seem non toxic to mammals [75,90], the entomotoxic and fungitoxic properties of these molecules are relevant when considering biotechnological strategies aiming to protect commercially-relevant crops against natural enemies. The evidences of an in vivo effect of soybean urease in protecting the plant from fungi [93] are exciting. The possibility of selecting soybean cultivars with higher urease content or increasing the production of these proteins in the plant through genetic manipulation, in order to increase the resistance against insects and fungi, is very promising.…”

Efficient soybean regeneration and Agrobacterium‐mediated transformation using a whole cotyledonary node as an explant

“…The transgenic method is an efficient way to decipher gene function and increase crop yield and stress resistance . We developed an efficient regeneration system with whole cotyledonary node explants for soybean cultivar Zhong Huang 13, in which the gus reporter gene was successfully transferred to the soybean genome mediated by Agrobacterium .…”

The Lesion Simulating Disease (LSD) gene family as a variable in soybean response to Phakopsora pachyrhizi infection and dehydration

“…The PI561356 genotype presents the Rpp1 gene (responsible for immune response against some isolates), mapped at the chromosome 18 (Kim et al 2012). Plants in the V2 stage, which consist of a fully developed trifoliolate leaf at the node above the unifoliolate nodes (Fehr and Caviness 1977), were grown in a greenhouse and sprayed with a fungal spore suspension according to the method of Wiebke-Strohm et al (2012). Leaves sprayed with a solution lacking fungal spores were used as mock-treated control.…”