Abstract
BackgroundGlutathione S-transferases (GSTs) have been reported to regulate the plant tolerance to environmental stresses. Many plant GSTs exhibited the roles on promoting tolerance to drought stress, oxidative stress and plant hormones. The biological function of GSTs has been well characterized in Arabidopsis thaliana in response to exogenous environmental stresses. However, their regulation function under exogenous environmental stresses regulating leaf abscission in cassava (Manihot esculenta Crantz) remained unknown.ResultsHere, 83 GSTs were identified from tropical plant cassava. The amino acid motifs and phylogenetic analyses indicated that MeGSTs were divided into 9 classes. The global expression analyses were carried out to analyze the gene expression patterns of MeGST in cassava abscission zones by comparing the MeGST genes expression patterns in both ethylene and drought induced cassava leaf abscission. Totally, 34 GSTs were detected to express in both ethylene and drought induced leaf abscission in cassava abscission zones. Comparison of GST expression profiling between ethylene and drought induced leaf abscission suggested that Tau GST genes showed with the similar expression in both treatments induced leaf abscission in cassava abscission zone. GO annotation indicated that all 17 Tau GST genes participated in the pathway of toxin catabolism (GO: 0009407). The expression levels of 17 Tau MeGST genes were analyzed in two cassava cultivars, ‘SC124’ and ‘Arg7’, the two cultivars exhibit different levels of leaf abscission when suffered from the same environmental stress. Higher expression levels of Tau MeGSTs were detected in the precocious abscission Arg7 cultivar, while lower expression levels in delayed abscission SC124 cultivar. All the results indicated that Tau MeGSTs have the function in regulation the cassava leaf abscission under environmental stresses.ConclusionAnalysis of the expression patterns of GSTs in various abscission-promoting treatments in cassava abscission zones helps us to understand the possible roles of GSTs in cassava leaf abscission.
Highlights
Glutathione S-transferases (GSTs) have been reported to regulate the plant tolerance to environmental stresses
The Tau GST class showed have the maximum number of members, including 59 members came from cassava and 58 from Populus, respectively
Many MeGSTUs were detected to express in both treatments induced leaf abscission, and Gene ontology (GO) annotation suggested that most of the GSTUs participated in the pathway of toxin catabolism (GO: 0009407), suggesting that these genes may detoxify the Reactive oxygen species (ROS) that produced during both ethylene and drought treatments induced leaf abscission in cassava
Summary
Glutathione S-transferases (GSTs) have been reported to regulate the plant tolerance to environmental stresses. The biological function of GSTs has been well characterized in Arabidopsis thaliana in response to exogenous environmental stresses. Their regulation function under exogenous environmental stresses regulating leaf abscission in cassava (Manihot esculenta Crantz) remained unknown. Glutathione S-transferases (GSTs; EC 2.5.1.18), as detoxification enzymes, are widely presented in plants, bacteria, fungi and animals [1]. In Arabidopsis, GSTs can be divided into eight subfamilies based on amino acid sequence similarity, including Phi, Tau, Theta, Zeta, Lambda, DHAR, TCHQD and MAPEG [1, 2]. Phi and Tau are the two largest plant-specific GSTs; these GSTs can regulate stress responses [1, 2]. Numerous GST gene family members have been identified in various species by genome-wide analysis, i.e., 81 GST genes in Populus [5], 55 GST genes in Arabidopsis [6], 79 in rice [7, 8], 84 in barley [9], 23 in sweet orange [10], 27 in Japanese larch [1, 10], and 59 and 49 in the G. raimondii and G. arboreum genome [1]
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