Identification and Expression Profiling of TGA Transcription Factor Genes in Sugarcane Reveals the Roles in Response to Sporisorium scitamineum Infection

Abstract

TGA transcription factor (TF) family genes play a major role in the regulation of plant growth and development as well as in the defense against pathogen attack. Little is known about the TGA family genes and their functions in sugarcane. Here, a total of 16 TGA members were identified in the sugarcane genome by bioinformatic approaches. All members exhibited similar conserved motifs and contained a bZIP domain and a DOG1 domain, except for ShTGA15/16. Phylogenetic analysis demonstrated that 16 ShTGA family genes could be divided into eight clades, and evolved differently from Arabidopsis TGAs. All ShTGA family genes suffered a purifying selection during evolution. A wide range of cis-regulatory elements were found in the promoter of ShTGA genes including hormone regulatory elements, adversity response elements, light responsive elements, and growth and development regulatory elements. Most ShTGA expressions were increased in bud growth and developmental processes except for ShTGA10/11. It is worth noting that the expression of ShTGA13 was decreased after sugarcane was infected with Sporisorium scitamineum, and it was highly expressed in the resistant variety compared to the susceptible variety. Adding IAA, GA3 and SA restored the expression of ShTGA13, suggesting an association with plant hormone regulatory pathways. Our study provides a framework for further functional studies of important ShTGA genes in development and stress response, and uncovered a previously unrecognized role of ShTGA13 in regulating resistance against S. scitamineum.

A Comprehensive Analysis of Transcriptomics and Metabolomics Revealed Key Pathways Involved in Saccharum spontaneum Defense against Sporisorium scitamineum

“…The hormone involved in the S. spontaneum – S. scitamineum interactions had not been completely consistent in previous studies. It was found that auxin, ABA, ET, GA, and BR were induced by S. scitamineum attack, while no changes were observed in the SA and JA signals. , But it was also reported that CK, JA, and SA signal genes were responsive to S. scitamineum stress in sugarcane. ,, In this study, auxin, ABA, ET, GA, BR, CK, JA, and SA related signal genes were all identified in relation to S. scitamineum infection in S. spontaneum. Interestingly, there was a significant difference in hormone responses between the resistant and susceptible lines.…”

“…9,11 But it was also reported that CK, JA, and SA signal genes were responsive to S. scitamineum stress in sugarcane. 8,12,27 In this study, auxin, ABA, ET, GA, BR, CK, JA, and SA related signal genes were all identified in relation to S. scitamineum infection in S. spontaneum. Interestingly, there was a significant difference in hormone responses between the resistant and susceptible lines.…”

“…42 The hub regulatory module could serve as an integration site for many hormone signals and is critical for elucidating how hormones alter cellular function and plant behavior. 43 Some TFs, such as ScWRKY3, 44 ShTGA13, 27 and ShMYC4, 19 have been identified to be involved in response to smut pathogens. Here, two hub transcription factors TGA2.2 and ARF14, identified from the disease-related module in the coexpression networks, are expected to play the positive and negative roles, respectively, in the plant's defense against the pathogen.…”

“…IAA (indole-3-acetic acid) obtained from Shyuanye, China (S18031), was dissolved in ethanol and then diluted with water to achieve a concentration of 10 mM. At least 60 setts per treatment were submerged in a solution containing 1 mM IAA for 24 h prior to S. scitamineum inoculation . Following the inoculation, the buds were placed in plastic bags to maintain 80% humidity at a temperature of 26 °C for 24 h. Then, the materials were planted in plastic buckets and kept in a greenhouse.…”

“…At least 60 setts per treatment were submerged in a solution containing 1 mM IAA for 24 h prior to S. scitamineum inoculation. 27 Following the inoculation, the buds were placed in plastic bags to maintain 80% humidity at a temperature of 26 °C for 24 h. Then, the materials were planted in plastic buckets and kept in a greenhouse. Daytime temperatures in the greenhouse ranged from 25 to 35 °C, while nighttime temperatures ranged from 13 to 20 °C.…”