Transcriptomic and Proteomic Landscape of Sugarcane Response to Biotic and Abiotic Stressors.

Sugarcane, a C4 plant, provides most of the world's sugar, and a substantial amount of renewable bioenergy, due to its unique sugar-accumulating and feedstock properties. Brazil, India, China, and Thailand are the four largest sugarcane producers worldwide, and the crop has the potential to be grown in arid and semi-arid regions if its stress tolerance can be improved. Modern sugarcane cultivars which exhibit a greater extent of polyploidy and agronomically important traits, such as high sugar concentration, biomass production, and stress tolerance, are regulated by complex mechanisms. Molecular techniques have revolutionized our understanding of the interactions between genes, proteins, and metabolites, and have aided in the identification of the key regulators of diverse traits. This review discusses various molecular techniques for dissecting the mechanisms underlying the sugarcane response to biotic and abiotic stresses. The comprehensive characterization of sugarcane's response to various stresses will provide targets and resources for sugarcane crop improvement.

[Identification of GeERF transcription factors in Gelsmium elegans and their expression under low temperature stress].

With prominent medicinal value, Gelsemium elegans has been overexploited, resulting in the reduction of the wild resource. As a result, artificial cultivation turns out to be a solution. However, this medicinal species is intolerant to low temperature, and thus genes responding to the low temperature are important for the cultivation of this species. Based on the transcriptome database of G. elegans at 4 ℃, 29 differentially expressed GeERF genes were identified. Bioinformatics analysis of 21 GeERF gene sequences with intact open reading frames showed that 12 and 9 of the GeERF proteins respectively clustered in DREB subgroup and ERF subgroup. GeDREB1 A-1-GeERF6 B-1, with molecular weight of 23.78-50.96 kDa and length of 212-459 aa, were all predicted to be hydrophilic and in nucleus. Furthermore, the full-length cDNA sequence of GeERF2B-1 was cloned from the leaves of G. elegans. Subcellular localization suggested that GeERF2B-1 was located in the nucleus. According to the quantitative reverse-transcription PCR(qRT-PCR), GeERF2B-1 showed constitutive expression in roots, stems, and leaves of G. elegans, and the expression was the highest in roots. In terms of the response to 4 ℃ treatment, the expression of GeERF2B-1 was significantly higher than that in the control and peaked at 12 h, suggesting a positive response to low temperature. This study lays a scientific basis for the functional study of GeERF transcription factors and provides gene resources for the improvement of stress resistance of G. elegans.

[Effect of subsoiling depths on soil physical characters and sugarcane yield]. / 耕作深度对蔗地土壤物理性状及甘蔗产量的影响.

We investigated the physical properties of the plough soil and the components of sugarcane yield in the depth of mechanized subsoiling of sugarcane field, along with the clarification on the specific soil location and obstacle factors of subsoiling, with the aim to provide scientific basis for the construction of a good sugarcane cultivation layer and the development of soil improvement strategies. Three depths of subsoiling operation (35, 40 and 45 cm) were set up, with nosubsoiling as control. Soil physical properties, including compactness, bulk density, water content, porosity, three-phase volume ratio, and yield components and cane yield of sugarcane in the fields were investigated. The results showed that subsoiling depth was significantly correlated with the soil structure characteristics and the improvement of sugarcane yield in sugarcane field. Subsoiling broke down the plow bottom, significantly reduced soil compaction, bulk density, and the corresponding penetration resistance and shear strength during mechanical operation, especially for the above factors in 20-30 cm soil layer, with positive consequences for sugarcane yield. Moreover, subsoiling significantly increased the liquid volume rate of the soil layer within 30 cm and soil moisture storage capacity, and thus significantly improved the water index of the 10-30 cm soil layer. The 10-30 cm soil layer was the location for the most significant effect of subsoiling on the improvement of solid volume rate in the plough soil. The effective stem number, plant height, cane yield and sucrose content of sugarcane were significantly promoted by subsoiling. In view of the common equipment level in the sugarcane planting area, we suggested that the operating depth standard of mechanized subsoiling should not be less than 40 cm.

Molecular cloning and characterization of two pathogenesis-related ß-1,3-glucanase genes ScGluA1 and ScGluD1 from sugarcane infected by Sporisorium scitamineum.

KEY MESSAGE: Two ß-1,3-glucanase genes from sugarcane were cloned and characterized. They were all located in apoplast and involves in different expression patterns in biotic and abiotic stress. Smut caused by Sporisorium scitamineum is a serious disease in the sugarcane industry. ß-1,3-Glucanase, a typical pathogenesis-related protein, has been shown to express during plant-pathogen interaction and involves in sugarcane defense response. In this study, ß-1,3-glucanase enzyme activity in the resistant variety increased faster and lasted longer than that of the susceptible one when inoculated with S. scitamineum, along with a positive correlation between the activity of the ß-1,3-glucanase and smut resistance. Furthermore, two ß-1,3-glucanase genes from S. scitamineum infected sugarcane, ScGluA1 (GenBank Accession No. KC848050) and ScGluD1 (GenBank Accession No. KC848051) were cloned and characterized. Phylogenetic analysis suggested that ScGluA1 and ScGluD1 clustered within subfamily A and subfamily D, respectively. Subcellular localization analysis demonstrated that both gene products were targeted to apoplast. Escherichia coli Rosetta (DE3) cells expressing ScGluA1 and ScGluD1 showed varying degrees of tolerance to NaCl, CdCl2, PEG, CuCl2 and ZnSO4. Q-PCR analysis showed up-regulation of ScGluA1 and slight down-regulation of ScGluD1 in response to S. scitamineum infection. It suggested that ScGluA1 may be involved in the defense reaction of the sugarcane to the smut, while it is likely that ScGluD1 was inhibited. The gene expression patterns of ScGluA1 and ScGluD1, in response to abiotic stresses, were similar to sugarcane response against smut infection. Together, ß-1,3-glucanase may function in sugarcane defense mechanism for S. scitamineum. The positive responses of ScGluA1 and the negative responses of ScGluD1 to biotic and abiotic stresses indicate they play different roles in interaction between sugarcane and biotic or abiotic stresses.

[Trait stability and test site representativeness of sugarcane varieties based on GGE-biplot analysis].

Arithmetic mean method is commonly used to evaluate the yield stability and adaptability of sugarcane varieties, and variance analysis is applied to estimate the errors in regional trials. However, it is difficult to accurately evaluate the differences of the varieties due to the discrepancies across test sites and years. In this paper, GGE-biplot method was adopted to analyze the data from the regional trials with seven sugarcane varieties at five sites from 2008 to 2009, aimed to objectively evaluate the yield stability and adaptability of sugarcane varieties in China. Among the test sugarcane varieties, Funong No. 30 had higher cane yield and better yield stability, Yuegan No. 18 had higher sugar content and better trait stability, Funong No. 28 and Yunzhe 99-91 had high sucrose content and trait stability, while Yuegan No. 16 had the highest cane yield and sugar content but ordinary stability. In the test sites, Zhangzhou City in Fujian Province and Suixi City in Guangdong Province had the best representativeness and discrimination. This study showed that GGE-biplot analysis provided a simple and effective method to analyze the high yield and stability of sugarcane varieties in regional trials, and supplied the basis for the approval and extension of new sugarcane varieties.

Differential gene expression in sugarcane in response to challenge by fungal pathogen Ustilago scitaminea revealed by cDNA-AFLP.

Differential gene expression in sugarcane during sugarcane-Ustilago scitaminea interaction was conducted in a smut-resistant genotype. Using cDNA-AFLP along with silver staining, a total of 136 transcript-derived fragments (TDFs) were found to be differentially expressed in response to challenge by U. scitaminea. Forty TDFs, 34 newly induced plus six with obvious upregulated expression after infection, were sequenced and validated by RT-PCR analysis. These results demonstrated that the expression of 37 out of these TDFs in RT-PCR analysis was consistent with that in cDNA-AFLP analysis. Based on BlastX in NCBI, 28 TDFs were assumed to function in sugarcane under U. scitaminea stress. Analysis of expression profile of three TDFs revealed that they responded differently after infection with U. scitaminea, and the transcription was significantly enhanced. The response of two TDFs, SUC06 and SUC09, occurred before that of SUC10. This study enriches our knowledge of the molecular basis for sugarcane response to U. scitaminea infection.