- Results: A hypoploid clone 12 – 23 (2n = 54) and hyperploid clone 15 – 28 (2n = 92) of S. - Compared with clone 15 – 28, clone 12 – 23 plants had lower plant height, leaf length, internode length, stem diameter, and leaf width. - Compared with clone 15 – 28, clone 12 – 23 showed significantly lower electrical conductivity, significantly higher water content, soluble protein content, and superoxide dismutase activity, and significantly higher soluble sugar content and peroxidase activity. - Under cold stress, the number of upregulated genes and downregulated genes of clone 12 – 23 was higher than clone 15 – 28, and many stress response genes and pathways were affected and enriched to varying degrees, particularly sugar and starch metabolic pathways and plant hormone signalling pathways. - brassinosteroid-signalling kinase and the content of trehalose and brassinosteroids of clone 12 – 23 increased.. - Conclusions: Compared with hyperploid clone 15 – 28, hypoploid clone 12 – 23 maintained a more robust osmotic adjustment system through sugar accumulation and hormonal regulation, which resulted in stronger cold tolerance.. - Full list of author information is available at the end of the article. - Sugarcane (Saccharum spp.) is an important sugar and energy crop, contributing 80% of the world’s sugar pro- duction and 40% of that of ethanol [1]. - spon- taneum belongs to the perennial herb of the family Gra- mineae and genus Saccharum, has both asexual and sexual reproductive abilities [3, 4], can grow in a variety of environments, such as drought, cold and high salt conditions [5], has varied phenotypes and strong adapt- ability, can provide rich genetic diversity for sugarcane breeding, and is the main source of desirable genes re- sistant to pests, diseases, cold, and drought [6, 7].. - spontaneum to low temperature varied, with the hypoploid clone 12–23 (2n = 54) being highly cold-resistant, whereas the hyper- ploid clone 15–28 (2n = 92) was typically cold-sensitive (Additional file 1: Supplement). - Morphological and microscopic comparison of two clones The morphological characteristics of clones 12–23 and 15–28 showed significant differences under the growth conditions of the greenhouse. - Compared with clone 15–. - 28 plants, clone 12–23 plants were relatively shorter (Fig. - The morphological characteristics of the two clones were fur- ther measured at the maturity stage. - The five morpho- logical characteristics, including plant height, leaf length, internode length, stem diameter, and leaf width, of clone 12–23 were smaller than those of clone 15–28 (Fig. - In addition, leaf anatomical analysis showed that the sto- mata of the 12–23 clone were depressed, and the bristles and papillae were prominent (Fig. - whereas the stomata of clone 15–28 were not depressed, and their bristles and papillae were fewer in number and not prominent (Fig. - The comparison of transverse sections of the leaves of the two clones showed that the leaf thickness of clone 12–23 was considerably larger than that of clone 15–28 (Fig. - the bulliform cell groups of clone 12–23 was higher than that of the clone 15–28 (Fig. - and the adaxial epidermal thickness of clone 12–23 is greater than that of clone 15–28 (Fig. - After cold stress, the physiological indexes, including plasma permeability, leaf water content, soluble protein content, soluble sugar content, superoxide dismutase ac- tivity, and peroxidase activity were significantly different between clones 12–3 and 15–28 (Fig. - The electrical conductivity of clone 12–23 was significantly lower than that of clone 15–28 (Fig. - The relative water content, soluble sugar content, soluble protein content, super- oxide dismutase activity, and peroxidase activity of clone 12–23 were higher than those of clone 15–28, of which. - Differences in Transcriptomic data of clones 12 – 23 and 15 – 28 after cold stress. - transcriptome data analysis of the two ploidy S. - sponta- neum was performed to further understand the cold tol- erance mechanism of the hypoploid clone 12–23 at the molecular level. - Transcriptome data of the clone 12–23 low temperature stress treatment group (LL), clone 15–. - 28 low temperature stress treatment group (HL), clone 12–23 control group (LC) and clone 15–28 control group (HC) were compared. - 1 Morphological features of the Saccharum spontaneum clones 12 – 23 and 15 – 28. - clone 12 – 23 and (e) (e. - clone 15 – 28. - clone 12 – 23 and (g) (g. - Transcriptome data of clones 12–23 included the low temperature stress group (LL) and control group (LC), and transcriptome data of clones 15–28 in- cluded the low temperature stress group (HL) and control group (HC). - The transcriptomic data of clones 12–23 and 15–28 were analysed in four pair- wise comparisons: LL vs. - HC was 34,087, of which 23,377 genes were upregulated and 10,710 genes were downregulated, in- dicating that the cold-tolerant clone 12–23 had more up- and downregulated genes than the cold-sensitive clone 15–28. - More- over, among the pathways obtained through KEGG enrichment analysis of the DEGs identified from LL vs. - Fur- ther comparison of the P-value of the pathways obtained through KEGG enrichment analysis of DEGs identified from the pairwise comparisons of LL vs. - 2 Differences in various physiological characteristics between clones 12 – 23 and 15 – 28 after low temperature stress. - b Relative water content of the leaves. - The DEGs in the sugar and starch metabolic pathways were further ana- lysed by means of ORFfinger alignment and functional annotation (KO and GO), and then the FPKM values of the screened genes were compared. - We found that the FPKM values of the 6-phosphate glucose trehalose syn- thase (TPS) and trehalose phosphate phosphatase (TPP) genes controlling trehalose synthesis were the highest (Fig. - Furthermore, we determined the change in trehalose content in clones 12–23 and 15–28 under cold stress and control condi- tions. - After cold stress, trehalose content increased in both clones, although the trehalose content of clone 12–23 was sig- nificantly higher than that of clone 15–28 (Fig. - 6a), and for both clones 12–23 and 15–28, the FPKM values increased after cold stress (Fig. - expression of the BSK gene was verified by RT-qPCR using 18S rRNA and GAPDH genes as internal refer- ences. - We further determined the change in brassi- nosteroid content of clones 12–23 and 15–28 subjected to cold stress. - After cold treatment, the brassinosteroid content increased in both clones, and its content was significantly higher in clone 12–23 than in clone 15–28 (Fig. - Stomata are also in the joint point of primary productivity of terrestrial ecosystems with water transpiration and can be used as an indicator of the strength of plant resistance [30]. - 3 Differentially expressed genes (DEGs) in clones 12 – 23 and 15 – 28 under control and cold conditions. - a Number of upregulated and downregulated genes in clones 12 – 23 and 15 – 28 exposed to cold vs. - HC) and in clone 12 – 23 vs. - 15 – 28 under cold conditionss (LL vs HL) as revealed by RNA-seq. - b Venn diagram analysis of the common and specific upregulated and downregulated genes using different pairwise comparisons. - a The top 20 enriched pathways of the DEGs between clones 12 – 23 and clone 15 – 28 under cold conditions (LL vs. - b Heat map of input number and background number of the KEGG enriched pathways of the DEGs of clones under cold conditions (LL vs. - c Heat map of the KEGG enriched pathways of the DEGs of the pairwise comparisons LL vs. - The results of this study indicated that the stomata of clone 12–23 were depressed, and the bristles and papillae were prominent, whereas clone 15–. - In addition, clone 12–23 showed taller bulliform cells and thicker adaxial epidermis than that of clone 15–28. - Thus, based on the anatomical structure of the leaves, clone 12–23 pos- sesses cold-tolerant characteristics.. - The relative permeability of the cell plasma mem- brane is positively correlated with the degree of cell membrane damage [23]. - therefore, the value of the. - The results of our study indicated that the physiological in- dexes of the two clones were significantly different under cold stress. - The electrical conductivity of clone 12–23 was lower than that of clone 15–28. - a Heat map of the FPKM values generated from the RNA-seq analysis of clones 12 – 23 and 15 – 28 under control (column 2 on the right) and cold stress (column 2 on the left) conditions. - The IDs of the reference homologous genes and their enzymes collected from the genomic databases are shown on the left. - c Trehalose content of clones 12 – 23 and 15 – 28 under control and cold stress conditions. - content, soluble sugar content, soluble protein content, superoxide dismutase activity, and peroxidase activity of clone 12–23 were greater than those of clone 15–28.. - These results indicate that clone 12–23 is more tolerant to cold.. - Transcriptional regulation is an important regulatory mechanism of the transcriptome in response to abiotic stress in plants [36]. - In this study, the transcriptomic analysis that clone 12–23 revealed changes in gene expression under cold stress, which might involve more metabolic pathways and regulatory mechanisms to adapt to the cold environment.. - In this study, we found that among all the pathways revealed through KEGG enrichment analysis of the DEGs from the LL vs. - Comparison of P-values of the KEGG enriched pathways of DEGs from clones 12–23 and 15–28 under cold stress indicated that for the pairwise compari- sons of LL vs. - a Heat map of the log 2 (fold change) value generated by RNA-seq analysis of the four pairwise comparisons (LL vs. - c Brassinosteroid content in clones 12 – 23 and 15 – 28 plants under control vs. - cold stress. - Interestingly, we found that under cold stress, the trehalose content of clone 12–23 was higher than that of clone 15–28, suggesting that TPS and TPP play an im- portant role in the enhancement of cold tolerance of hy- poploid S. - The results of this study showed that PP2C related to ABA synthesis was significantly higher than that of the control group under low temperature stress, indicat- ing that ABA plays an important role in resistance to low temperature stress. - The comparison between low- ploidy clones 12–23 and high-ploidy clones 15–28 under low temperature stress indicated that brassinolactone was the major hormone variable, that is, by comparing log 2 (fold changes) and FPKM values, we found that BSKs were the most frequent signals involved in responses to cold stress. - Furthermore, the BR content in clone 12–23 was significantly higher than that in clone 15–28 under cold stress, further indicating that the BSK gene plays an important role in cold toler- ance in hypoploid S. - An in-depth study of the resistance of different ploidies of S. - spontaneum clone 12–23 (2n = 54) possesses strong cold tolerance and can. - The results of our study improve our understanding of the morphological characteristics and molecular mech- anisms of cold tolerance in hypoploid S. - Compared with the hyperploid clones 15–28, the hypo- ploid clones 12–23 exhibited different morphological and physiological characteristics, and exhibited signifi- cant tolerance to cold. - The transcriptomic data showed that low temperature stress altered the expression of many stress response genes and pathways in clone 12–. - spontaneum cold-resistant clone 12–23 (2n = 54, col- lected from Tibet, China) and the cold-sensitive clone 15–. - At the mature stage, the agronomic traits of the clones were investigated. - Finally, dewaxing, safranin O–fast green staining, and photography were conducted, and the cross- sectional anatomy of the leaves was assessed by Case- viewer 2.0 software [11]. - Finally, the sam- ple was placed on the double-sided adhesive tape of the conductive carbon film and placed on the sample table of the ion sputtering apparatus (IXRF, MSP-2S). - The gold was sprayed on the sample stage of the ion sputter- ing apparatus (HITACHI, SU8010) [11].. - After 3 days of cold stress treatment [5], the leaves of the seedlings from the con- trol and low temperature stress treatments were col- lected, and 3 replicates of sampling were used per treatment. - The + 1 leaves (top visible dewlap leaf) of the same size and phenotype were collected as the test ma- terial. - This operation was repeated until the saturated weight of the sample was stable, and the saturated fresh weight was recorded (labelled W t. - RNA of the leaf samples de- scribed above was extracted for RT-qPCR analysis.. - Ploidy identification of 12 – 23 clones and 15 – 28 clones.. - Allele-defined genome of the autopolyploid sugarcane Saccharum spontaneum L. - Quantitative chromosome map of the polyploid Saccharum spontaneum by multicolor fluorescence in situ hybridization and imaging methods. - The importance of the wild cane Saccharum spontaneum for bioenergy genetic breeding. - A BAC library of the SP80 – 3280 sugarcane variety (saccharum sp.) and its inferred microsynteny with the sorghum genome.. - Overexpression of the transcription factor AP37 in Rice improves grain yield under drought Conditions 1[W. - Transcriptome analysis of the Chinese bread wheat cultivar Yunong 201 and its ethyl
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