The phosphate transporter (PHT) family of proteins plays an imperative role in regulating phosphorus (P) acquisition as well as in translocation from the soil into cells and organs. Phosphorus is an essential macronutrient required for plant life that is not readily available to crops, and resources are diminishing rapidly because of the huge needs of global agriculture. In this study, 23 ShPHT genes were identified in the sugarcane (Saccharum spp.) genome through a comprehensive genome-wide in silico analysis. Phylogeny, gene structure, and conserved motif analysis of PHT genes in sugarcane (ShPHTs) indicated five subfamilies (PHT1-4 and PHO1 subfamily). Gene ontology (GO) analysis revealed that the ShPHT genes were largely involved in phosphate ion transport, phosphate starvation, stimulus response, stress response, and symporter activity. Gene expression analysis under salinity stress confirmed strong induction of PHT genes in wild genotype sugarcane (IND99-907). PHT1-1, PHT1-2, and PHT1-3 members were notably up-regulated in roots under salt stress. The upstream region of PHT genes contained PHR1-binding sites (P1BS), MYB-type, and WRKY- type binding elements. Overall, the present study paves the way for a deeper understanding of the evolution of sugarcane PHT genes and their role in salinity and Pi stress tolerance in sugarcane.

Plant nuclear factor (NF-Y) is a transcriptional activating factor composed of three subfamilies: NF-YA, NF-YB, and NF-YC. These transcriptional factors are reported to function as activators, suppressors, and regulators under different developmental and stress conditions in plants. However, there is a lack of systematic research on the NF-Y gene subfamily in sugarcane. In this study, 51 NF-Y genes (ShNF-Y), composed of 9 NF-YA, 18 NF-YB, and 24 NF-YC genes, were identified in sugarcane (Saccharum spp.). Chromosomal distribution analysis of ShNF-Ys in a Saccharum hybrid located the NF-Y genes on all 10 chromosomes. Multiple sequence alignment (MSA) of ShNF-Y proteins revealed conservation of core functional domains. Sixteen orthologous gene pairs were identified between sugarcane and sorghum. Phylogenetic analysis of NF-Y subunits of sugarcane, sorghum, and Arabidopsis showed that ShNF-YA subunits were equidistant while ShNF-YB and ShNF-YC subunits clustered distinctly, forming closely related and divergent groups. Expression profiling under drought treatment showed that NF-Y gene members were involved in drought tolerance in a Saccharum hybrid and its drought-tolerant wild relative, Erianthus arundinaceus. ShNF-YA5 and ShNF-YB2 genes had significantly higher expression in the root and leaf tissues of both plant species. Similarly, ShNF-YC9 had elevated expression in the leaf and root of E. arundinaceus and in the leaf of a Saccharum hybrid. These results provide valuable genetic resources for further sugarcane crop improvement programs.

Phosphorus (P) is the second-most essential macronutrient required for the growth and development of plants. It is involved in a number of cellular processes that contribute to the plant’s growth and development. This study investigated Saccharum spp. hybrid and Sorghum bicolor promoter regions of Phosphate transporters (PHT), viz., PHT1, PHT2, PHT3, PHT4, and PHO1, through in silico analysis. The transcription start sites (TSS), conserved motifs, and CpG islands were studied using various computational techniques. The distribution of TSSs indicated the highest promoter prediction scores (1.0). MSh2 and MSb4 were recognized as the common promoter motifs for PHT promoters, found in with 85 to 100% percentage of distribution. The CpG analysis revealed that the promoter regions of most PHT genes had low CpG density, indicating a possible tissue-specific expression. The PHT promoters were investigated for the presence of biotic- and abiotic-stress-associated transcription factor binding sites (TFbs) that revealed the presence of binding motifs for major transcription factors (TFs), namely, AP2/ERF, bHLH, bZIP, MYB, NAC, and WRKY. Therefore, the in-silico analysis of the promoter regions helps us to understand the regulation mechanism of phosphate transporter promoters and gene expression under stress management. The 5′ regulatory region of the EaPHT gene was isolated from Erianthus, a wild relative of the genus Saccharum. The promoter construct was prepared and transformed in tobacco wherein the promoter drove the expression of GUS. Analysis of GUS expression in transgenic tobacco revealed enhanced expression of GUS under salt-stress conditions. This is the first report of the isolation and characterization of a phosphate transporter gene promoter from Erianthus and is expected to be useful for the development of salt-stress transgenic crop plants.

Phosphorus deficiency highly interferes with plant growth and development. Plants respond to persistent P deficiency by coordinating the expression of genes involved in the alleviation of stress. Promoters of phosphate transporter genes are a great choice for the development of genetically modified plants with enhanced phosphate uptake abilities, which improve crop yields in phosphate-deficient soils. In our previous study, the sugarcane phosphate transporter PHT1;2 gene showed a significantly high expression under salinity stress. In this study, the Erianthus arundinaceus EaPHT1;2 gene was isolated and characterized using various in silico tools. The deduced 542 amino acid residues have 10 transmembrane domains, with a molecular weight and isoelectric point of 58.9 kDa and 9.80, respectively. They displayed 71–96% similarity with Arabidopsis thaliana, Zea mays, and the Saccharum hybrid. To elucidate the function of the 5′ regulatory region, the 1.1 kb promoter was isolated and validated in tobacco transgenics under Pi stress. The EaPHT1;2 promoter activity was detected using a β-glucuronidase (GUS) assay. The EaPHT1;2 promoter showed 3- to 4.2-fold higher expression than the most widely used CaMV35S promoter. The 5′ deletion analysis with and without 5′ UTRs revealed a small-sized 374 bp fragment with the highest promoter activity among 5′ truncated fragments, which was 2.7 and 4.2 times higher than the well-used CaMV35S promoter under normal and Pi deprivation conditions, respectively. The strong and short promoter of EaPHT1;2 with 374 bp showed significant expression in low-Pi-stress conditions and it could be a valuable source for the development of stress-tolerant transgenic crops.

Phosphorus deficiency highly interferes with plant growth and development. Plants respond to the persistent P deficiency by coordinating the expression of genes involved in the alleviation of the stress. Promoters of phosphate transporter genes are of great choice for the development of genetically modified plants with enhanced phosphate uptake abilities, which improve crop yields in phosphate-deficient soils. In our previous study, the sugarcane phosphate transporter PHT1;2 gene, showed a significantly high expression under salinity stress. In this study, the Erianthus arundinaceus EaPHT1;2 gene was isolated and characterized using various in-silico tools. The deduced 542 amino acid residues have 10 transmembrane domains, with a molecular weight and isoelectric point of 58.9 kDa and 9.80, respectively. They displayed 71–96% similarity with Arabidopsis thaliana, Zea mays, and Saccharum hybrid. To elucidate the function of the 5’ regulatory region, the 1.1kb promoter was isolated and validated in tobacco transgenics under Pi stress. The EaPHT1;2 promoter activity was detected using the β-glucuronidase (GUS) assay. While the EaPHT1;2 promoter showed 3 to 4.2-fold higher expression than the most widely used CaMV35S promoter. The 5’ deletion analysis with and without 5’UTR regions, revealed that a small size 374 bp fragment with the highest promoter activity among 5′ truncated fragments, which was 2.7 and 4.2 times higher than the well-used CaMV35S promoter under normal and Pi-deprivation conditions, respectively. The strong and short promoter of EaPHT1;2 with 374 bp showed significant expression in low Pi-stress conditions and it could be a valuable source for the development of stress-tolerant transgenic crops