Erianthus arundinaceus is a valuable source of agronomic traits for sugarcane improvement such as ratoonability, biomass, vigor, tolerance to drought and water logging, as well as resistance to pests and disease. To investigate the introgression of the E. arundinaceus genome into sugarcane, five intergeneric F₁ hybrids between S. officinarum and E. arundinaceus and 13 of their BC₁ progeny were studied using the genomic in situ hybridization (GISH) technique. In doing so, we assessed the chromosome composition and chromosome transmission in these plants. All F₁ hybrids were aneuploidy, containing either 28 or 29 E. arundinaceus chromosomes. The number of E. arundinaceus chromosomes in nine of the BC₁ progeny was less than or equal to 29. Unexpectedly, the number of E. arundinaceus chromosomes in the other four BC₁ progeny was above 29, which was more than in their F₁ female parents. This is the first cytogenetic evidence for an unexpected inheritance pattern of E. arundinaceus chromosomes in sugarcane. We pointed to several mechanisms that may be involved in generating more than 2n gametes in the BC₁ progeny. Furthermore, the implication of these results for sugarcane breeding programs was discussed.

Drought is the main abiotic stress that constrains sugarcane growth and production. To understand the molecular mechanisms that govern drought stress, we performed a comprehensive comparative analysis of physiological changes and transcriptome dynamics related to drought stress of highly drought-resistant (ROC22, cultivated genotype) and weakly drought-resistant (Badila, wild genotype) sugarcane, in a time-course experiment (0 h, 4 h, 8 h, 16 h and 32 h). Physiological examination reviewed that ROC22, which shows superior drought tolerance relative to Badila, has high performance photosynthesis and better anti-oxidation defenses under drought conditions. The time series dataset enabled the identification of important hubs and connections of gene expression networks. We identified 36,956 differentially expressed genes (DEGs) in response to drought stress. Of these, 15,871 DEGs were shared by the two genotypes, and 16,662 and 4423 DEGs were unique to ROC22 and Badila, respectively. Abscisic acid (ABA)-activated signaling pathway, response to water deprivation, response to salt stress and photosynthesis-related processes showed significant enrichment in the two genotypes under drought stress. At 4 h of drought stress, ROC22 had earlier stress signal transduction and specific up-regulation of the processes response to ABA, L-proline biosynthesis and MAPK signaling pathway–plant than Badila. WGCNA analysis used to compile a gene regulatory network for ROC22 and Badila leaves exposed to drought stress revealed important candidate genes, including several classical transcription factors: NAC87, JAMYB, bHLH84, NAC21/22, HOX24 and MYB102, which are related to some antioxidants and trehalose, and other genes. These results provide new insights and resources for future research and cultivation of drought-tolerant sugarcane varieties.

A genetic diversity analysis and identification of plant germplasms and varieties are important and necessary for plant breeding. Deoxyribonucleotide (DNA) fingerprints based on genomic molecular markers play an important role in accurate germplasm identification. In this study, Specific-Locus Amplified Fragment Sequencing (SLAF-seq) was conducted for a sugarcane population with 103 cultivated and wild accessions. In total, 105,325 genomic single nucleotide polymorphisms (SNPs) were called successfully to analyze population components and genetic diversity. The genetic diversity of the population was complex and clustered into two major subpopulations. A principal component analysis (PCA) showed that these accessions could not be completely classified based on geographical origin. After filtration, screening, and comparison, 192 uniformly-distributed SNP loci were selected for the 32 chromosomes of sugarcane. An SNP complex genotyping detection system was established using the SNaPshot typing method and used for the precise genotyping and identification of 180 sugarcane germplasm samples. According to the stability and polymorphism of the SNPs, 32 high-quality SNP markers were obtained and successfully used to construct the first SNP fingerprinting and quick response codes (QR codes) for sugarcane. The results provide new insights for genotyping, classifying, and identifying germplasm and resources for sugarcane breeding

Erianthus arundinaceus (E. arundinaceus) has many desirable agronomic traits for sugarcane improvement, such as high biomass, vigor, rationing ability, tolerance to drought, and water logging, as well as resistance to pests and disease. To investigate the introgression of the E. arundinaceus genome into sugarcane in the higher generations, intergeneric BC₂ and BC₃ progeny generated between Saccharum spp. and E. arundinaceus were studied using the genomic in situ hybridization (GISH) technique. The results showed that the BC₂ and BC₃ generations resulted from n + n chromosome transmission. Furthermore, chromosome translocation occurred at terminal fragments from the E. arundinaceus chromosome in some progeny of Saccharum spp. and E. arundinaceus. Notably, the translocated chromosomes could be stably transmitted to their progeny. This study illustrates the characterization of chromosome inheritance of the intergeneric BC₂ and BC₃ progeny between Saccharum spp. and E. arundinaceus. This work could provide more useful molecular cytogenetic information for the germplasm resources of E. arundinaceus, and may promote further understanding of the germplasm resources of E. arundinaceus for sugarcane breeders to accelerate its progress in sugarcane commercial breeding.

Interspecific hybridization is an effective strategy for germplasm innovation in sugarcane. Nobilization refers to the breeding theory of development and utilization of wild germplasm. Saccharum spontaneum is the main donor of resistance and adaptive genes in the nobilization breeding process. Chromosome transfer in sugarcane is complicated; thus, research of different inheritance patterns can provide guidance for optimal sugarcane breeding. Through chromosome counting and genomic in situ hybridization, we found that six clones with 80 chromosomes were typical S. officinarum and four other clones with more than 80 chromosomes were interspecific hybrids between S. officinarum and S. spontaneum. These data support the classical view that S. officinarum is characterized by 2n = 80. In addition, genomic in situ hybridization showed that five F1 clones were products of a 2n + n transmission and one F1 clone was the product of an n + n transmission in clear pedigree noble hybrids between S. officinarum and S. spontaneum. Interestingly, Yacheng 75–408 and Yacheng 75–409 were the sibling lines of the F1 progeny from the same parents but with different genetic transmissions. This is the first clear evidence of Loethers, Crystallina, Luohanzhe, Vietnam Niuzhe, and Nanjian Guozhe were typical S. officinarum by GISH. Furthermore, for the first time, we identified the chromosome transmission of six F1 hybrids between S. officinarum and S. spontaneum. These findings may provide a theoretical basis for germplasm innovation in sugarcane breeding and guidance for further sugarcane nobilization.