Comparative profiling of drought induced root metabolic responses in sugarcane wild relative Erianthus arundinaceus (IND 04-1335) and a commercial variety Co 99004

Aim: To study the metabolic changes in roots of a drought tolerant wild relative of sugarcane Erianthus arundinaceus clone (IND 04-1335) and a commercial sugarcane cultivar Co 99004. Methodology: Setts of Erianthus arundinaceus (IND 04-1335) and a commercial variety Co 99004 were planted in medium size pots in replication. After 45 days of planting, drought stress was imposed by withholding irrigation. The corresponding control pots were maintained under continuous irrigation. On 26th day of drought, stress morphological and physiological traits such as leaf drying, canopy temperature, leaf relative water content and chlorophyll fluorescence were recorded. Root samples were subjected to metabolomic analysis using GC-MS. Results: After 26 days of drought exposure, IND 04-1335 were found to be tolerant without any drought induced morphological symptoms. The comparative metabolite profiling identified a total of 143 metabolites in the control and drought exposed roots. Hierarchical cluster analysis showed that roots of IND04-1335 control and Co 99004 stress had the most similar metabolite profiles, while the profile of IND04-1335 stressed root was distinctive.The metabolomic profile of IND04-1335 under drought stress showed an increased accumulation of sugars (melezitose, trehalose), sugar alcohols (mannitol), amino acid (proline) and carotenoids (rhodopin, carotene) as compared to Co 99004. Interpretation: Differentially accumulated metabolites in IND04-1335 under drought stress may play an important role as osmoregulants, antioxidants and chelating agents thereby imparting better tolerance mechanism to this genotype.

Chromosome behavior during meiosis in pollen mother cells from Saccharum officinarum × Erianthus arundinaceus F1 hybrids

Background In recent years, sugarcane has attracted increasing attention as an energy crop. Wild resources are widely used to improve the narrow genetic base of sugarcane. However, the infertility of F1 hybrids between Saccharum officinarum (S. officinarum) and Erianthus arundinaceus (E. arundinaceus) has hindered sugarcane breeding efforts. To discover the cause of this infertility, we studied the hybridization process from a cytological perspective. Results We examined the meiotic process of pollen mother cells (PMCs) in three F1 hybrids between S. officinarum and E. arundinaceus. Cytological analysis showed that the male parents, Hainan 92–77 and Hainan 92–105, had normal meiosis. However, the meiosis process in F1 hybrids showed various abnormal phenomena, including lagging chromosomes, micronuclei, uneven segregation, chromosome bridges, and inability to form cell plates. Genomic in situ hybridization (GISH) showed unequal chromatin distribution during cell division. Interestingly, 96.70% of lagging chromosomes were from E. arundinaceus. Furthermore, fluorescence in situ hybridization (FISH) was performed using 45S rDNA and 5S rDNA as probes. Either 45S rDNA or 5S rDNA sites were lost during abnormal meiosis, and results of unequal chromosomal separation were also clearly observed in tetrads. Conclusions Using cytogenetic analysis, a large number of meiotic abnormalities were observed in F1. GISH further confirmed that 96.70% of the lagging chromosomes were from E. arundinaceus. Chromosome loss was found by further investigation of repeat sequences. Our findings provide insight into sugarcane chromosome inheritance to aid innovation and utilization in sugarcane germplasm resources.