The potential of sugarcane as a food and bioenergy crop is currently driving the expansion of sugarcane production areas throughout the world. This crop may be constantly subjected to unusual environments such as acid soils with aluminum in toxic form (Al 3+), leading to problems in cultivation when the soil is not properly prepared. The aim of this research was to select most tolerant sugarcane genotypes to aluminum toxicity by determining root growth and proline content in the leaves. The experiment employed a factorial that was entirely randomized, with four sugarcane genotypes (CTC-2, CTC-14, RB855453, and RB966928) combined with aluminum concentrations (45, 88, 221, 444, 600, 897, 1000 µmol L-1), with three replications. Our results suggest that CTC-2 showed higher tolerance to aluminum, with more biomass accumulation in roots when compared to the other genotypes (descending order of tolerance: CTC-2 > CTC-14 > RB855453 > RB966928). Proline level was clearly different for tested genotypes. CTC-2 showed an increase of 58% in the proline level, while genotype RB855453 showed a 24% increase, but only when the aluminum concentration was 897µmolL-1 .

The agricultural yield of sugarcane (Saccharum spp.) is influenced by various abiotic stresses, including aluminum toxicity (Al 3+). MicroRNAs (miRNAs) play a role in plant tolerance to such stresses by modulating the expression of several important target genes involved in plant growth. This study investigated the possible tolerance mechanisms of two sugarcane genotypes (CTC-2 and RB855453) under Al 3+ stress through miRNA expression profiles and in silico analysis of target genes. The expression data obtained using RT-qPCR and coexpression network analysis identified two possible regulatory mechanisms in the tolerant genotype (CTC-2) under Al 3+ stress. miR395 was involved in Al 3+ detoxification, whereas miR160, miR6225-5p, and miR167 participated in the process of lateral root formation, conferring tolerance to the genotype. These findings might be useful for biotechnological strategies that aim for miRNA silencing or gene overexpression and provide subsidies for future genetic improvement programs aimed at the development of abiotic stress-tolerant sugarcane genotypes.

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