Sugarcan e is a major crop for sugar and biofuel production and is cultivated in tropical and subtropical areas worldwide. Sugarcane growth is constrained because of winter’s low-temperature stress, and cold resistance is an important limitation in sugarcane growth enhancement. Therefore, in this study, we identified a gene involved in the low-temperature stress response of sugarcane. Calcineurin B-like (CBL) protein is a calcium signal receptor involved in the cold stress response. Five sugarcane CBL genes were cloned, sequenced, and named SoCBL1, SoCBL3, SoCBL5, SoCBL6, and SoCBL9. The protein sequences of these genes were analyzed. The calculated molecular weight of these proteins was 24.5, 25.9, 25.2, 25.6, and 26.3 kD, respectively. Subcellular localization analysis revealed that SoCBL1, SoCBL3, SoCBL6, and SoCBL9 were situated in the cytoplasm, while SoCBL5 was present in mitochondria. Secondary structure analysis showed that these five CBL proteins had similar secondary structures. Conserved domain analysis displayed that each sugarcane CBL protein contained three conserved EF domains. According to the self-expanding values of the phylogenetic tree, the CBL gene family was divided into four groups. The CBL1 and CBL9 genes were classified into one group, illustrating that these two genes might possess a similar function. The expression analysis of the SoCBL gene under low temperatures showed that SoCBL3 and SoCBL5 were affected significantly, while SoCBL1 and SoCBL9 were less affected. These results demonstrate that the CBL genes in sugarcane have similar characteristics and present differences in genetic diversity and gene expression response to low temperatures. Therefore, these genes might be novel candidates for fighting cold stress in sugarcane.

Ratoon stunt caused by Leifsonia xyli subsp. xyli (Lxx) is widely spread across sugarcane planting regions. Here, transcriptomics and cytology were conducted to analyze the changes in gene expression levels and chloroplast ultrastructures after Lxx inoculation. A total of 90.26 Gb clean bases, 156,713 unigenes and 406 differentially expressed genes were obtained. The genes of HSP and ACS were continuously differentially expressed. The photosynthesis-related genes of PsbO, PsbQ, PsaD, PsaE, PsaG and PsaH were up-regulated. PIRH2, WRKY, NCED, AHP and GST were identified as the important specific genes that responded to Lxx inoculation. Lxx inoculation also altered the shape and damaged the membrane of chloroplasts in sugarcane leaves. Sugarcane responds to Lxx infection likely via changing the expression levels of some specific genes and interfered with photosynthesis. A possible molecular regulation network induced by Lxx was speculated. These findings broaden the understanding to the mechanisms of the interaction between sugarcane and Lxx.

Sugarcane (Saccharum officinarum L.) faces significant challenges in China, including labor-intensive cultivation, low yields, and environmental stresses. Enhancing root development and stress tolerance through phytohormones and molecular breeding is a promising approach to boosting productivity. Indole-3-butyric acid is a phytohormone known for promoting root development and stress resistance. However, its effects on sugarcane root development under low temperature remain poorly understood. This study demonstrated that IBA markedly promoted root initiation, elongation, and biomass under low temperature, and significantly increased the levels of phytohormones, including GA₃, ABA, JA, IAA, and ZT, suggesting the activation of multiple signaling pathways. Transcriptome analysis revealed numerous differentially expressed genes related to metabolic pathways such as glycolysis, the tricarboxylic acid cycle, and glutathione metabolism. Weighted gene co-expression network analysis identified core gene modules correlated with phytohormone activities, highlighting their role in the IBA-mediated stress response. Eleven core genes, including GSTU6, FAR1, and BCAT3, and nine hub genes, such as Ub-CEP52-1 and ACS1, were identified as critical components for IBA-induced root development and stress mitigation. These findings provide insights into the molecular mechanisms underlying IBA-induced root development and stress tolerance in sugarcane, offering candidate genes for breeding high-yield, stress-tolerant varieties and demonstrating IBA’s potential as a strategy to enhance productivity under challenging conditions.

Sugarcane is the most important sugar crop and one of the leading energy-producing crops in the world. Ratoon stunting disease (RSD), caused by the bacterium Leifsonia xyli subsp. xyli, poses a huge threat to ratoon crops, causing a significant yield loss in sugarcane. Breeding resistant varieties is considered the most effective and fundamental approach to control RSD in sugarcane. The exploration of resistance genes forms the foundation for breeding resistant varieties through molecular technology. The pglA gene is a pathogenicity gene in L. xyli subsp. xyli, encoding an endopolygalacturonase. In this study, the pglA gene from L. xyli subsp. xyli and related microorganisms was analyzed. Then, a non-toxic, non-autoactivating pglA bait was successfully expressed in yeast cells. Simultaneously the yeast two-hybrid library was generated using RNA from the L. xyli subsp. xyli-infected sugarcane. Screening the library with the pglA bait uncovered proteins that interacted with pglA, primarily associated with ABA pathways and the plant immune system, suggesting that sugarcane employs these pathways to respond to L. xyli subsp. xyli, triggering pathogenicity or resistance. The expression of genes encoding these proteins was also investigated in L. xyli subsp. xyli-infected sugarcane, suggesting multiple layers of regulatory mechanisms in the interaction between sugarcane and L. xyli subsp. xyli. This work promotes the understanding of plant–pathogen interaction and provides target proteins/genes for molecular breeding to improve sugarcane resistance to L. xyli subsp. xyli.