Background: Plant genomes contain a large number of HAK/KUP/KT transporters, which play important roles in potassium uptake and translocation, osmotic potential regulation, salt tolerance, root morphogenesis and plant development. Potassium deficiency in the soil of a sugarcane planting area is serious. However, the HAK/KUP/KT gene family remains to be characterized in sugarcane (Saccharum). Results: In this study, 30 HAK/KUP/KT genes were identified in Saccharum spontaneum. Phylogenetics, duplication events, gene structures and expression patterns were analyzed. Phylogenetic analysis of the HAK/KUP/KT genes from 15 representative plants showed that this gene family is divided into four groups (clades I-IV). Both ancient whole-genome duplication (WGD) and recent gene duplication contributed to the expansion of the HAK/KUP/KT gene family. Nonsynonymous to synonymous substitution ratio (Ka/Ks) analysis showed that purifying selection was the main force driving the evolution of HAK/KUP/KT genes. The divergence time of the HAK/KUP/KT gene family was estimated to range from 134.8 to 233.7 Mya based on Ks analysis, suggesting that it is an ancient gene family in plants. Gene structure analysis showed that the HAK/KUP/KT genes were accompanied by intron gain/loss in the process of evolution. RNA-seq data analysis demonstrated that the HAK/KUP/KT genes from clades II and III were mainly constitutively expressed in various tissues, while most genes from clades I and IV had no or very low expression in the tested tissues at different developmental stages. The expression of SsHAK1 and SsHAK21 was upregulated in response to low-K⁺ stress. Yeast functional complementation analysis revealed that SsHAK1 and SsHAK21 could rescue K⁺ uptake in a yeast mutant. Conclusions: This study provided insights into the evolutionary history of HAK/KUP/KT genes. HAK7/9/18 were mainly expressed in the upper photosynthetic zone and mature zone of the stem. HAK7/9/18/25 were regulated by sunlight. SsHAK1 and SsHAK21 played important roles in mediating potassium acquisition under limited K⁺ supply. Our results provide valuable information and key candidate genes for further studies on the function of HAK/KUP/KT genes in Saccharum.

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.

Plasma membrane intrinsic proteins (PIPs), as members of the aquaporin (AQPs) family, can transport not only water but also urea, CO₂, H₂O₂, metal ions, and trace elements. They are crucial for maintaining water balance, substance transport, and responding to various stresses. This article delves into the structure, function, response mechanism, molecular mechanism, and regulatory mechanism of PIPs as a result of biological and abiotic stresses. It also summarizes current research trends surrounding PIPs and highlights potential research directions for further exploration. The aim is to assist researchers in related fields in gaining a more comprehensive understanding and precise insight into the advancements in PIP research.

Sugarcane is of important economic value for producing sugar and bioethanol. Tripidium arundinaceum (old name: Erianthus arundinaceum) is an intergeneric wild species of sugarcane that has desirable resistance traits for improving sugarcane varieties. However, the scarcity of chromosome markers has hindered the cytogenetic study of T. arundinaceum. Here we applied maize chromosome painting probes (MCPs) to identify chromosomes in sorghum and T. arundinaceum using a repeated fluorescence in situ hybridization (FISH) system. Sequential FISH revealed that these MCPs can be used as reliable chromosome markers for T. arundinaceum, even though T. arundinaceum has diverged from maize over 18 MYs (million years). Using these MCPs, we identified T. arundinaceum chromosomes based on their sequence similarity compared to sorghum and labeled them 1 through 10. Then, the karyotype of T. arundinaceum was established by multiple oligo-FISH. Furthermore, FISH results revealed that 5S rDNA and 35S rDNA are localized on chromosomes 5 and 6, respectively, in T. arundinaceum. Altogether, these results represent an essential step for further cytogenetic research of T. arundinaceum in sugarcane breeding.

Background: The identification and functional analysis of genes that improve tolerance to low potassium stress in S. spontaneum is crucial for breeding sugarcane cultivars with efficient potassium utilization. Calcineurin B-like (CBL) protein is a calcium sensor that interacts with specific CBL-interacting protein kinases (CIPKs) upon plants’ exposure to various abiotic stresses. Results: In this study, nine CBL genes were identified from S. spontaneum. Phylogenetic analysis of 113 CBLs from 13 representative plants showed gene expansion and strong purifying selection in the CBL family. Analysis of CBL expression patterns revealed that SsCBL01 was the most commonly expressed gene in various tissues at different developmental stages. Expression analysis of SsCBLs under low K⁺ stress indicated that potassium deficiency moderately altered the transcription of SsCBLs. Subcellular localization showed that SsCBL01 is a plasma membrane protein and heterologous expression in yeast suggested that, while SsCBL01 alone could not absorb K⁺, it positively regulated K⁺ absorption mediated by the potassium transporter SsHAK1. Conclusions: This study provided insights into the evolution of the CBL gene family and preliminarily demonstrated that the plasma membrane protein SsCBL01 was involved in the response to low K⁺ stress in S. spontaneum.

Sugarcane is an important sugar and energy crop in the world. Germplasm innovation is a significant way to breed breakthrough sugarcane varieties. Modern sugarcane varieties all contain the blood relationship of Saccharum officinarum and Saccharum spontaneum. High sugar results from S. officinarum and the resistance genes from S. spontaneum. In order to improve the sugarcane quality, breeders use S. officinarum and S. spontaneum to cross and obtain hybrid offspring with high sugar and high resistance. Therefore, the authenticity of S. officinarum and S. spontaneum progeny materials directly affects the efficiency of sugarcane breeding. In this study, the tetra-primer amplification hindered mutation system (ARMS PCR) was used to identify ten suspected S. officinarum and eleven suspected S. spontaneum germplasm materials, then further validated by chromosome counting and genome in situ hybridization (GISH). Among the ten suspected S. officinarum materials to be identified, three were real S. officinarum materials, they were 14NG124, 51NG103, and Guan A. Nine of the eleven suspected S. spontaneum to be identified were fake S. spontaneum materials, these were Yunge 2007-12-165, Guangxi 87-20, Yunnan 82-16, Yunge 2007-11, YNLC 16, Laos No. 2, Yunnan 82-29, 2015-83, and 2013-20. The ARMS PCR results were the same as the GISH results. The three real S. officinarum materials had 80 chromosomes. Using ARMS PCR and GISH, three S. officinarum and nine S. spontaneum materials were proven to be authentic. Through chromosome number statistics, it was found that the three real S. officinarum had 80 chromosomes. Authentic materials were identified and selected to enrich the genetic background of sugarcane through hybridization and reduce the influence on the breeding process of the misuse of fake S. officinarum and S. spontaneum.