Aluminum (Al) is the third, most abundant element in the Earth's crust. When soil pH drops below 5.5, Al is released from minerals, which threatens plant growth. The roots are particularly vulnerable to Al stress because Al ions can penetrate them, causing growth reduction by inhibiting the cell cycle and decreasing root cell elongation. Al has the ability to bind to cell structures, including cell walls, cytoskeleton, or DNA, which disturb their functions. Plants have developed various response strategies, such as the exclusion of organic acids into the rhizosphere or the detoxification of Al in the vacuole. STOP1 (Sensitive To Proton Rhizotoxicity 1) is the critical regulator of the expression of tolerance-related genes and is present in both mono- and dicots plants. The activity of STOP1 can be regulated on post-transcription and post-translation levels. This review paper presents an overview of the latest literature, aiming to accurately present the problem of Al toxicity and its effect on plant functioning. Moreover, the well-studied mechanisms of plant response and future prospects, like the use of polyamines, miRNAs, or DDR (DNA Damage Response) pathway, will be presented, which are opportunities to develop new plant varieties that are tolerant to Al stress.

Watermelon (Citrullus lanatus) has been cultivated for nearly one thousand years and remains a commercially important crop. However, continuous planting often leads to the aggravation of many diseases. Watermelon Fusarium wilt (FW) is one of them, which is a fungal soil-borne disease caused by Fusarium oxysporum f. sp. niveum (Fon) that damages plant roots by invading vascular bundles. Therefore, it is imperative to comprehensively characterize the mechanism mediating disease resistance or susceptibility, as well as identify effective resistance genes, in order to breed improved disease-resistant watermelon varieties. miRNAs are endogenous non-coding RNAs that are widely involved in plant growth, development, metabolism, transport, stress response, and pathogen defense. However, there are few reports of disease-associated miRNAs, or their mechanisms of action, in Cucurbitaceae crops. In this study, the roots of both Fon-susceptible and resistant watermelon varieties were infected with GFP-labeled Fon. Three key infection time points were identified. Illumina sequencing was used to obtain Fon-resistance related miRNAs, and degradome sequencing was used to obtain miRNA target genes. A total of 23 differentially expressed miRNAs were identified at the three key infection time points, the degradation group sequencing found their only target gene. The results of this study provide a theoretical basis for studies of miRNA function and regulation during the interaction between Fon and watermelon plants and clues for the screening of watermelon resistance genes. In addition, this information can be used to breed diseaseresistant watermelon varieties.

Background: MicroRNA (miRNA) plays an important role in hepatic stellate cell (HSCs) activation and liver fibrosis. The purpose of this study is to explore the effect of hypoxia on the differential expression of mRNAs and miRNAs in rat HSCs. Methods: HSC-T6 cells were treated with cobalt chloride (CoCl2), and the activity of HSC-T6 cells was measured by the CCK-8 assay. The mRNA expression levels of hypoxia inducible factor-1 alpha (HIF-1 alpha), collagen type I, transforming growth factor-131 (TGF-131), and Smad7 were measured by RT-qPCR. The protein expression levels of HIF-1 alpha, Bax, Bcl-2, and caspase-3 were assayed by western blot. We used basal medium and 400 mu mol/L CoCl2 medium to treat HSC-T6 cells for 48 h. Cells were harvested after 48 h to extract RNA. Transcriptome sequencing was performed to investigate differentially expressed miRNAs and mRNAs (fold change >2; P<0.05). Bioinformatics analysis was performed to predict the functions of differentially expressed miRNAs and mRNAs. Further, we used RT-qPCR to detect the expression of mRNAs and miRNAs to confirm the accuracy of sequencing. Results: With the increase of CoCl2 concentration, the activity of HSC-T6 cells decreased (P<0.05). The mRNA expression levels of HIF-1 alpha, collagen I, TGF-131, and Smad7, and the protein expressions levels of HIF-1 alpha, Bax, caspase-3, and the Bcl-2/Bax ratio were increased compared with the control group (P<0.05), while the expression of Bcl-2 decreased. A total of 54 miRNAs (20 upregulated and 34 downregulated) and 1,423 mRNAs (685 upregulated and 738 downregulated) were differentially expressed in the 400 mu mol/L CoCl2 medium group compared to the control basal medium group. Further bioinformatics analysis demonstrated that the differentially expressed mRNAs and miRNAs were mainly enriched in the synthesis of extracellular matrix. In addition, we used RT-qPCR to detect the expression of mRNAs and miRNAs to confirm the accuracy of sequencing. Conclusions: Our results presented the profiles of mRNAs and miRNAs in hypoxia-induced HSC-T6 cells in rats, the signaling pathways, and co-expression networks. These findings may suggest novel insights for the early diagnosis and treatment of HSC activation and liver fibrosis.