Background: Although many studies suggested that aluminum (Al) induced programmed cell death (PCD) in plants, the mechanism of Al-induced PCD and its effects in Al tolerance is limited. This study was to investigate the mechanism and type of Al induced PCD and the relationship between PCD and Al tolerance. Results: In this study, two genotypes of peanut 99-1507 (Al tolerant) and ZH2 (Al sensitive) were used to investigate Al-induced PCD. Peanut root growth inhibition induced by AlCl₃ was concentration and time-dependent in two peanut varieties. AlCl₃ at 100 μM could induce rapidly peanut root tip PCD involved in DNA cleavage, typical apoptotic chromatin condensation staining with DAPI, apoptosis related gene Hrs203j expression and cytochrome C (Cyt c) release from mitochondria to cytosol. Caspase3-like protease was activated by Al; it was higher in ZH2 than in 99-1507. Al increased the opening of mitochondrial permeability transition pore (MPTP), decreased inner membrane potential (ΔΨ_m) of mitochondria. Compared with the control, Al stress increased O₂ ^•- and H₂O₂ production in mitochondria. Reactive oxygen species (ROS) burst was produced at Al treatment for 4 h. Conclusions: Al-induced PCD is earlier and faster in Al-sensitive peanut cultivar than in Al-tolerant cultivar. There is a negative relationship between PCD and Al resistance. Mitochondria- dependence PCD was induced by Al and ROS was involved in this process. The mechanism can be explained by the model of acceleration of senescence under Al stress.

Pinellia ternata, as one of the traditional Chinese medicines, has a significant effect on eliminating dampness, stopping vomiting and calm the adverse-rising energy. There are few researches on the structural characteristics of the chloroplast genome of P. ternata, which is not conducive to its further development. Therefore, we studied the chloroplast genome sequence of P. ternata to provide scientific basis for the development of P. ternata and phylogenetic analysis of Araceae. We fabricate the complete chloroplast genomes of P. ternata using Illumina (HiSeq X) sequencing technology. The chloroplast genome of P. ternata has the same gene order and organization as the chloroplast genomes of other Araceae. The P. ternata complete chloroplast genomes is 163 711 bp in length, exhibits a conserved quadripartite structure with a large single-copy (LSC; 92 562 bp) region, and a small single-copy (SSC; 23 805 bp) region interspersed between inverted repeat (IRa/IRb; 25 474 bp) region. A total of 128 unique genes were annotated, including 83 protein-coding genes, 37 tRNA, and 8 rRNA. 143 SSR loci were retrieved from the genome, with mononucleotide is the most frequently distributed type, and hexanucleotides are the rarest type. In addition, 50 long repeats sequences were found in tandem repeats. We made phylogenetic trees from 18 Araceae species and 2 Caldesia species using ML method. This study provides a valuable reference for the systematic location and chloroplast genome information of Pinellia ternata in Araceae.

In this study, a potting water control experiment was conducted indoors. Using Pinellia ternata from five different producing areas (Leshan, Sichuan; Zhangjiakou, Hebei; Heze, Shandong; Yongzhou, Hunan; Shangluo, Shaanxi) as experimental materials, we set up three treatment groups with different soil water contents to investigate the effects of drought stress on the growth, physiology, contents of total alkaloids and total polysaccharides of Pinellia ternata. The results showed that stem tuber weight, leaf net photosynthetic rate, stomatal conductance, transpiration rate, Electron transport rate (ETR), Photochemical quenching coefficient (qP), Relative water content (RWC) and Peroxidase (POD) were gnificantly decreased. The contents of Soluble Protein (SP) and Proline (PRO) were significantly increased, Catalase (CAT) and Glutathione (GSH) increased first and then decreased.Under the treatment of regular watering for 20 days followed by a 10-day period without watering, the contents of total alkaloids and total polysaccharides in certain Pinellia ternata germplasms increased significantly. First water normally for 20 days and then stop watering and grow for 10 days, the total alkaloid content and total polysaccharide content of some Pinellia ternata germplasm were significantly increased. Principal component analysis showed that ground diameter, transpiration rate, GSH content, Chlorophyll b content and intercellular CO₂ concentration played a leading role in drought resistance evaluation of Pinellia ternata. Correlation analysis showed that GSH content was significantly negatively correlated with POD activity (P < 0.05), SP was significantly negatively correlated with SP (P < 0.01), and total alkaloid content was significantly positively correlated with GSH content (P < 0.01), alkaloids and total polysaccharides among the five Pinellia ternata species (P < 0.05). It can be concluded that there are significant differences in resistance physiological indicators, total alkaloids and total polysaccharides among the five Pinellia ternata species (P < 0.05), the underground biomass and leaf photosynthesis ability of Pinellia ternata are significantly reduced by drought stress. To some extent, drought stress promotes the accumulation of total alkaloids and total polysaccharides in P. ternata, except for the P. ternata from Zhangjiakou, the contents of total alkaloids in P. ternata from the other producing areas increased significantly under drought stress. The contents of total polysaccharides in P. ternata from Leshan, Yongzhou and Heze increased to varying degrees under the influence of drought stress.