Search

Proso millet (Panicum miliaceum L.) has potential applications as a new source of bioenergy owing to its high‐yielding C4 attribute. Besides, it has a short life cycle, high harvest index, low planting costs, and strong adaptability and resistance. This study comprehensively reveals the sodium ion (Na+) toxicity resistance strategies from germination to the seedling stage, root to leaf, outside to inside, macro to micro, and the phenotype to the mechanism. Comparative phenotypic and physiological analysis suggested that salt‐tolerant proso millet (ST 47) had better salt tolerance, biomass accumulation, and osmo‐protection than salt‐sensitive proso millet (SS 212). Microstructural analysis indicated that ST 47 could maintain better internal surfaces and intact structures to resist Na+ toxicity and maintain optimal growth. Further, digital RNA sequence analysis indicated that ST 47 could maintain better Na+ and K+ homeostasis by coordinated regulation of transporter genes; the abundance of transcripts involved in chlorophyll metabolism and photosynthesis pathways was higher in ST 47 than SS 212, which contributed to the biomass accumulation. These results suggest that ST 47 resists Na+ toxicity via coordinated physiological, morphological, and molecular mechanisms. Therefore, this crop can serve as an emerging salt‐tolerant bioenergy crop for sustainable saline agriculture and simultaneous phytoremediation.

Broomcorn millet (BM), one of the earliest domesticated cereal crops originating in northern China, can tolerate extreme conditions, such as drought and high temperatures, which are prevalent in saline-alkali, arid, and barren landscapes. However, its adaptive mechanism to alkali stress is yet to be comprehensively understood. In this study, 80 and 40 mM standard alkali stress concentrations were used to, respectively, evaluate the alkali tolerance at the germination and seedling stages of 296 BM genotypes. Principal component analysis (PCA), Pearson's correlation analysis, and F-value comprehensive analysis were performed on the germination parameters (germination potential, germination index, germination rate, vigor index, root length/weight, sprout length/weight, and alkali damage rate). Based on their respective F-values, the BM genotypes were divided into five categories ranging from highly alkali resistant to alkali sensitive. To study the response of seedlings to alkaline stress, we investigated the phenotypic parameters (plant height, green leaf area, biomass, and root structure) of 111 genotypes from the above five categories. Combining the parameters of alkali tolerance at the germination and seedling stages, these 111 genotypes were further subdivided into three groups with different alkali tolerances. Variations in physiological responses of the different alkali-tolerant genotypes were further investigated for antioxidant enzyme activity, soluble substances, malondialdehyde (MDA) content, electrolyte leakage rate, and leaf structure. Compared with alkali-sensitive genotypes, alkali-tolerant genotypes had high antioxidant enzyme activity and soluble osmolyte content, low MDA content and electrolyte leakage rate, and a more complete stomata structure. Taken together, this study provides a comprehensive and reliable method for evaluating alkali tolerance and will contribute to the improvement and restoration of saline-alkaline soils by BM.

Pea (Pisum sativum L.), as a major source of plant protein, is becoming one of the major cultivated crop species worldwide. In pea, the pericarp is an important determinant of the morphological characteristics and seed yield. To investigate the molecular mechanism of pericarp elongation as well as sucrose and starch accumulation in the pods of different pea cultivars, we performed transcriptomic analysis of the pericarp of two types of pea cultivar (vegetable pea and grain pea) using RNA-seq. A total of 239.44 Gb of clean sequence data were generated, and were aligned to the reference genome of Pisum sativum L. In the two samples, 1935 differentially expressed genes (DEGs) were identified. Among these DEGs, three antioxidant enzyme superoxide dismutase (SOD) were detected to have higher expression levels in the grain pea pericarps at the pod-elongating stages. Otherwise, five peroxidase (POD)-encoding genes were detected to have lower expression levels in the vegetative pericarps at the development stage of pea pod growth. Furthermore, genes related to starch and sucrose metabolism in the pea pod, such as SUS, INV, FBA, TPI, ADPase, SBE, SSS, and GBSS, were found to be differentially expressed. The RNA-seq data were validated through real-time quantitative RT-PCR of 13 randomly selected genes. Our findings provide the gene expression profile of, as well as differential expression information on, the two pea cultivars, which will lay the foundation for further studies on pod development and nutrition accumulation in the pea and provide valuable information for pea cultivar improvement.