The Alkali Tolerance of Broomcorn Millet (Panicum miliaceum L.) at the Germination and Seedling Stage: The Case of 296 Broomcorn Millet Genotypes

Abstract

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.

RNA-Seq Analysis Demonstrates Different Strategies Employed by Tiger Nuts (Cyperus esculentus L.) in Response to Drought Stress

“…The bud stage is the most sensitive stage in plants under abiotic stresses, which could affect growth in later stages [ 38 ]. Drought stress limits the growth, development and survival rate of plants, leading to tremendous losses in yield, thus threatening global agricultural production [ 39 ].…”

Comparative transcriptomic and metabolomic study reveal that exogenous 24‐epiandrosterone mitigate alkaline stress in broomcorn millet (Panicum miliaceum L.) via regulating photosynthesis and antioxidant capacity

“…When the seedlings grow to the three‐leaf one‐heart stage, they are subjected to alkaline stress. According to our previous research (Ma et al, 2021), two varieties of broomcorn millet were selected: alkaline‐tolerant variety TA289 and the alkaline‐sensitive variety SA223 (provided by the Science and Technology Innovation Team of Minor Grain Crops of Northwest A&F University). An alkaline concentration of 40 mmol L −1 (molar ratio NaHCO 3 :Na 2 CO 3 = 9:1) was determined to be an appropriate stress condition (Ma et al, 2021).…”

“…According to our previous research (Ma et al, 2021), two varieties of broomcorn millet were selected: alkaline‐tolerant variety TA289 and the alkaline‐sensitive variety SA223 (provided by the Science and Technology Innovation Team of Minor Grain Crops of Northwest A&F University). An alkaline concentration of 40 mmol L −1 (molar ratio NaHCO 3 :Na 2 CO 3 = 9:1) was determined to be an appropriate stress condition (Ma et al, 2021). Four treatments were used in the experiment: CK (nutrient solution only), CE (nutrient solution + 0.5 mg L −1 BR), AS (alkaline stress), and AB (alkaline stress + 0.5 mg L −1 BR).…”

“…Broomcorn millet ( Panicum miliaceum L.) is one of the earliest domesticated cereal/bioenergy crops in the world (Ma et al, 2021; Yuan et al, 2022; Zou et al, 2019). In the northern China, broomcorn millet is an indispensable food crop and forage grass.…”

“…Currently, most of the existing studies have focused on broomcorn millet under low nitrogen, drought, and neutral salt stress (Liu et al, 2020; Yuan, Li, et al, 2021; Yuan, Liu, et al, 2021) rather than alkaline stress. The research on alkaline resistance of broomcorn millet is still at the stage of alkaline‐tolerant resource screening (Ma et al, 2021) and physiological and biochemical responses in germination (Ma et al, 2022). Additionally, breeding is a long‐term and challenging project.…”