Maize Seed Germination Under Low-Temperature Stress Impacts Seedling Growth Under Normal Temperature by Modulating Photosynthesis and Antioxidant Metabolism

Abstract

Spring maize is usually subjected to low-temperature stress during seed germination, which retards seedling growth later even under a suitable temperature. However, the mechanism underlying maize seed germination under low-temperature stress impacting seedling growth is still ambiguous. In this study, we used one low-temperature sensitive maize (SM) and one low-temperature resistance maize (RM) to investigate the mechanism. The results showed that the SM line had higher malondialdehyde content and lower total antioxidant capacity (TAC) and germination percentage than the RM line under low-temperature stress, indicating the vulnerability of SM line to low-temperature stress. Further transcriptome analysis revealed that seed germination under low-temperature stress caused the down-regulation of photosynthesis-related gene ontology terms in two lines. Moreover, the SM line displayed down-regulation of ribosome and superoxide dismutase (SOD) related genes, whereas genes involved in SOD and vitamin B6 were up-regulated in the RM line. Kyoto Encyclopedia of Genes and Genomes enrichment analysis revealed that photosynthesis and antioxidant metabolism-related pathways played essential roles in response to low-temperature stress during seed germination. The photosynthetic system displayed a higher degree of damage in the SM line. Both qRT-PCR and physiological characteristics experiments showed similar results with transcriptome data. Taken together, we propose a model for maize seed germination in response to low-temperature stress.

Evaluating the Impact of Nitrogen Application on Growth and Productivity of Maize Under Control Conditions

“…The response of maize seed emergence to temperature was best with minimum cardinal temperatures ranging from 8 to 37.5°C, and optimum temperatures of 25.9 to 37.0°C (Edalat and Kazemeini, 2014 ). Hence, an increased temperature enhanced the germination capacity coupled with the indication that optimum temperature is the pre-requirement for the maize germination process (Meng et al, 2022 ). It is predicted in the scenarios, air temperature will increase due to climate change, which could limit the length of the maize-growing season if other resources are not limited (Odgaard et al, 2011 ).…”

Understanding and Comprehensive Evaluation of Cold Resistance in the Seedlings of Multiple Maize Genotypes

“…Maize ( Zea mays ), originating from tropical and subtropical regions, is extremely sensitive to cold stress, particularly at the seedling emergence stage [ 1 ]. Cold damage during maize seedlings development in early spring usually occurs at suboptimal temperatures of 10–15 °C or at even lower temperatures of 2–8 °C [ 2 ], which normally results in low seedling emergence/uniformity and biomass production, growth retardation, as well as occasionally irreversible tissue damage [ 3 , 4 , 5 ]. The growth of cold-sensitive maize is limited in Northeast China, high–latitude areas since a transient chilling exposure, on average, every 3–4 years, may cause yield losses of 20% to 30% [ 1 , 6 ].…”

“…Significant progress has been made in understanding cold–resistance mechanisms in maize. Low-temperature pressure caused lipid peroxidation, DNA damage, protein denaturation, carbohydrate oxidation, pigment decomposition, and even subsequent cell death in maize seedlings through excessive production of reactive oxygen species (ROS; including O 2 •− , OH − , and H 2 O 2 ) [ 3 , 4 ]. ROS production also damaged the chloroplast, mitochondria, and metabolic enzymes [ 4 , 5 ].…”

“…Low-temperature pressure caused lipid peroxidation, DNA damage, protein denaturation, carbohydrate oxidation, pigment decomposition, and even subsequent cell death in maize seedlings through excessive production of reactive oxygen species (ROS; including O 2 •− , OH − , and H 2 O 2 ) [ 3 , 4 ]. ROS production also damaged the chloroplast, mitochondria, and metabolic enzymes [ 4 , 5 ]. The pale green appearance is caused by low levels of chlorophyll (Chl) a and Chl b, resulting in decreased electron transport in the photosystems, the activity of the enzymes involved in carbon fixation including 1,5–biphosphate carboxylase (Rubisco), NADP-malic enzyme (NADP–ME), pyruvate phosphate dikinase (PPDK), and phosphoenolpyruvate carboxykinase (PEPCK), and net photosynthesis efficiency [ 5 ].…”

“…Cold temperatures also affected the abundance of carotenoids, which enhanced photoprotection by promoting the dissipation of excitation energy [ 3 ]. In addition, maize seedlings evolved an efficient antioxidant system including superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), glutathione peroxidase (GPX), and ascorbate peroxidase (APX) to prevent extremely ROS accumulation under low-temperature stress [ 4 , 7 ]. Consequently, enhanced levels of different antioxidant gene transcripts have been found in maize as a potential low-temperature stress defense strategy.…”