Phospholipase C is an enzyme that catalyzes the hydrolysis of glycerophospholipids and can be classified as phosphoinositide-specific PLC (PI-PLC) and non-specific PLC (NPC), depending on its hydrolytic substrate. In maize, the function of phospholipase C has not been well characterized. In this study, the phospholipase C inhibitor neomycin sulfate (NS, 100 mM) was applied to maize seedlings to investigate the function of maize PLC. Under the treatment of neomycin sulfate, the growth and development of maize seedlings were impaired, and the leaves were gradually etiolated and wilted. The analysis of physiological and biochemical parameters revealed that inhibition of phospholipase C affected photosynthesis, photosynthetic pigment accumulation, carbon metabolism and the stability of the cell membrane. High-throughput RNA-seq was conducted, and differentially expressed genes (DEGS) were found significantly enriched in photosynthesis and carbon metabolism pathways. When phospholipase C activity was inhibited, the expression of genes related to photosynthetic pigment accumulation was decreased, which led to lowered chlorophyll. Most of the genes related to PSI, PSII and TCA cycles were down-regulated and the net photosynthesis was decreased. Meanwhile, genes related to starch and sucrose metabolism, the pentose phosphate pathway and the glycolysis/gluconeogenesis pathway were up-regulated, which explained the reduction of starch and total soluble sugar content in the leaves of maize seedlings. These findings suggest that phospholipase C plays a key role in photosynthesis and the growth and development of maize seedlings.

Saline-alkali stress seriously affects the growth and development of crops. Sorghum bicolor (L.), a C4 plant, is an important cereal crop in the world, and its growth and geographical distribution are limited by alkali conditions. In this study, sorghum genotypes with different alkaline resistance (alkaline-sensitive Z1 and alkaline-tolerant Z14) were used as experimental materials to explore the effects of alkali on sorghum seedlings. RNA-seq technology was used to examine the differentially expressed genes (DEGs) in alkali-tolerant Z14 to reveal the molecular mechanism of sorghum response to alkali stress. The results showed that plant height, root length, and biomass of both cultivars decreased with time under 80 mM NaHCO₃ treatment, but Z14 showed better water retention abilities. The photosynthetic fluorescence parameters and chlorophyll content also decreased, but the Fv/Fm, ETH, ΦPSII, and chlorophyll content of Z14 were significantly higher than those of Z1. The level of reactive oxygen species (ROS) increased in both sorghum varieties under alkali stress, while the enzyme activities of SOD, POD, CAT, and APX were also significantly increased, especially in Z14, resulting in lower ROS compared with Z1. Transcriptome analysis revealed around 6000 DEGs in Z14 sorghum seedlings under alkali stress, among which 267 DEGs were expressed in all comparison groups. KEGG pathways were enriched in the MAPK signaling pathway, plant hormone signal transduction, and RNA transport. bHLHs, ERFs, NACs, MYBs, and other transcription factor families are actively involved in the response to alkali stress. A large number of genes involved in photosynthesis and the antioxidant system were found to be significantly activated under alkali stress. In the stress signal transduction cascades, Ca²⁺ signal transduction pathway-related genes were activated, about 23 PP2Cs in ABA signaling were upregulated, and multiple MAPK and other kinase-related genes were triggered by alkali stress. These findings will help decipher the response mechanism of sorghum to alkali stress and improve its alkali tolerance.