Background Giant Juncao is often used as feed for livestock because of its huge biomass. However, drought stress reduces forage production by affecting the normal growth and development of plants. Therefore, investigating the molecular mechanisms of drought tolerance will provide important information for the improvement of drought tolerance in this grass. Results A total of 144.96 Gb of clean data was generated and assembled into 144,806 transcripts and 93,907 unigenes. After 7 and 14 days of drought stress, a total of 16,726 and 46,492 differentially expressed genes (DEGs) were observed, respectively. Compared with normal irrigation, 16,247, 23,503, and 11,598 DEGs were observed in 1, 5, and 9 days following rehydration, respectively. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses revealed abiotic stress-responsive genes and pathways related to catalytic activity, methyltransferase activity, transferase activity, and superoxide metabolic process. We also identified transcription factors belonging to several families, including basic helix-loop-helix (bHLH), WRKY, NAM (no apical meristem), ATAF1/2 and CUC2 (cup-shaped cotyledon) (NAC), fatty acyl-CoA reductase (FAR1), B3, myeloblastosis (MYB)-related, and basic leucine zipper (bZIP) families, which are important drought-rehydration-responsive proteins. Weighted gene co-expression network analysis was also used to analyze the RNA-seq data to predict the interrelationship between genes. Twenty modules were obtained, and four of these modules may be involved in photosynthesis and plant hormone signal transduction that respond to drought and rehydration conditions. Conclusions Our research is the first to provide a more comprehensive understanding of DEGs involved in drought stress at the transcriptome level in Giant Juncao with different drought and recovery conditions. These results may reveal insights into the molecular mechanisms of drought tolerance in Giant Juncao and provide diverse genetic resources involved in drought tolerance research.

Background Drought is one of the main environmental factors limiting plant growth and development. Pennisetum purpureum Schum. was used to explore the mitigation effects of exogenous strigolactone (SL) on drought stress during the seedling stage. The effects of different concentrations (1, 3, 5, and 7 μmol·L− 1) of SL on the photosynthesis characteristics, growth performance, and endogenous abscisic acid (ABA) of P. purpureum under drought stress were studied. Results Exogenous SL could effectively alleviate the inhibitory effect of drought stress on P. purpureum growth. Compared with drought stress, the net photosynthesis rate, stomatal conductance, transpiration rate, and water-use efficiency of the leaves of P. purpureum after SL treatment significantly increased, thereby exerting a significant mitigation effect on the decrease in photosystem II maximum photochemical efficiency and the performance index based on light absorption caused by drought. Moreover, the exogenous application of SL can effectively increase the fresh and dry weight of the leaves and roots and the main-root length. After applying SL for 120 h, the ABA content of P. purpureum decreased significantly. The activity of key enzymes of photosynthesis significantly increased after 48 h of external application of SL to P. purpureum. Conclusions SL treatment can improve the photosynthesis performance of P. purpureum leaves under drought conditions and increase the antioxidant capacity of the leaves, thereby reducing the adverse effects of drought, promoting the growth of P. purpureum, and effectively improving the drought resistance of P. purpureum.

Background: Drought is one of the main environmental factors limiting plant growth and development. To explore the mitigation effects of exogenous strigolactones (SLs) on drought stress during the seedling stage, the Pennisetum Purpureum Schum. were used as the material. The effects of different concentrations (1, 3, 5, and 7 μmol·L−1) of SLs on the photosynthetic characteristics, growth performance, and endogenous abscisic acid (ABA) of P. Purpureum under drought stress were studied. Results: Exogenous SLs could effectively alleviate the inhibitory effect of drought stress on the growth of P. Purpureum. Compared with drought stress, the net photosynthetic rate, stomatal conductance, transpiration rate, and water use efficiency of the leaves of P. Purpureum after SL treatment were significantly increased, which has a significant mitigation effect on the decrease of photosystem II maximum photochemical efficiency and the performance index based on light absorption caused by drought. In addition, the exogenous application of SLs can effectively increase the fresh and dry weight of the leaves and roots and the length of the main roots. After applying SLs for 120 h, the ABA content of P. Purpureum decreased significantly. The activity of key enzymes of photosynthesis significantly increased after 48 h of external application of SLs to P. Purpureum. Conclusions: In summary, SL treatment can improve the photosynthetic performance of P. Purpureum leaves under drought conditions and increase the antioxidant capacity of the leaves, thereby reducing the adverse effects of drought, promoting the growth of P. Purpureum, and effectively improving the drought resistance of P. Purpureum.