Search

Background: Drought stress is a major abiotic factor that affects rapeseed (Brassica napus L.) productivity. Though previous studies indicated that long non-coding RNAs (lncRNAs) play a key role in response to drought stress, a scheme for genome-wide identification and characterization of lncRNAs' response to drought stress is still lacking, especially in the case of B. napus. In order to further understand the molecular mechanism of the response of B. napus to drought stress, we compared changes in the transcriptome between Q2 (a drought-tolerant genotype) and Qinyou8 (a drought-sensitive genotype) responding drought stress and rehydration treatment at the seedling stage., Results: A total of 5546 down-regulated and 6997 up-regulated mRNAs were detected in Q2 compared with 7824 and 10,251 in Qinyou8, respectively; 369 down-regulated and 108 up- regulated lncRNAs were detected in Q2 compared with 449 and 257 in Qinyou8, respectively. LncRNA-mRNA interaction network analysis indicated that the co-expression network of Q2 was composed of 145 network nodes and 5175 connections, while the co-expression network of Qinyou8 was composed of 305 network nodes and 22,327 connections. We further identified 34 transcription factors (TFs) corresponding to 126 differentially expressed lncRNAs in Q2, and 45 TFs corresponding to 359 differentially expressed lncRNAs in Qinyou8. Differential expression analysis of lncRNAs indicated that up- and down-regulated mRNAs co-expressed with lncRNAs participated in different metabolic pathways and were involved in different regulatory mechanisms in the two genotypes. Notably, some lncRNAs were co-expressed with BnaC07g44670D, which are associated with plant hormone signal transduction. Additionally, some mRNAs co-located with XLOC_052298, XLOC_094954 and XLOC_012868 were mainly categorized as signal transport and defense/stress response., Conclusions: The results of this study increased our understanding of expression characterization of rapeseed lncRNAs in response to drought stress and re-watering, which would be useful to provide a reference for the further study of the function and action mechanisms of lncRNAs under drought stress and re-watering.

The naturally drought-prone climate of the Tibetan Plateau has produced highly drought-resistant Brassica juncea. The objective of the present study was to examine improvement in drought resistance in B. napus by distant hybridisation between B. juncea and B. napus. Distant hybridisation was performed to generate F1 hybrids, which were open-pollinated by a set of breeding lines of B. napus. Continuous self-crossing was then performed to produce the F2–F6 generations, and 74 lines of new-type Brassica napus with stable fertility and morphological phenotypes were selected. The drought resistance of the 74 lines was evaluated during the germination stage by simulating drought stress at 15% PEG-6000, and a wide range of genetic variation in drought resistance was scored. Cytological identification of four lines chosen from strongly, intermediate and weakly drought-resistant clusters demonstrated that their chromosomes had gradually stabilised to B. napus (2n = 38) after advanced self-crossing. A drought-resistant line (line 290) and a drought-susceptible line (line 299) were selected to determine the physiological response to drought stress at the seedling stage. The results showed that proline, soluble protein and malondialdehyde contents of the drought-resistant line were always lower than those of the drought-susceptible line and other common rapeseed variety under drought stress and rewatering conditions. This indicates that the drought-resistant line may have a better reactive oxygen species scavenging system with a less extreme reaction to drought stress. Additionally, the results revealed that the genetic diversity of B. napus under drought resistance was broadened by distant hybridisation, which could encourage breeders to utilise the germplasm resources of B. juncea in the Tibetan Plateau to achieve the goal of drought resistance. Drought being one of the most influential abiotic stress factors affecting crop yield, we examined improvement in drought resistance in Brassica napus by distant hybridisation between B. juncea and B. napus. The results indicated broadened genetic diversity of the new-type B. napus with regard to drought resistance; a drought-resistant line may have a better ROS-scavenging system with a less extreme reaction to drought stress than that of drought-susceptible lines. These results provided new insights on the physiological mechanisms of drought resistance and new evidence supporting the breeding of drought-resistant B. napus via distant hybridisation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Drought stress negatively affect the sustainable crop production in various ways. • Moisture deficits drastically reduced crop yields and regional economies. • Understanding the drivers of yield levels under deficient water is required. • Biochar with high carbon is being recognized by scientists for its potential role. • Biochar improve soil status and enhance utilization of soil water and nutrients. The depletion of soil fertility and freshwater reservoirs in dry and arid conditions of the world are alarming for food and crop productivity. Although many research studies have explored the effect of biochar on plant growth and soil fertility, however, information on the role of biochar on rapeseed under drought stress is limited. The current study was conducted to investigate the effect of biochar on photosynthesis, antioxidants activities, osmolytes contents, growth and yield of rapeseed under drought stress. Rapeseed plants at the flowering stage were subjected to two moisture conditions, no stress (NS) and drought stress (DS) along with four biochar treatments (B0:0, B15:15, B30:30 and B60:60 t ha−1). Drought stress negatively affected rapeseed growth due to the over-production of hydrogen peroxide (H 2 O 2) by increasing 45 %, malondialdehyde (MDA) 21 % and electrolyte leakage (EL%) 40 % in (BO + DS) treatment as compared to control (BO + NS). However, the addition of biochar at 30 t ha−1 alleviated the hostile effects of drought stress in rapeseed to reduce the contents of MDA, H 2 O 2 , EL by increasing the activities of superoxide dismutase (SOD) by 63 %, peroxidase (POD) 48 %, and catalase (CAT) 62 % compared to stress-controlled treatment (BO + DS). The results revealed that biochar could alleviate the harmful effects of drought stress by enhancing the activities of antioxidants, osmoprotectants, soil fertility, and the physiological processes of rapeseed which indicate that the biochar application might be a sustainable strategy to enhance rapeseed growth under drought stress. [ABSTRACT FROM AUTHOR]

• Melatonin-priming improved seed germination under the drought stress. • Melatonin-priming detoxified the ROS activities through enhancement of antioxidants. • Melatonin-priming potentially regulated stomatal traits coping with drought stress. • Seed priming with melatonin prevented chloroplasts autopepsia and cell wall degradation. Water stress encumbers the rapeseed growth and development primarily by oxidative alteration to biological membranes and interrupted tissue water status. Seedling tolerance to water stress is vital for better crop development through the entire period under drought stress condition. The enhancement of plant stress tolerance due to melatonin application is already known; however, the specific underlying mechanisms are still not fully understood. The current study was done to investigate the effect of melatonin-priming on rapeseed germination and subsequent seedling growth under PEG-6000 simulated drought stress. Drought stress significantly inhibited germination and seedling growth, led to oxidative stress from excessive H 2 O 2 generation, and reduced the chlorophyll content. Melatonin-priming alleviated the oxidative damage and the amount of chlorophyll reduction in rapeseed seedlings under the drought stress. The stomatal traits such as number, stomatal length and width were greatly improved in melatonin-primed treatment. Melatonin-priming also preserved the chloroplast structure, maintained cells expansion and strengthened the cell wall in response to drought stress. The results revealed that the ameliorative effects of melatonin-priming may be ascribed to enhancement of antioxidant enzymes activities, increase in the content of non-enzymatic antioxidants, and increase in the amounts of osmo-protectants. The present data suggest that priming seeds with melatonin can be a prime strategy regarding the development of crop drought resistant in crop production. [ABSTRACT FROM AUTHOR]