This study was conducted in order to determine the effect of priming with γ-aminobutyric acid (GABA) at 0.5 mM on rice (Oryza sativa L.) seed germination under osmotic stress (OS) induced by polyethylene glycol (30 g/L PEG 6000); and salinity stress (S, 150 mM NaCl) and their combination (OS+S). Priming with GABA significantly alleviated the detrimental effects of OS, S and OS+S on seed germination and seedling growth. The photosynthetic system and water relation parameters were improved by GABA under stress. Priming treatment significantly increased the GABA content, sugars, protein, starch and glutathione reductase. GABA priming significantly reduced Na⁺ concentrations, proline, free radical and malonaldehyde and also significantly increased K⁺ concentration under the stress condition. Additionally, the activities of antioxidant enzymes, phenolic metabolism-related enzymes, detoxification-related enzymes and their transcription levels were improved by GABA priming under stress. In the GABA primed-plants, salinity stress alone resulted in an obvious increase in the expression level of Calcineurin B-like Protein-interacting protein Kinases (CIPKs) genes such as OsCIPK01, OsCIPK03, OsCIPK08 and OsCIPK15, and osmotic stress alone resulted in obvious increase in the expression of OsCIPK02, OsCIPK07 and OsCIPK09; and OS+S resulted in a significant up-regulation of OsCIPK12 and OsCIPK17. The results showed that salinity, osmotic stresses and their combination induced changes in cell ultra-morphology and cell cycle progression resulting in prolonged cell cycle development duration and inhibitory effects on rice seedlings growth. Hence, our findings suggested that the high tolerance to OS+S is closely associated with the capability of GABA priming to control the reactive oxygen species (ROS) level by inducing antioxidant enzymes, secondary metabolism and their transcription level. This knowledge provides new evidence for better understanding molecular mechanisms of GABA-regulating salinity and osmotic-combined stress tolerance during rice seed germination and development.

Nitrogen (N) is an essential and often limiting nutrient to plant growth and development. Previous studies have shown that the mRNA expressions of numerous genes are regulated by nitrogen supplies; however, little is known about the expressed non-coding elements, for example long non-coding RNAs (lncRNAs) that control the response of maize (Zea mays L.) to nitrogen. LncRNAs are a class of non-coding RNAs larger than 200 bp, which have emerged as key regulators in gene expression. In this study, we surveyed the intergenic/intronic lncRNAs in maize B73 leaves at the V7 stage under conditions of N-deficiency and N-sufficiency using ribosomal RNA depletion and ultra-deep total RNA sequencing approaches. By integration with mRNA expression profiles and physiological evaluations, 7245 lncRNAs and 637 nitrogen-responsive lncRNAs were identified that exhibited unique expression patterns. Co-expression network analysis showed that the nitrogen-responsive lncRNAs were enriched mainly in one of the three co-expressed modules. The genes in the enriched module are mainly involved in NADH dehydrogenase activity, oxidative phosphorylation and the nitrogen compounds metabolic process. We identified a large number of lncRNAs in maize and illustrated their potential regulatory roles in response to N stress. The results lay the foundation for further in-depth understanding of the molecular mechanisms of lncRNAs’ role in response to nitrogen stresses.

One of the most popular ornamental plants worldwide, roses (Rosa sp.), are very susceptible to Botrytis gray mold disease. The necrotrophic infection of rose petals by B. cinerea causes the collapse and death of these tissues in both the growth and post-harvest stages, resulting in serious economic losses. To understand the molecular basis of rose resistance against B. cinerea, we profiled the petal transcriptome using RNA-Seq technology. We identified differentially transcribed genes (DTGs) in petals during B. cinerea infection at 30 h post inoculation (hpi) and/or 48 hpi. Gene ontology term enrichment and pathway analyses revealed that metabolic, secondary metabolite biosynthesis, plant-pathogen interaction, and plant hormone signal transduction pathways were involved. The expression of 370 cell-surface immune receptors was upregulated during infection. In addition, 188 genes encoding transcription factors were upregulated, particularly in the ERF, WRKY, bHLH, MYB, and NAC families, implying their involvement in resistance against B. cinerea. We further identified 325 upregulated DTGs in the hormone signal transduction pathways. Among them, the brassinosteroid (BR)-related genes were the most significantly enriched. To confirm the role of BR in Botrytis resistance, exogenous BR was applied to rose flowers before the inoculation of B. cinerea, which enhanced the defense response in these petals. Our global transcriptome profiling provides insights into the complex gene regulatory networks mediating the rose petal response to B. cinerea. We further demonstrated the role of the phytohormone BR in the resistance of petals to necrotrophic fungal pathogens.

Phosphate solubilizing microorganisms (PSMs) are known as bacteria or fungi that make insoluble phosphorus in soil available to plants. To date, as beneficial microbes, studies on PSMs indicated they have potential applications in agriculture, environmental engineering, bioremediation, and biotechnology. Currently high cost and competition from local microbe are the most important factors hindering PSMs commercialization and application as for instance biofertilizer, soil conditioner or remediation agent, etc. There are several technical strategies can be engaged to approach the solutions of these issues, for instance mass production, advance soil preparation, genetic engineering, etc. On the other hand, further studies are needed to improve the efficiency and effectiveness of PSMs in solubilizing phosphates, promoting plant growth, soil remediation preferably. Hopefully, PSMs are going to be developed into ecofriendly tools for sustainable agriculture, environment protection and management in the future.

Salt stress is a major problem happening in almost all the world, affecting soil metabolism and acting further negatively soil fertility and soil quality, causing land degradation and low ecosystem service functions and ecosystem productivity. In marshy area as one type of important marginal land resources, salt is also the main barrier to be improved and the driving force to make vegetation succeed. This commentary briefly reviews the main advance focusing on salt‐affected soil and introduced the publications in this Special Issue: Salt Soil Improvement and Efficient Development in Land Degradation & Development 29, 2018, to promote global cooperation for studying salt‐affecting soil quality, land degradation, and eco‐restoration.

Feedstocks for industrial applications ranging from polymers to lubricants are largely derived from petroleum, a non-renewable resource. Vegetable oils with fatty acid structures and storage forms tailored for specific industrial uses offer renewable and potentially sustainable sources of petrochemical-type functionalities. A wide array of industrial vegetable oils can be generated through biotechnology, but will likely require non-commodity oilseed platforms dedicated to specialty oil production for commercial acceptance. Here we show the feasibility of three Brassicaceae oilseeds crambe, camelina, and carinata, none of which are widely cultivated for food use, as hosts for complex metabolic engineering of wax esters for lubricant applications. Lines producing wax esters >20% of total seed oil were generated for each crop and further improved for high temperature oxidative stability by down-regulation of fatty acid polyunsaturation. Field cultivation of optimized wax ester-producing crambe demonstrated commercial utility of these engineered crops and a path for sustainable production of other industrial oils in dedicated specialty oilseeds.