The Agrobacterium-mediated transient transformation is a versatile and indispensable way of rapid analyzing gene function in plants. Despite this transient expression system has been successfully applied in a number of plant species, it is poorly developed in Caragana intermedia. In this study, we established an Agrobacterium-mediated transient expression system in C. intermedia leaves and optimized the effect of different Agrobacterial strains, several surfactants and the concentration of Silwet L-77, which would affect transient expression efficiency. Among the 5 Agrobacterial strains examined, GV3101 produced the highest GUS expression level. Besides, higher level of transient expression was observed in plants infiltrated with Silwet L-77 than with Triton X-100 or Tween-20. Silwet L-77 at a concentration of 0.001% greatly improved the level of GUS transient expression. Real-time PCR showed that expression of CiDREB1C was highly up-regulated in transiently expressed plants and reached the highest level at the 2nd day after infiltration. Based on this optimized transient transformation method, we characterized CiDREB1C function in response to drought, salt and ABA treatment. The results showed that transiently expressed CiDREB1C in C. intermedia leaves could enhance the survival rate and chlorophyll content, and reduce the lodging rate compared with the control seedlings under drought, salt and ABA treatments. Furthermore, the rate of leaf shedding of CiDREB1C transient expression seedlings was lower than that of the control under ABA treatment. The optimized transient expression condition in C. intermedia leaves were infiltrated with Agrobacterial strains GV3101 plus Silwet L-77 at a concentration of 0.001% added into the infiltration medium. Transiently expressed CiDREB1C enhanced drought, salt and ABA stress tolerance, indicated that it was a suitable and effective tool to determine gene function involved in abiotic stress response in C. intermedia.

Caragana intermedia, a leguminous shrub widely distributed in cold and arid regions, is rich in secondary metabolites and natural active substances, with high nutritional and medical values. It is interesting that the pods of C. intermedia often show different colors among individual plants. In this study, 10-, 20- and 30-day-old red and green pods of C. intermedia were used to identify and characterize important metabolites associated with pod color. A total 557 metabolites, which could be classified into 21 groups, were detected in the pod extracts using liquid chromatography coupled with ESI-triple quadrupole-linear ion trap mass spectrometer (LC-ESI-MS/MS). Metabolomics analysis revealed significant differences in 15 groups of metabolites between red and green pods, including amino acids, nucleotide derivatives, flavonoids, and phytohormones. Metabolic pathway analysis showed that the shikimic acid and the phytohormone metabolic pathways were extraordinarily active in red pods, and the difference between red and green pods was obvious. Moreover, red pods showed remarkable flavonoids, cytokinins, and auxin accumulation, and the content of total flavonoids and proanthocyanidins in 30-day-old red pods was significantly higher than that in green pods. This metabolic profile contributes to valuable insights into the metabolic regulation mechanism in different color pods.

Clavibacter sp. strain CF11, which was isolated from soil at a tomato-planting greenhouse in Inner Mongolia, North China, has a high capability for producing cold-active cellulase at low temperatures. Here, we report the draft genome sequence of strain CF11, which comprises 2,437 protein-coding sequences and 49 RNA-coding sequences.

To reveal the mechanisms underlying root adaptation to drought stress, we isolated and characterized an Arabidopsis mutant, dig5 (drought inhibition of lateral root growth 5), which exhibited increased sensitivity to the phytohormone abscisic acid (ABA) for the inhibition of lateral root growth. The dig5 mutant also had fewer lateral roots under normal conditions and the aerial parts were yellowish with a lower level of chlorophylls. The mutant seedlings also displayed phenotypes indicative of impaired auxin transport, such as abnormal root curling, leaf venation defects, absence of apical hook formation, and reduced hypocotyl elongation in darkness. Auxin transport assays with [³H]-labeled indole acetic acid (IAA) confirmed that dig5 roots were impaired in polar auxin transport. Map-based cloning and complementation assays indicated that the DIG5 locus encodes a chloroplast-localized tRNA adenosine deaminase arginine (TADA) that is involved in chloroplast protein translation. The levels of flavonoids, which are naturally occurring auxin transport inhibitors in plants, were significantly higher in dig5 roots than in the wild type roots. Further investigation showed that flavonoid biosynthetic genes were upregulated in dig5. Introduction of the flavonoid biosynthetic mutation transparent testa 4 (tt4) into dig5 restored the lateral root growth of dig5. Our study uncovers an important role of DIG5/TADA in retrogradely controlling flavonoid biosynthesis and lateral root development. We suggest that the DIG5-related signaling pathways, triggered likely by drought-induced chlorophyll breakdown and leaf senescence, may potentially help the plants to adapt to drought stress through optimizing the root system architecture.

The PADRE (Pathogen and abiotic stress response, cadmium tolerance, disordered region-containing) family of genes, which contains the structural DUF4228 domain of unknown function (DUF), has been reported to be associated with plant responses to abiotic stresses. However, the specific functions of this family in the salt stress response remain unknown. AtPADRE13 is induced by salt stress and ABA (abscisic acid). After the overexpression of AtPADRE13 in Arabidopsis, seeds were found to be insensitive to ABA treatment. After salt treatment, the overexpression lines presented a significantly lower survival rate, increased MDA (Malondialdehyde) content, and reduced antioxidant enzyme activities compared with the wild-type, and were more sensitive to salt stress. Transcriptome data analysis further revealed that AtPADRE13 overexpression resulted in different degrees of down-regulation for a series of positive regulators related to ABA catabolism, transport, and their mediated plant responses to salt stress. In addition, the expression of genes related to ROS (reactive oxygen species) scavenging was down-regulated. In conclusion, AtPADRE13 plays a negative regulatory role in the response to salt stress in Arabidopsis.

Hibiscus manihot L. seed oil is an emerging high-value edible vegetable oil that also has a variety of important health functions, and concerns about its pressing method have great significance for commercial and consumer health. This study compared triacylglycerols (TAGs), diacylglycerol (DAG), free fatty acids (FFAs), and volatile flavor compounds for discriminating cold-pressed oil from hot-pressed oil. The profiles of TAGs, DAGs, FFAs, and flavor compounds were established by a lipidomic approach and electronic-nose (E-nose). Our results demonstrated that a slight decrease in TAG content and a significant increase in FFA and DAG contents were observed after roasting. The E-nose results showed that sulfides, terpenes, methane, compounds containing oxygen and nitrogen, alcohol and aromatic compounds greatly influenced the oil flavor. The PCA result of the E-nose data indicated that flavor compounds showed great promise for distinguishing the two samples. The quality indices and the oxidative stability of oil samples were detected to identify their nutritional value and edible quality. This study revealed that roasting greatly influenced the lipid and flavor substances of the Hibiscus manihot L. seed oil. Our findings could provide useful information on the impact of the pressing method for Hibiscus manihot L. seed oil.