Vitrification–cryopreservation,an efficient method for eliminating <Emphasis Type="Italic">Candidatus</Emphasis><Emphasis Type="Italic"> Liberobacter asiaticus</Emphasis>, the citrus Huanglongbing pathogen,from in vitro adult shoot tips

Huanglongbing disease (HLB), caused by Candidatus Liberobacter asiaticus, constitutes a most serious problem for the Chinese citrus industry. In this work, the use of vitrification-cryopreservation for eliminating Ca. L. asiaticus from naturally infected plants of several citrus species was investigated. Proliferating meristems were produced in vitro and excised tissue clumps were cryopreserved through vitrification using a plant vitrification solution 2. The health status of regenerated in vitro plants was checked by nested PCR. The putative HLB bacterial-free materials were subsequently re-tested after greenhouse acclimatization. Up to 98.1% of the plants obtained by cryopreservation were free from HLB bacterium, as compared with a sanitation rate of 25.3% yielded by conventional meristem tip culture. Light and electron microscopy observations of the meristem tips showed that the majority of the meristematic cells were injured either during the freezing/thawing step or during the osmotic dehydration step with plant vitrification solution 2. Only small areas of the meristematic dome survived the cryopreservation process, thereby increasing the probability of regenerating cells free of Ca. L. asiaticus. Large cells with big vacuoles and high water content, which are more likely to be infected by Ca. L. asiaticus, apparently cannot survive freezing in liquid nitrogen (LN). By contrast, small cells with dense cytoplasm located in the top layers of the meristem are more likely to escape invasion by Ca. L. asiaticus and can survive freezing in LN.     

Pharmacokinetics, Tissue Distribution, and Plasma Protein Binding Study of Platinum Originating from Dicycloplatin, a Novel Antitumor Supramolecule, in Rats and Dogs by ICP-MS

Dicycloplatin, as a new antitumor supramolecule, was considered to have higher solubility and higher stability compared with carboplatin. The aim of the present study was to evaluate the pharmacokinetic characteristics of platinum originating from dicycloplatin. A rapid, sensitive, and specific method with inductively coupled plasma mass spectrometry (ICP-MS) has been developed for the determination of platinum in bio-samples. The study was performed in male rats and dogs at a single dose of 10 and 5 mg kg(-1) separately by intravenous injection. Pharmacokinetic parameters were calculated by non-compartmental method, and the dose of platinum was used in the calculation of these parameters. Results showed that plasma concentrations of platinum began to decrease rapidly initially but decline slowly with a long terminal phase. The mean half-life was 27.39 and 100.98 and clearance was 0.77 and 0.08 L/h/kg for rats and dogs separately. Tissue distribution showed that platinum originating from dicycloplatin had a certain distribution in testis and prostate. Plasma protein binding proportion of platinum was increased with time. In conclusion, this research investigated the pharmacokinetic characteristics including plasma kinetics, tissue distribution, and plasma protein binding of platinum originating from dicycloplatin in rats and dogs in detail for the first time by ICP-MS.     

Pyramiding Bt genes for increasing resistance of cotton to two major lepidopteran pests: Spodoptera litura and Heliothis armigera

To more effectively control two major cotton insects (cotton bollworm and Spodoptera litura) and improve the efficacy of the pest resistance management, novel transgenic plants expressing Bacillus thuringiensis Cry9C gene were generated, and gene stacking strategy was incorporated. Initially, a binary plasmid vector harboring Cry9C gene was introduced into an elite cotton cultivar Simian-3 by Agrobacterium-mediated transformation. Integration and expression of the Cry9C genes in three transgenic lines were confirmed by PCR and RT-PCR. Among these transgenic lines, T0 generation of line 16 (L-16) with normal phenotypes were selected by ELISA assays for its highest expression level of Cry9C. In T1 population of L-16, the expression level of Cry9C ranged from 29 to 45 μg/g fresh leaf. The following insect bioassays demonstrated that transgenic S3-35S::Cry9C cotton plants exhibited moderate toxicity to Heliothis armigera but strong toxicity to S. litura compared with the transgenic plants expressing Cry 1Ac gene. For incorporation of gene staking strategy, Cry9C gene and Cry 2A or Cry 1Ac were pyramided, respectively by sexual crossing. The expression of Cry9C protein in all F1 progenies had a similar level as the parent plants indicating the high heritability of Bt genes in transgenic progenies. Progenies from both Cry9C × Cry 2A and Cry9C × Cry 1Ac exhibited higher resistance to S. litura compared with their parents. Together our data demonstrated that our newly generated transgenic plants represent a reservoir of novel insect-resistant materials in cotton breeding, and the successful incorporation of gene pyramiding technology can provide a new solution of developing multiple resistance management strategies.     

Overexpression of KcNHX1 gene confers tolerance to multiple abiotic stresses in Arabidopsis thaliana

Journal of Plant Research - Abiotic stresses such as drought, salinity, and heat affect plant growth and development. Karelinia caspica is a unique perennial herb that grows in desert area for a...