Seed characteristics and fatty acid composition of castor (<i>Ricinus communis</i> L.) varieties in Northeast China

Oil content and fatty acid composition were investigated on 12 castor varieties and strains by using the soxhlet extraction method and capillary gas chromatography. This was made to provide a reference and theoretical basis for castorbean breeding with high oil content, determine variability of seed compounds for breeding purposes, and broaden chemical material choices. Results revealed that crude fat percentage in seeds ranged from 18.91 to 35.84% with an average of 25.91%; the absolute content of ricinoleic acid varied between 171.65 g/kg and 314.03 g/kg with an average of 222.43 g/kg, and kernel crude fat percentage was between 24.28 and 46.97% with an average of 34.30%. All these study variables were highest in the 2129 strain. The percentage of ricinoleic acid in crude fat was between 83.85 to 87.62%, and the highest value was found in the zhebi4 accession. The other fatty acids appeared in small concentrations, and showed small amplitude: 1.12 to 1.61%, 1.21 to 1.61%, 3.53 to 4.80%, 5.35 to 6.38%, 0.52 to 0.79%, 0.05 to 0.08% and 0.43 to 0.55%, for palmitic, stearic, oleic, linolic, linolenic, arachidic, and arachidonic acids, respectively. One hundred seed weight was determined for each accession. One hundred seed weight ranged from 25.7 g to 34.0 g with an average of 29.9 g. There was a significant correlation between seed weight and oil content, but the correlation value was low (r=0.51). Cluster analysis by SSPS based on the content of fatty acid composition revealed that the accessions were divided into three independent clusters. These findings will clearly provide useful information for further research in breeding and utilization of castor oil.     

CNGCs: prime targets of plant cyclic nucleotide signalling?

Cyclic nucleotide-gated channels (CNGCs) are a recently identified family of plant ion channels. They show a high degree of similarity to Shaker-type voltage-gated channels and contain a C-terminal cyclic nucleotide-binding domain with an overlapping calmodulin-binding domain. Heterologously expressed plant CNGCs show activation by cyclic nucleotides and permeability to monovalent and divalent cations. In plants, downstream effectors of cyclic nucleotide signals have so far remained obscure, and CNGCs might be their prime targets. The unique position of CNGCs as ligand-gated Ca(2+)-permeable channels suggests that they function at key sites where cyclic nucleotide and Ca(2+) signalling pathways interact. Such processes include plant defence responses, and two recently characterized Arabidopsis mutants in CNGC genes indeed show altered pathogen responses.     

Pathogenicity,characterization and comparative virulence of Rhizoctonia spp. from insect-galled roots of Lepidium draba in Europe

The association of Rhizoctonia spp. with insect-damaged and diseased tissue of the invasive perennial Lepidium draba was documented throughout the range of L. draba that was surveyed in Europe, including Hungary, Austria, Switzerland and France. Samples that could be both maintained under cooled conditions after collection and promptly processed consistently yielded Rhizoctonia solani, 11 isolates of which anastomosed with AG-4, one with AG-2-1 and one isolate was determined to be binucleate. Comparative virulence among the isolates was analyzed using nonparametric survival analysis for interval-censored data. This analysis indicated that there were significant differences among the isolates. These findings provide further evidence that both root-attacking insects and soilborne pathogens are associated with the lower density of a perennial invasive species in its native range. Prioritization of prospective biocontrol agents should include the ability to engage in insect/plant pathogen synergisms. The application of nonparametric maximum likelihood estimation to interval-censored data for the assessment of comparative virulence among several strains of a plant pathogen is more accessible than calculation of the area under the disease progress curve.     

Nonparametric estimation of the joint distribution of a survival time subject to interval censoring and a continuous mark variable

This article considers three nonparametric estimators of the joint distribution function for a survival time and a continuous mark variable when the survival time is interval censored and the mark variable may be missing for interval-censored observations. Finite and large sample properties are described for the nonparametric maximum likelihood estimator (NPMLE) as well as estimators based on midpoint imputation (MIDMLE) and coarsening the mark variable (CMLE). The estimators are compared using data from a simulation study and a recent phase III HIV vaccine efficacy trial where the survival time is the time from enrollment to infection and the mark variable is the genetic distance from the infecting HIV sequence to the HIV sequence in the vaccine. Theoretical and empirical evidence are presented indicating the NPMLE and MIDMLE are inconsistent. Conversely, the CMLE is shown to be consistent in general and thus is preferred.     

The Arabidopsis thaliana aquaglyceroporin AtNIP7;1 is a pathway for arsenite uptake

We studied the effect of loss of function in the NIP subfamily II in Arabidopsis thaliana to assess their potential role(s) in arsenite (AsIII) uptake. Loss of function in AtNIP7;1 led to increased plant tolerance to AsIII and reduced total As in planta. AtNIP7;1 expression in various yeast backgrounds increased AsIII sensitivity. In the acr3Δ yeast genotype, AtNIP7;1 caused a moderate increase in AsV tolerance. Short-term As uptake in fsp1Δ expressing AtNIP7;1 was significantly larger than that in the empty vector control.

The data suggest that AtNIP7;1 can mediate AsIII transport and contributes to AsIII uptake in plants.