Antioxidative polyphenols from walnuts (Juglans regia L.)

Three hydrolyzable tannins, glansrins A-C, together with adenosine, adenine, and 13 known tannins were isolated from the n-BuOH extract of walnuts (the seeds of Juglans regia L.). Glansrins A-C were characterized as ellagitannins with a tergalloyl group, or related polyphenolic acyl group, based on spectral and chemical evidence. The 14 walnut polyphenols had superoxide dismutase (SOD)-like activity with EC(50) 21.4-190 microM and a remarkable radical scavenging effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (EC(50) 0.34-4.72 microM).     

Phylogeny and biogeography of Juglans (Juglandaceae) based on matK and ITS sequence data

We investigated phylogenetic and biogeographic relationships within Juglans (walnuts), a Tertiary disjunct genus, using 15 species of Juglans and related (Juglandaceae) outgroups. The relationships were analyzed using nucleotide sequences of the chloroplast gene matK and its flanking spacers and of the internal transcribed spacers (ITS) and 5.8S gene of the nuclear ribosomal DNA. The DNA sequences provided 246 informative characters for parsimony analysis. ITS data supported as monophyletic groups the four generic sections, Cardiocaryon, Dioscaryon, Rhysocaryon, and Trachycaryon. Within Rhysocaryon, the temperate black walnuts and the tropical black walnuts were supported as monophyletic groups. When the two data sets were combined, J. cinerea was nested within Cardiocaryon. Combined analysis with published nuclear DNA restriction site data placed J. cinerea in a monophyletic group with Cardiocaryon. These analyses consistently supported Juglans as a monophyletic group and as the sister group to the genus Pterocarya. The results of this work are consistent with the known geological history of Juglans. The fossil record suggests that the butternuts had evolved by the early Oligocene in North America. The presence of butternuts in Eurasia could be the result of migration from North America to Eurasia during the warming trend of the mid Oligocene.     

Searching for pheromone strains in the pecan nut casebearer

The pecan nut casebearer, Acrobasis nuxvorella Nuenzig (Lepidoptera: Pyralidae), is the most damaging insect pest of pecan, Carya illinoinensis (Wang) K. Koch (Juglandaceae), in the USA and Mexico. A pheromone monitoring program for A. nuxvorella has been developed to assist pecan growers in the timing of insecticide applications. The discovery that there are two pheromone types produced by A. nuxvorella has led to complications in the implementation of pheromone monitoring programs. One pheromone (referred to as standard) is attractive to moths in the southern USA, but not in Mexico. The other pheromone (referred to as Mexican) is attractive to moths in the southern USA and in Mexico. Because most male lepidopterans respond only to a specific pheromone, it was suspected that there were two pheromone strains of A. nuxvorella, one exclusively present in the northern distribution of A. nuxvorella (USA strain) and the other widely distributed from Sonora, Chihuahua, and Durango in northern Mexico to Texas, Georgia, and Oklahoma in the USA (Mexican strain). The goal of this research was to determine whether differences in pheromone response are sufficient to genetically isolate A. nuxvorella into pheromone strains. To confirm the existence of the two alleged pheromone strains, amplified fragment length polymorphism (AFLP) markers were obtained and analyzed. Four primer combinations were used to obtain a total of 483 polymorphic AFLP markers. Our results indicated that the standard and Mexican pheromones did not group A. nuxvorella into pheromone strains. However, three genetically distinct populations of A. nuxvorella were identified. Two of those three populations are sympatric throughout the southern USA and one is allopatric relative to the other two and occurs exclusively in pecan growing regions of Mexico.     

Naturally occurring quinols and quinones studied as semiquinones by electron spin resonance

A simple procedure using electron spin resonance techniques was applied to detect, identify and quantify quinones and quinols in crude plant extracts. Hydroquinone was determined in Pyrus, plumbagin in Drosera and Ceratostigma, and hydrojuglone in Juglandaceae. Hydrojuglone is found in markedly higher concentrations in Pterocarya and in Juglans than in Carya. Plastoquinol has been observed in 500 of 700 plant extracts studied. Esters of phenolic acids are easily detected and distinguished, e.g. chlorogenic and rosmarinic acids. Esters of homoprotocatechuic and of dihydrocaffeic acid occur widely in the Oleaceae. The limitations of the method are discussed.     

Fungal communities associated with roots of two closely related Juglandaceae species with a disjunct distribution in the tropics

We studied the biogeography and community structure of root-associated and ectomycorrhizal fungal communities in two related species of tropical Juglandaceae that have disjunct distributions in Asia and Mesoamerica. We tested the effects of environmental and dispersal factors in structuring root-associated fungi at a regional scale. We used Illumina sequencing to document fungi on the roots of Oreomunnea mexicana in Panama and Mexico and Alfaropsis roxburghiana in China. Ectomycorrhizal fungi dominated the communities with both hosts but we detected a more diverse root-associated fungal community in Alfaropsis but higher ectomycorrhizal fungi richness in Oreomunnea. Geographic distance was the best predictor of variation in fungal species composition, when including both hosts and when analyzing each host independently. However, our results showed a high correlation between geographic distance and abiotic variables, and therefore we were not able to determine if the observed changes in fungal community composition were explained also by spatially structured environmental or phylogenetic factors.