Molecular phylogeny of Juglans (Juglandaceae): a biogeographic perspective

Abstract

The eastern Asian and eastern North American disjunction in Juglans offers an opportunity to estimate the time since divergence of the Eurasian and American lineages and to compare it with paleobotanical evidence. Five chloroplast DNA noncoding spacer (NCS) sequences: trnT−trnF, psbA−trnH, atpB−rbcL, trnV-16S rRNA, and trnS-trnfM and data from earlier studies (matK, ITS, and nuclear RFLP) were used to reconstruct phylogeny and to estimate the divergence time of major lineages. Seventeen taxa from four sections of Juglans and two outgroup taxa, Pterocarya stenoptera and Carya illinoiensis were included. NCS data was congruent only with matK data. Both maximum parsimony (MP) and maximum likelihood (ML) cladograms were concordant at the sectional level and revealed three well-supported monophyletic clades corresponding to sections Juglans, Cardiocaryon, and Rhysocaryon in both NCS and combined analyses. The single extant American butternut, Juglans cinerea was placed within the poorly resolved, but well-supported Rhysocaryon. Placement of taxa within Rhysocaryon and Cardiocaryon were inconsistent between NCS and combined analyses. Overall, the results suggest that: (1) the NCS sequence divergence observed within and between sections of Juglans is low and the addition of matK data only marginally improved resolution within Rhysocaryon;(2) the early divergence of section Juglans in both MP and ML analyses of NCS and combined data implies its ancient origin in contrast to fossil evidence, which suggests the earliest divergence of sections Rhysocaryon and Cardiocaryon; and (3) the extant taxa may not hold the footprints to unravel the evolutionary history of the genus.

Walnut: past and future of genetic improvement

“…In addition, there was an adaptation to Neogene cool climate (~23 to~3 mya) (Wolfe 1978) and other expansions towards Southeastern Europe and Central and South America during late Myocene (~12 to~5 mya). From studying chloroplast DNA (cpDNA) intergenic spacer sequences, it seems that the division within genus Juglans (Rhysocaryon, Cardiocaryon, and Dioscaryon sections only) occurred during a period ranging from~50 to~40 mya, which matches with fossil analyses (Aradhya et al 2006(Aradhya et al , 2007 (Fig. 2).…”

“…In walnut, buds enter dormancy from mid- Fig. 2 Simplified distribution of Juglans taxa adapted from Aradhya et al (2007) and Germain et al (1999). Distribution of cultivated species J. regia extends beyond its natural range August to early October and under temperate climate conditions; chilling requirements necessary for breaking dormancy are normally met by early January (Germain et al 1999).…”

Toxicidad, actividad antioxidante in vitro e hipoglicemiante in vitro e in vivo del extracto acuoso de Juglans neotropica Diels (nogal peruano)

“…La Juglans neotropica Diels, nogal peruano, crece en la zona norte y oriente del país (14) , es una especie cuyo uso más reconocido ha sido en la coloración de textiles (15) , pero también se ha descubierto que sus hojas favorecen a la cicatrización de las heridas (16) y mejoran procesos respiratorios por posibles efectos antibacterianos (17) . Trabajos previos que sugieren una alta actividad antioxidante (18) se da la posibilidad de evaluar el posible efecto hipoglicemiante que podría tener esta planta.…”

The complete chloroplast genome of common walnut (Juglans regia)

“…Juglans L. is one of the eight living genera in the family Juglandaceae consisting of 21 extant taxa (Manning 1978;Aradhya et al 2007). The common walnut (Juglans regia L.) is the most economically important member of the genus Juglans because of its high-quality timber and nutritious nuts (Pollegioni et al 2015).…”