ABSTRACT. The fruit peach originated in China and has a history of domestication of more than 4000 years. Numerous local cultivars were selected during the long course of cultivation, and a great morphological diversity exists. To study the diversity and genetic background of local peach cultivars in China, a set of 158 accessions from different ecological regions, together with 27 modern varieties and 10 wild accessions, were evaluated using 49 simple sequence repeats (SSRs) covering the peach genome. Broad diversity was also observed in local cultivars at the SSR level. A total of 648 alleles were amplified with an average of 13.22 observed alleles per locus. The number of genotypes detected ranged from 9 (UDP96015) to 58 (BPPCT008) with an average of 27.00 genotypes per marker. Eight subpopulations divided by STRUCTURE basically coincided with the dendrogram of genetic relationships and could be explained by the traditional groups. The 8 subpopulations were juicy honey peach, southwestern peach I, wild peach, Buddha peach + southwestern peach II, northern peach, southern crisp peach, ornamental peach, and Prunus davidiana + P. kansuensis. Most modern varieties carried the genetic backgrounds of juicy honey peach and southwestern peach I, while others carried diverse genetic backgrounds, indicating that local cultivars were partly used in modern breeding programs. Based on the traditional evolution pathway, a modified pathway for the development of local peach cultivars in China was proposed using the genetic background of subpopulations that were identified by SSRs. Current status and prospects of utilization of Chinese local peach cultivars were also discussed according to the SSR information.

Epigenetic variation may contribute to traits that are important in domestication, but how patterns of genetic and epigenetic variation differ between cultivated and wild plants remains poorly understood. In particular, we know little about how selection may shape epigenetic variation in natural and cultivated populations. In this study, we investigated 11 natural populations and 6 major cultivated populations using amplified fragment length polymorphism (AFLP) and methylation-sensitive AFLP (MS-AFLP or MSAP) markers to identify patterns of genetic and epigenetic diversity among Corydalis yanhusuo populations. We further explored correlations among genetic, epigenetic, alkaloidal, and climatic factors in natural and cultivated C. yanhusuo . We found support for a single origin for all cultivated populations, from a natural population which was differentiated from the other natural populations. The magnitude of F ST based on AFLP was significantly correlated with that for MSAP in pairwise comparisons in both natural and cultivated populations, suggesting a relationship between genetic and epigenetic variation in C. yanhusuo . This relationship was further supported by dbRDA (distance-based redundancy analyses) where some of the epigenetic variation could be explained by genetic variation in natural and cultivated populations. Genetic variation was slightly higher in natural than cultivated populations, and exceeded epigenetic variation in both types of populations. However, epigenetic differentiation exceeded that of genetic differentiation among cultivated populations, while the reverse was observed among natural populations. The differences between wild and cultivated plants may be partly due to processes inherent to cultivation and in particular the differences in mode of reproduction. The importance of epigenetic compared to genetic modifications is thought to vary depending on reproductive strategies, and C. yanhusuo usually reproduces sexually in natural environments, while the cultivated C. yanhusuo are propagated clonally. In addition, alkaloid content of C. yanhusuo varied across cultivated populations, and alkaloid content was significantly correlated to climatic variation, but also to genetic (6.89%) and even more so to epigenetic (14.09%) variation in cultivated populations. Our study demonstrates that epigenetic variation could be important in cultivation of C. yanhusuo and serve as a source of variation for response to environmental conditions.

The application effect of biochar in soil is often affected by environmental factors, but the effect of rhizosphere processes on the properties and functions of biochar remains unclear. The purpose of this study was to explore the effect of the aging process in the rhizosphere on the properties of biochar and the influence of the rhizosphere effect on the performance of biochar for immobilization of heavy metals through different wheat rhizosphere simulation experiments. After aging in the wheat rhizosphere, the physicochemical properties of rice husk biochar (RH BC) and sludge biochar (Sl BC) changed significantly. In general, ash content, specific surface area (SAA), and thermal stability were significantly reduced, while the oxygen (O) content, polarity and surface O-containing functional groups content were significantly increased. The increase of C = O and O = C-OH on the aged biochar surface promotes its adsorption capability for Cd2+ and Pb2+. In addition, the results of the root box experimental showed that the RH BC and Sl BC could effectively reduce the concentration of bioavailable heavy metals in soil, while the rhizosphere effect increases the bioavailability of heavy metals in rhizosphere soil, and then weakens the immobilization effect of RH BC, but has no significant effect on the Sl BC. The increased dissolved organic matter (DOM) content in the rhizosphere soil caused by wheat roots may be an important factor contributing to this phenomenon. Therefore, although the aging process in the rhizosphere may enhance the adsorption performance of biochar for heavy metal, the immobilization effect of biochar for heavy metals in the rhizosphere soil is still at risk of being weakened by the rhizosphere effect.

Correction for 'Arbuscular mycorrhizal fungi enhance the copper tolerance of Tagetes patula through the sorption and barrier mechanisms of intraradical hyphae' by Xishi Zhou et al., Metallomics, 2017, DOI: .