There are approximately 450 species of oaks (Quercus L., Fagaceae) and they are the dominant tree species in many ecosystems and landscapes throughout the Northern Hemisphere (Plomion et al., 2016).Classifying oak trees is challenging because of the existence of a large number of interspecific morphological characteristics and intraspecific morphological variations, partly due to hybridization and introgression, subsequently influencing the phylogenetic reconstruction of oak spe-

Key message It reports relevant traits of diploid and autotetraploid apple plants ('Hanfu' and 'Gala') in response to drought. The differences indicate that apple plants ('Hanfu' and 'Gala') may differ in their response to drought stress depending on ploidy level. Abstract The induction of polyploidy ameliorates the adverse effects of drought in many plants. In this study, the tolerance responses of diploid and autotetraploid apple with two cultivars were compared under drought stress treatment induced by polyethylene glycol (PEG)-6000 in the laboratory. Autotetraploid apple plants were previously induced in vitro from the diploid apple (Malus 9 domestica, 2n = 2x = 34) cultivar 'Hanfu' and 'Gala' by colchicine treatment. In this study, we elucidated the effects of drought stress on apple by investigating the following parameters in leaves: relative water content (RWC), proline content, malondialdehyde (MDA) content and expression of key aquaporin genes. Under drought stress, autotetraploid apple had higher RWC and chlorophyll fluorescence parameters and lower levels of MDA and proline compared with diploid apple. Key aquaporins genes were induced in leaves in response to PEG6000 treatment, including MdPIP1;1 and MdTIP1;1. The expression of these genes induced under drought stress treatment, and the genes were expressed at lower levels in the autotetraploid than in the diploid. Our combined physiological and molecular data reveal that polyploidization can enhance drought tolerance in 'Hanfu' and 'Gala' apple.

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Rice and drinking water are recognized as the dominant sources of arsenic (As) for human intake, while little is known about As accumulation and speciation in Chinese Herbal Medicines (CHMs), which have been available for many hundreds of years for the treatment of diseases in both eastern and western cultures. Inorganic arsenic was the predominant species in all of CHMs samples. The levels of inorganic arsenic in CHMs from fields and markets or pharmacies ranged from 63 to 550 ng/g with a mean of 208 ng/g and 94 to 8683 ng/g with a mean of 1092 ng/g, respectively. The highest concentration was found in the Chrysanthemum from pharmacies. It indicates that the risk of inorganic As in CHMs to human health is higher in medicines from markets or pharmacies than that collected directly from fields. Some CHMs may make a considerable contribution to the human intake of inorganic arsenic.

Peritrophic membranes (PMs) are composed of proteins, proteoglycans and chitin that play important roles in the structural formation and function of the PM. This study identified and characterized a new chitin binding protein named HpCBP45 by immunoscreening of the Holotrichia parallela larvae midgut expression library. The predicted amino acid sequence indicates that it contains eight tandem chitin binding domains belonging to the peritrophin-A family. The HpCBP45 protein was expressed as a recombinant protein in the yeast Pichia pastoris and chitin binding assay demonstrated that recombinant HpCBP45 protein could strongly bind to chitin. qRT-PCR analysis showed that HpCBP45 was mainly localized in the midgut, further confirming the H. parallela PM belongs to Type I PM. The discovery and characterization of the peritrophic membrane protein HpCBP45 provides a basis for the further investigation of its biochemical and physiological functions in H. parallela.

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The eastern Liaoning Province of China has rich morphological diversity in walnut fruit, which is beneficial for selecting promising characters for marketability purposes. However, only a few reports have addressed morphological diversity in this region. In this study, J. mandshurica nuts and kernels from six geographical provenances were assessed for morphological traits, such as nut longitudinal diameter, nut lateral diameter, nut transverse diameter, mean diameter, nut weight, kernel weight, shell thickness, nut sutural thickness, kernel percentage, and index of roundness. Morphological traits proved to be quite variable and showed differences both within and among the geographical provenances. The frequency distribution of the traits had single peaks and followed a normal distribution. Principal component analysis revealed that 81.062% of the total variance was explained by the first three components. An unweighted PGM with averaging cluster analysis divided the geographical provenances into two groups; cluster I, containing five geographical provenances, and cluster II, containing only one. The study highlighted that the traits related to nut weight were of importance for discrimination, and Fushun is the optimal geographical provenance for breeding and selection. This study could provide a basis and reference for further understanding of the genetic resources of Juglans mandshurica fruit types.