Burial of seeds by sediment often happens in lakes. Laboratory experiments were conducted to investigate the effects of burial by river sand and fishpond sediment on seed germination and seedling establishment of Vallisneria natans at depths of 0, 1, 3, and 5 cm. Sediment type had significant effects only on dry weight and total leaf area of the seedlings and did not interact with burial depth. In contrast, a significant negative correlation was observed between burial depth and all of the variables, including seed germination rate, seedling emergence rate, shoot length, dry weight, leaf number, total leaf area, root number, and total root length. Moreover, no seedlings emerged above the sediment surface in the 5 cm depth treatment in either sediment, even though seed germination was observed. In addition, the results showed that fishpond sediment was more effective than river sand in accumulation of dry matter and increase of leaf area. Therefore, taking measures to accelerate seed germination and seedling emergence could promote V. natans restoration when sowing seeds in eutrophic lakes.

A set of specific primer pairs was utilized to detect Apple chlorotic leaf spot virus (ACLSV) from seven different apple cultivars in Jiaodong Peninsula via reverse transcription polymerase chain reaction (RT-PCR), and the sequence of ACLSV genome was analysed. The results indicate that: (1) High-purity total RNA could be successfully isolated using plant RNA rapid extraction kit. The ratios of A260/A280 varied between 1.8 and 2.1. The fragmentation in agarose gel was good and the 28S and 16S bands were clear, which suggested that the extracted RNA had better quality and could be used for RT-PCR. (2) The amplified products by RT-PCR were approximately 220 bp, which showed the tested samples were infected by ACLSV in this study. (3) Sequencing analysis showed that the lengths of the target fragments were 217 bp, and the sequence identity rate ranged from 85.7% to 99.1% at the nucleotide level aligned with the corresponding sequences of other ACLSV strains in National Center for Biotechnology Information.

Juglans plant with important ecological and economic value is endangered in China. And the basis for its protection is the genetic diversity assessment. In the present study, the genetic diversity and the genetic structure of 134 samples from 9 natural J. mandshurica populations with 2 related species were surveyed by EST-SSR markers. The results showed that (1) 77 alleles were amplified within 9 EST-SSR markers which had high polymorphism (PIC = 0.5070). Compared with other Juglans species in China, the genetic diversity of J. mandshurica population in Shandong areas was relatively low (H O =0.3333, I=0.7051). (2) The AMOVA analysis showed that 89% variation occurred within the population of J. mandshurica in Shandong areas, and 11% occurred among the populations. The low genetic differentiation (F ST =0.103) and the high gene flow (Nm= 2.894) among populations may be related to the long-distance transmission of pollen. The results of Mantel test (r=-0.0870, p =0.4320) showed that there was no significant correlation between geographic distance and genetic distance. (3) UPGMA cluster analysis divided 8 J. mandshurica populations in Shandong areas into two groups. The results of STRUCTURE analysis suggested interspecific introgression exists between J. mandshurica and common walnuts ( J. regia L.). These genetic data would be great significance for biodiversity conservation for endangered J. mandshurica .

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