山东省林业科学研究院

[Objective]Acer truncatum is a unique woody oil plant in China,which is very suitable for development and utilization,but it is very difficult to propagate and root ex vivo in tissue culture,establish a reasonable complete tissue culture ex vivo regeneration system,obtain a large number of seedlings and the current year's bud stem segment in a short period of time,which will provide a new way for the large-scale production of excellent seedlings of this species,and provide a research basis for the selection and breeding of A.truncatum seeds,the preservation and promotion of germplasm resources,etc.[Method]The germ segments and seeds of A.truncatum were used as the test materials,and the sterilization method and axillary bud induction,sub-proliferation and rooting medium were designed and screened by orthogonal design screening method and univariate screening method.Different concentrations of 6-BA,NAA and TDZ hormones were added to MS,1/2MS and NN69 basal medium,respectively,and the most suitable medium for each stage of A.truncatum was found through different ratios.[Result]The best collection time for bud stem segments in April of the year,after brushing the surface and rinsing for half an hour with washing powder solution,the sterilization effect was best with 75%alcohol 30 s + 0.1%HgCl2 soaked for 10 min.The most suitable medium at each stage of the regeneration system was MS basal medium,and the addition of different concentrations of hormones on the basis could induce the differentiation of young shoots into different organs.At the beginning of the culture stage,6-BA had the greatest effect on axillary bud induction,and the induction rate of optimal medium could reach 73.33%.In the secondary proliferation stage,TDZ had the greatest effect on adventitious bud differentiation,with a proliferation coefficient of up to 4.31,and a univariate screening method was used in the rooting stage,and it was found that 0.2 mg·L-1 IBA had the highest rooting rate and rooting number,reaching 93.33%and 4.3.[Conclusion]The optimal medium for A.truncatum is 1)Initiation culture:MS + 0.06 mg·L-1 6-BA and 0.06 mg·L-1 NAA,induction rate was 73.33%;2)proliferation culture:MS+ 0.3 mg·L-1 TDZ and 0.05 mg·L-1 NAA;3)Rooting culture:MS+0.2 mg·L-1 IBA.

Six mulberry varieties in Shandong Province were used to investigate their quality, physiological properties and volatile aroma components by sensory evaluation, physicochemical analysis and gas chromatography-mass spectrometry techniques. The results showed that “Baiyuwang” and “Dashi” had the highest weight and shape index. “Heizhenzhu”and “Moyu” appeared the highest hardness (3.32, 2.67 kg/cm2) and solid-acid ratio (92.87, 82.76), as well as higher polygalacturonase (PG) and lipoxygenase (LOX) activity. But the higher juice yield (63.32%, 61.19%) was found in “Moyu” and “Dashi”. In addition, “Dashi” and “Hongguo” had higher anthocyanin (0.58, 0.53 mg/g), total phenolic content (2.48, 2.59 mg/g), strong DPPH and ABTS+ free radical scavenging ability, followed by “Longguai”, “Moyu” and “Heizhenzhu”, while “Baiyuwang” was the lowest in anthocyanin and total phenolic. The analysis of volatile aroma components showed that “Moyu” had the most aroma species and reached 62, followed by “Dashi” and “Baiyuwang”. Among them, the aroma components of “Heizhenzhu” and “Dashi” were mainly alcohols, however, “Moyu”, “Longguai” and “Baiyuwang” were mainly aldehydes, ketones and olefins. The common aroma components of the six varieties were mainly 2-amino-6-methylbenzoic acid and hexanal. The study provides a reference for the quality evaluation, processing and utilization of mulberry varieties.

Plant roots recruit enormous diverse microorganisms from the complex soil environment， the rhizosphere microbial communities， which is beneficial to plant health. In this work， the rhizosphere and non-rhizosphere soil samples were collected during the budding period， flowering period and fruiting period of walnut， respectively. The high-throughput sequencing and the subsequent analysis of differential species and function， and microbial ecological network correlation were performed to characterize the rhizosphere microbial communities of walnut during different growth periods. Results showed that there was certain difference in the dominant microorganisms dwelling in the walnut rhizosphere during different growth periods. The relative abundance of Bacillus and unidentified Fungi significantly increased during the budding period; unidentified Chloroplast， Cladosporium， Alternaria and Acaulium significantly increased during the flowering period; unidentified Micrococcaceae， Pseudomonas， Streptomyces， Gibberella and Mortierella significantly increased during the fruiting period. Among them， Bacillus （3.0%）， unidentified Chloroplast （4.5%） and Pseudomonas （17.9%） were the dominant beneficial genera in the rhizosphere soil during the budding period， flowering period and fruiting period， respectively. The structure of microbial communities in the rhizosphere also significantly changed during different growth periods （P＜0.05）. The topological features indicated that compared to the non-rhizosphere soil， the microbial ecological network in the rhizosphere soil showed stronger， more complex and tighter correlations. The network complexity of bacterial and fungal communities was highest during the fruiting period and budding period， respectively， while the positive correlation was highest during the budding period and fruiting period， respectively. Collectively， this study provided a theoretical basis for the collection of soil samples and the screening of beneficial bacteria for walnut growth promotion and biocontrol.