Community structure and diversity characteristics of rhizosphere and root endophytic bacterial community in different Acacia species.

Rhizosphere and endophytic microbiota significantly affect plant growth and development by influencing nutrient uptake and stress tolerance. Herein, root and rhizosphere soil of Acacia species were collected and analyzed to compare the structural differences of the rhizosphere and root endophytic bacterial communities. High-throughput 16S rRNA gene sequencing technology was employed to analyze the rhizosphere and root endophytic bacterial communities. A total of 4249 OTUs were identified following sequence analysis. The rhizosphere soil contained significantly more OTUs than the root soil. Principal component analysis (PCA) and hierarchical cluster analysis indicated that bacterial communities exhibited significant specificity in the rhizosphere and root soil of different Acacia species. The most dominant phylum in the rhizosphere soil was Acidobacteria, followed by Proteobacteria and Actinobacteria, whereas the dominant phylum in the root soil was Proteobacteria, followed by Actinobacteria and Acidobacteria. Among the various Acacia species, specific bacterial communities displayed different abundance. We systematically described the core bacteria in the rhizosphere and root endophytic bacterial communities and predicted their relevant functions. The type and abundance of specific bacteria were correlated with the nutrient absorption and metabolism of the Acacia species. This study addresses the complex host-microbe interactions and explores the rhizosphere and root bacterial community structure of different Acacia species. These results provide new insights into the role of rhizosphere and root endophytic bacterial communities on the growth and reproduction of Acacia, thus informing future efforts towards sustainable development and utilization of Acacia.

Mechanisms for Abscisic Acid Inhibition of Primary Root Growth.

Abscisic acid (ABA) plays pivotal roles in plant growth and development and in responses to diverse stresses. It also modulates the growth of primary and lateral roots. Much evidence indicated that key cellular components auxin, ethylene, PLETHs, reactive oxygen species and Ca2+ are involved in the regulation of ABA suppression of root elongation. In this review, we summary the molecular mechanism for ABA inhibiting primary root growth, focusing on the roles of these components in Arabidopsis.

[The exploration and practice of Genetic Engineering teaching].

Genetic Engineering is an important specialized basic course for the students majoring in life sciences. The quality of teaching is directly related to the students' professional quality and innovation ability. In order to improve the teaching quatity and train advanced biotechnical students, we made some reforms to the contents and teaching methods of Genetic Engineering according to the experience accumulated in recent years.

Heat stress increases the efficiency of EDTA in phytoextraction of heavy metals.

Solution culture and pot experiments were carried out to investigate the effects of root damage on phytoextraction of heavy metals. In hydroponics, roots of corn (Zea mays L.) seedlings were pretreated with heating stress, and then were exposed to 250 microM Pb+250 microM EDTA solutions for 7d. The results showed that the preheating treatment significantly increased Pb transportation from roots to shoots. In pot experiments, the effect of hot EDTA solution (95 degrees C) on the accumulation of heavy metal in the shoot of corn and pea (Pisum sativum L.) was also examined. Compared to normal EDTA (25 degrees C) treatment, application of hot EDTA solution to the soil surface increased the total removal of Pb in shoots of corn and pea by about 8- and 12-fold, respectively, in an artificially multimetal-contaminated soil. In addition, hot EDTA solution increased the shoot Cu removal by about 6-fold for corn and 9-fold for pea, respectively, in a naturally Cu-contaminated soil. These results suggested that exposure of roots to high temperature could increase the efficiency of EDTA on the accumulation of heavy metals in shoots. This new approach can help to minimize the amount of chelate applied in the field and reduce the potential risk of heavy metals' leaching.