关键词: 根系-微生物互作, 细根寿命, 细胞程序性死亡, 群感信号, 活性氧

Abstract:

Fine roots play important roles in biological and ecological processes of the forest ecosystem. The lifespans of fine roots are controlled by tree species genetics and environmental factors. Rhizosphere serves as an interaction zone among plant, soil and microbes, in which the biological and ecological processes demonstrate decisive significances on root lifespans. Based on the dominant factors controlling root lifespans, this review focuses on three topics about the effects of plant roots and microbes interaction on root lifespans (i.e, the carbon rhizo-deposition and micro-ecological processes in rhizosphere, the effects of roots on microbial communities assembly in rhizosphere soils, the potential mechanisms of microbial communities modulating fine root lifespan). In the review, the chemical cross-talk between plant and microbes is considered to be very important in the future studies about the relationship between roots and soils. The photosynthetic carbon provides the connection between roots and soil microbes. The carbon accumulation in rhizosphere soils promotes the colonization of microbes around the roots, leading to the significant differences of microbial communities between rhizosphere and bulk soils. The signal substances from roots and microbes might affect root growth and development during the root-soil interaction. As the important quorum sensing signal among bacteria, Acyl-homoserine lactones (AHLs) could attend the modulation of root cell apoptosis. The reactive oxygen species (ROS) was observed to be accumulated in the roots after being infected by fungi, which also modulated the root cell apoptosis; however, the study about microbes attending the modulation of root lifespan is still not reported. Two models should be established in the future, one is about the relationships between bacterial communities succession, quorum sensing signals expression, and fine root longevity, another is about the relationships between fungal infection, ROS homeostasis modulation, and fine root longevity. The models would provide insights into the micro-ecological modulation mechanism of fine roots senescence and apoptosis in trees, and also be helpful to reveal the effects of root-soil interaction on fine root lifespans.

Key words: roots-microbes interaction, fine root lifespan, programmed cell death, quorum sensing signal, reactive oxygen species (ROS)