tailieunhanh - Enzymes in the Environment: Activity, Ecology and Applications - Chapter 4

Mặc dù các vùng rễ hạn được đặt ra bởi Hiltner (1) để mô tả cụ thể sự tương tác giữa các gốc rễ của cây họ đậu và vi khuẩn, việc sử dụng của thuật ngữ này đã mở rộng. Hôm nay chúng ta xem xét các vùng rễ là vùng ảnh hưởng của tất cả các hệ thống rễ thực vật, và nó bao gồm các lớp tế bào khác nhau của gốc (endorhizosphere), mà các vi sinh vật có thể xâm chiếm, bề mặt chân răng (rhizoplane) và khu vực xung quanh thư mục gốc (ectorhizosphere). Hiện. | 4 Enzymes and Microorganisms in the Rhizosphere David C. Naseby University of Hertfordshire Hatfield Hertfordshire England James M. Lynch University of Surrey Guildford Surrey England I. INTRODUCTION Although the term rhizosphere was coined by Hiltner 1 to describe specifically the interaction between the roots of legumes and bacteria the usage of the term has broadened. Today we consider the rhizosphere to be the zone of influence of all plant root systems and it includes the various cell layers of the root itself the endorhizosphere which microorganisms can colonize the root surface the rhizoplane and the region surrounding the root the ectorhizosphere . There has been steady progress in our understanding of the rhizosphere during the last 100 years and an increasing realization that it can have many influences on crop productivity Table 1 . However there has been a sudden increase in interest and investment in rhizosphere research in the past few years. This is largely due to the growth of biotechnology in relation to agriculture and in particular our increasing ability to manipulate plants by using recombinant deoxyribonucleic acid DNA . Even with the genetic information of the plant modified however there will still be a highly influential microbial population associated with the roots. Therefore the possibility exists that the balance between beneficial and harmful rhizosphere microorganisms might be improved not only by modification of the plant genotype but also by inoculation with useful and compatible microorganisms. The source of these useful bacteria and fungi could be either other soils and rhizospheres hence amplifying the natural population or introduction of foreign organisms that have been genetically modified to elevate their useful properties and or increase their competence to colonize the rhizosphere. Given current public opinion the latter is unlikely in the near future. The general properties of rhizospheres have been described in several .