Abstract
Nitrogen is one of the essential plant nutrients and a major factor limiting crop productivity. To meet the requirements of sustainable agriculture, there is a need to maximize biological nitrogen fixation in different crop species. Legumes are able to establish root nodule symbiosis (RNS) with nitrogen-fixing soil bacteria which are collectively called rhizobia. This mutualistic association is highly specific, and each rhizobia species/strain interacts with only a specific group of legumes, and vice versa. Nodulation involves multiple phases of interactions ranging from initial bacterial attachment and infection establishment to late nodule development, characterized by a complex molecular signalling between plants and rhizobia. Characteristically, legumes like groundnut display a bacterial invasion strategy popularly known as “crack-entry’’ mechanism, which is reported approximately in 25% of all legumes. This article accommodates critical discussions on the bacterial infection mode, dynamics of nodulation, components of symbiotic signalling pathway, and also the effects of abiotic stresses and phytohormone homeostasis related to the root nodule symbiosis of groundnut and Bradyrhizobium. These parameters can help to understand how groundnut RNS is programmed to recognize and establish symbiotic relationships with rhizobia, adjusting gene expression in response to various regulations. This review further attempts to emphasize the current understanding of advancements regarding RNS research in the groundnut and speculates on prospective improvement possibilities in addition to ways for expanding it to other crops towards achieving sustainable agriculture and overcoming environmental challenges.
Highlights
Leguminosae, after Asteraceae and Orchidaceae, the third-largest family of angiosperms and includes many agronomically and economically important crops [1]
We reviewed the advances in research pertaining to symbiotic interaction in a complex ecological system and the progress made in the molecular aspects of root nodule symbiosis (RNS), with special reference to groundnut
This was further supported by the fact that, compared to rhizobia, which are enclosed within infection threads, the rhizobia spreading intercellularly are continuously exposed to the defense system of the plant, and require the suppression of the plant defense system [51]
Summary
Leguminosae, after Asteraceae and Orchidaceae, the third-largest family of angiosperms and includes many agronomically and economically important crops [1]. Legumes are distinct from non-legume species in terms of the nitrogen acquisition by developing root nodules that fix atmospheric nitrogen through symbiotic N2 -fixing rhizobia This trait is both ecologically and agriculturally important. The latest evidences came from recent studies which involved molecular-omics approaches to identify key factors controlling the inception and progress of symbiosis through ‘crack-entry’ in selected legumes including groundnut [15,16]. These studies provided evidence of the interactions of the Nod factor (specific signal molecules secreted by rhizobia) with several signalling and hormonal biosynthesis-related genes during rhizobial infection. We reviewed the advances in research pertaining to symbiotic interaction in a complex ecological system and the progress made in the molecular aspects of RNS, with special reference to groundnut
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call