Molecular basis of regulations for root nodule symbiosis between Bradyrhizobium and ‘crack-entry’ legume groundnut (Arachis hypogaea L.)

Authors: SHARMA, VINAY - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; BHATTACHARYYA, SAMRAT - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; KUMAR, RAKESH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; KUMAR, ASHISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; IBANEZ, FERNANDO - National University Of Rio Cuarto; WANG, JIANPING - University Of Florida; Guo, Baozhu; SUDINI, HARI - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; GOPALAKRISHNAN, SUBRAMANIAM - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; DASGUPTA, MAITRAYEE - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; VARSHNEY, RAJEEV - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India; PANDEY, MANISH - International Crops Research Institute For Semi-Arid Tropics (ICRISAT) - India

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2020
Publication Date: 2/20/2020
Citation: Sharma, V., Bhattacharyya, S., Kumar, R., Kumar, A., Ibanez, F., Wang, J., Guo, B., Sudini, H.K., Gopalakrishnan, S., Dasgupta, M., Varshney, R.K., Pandey, M.K. 2020. Molecular basis of regulations for root nodule symbiosis between Bradyrhizobium and ‘crack-entry’ legume groundnut (Arachis hypogaea L.). Plants. 9:276. https://doi.org/10.3390/plants9020276.
DOI: https://doi.org/10.3390/plants9020276

Interpretive Summary: Peanut is an important oil seed crop. Surprisingly, the N fixation efficiency in peanut is relatively low as compared to other legume species. In contrary to the model legume plants, the molecular mechanism of root nodule symbiosis in peanut is largely unknown. Therefore, understanding towards the evolution of nitrogen-fixation by plant nodules and identification of key genes involved in this phenomenon in different legume species is important for sustainable crop production. In legumes, peanut can be used as a model crop plant to understand the crack entry mechanism during root nodule symbiosis (RNS). Further, combining the available knowledge and the molecular explanations from peanut will help researcher in developing in-depth understanding of the biological mechanism controlling RNS. In this article, the information was summarized in the area of advancement in research pertaining to symbiotic interaction in a complex ecological system and the progress made in the molecular aspects of RNS, with special interest to peanut.

Technical Abstract: Nitrogen is one of the essential plant nutrients and a major limiting factor in crop productivity. To meet the challenges of sustainable agricultural production, there is a need to maximize biological nitrogen fixation in different crop species. Legume plants are capable to engage in root nodule symbiosis (RNS) with nitrogen-fixing soil bacteria collectively called rhizobia. This mutualistic association is highly specific, where each rhizobia species/strain interacts only with a specific group of legumes, and vice versa. The signaling communication between plants and rhizobia is complex, involving multiple phases of interactions ranging from initial bacterial attachment and infection establishment to late nodule development. Characteristically, legumes like groundnut have a bacterial invasion strategy popularly known as “crack-entry’’ mechanism, which is reported approximately in 25% of all the legumes. This article captures the critical discussions on the diversity of rhizobia strains, components of symbiotic signaling, genetic control of root nodule organogenesis, dynamics of nod factor perception, bacterial infection modes and the effects of abiotic stresses and phytohormone homeostasis related to root nodule symbiosis. These parameters can help to understand how groundnut RNS has evolved to recognize and establish complex ecological relationships with particular species and strains of rhizobia, adjusting gene expression in response to bacterial identity determinants. This review further attempts to emphasize the current understanding of molecular advancements regarding RNS research in groundnut and speculates prospective scopes.