A convenient, soil‐free method for the production of root nodules in soybean to study the effects of exogenous additives

Abstract

Legumes develop root nodules that harbor endosymbiotic bacteria, rhizobia. These rhizobia convert nitrogen to ammonia by biological nitrogen fixation. A thorough understanding of the biological nitrogen fixation in legumes and its regulation is key to develop sustainable agriculture. It is well known that plant hormones affect nodule formation; however, most studies are limited to model legumes due to their suitability for in vitro, plate‐based assays. Specifically, it is almost impossible to measure the effects of exogenous hormones or other additives during nodule development in crop legumes such as soybean as they have huge root system in soil. To circumvent this issue, the present research develops suitable media and growth conditions for efficient nodule development under in vitro, soil‐free conditions in an important legume crop, soybean. Moreover, we also evaluate the effects of all major phytohormones on soybean nodule development under identical growing conditions. Phytohormones such as abscisic acid (ABA) and jasmonic acid (JA) had an overall inhibitory effect and those such as gibberellic acid (GA) or brassinosteroids (BRs) had an overall positive effect on nodule formation. This versatile, inexpensive, scalable, and simple protocol provides several advantages over previously established methods. It is extremely time‐ and resource‐efficient, does not require special training or equipment, and produces highly reproducible results. The approach is expandable to other large legumes as well as for other exogenous additives.

Improvement of Medicago sativa Crops Productivity by the Co-inoculation of Sinorhizobium meliloti–Actinobacteria Under Salt Stress

“…IAA, besides being critical for nodule formation, have also been reported as essential trigger of cell proliferation and differentiation and formation. of vascular bundles [ 37 ]. As previously reported in previous studies, the phosphate solubilization ability was also present in our isolates [ 38 ].…”

Legume plant defenses and nutrients mediate indirect interactions between soil rhizobia and chewing herbivores

“…Jasmonic acid and ethylene are two key systemic defense pathways induced in plants against chewing herbivores (Pangesti et al, 2015;2016;Zhu et al, 2018). Similarly, beneficial microbes often also stimulate biosynthesis of abscisic acid (Sgroy et al, 2009;Jha & Subramanian, 2013), even though abscisic acid signaling can have negative effects on nodulation (Tominaga et al, 2010;Roy Choudhury, Johns & Pandey, 2019). Our study provides further evidence that rhizobia can affect herbivores by altering physical defenses such as callose (Ballhorn et al, 2014;Gaudioso-Pedraza et al, 2018) and antioxidants (Walz, Juenger, Schad & Kehr, 2002, Dumanović, Nepovimova, Natić, Kuča, & Jaćević, 2021.…”

An appraisal of bacterial Endophytes

“…In primordium cells, the microorganisms get to be distinctly encompassed by the plant membrane. Together shapes the symbioses, in which atmospheric nitrogen (N 2 ) is ixed and moved in return for starch (Choudhury et al, 2019). Symbioses have a structure like that of mycorrhizal arbuscular, additionally encompassed by a plant membrane.…”