Brassinosteroids play multiple roles in nodulation of pea via interactions with ethylene and auxin
- PDF / 3,136,551 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 93 Downloads / 140 Views
SHORT COMMUNICATION
Brassinosteroids play multiple roles in nodulation of pea via interactions with ethylene and auxin Peter N. McGuiness1 · James B. Reid1 · Eloise Foo1 Received: 9 June 2020 / Accepted: 18 September 2020 © Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Main conclusion A comprehensive analysis of the role of brassinosteroids in nodulation, including their interactions with auxin and ethylene revealed that brassinosteroids inhibit infection, promote nodule initiation but do not influence nodule organogenesis or function. Abstract Nodulation, the symbiosis between legumes and rhizobial bacteria, is regulated by a suite of hormones including brassinosteroids. Previous studies have found that brassinosteroids promote nodule number by inhibiting ethylene biosynthesis. In this study, we examined the influence of brassinosteroids on the various stages of infection and nodule development. We utilise pea mutants, including brassinosteroid mutants lk, lka and lkb, the ethylene insensitive ein2 mutant and the lk ein2 double mutant, along with transgenic lines expressing the DR5::GUS auxin activity marker to investigate how brassinosteroids interact with ethylene and auxin during nodulation. We show that brassinosteroids inhibit the early stages of nodulation, including auxin accumulation, root hair deformation and infection thread formation, and demonstrate that infection thread formation is regulated by brassinosteroids in an ethylene independent manner. In contrast, brassinosteroids appear to act as promoters of nodule initiation through both an ethylene dependent and independent pathway. Although brassinosteroids positively influence the ultimate number of nodules formed, we found that brassinosteroid-deficiency did not influence nodule structure including the vascular pattern of auxin activity or nitrogen-fixation capacity. These findings suggest that brassinosteroids are negative regulators of infection but positive regulators of nodule initiation. Furthermore, brassinosteroids do not appear to be essential for nodule organogenesis or function. Given the influence of brassinosteroids on discreet stages of nodulation but not nodule function, manipulation of brassinosteroids may be an interesting avenue for future research on the optimisation of nodulation. Keywords Auxin · Brassinosteroid · Ethylene · Nodulation · Nitrogen fixation · Pea
Introduction Nodulation is a plant–microbe symbiosis formed almost exclusively between legumes and nitrogen fixing rhizobial bacteria (Mus et al. 2016). The plant provides energy to the bacteria, which in turn converts atmospheric nitrogen into ammonia for the plant (Lardi et al. 2016; Lodwig et al. 2003). Regulation of nodulation includes prominent roles Communicated by Soheil S Mahmoud. * Eloise Foo [email protected] 1
School of Natural Sciences, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
for plant hormones (Mathesius 2020). Auxin is a key hormone in nodulation, including promoting rhizobial infection, cell
Data Loading...
