Date of Completion

2018

Document Type

Honors College Thesis

Department

Plant Biology

Type of Thesis

Honors College

First Advisor

Jeanne Harris

Second Advisor

Stephen Keller

Third Advisor

Jill Preston

Keywords

symbiosis, legume, nitrogen, root architecture, phenotyping

Abstract

Determining the function of the NPF1B and NPF1C genes in root and nodule development in Lotus japonicus

Legumes form a symbiosis with a group of soil bacteria collectively known as Rhizobium. In this symbiosis, Rhizobium induce the legumes to form lateral root organs called nodules, which house the Rhizobium. The legumes provide sugars to their symbiotic partners, and in exchange, the Rhizobium convert atmospheric nitrogen to a form that their host plant can assimilate through a process known as nitrogen fixation (Haag et al., 2012). The LATD/NIP gene provides a strong piece of evidence for the hypothesis that nodules evolved from lateral roots, as it is required for the development of both roots and nodules in M. truncatula (Bright, Liang, Mitchell, & Harris, 2005). The LATD/NIP gene is part of the Nitrate and Peptide Transporter Family (NPF) (Léran et al., 2014). Subfamily 1 (NPF1) is comprised of five clades (A, B, C, D1, and D2) based on their evolutionary relationships. MtLATD/NIP falls in NPF1C (G. Sassi, unpublished data). The evolution of the NPF1 subfamily shows interesting patterns of gene retention, duplication, and loss, but up until this point, MtLATD/NIP was the only phenotypically characterized gene in planta in the NPF1 subfamily. Here, the NPF1B and NPF1C (LATD/NIP) genes are phenotypically characterized in the model legume species Lotus japonicus. Here I show that in L. japonicus, LATD/NIP is indeed involved in lateral root and nodule formation. I also show that LjNPF1B is involved in the development of both lateral and primary roots, but does not seem to be involved in nodule formation. The work presented here has interesting implications for the evolution of the NPF1 subfamily of genes.

Haag, A. F., Arnold, M. F. F., Myka, K. K., Kerscher, B., Dall’Angelo, S., Zanda, M., . . . Ferguson, G. P. (2012). Molecular insights into bacteroid development duringRhizobium–legume symbiosis. FEMS Microbiology Reviews, 37, 364-383.

Bright, L. J., Liang, Y., Mitchell, D. M., & Harris, J. M. (2005). The LATD Gene of Medicago truncatula Is Required for Both Nodule and Root Development. Molecular Plant-Microbe Interactions, 18(6), 521-532.

Léran, S., Varala, K., Boyer, J.-C., Chiurazzi, M., Crawford, N., Daniel-Vedele, F., . . . Lacombe, B. (2014). A unified nomenclature of NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER family members in plants. Trends in Plant Science, 19, 5-9

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License.

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