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Identification and Characterization of Bacterial Genes Involved in the Medicago-Sinorhizobium Symbiosis.

Record Type:	Language materials, manuscript : Monograph/item
Title/Author:	Identification and Characterization of Bacterial Genes Involved in the Medicago-Sinorhizobium Symbiosis./
Author:	Nelson, Matthew S.
Description:	1 online resource (160 pages)
Notes:	Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
Contained By:	Dissertation Abstracts International79-04B(E).
Subject:	Plant sciences. -
Online resource:	click for full text (PQDT)
ISBN:	9780355522020

Identification and Characterization of Bacterial Genes Involved in the Medicago-Sinorhizobium Symbiosis.
Nelson, Matthew S.

Identification and Characterization of Bacterial Genes Involved in the Medicago-Sinorhizobium Symbiosis. - 1 online resource (160 pages)

Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.

Thesis (Ph.D.)

Includes bibliographical references

Biological nitrogen fixation is both ecologically and agriculturally important. Rhizobia are soil bacteria which form a symbiosis with legumes, fixing nitrogen in exchange for carbon. The goal of this research was to identify and determine the function of genes which are not required for the establishment of symbiosis, but have an effect on the efficacy of the symbiotic interaction. In Chapter 1, I demonstrate the type IV secretion system has an effect on symbiosis. Bacterial proteins were tested for their ability to translocate through the type IV secretion system into the host cell. One protein, TfeA, was transported into the host cell. Deleting tfeA resulted in decrease nodule number and strain competitiveness for nodule occupancy. TfeA-like proteins were also identified in 12 different rhizobia species. In Chapter 2, I showed TfeA binds to Medicago truncatula ARF2 in vivo and Glycine max ARF27. Constitutively expressed tfeA was unable to be recovered in Medicago sativa (alfalfa) or M. truncatula. Inducible tfeA was successfully transformed in M. truncatula, but expression is inconsistent. TfeA binding to ARF2 in planta offers additional insights into the role of auxin during nodule formation. In Chapter 3, I use PacBio sequencing technology to assemble 10 strains of Sinorhizobium. Analysis of 16 Sinorhizobium complete genomes showed that most strains have small accessory plasmids. These plasmids carry genes which are not required for symbiosis, but have an effect on the symbiotic process. Accessory plasmids combine with pSymA to allow for the gain and loss of symbiosis genes. The type IV secretion system and tfeA was found on pSymA or an accessory plasmid depending on the strain. Overall, this research identified important bacterial genes which modulate symbiosis.

Electronic reproduction.
Ann Arbor, Mich. :
ProQuest,
2018

Mode of access: World Wide Web

ISBN: 9780355522020Subjects--Topical Terms:

1179743
Plant sciences.
Index Terms--Genre/Form:

554714
Electronic books.

Identification and Characterization of Bacterial Genes Involved in the Medicago-Sinorhizobium Symbiosis.
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245 1 0 $a Identification and Characterization of Bacterial Genes Involved in the Medicago-Sinorhizobium Symbiosis.
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500 $a Source: Dissertation Abstracts International, Volume: 79-04(E), Section: B.
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502 $a Thesis (Ph.D.) $c University of Minnesota $d 2017.
504 $a Includes bibliographical references
520 $a Biological nitrogen fixation is both ecologically and agriculturally important. Rhizobia are soil bacteria which form a symbiosis with legumes, fixing nitrogen in exchange for carbon. The goal of this research was to identify and determine the function of genes which are not required for the establishment of symbiosis, but have an effect on the efficacy of the symbiotic interaction. In Chapter 1, I demonstrate the type IV secretion system has an effect on symbiosis. Bacterial proteins were tested for their ability to translocate through the type IV secretion system into the host cell. One protein, TfeA, was transported into the host cell. Deleting tfeA resulted in decrease nodule number and strain competitiveness for nodule occupancy. TfeA-like proteins were also identified in 12 different rhizobia species. In Chapter 2, I showed TfeA binds to Medicago truncatula ARF2 in vivo and Glycine max ARF27. Constitutively expressed tfeA was unable to be recovered in Medicago sativa (alfalfa) or M. truncatula. Inducible tfeA was successfully transformed in M. truncatula, but expression is inconsistent. TfeA binding to ARF2 in planta offers additional insights into the role of auxin during nodule formation. In Chapter 3, I use PacBio sequencing technology to assemble 10 strains of Sinorhizobium. Analysis of 16 Sinorhizobium complete genomes showed that most strains have small accessory plasmids. These plasmids carry genes which are not required for symbiosis, but have an effect on the symbiotic process. Accessory plasmids combine with pSymA to allow for the gain and loss of symbiosis genes. The type IV secretion system and tfeA was found on pSymA or an accessory plasmid depending on the strain. Overall, this research identified important bacterial genes which modulate symbiosis.
533 $a Electronic reproduction. $b Ann Arbor, Mich. : $c ProQuest, $d 2018
538 $a Mode of access: World Wide Web
650 4 $a Plant sciences. $3 1179743
650 4 $a Microbiology. $3 591510
655 7 $a Electronic books. $2 local $3 554714
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