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United States Department of Agriculture

Agricultural Research Service

Research Project: NATIONAL RHIZOBIUM GERMPLASM RESOURCE COLLECTION, GENETIC RESOURCE MANAGEMENT, SYSTEMATICS, AND BIOINFORMATICS Title: Sinorhizobium meliloti strains TII7 and A5 by Multilocus Sequence Typing (MLST) have chromsomes identical with Rm1021 and form an effective and ineffective symbiosis with Medicago truncatula line Jemalong A17, respectively

Authors
item Zribi, Kais -
item Mhadhbi, Haythem -
item Badri, Yazid -
item Aouani, Mohamed -
item Van Berkum, Peter

Submitted to: Canadian Journal of Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 15, 2011
Publication Date: October 1, 2011
Citation: Zribi, K., Mhadhbi, H., Badri, Y., Aouani, M.E., Van Berkum, P.B. 2011. Sinorhizobium meliloti strains TII7 and A5 by Multilocus Sequence Typing (MLST) have chromsomes identical with Rm1021 and form an effective and ineffective symbiosis with Medicago truncatula line Jemalong A17, respectively. Canadian Journal of Microbiology. 59:996-1002.

Interpretive Summary: Certain crops called legumes, important to North American agriculture, require bacteria to be associated with them in order to produce nitrogen for growth and production. Most of these crops originally came from other countries. So the problem is how to find the best bacteria to help these plants grow since the bacteria that evolved with the crops did not necessarily come to North America when the crops were brought here. In this work we wanted to find out if a certain type of alfalfa varied in its growth capability when associated with different bacteria. We identified two bacteria from North Africa, one with which the plant grew well and the other with which the plant did not grow well. We inspected the genes that are thought to influence this difference in plant growth. However, these genes in both bacteria were the same. This would indicate that other bacterial genes control whether the plant does or does not grow well. We suggested two possible methods that could be used to discover the genes that cause the difference in plant growth. Our results also indicate the necessity to provide the correct bacteria at planting so that the crop is able to grow and produce. This information will be valuable to companies who sell these bacteria for crops. Also, geneticists will find this information useful in their studies to determine how these bacteria can change the growth of crop plants.

Technical Abstract: The strains TII7 and A5 formed an effective and ineffective symbiosis with Medicago truncatula Jemalong A17, respectively. Both were shown to have identical chromsomes with strains Rm1021 and RCR2011 using a Multilocus Sequence Typing method. The 2260 bp segments of DNA stretching from the 3’ end of exoI through ORFs of hypothetical proteins SM_b20952 and SM_b20953 through exoH into the 5’ end of exoK in strains TII7 and Rm1021 differed by a single nucleotide at base 127 of hypothetical protein SM_b20953. However, this ORF in the effective and ineffective strains TII7 and A5 were identical. The exoH genes of strains TII7, Rm1021 and A5 were identical but varied with the gene in strain Rm41 by a single position. In strain Rm41 a “CT” repeat sequence was identified upstream of exoH where in Rm1021 the start codon of SM_b20953 is located, perhaps altering the expression of exoH in Rm41. Complemention or complete genome sequence analyses involving strains TII7 and A5 might be useful approaches to investigate the molecular bases for the differential symbiotic response with M. truncatula Jemalong A17.

Last Modified: 12/22/2014
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