Abstract Detail



Comparative Genomics/Transcriptomics

Ruhlman , Tracey A [1], Choi, In-Su [2], Jansen, Robert [1].

Lost and Found: Return of the inverted repeat in the legume clade defined by its absence.

The plant genome comprises a coevolving, integrated genetic system housed in three subcellular compartments: the nucleus, mitochondrion and the plastid.  The typical land plant plastid genome (plastome) comprises the sum of repeating units of 130-160 kb in length present in all plastid types in all cells of an individual.  The plastome inverted repeat (IR) divides each plastome monomer into large and small single copy regions, an architecture highly conserved across land plants.  There have been varying degrees of expansion or contraction of the IR, and in a few distinct lineages, including the inverted repeat lacking clade (IRLC) of papilionoid legumes, one copy of the IR has been lost.  Completion of plastome sequencing and assembly for 19 Medicago species and Trigonella foenum-graceum and comparative analysis with other IRLC taxa revealed modest divergence with regard to structural organization overall.  However, one clade contained unique variation suggesting an ancestor had experienced repeat-mediated, recombination dependent changes in plastome structure.  Taxa in this unique lineage contain oppositely oriented, duplicated sequences reminiscent of the ancestral IR.  In M. lupulina a quasi-IR structure was identified and in M. minima a novel IR of ~9 kb contained three of the four rRNA genes and the gene encoding trnR-ACG found in the typical angiosperm IR.  Plastome sequences were generated for additional taxa within the IR-reemergence clade to ascertain if other clade members contain novel structures.  Field collections of populations of M. minima and M. lupulina are underway in Texas.  The population study will employ a PCR strategy to survey for variation in the extent of the IR and IR-like structures.  


1 - University of Texas at Austin, Integrative Biology, Austin, TX, 78712, USA
2 - University Of Texas At Austin, Integrative Biology, 205 W 24th St, Austin, TX, 22212, United States

Keywords:
plastome
recombination
inverted repeat.

Presentation Type: Poster This poster will be presented at 5:30 pm. The Poster Session runs from 5:30 pm to 7:00 pm. Posters with odd poster numbers are presented at 5:30 pm, and posters with even poster numbers are presented at 6:15 pm.
Number: PGT009
Abstract ID:404
Candidate for Awards:None


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