Botany and Plant Pathology Seminar Series
Speaker: Mr. Chris Dugard - Department of Botany and Plant Pathology - Purdue University
Topic: Utilizing next-generation sequencing technology to rapidly identify cell wall mutants
When: Wednesday, February 27, 2013 at 3:30 pm in WSLR 116

There has always been interest in the plant cell wall because of its importance in areas such as the food and textiles industry.  With cellulose being the primary substrate in the production of ethanol, interest in recent years is even higher.  The plant cell wall is a rigid yet dynamic structure of cellulose microfibrils tethered by an array of structurally diverse cross-linking glycans to form a strong, stable network.  This network is embedded in a pectin matrix that is sometimes cross-linked further with structural proteins or phenolic substances.  Plants devote roughly 10% of their genome to the synthesis of the cell wall.  Forward genetics has been an important tool in the discovery of some of the key genes in this process.  For example, the EMS-derived murus mutants have aided in the discovery of several genes related to nucleotide interconversion, xyloglucan synthesis, and cellulose synthesis.  Through a combination of traditional marker-based mapping and the utilization of next-generation sequencing, we found that low cell-wall arabinose mutant, mur5, encodes a defective allele of Reversibly Glycosylated Polypeptide 2 (RGP2) – a mutase implicated in the interconversion of UDP-arabinopyranose and UDP-arabinofuranose.  Identity of the mutant was confirmed by complementation of mur5 and two associated SALK alleles with wild-type RGP2 placed under the control of the 35S promoter, which recovered wild-type arabinose levels. We have also attempted to improve on current mapping techniques by directly sequencing mur6, mur7, and mur8 without developing a mapping population.  If the original background of the parental line is known and the mutants have been sufficiently backcrossed, G®A transitions should be enriched around the causal mutation, allowing for its identification.  Use of this technique would greatly hasten the identification and characterization of cell wall mutants.

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