Poster abstracts

Poster number 18 submitted by Manohar Chakrabarti

Exploring role of alternative polyadenylation during tall fescue-endophyte symbiosis under drought stress using genome wide approaches.

Manohar Chakrabarti (Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546), Randy D. Dinkins (USDA-ARS, Forage-Animal Production Research Unit, Lexington, KY 40546 ), Arthur G. Hunt (Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546)

Abstract:
Polyadenylation is a key step during mRNA processing. Although, poly (A) tails are predominantly added at the 3ʹ UTRs of mRNAs, however they can also be added at other parts of transcriptional units, like protein coding regions, introns and 5ʹ UTRs. Such instances of alternative polyadenylation can impact gene expression, mRNA stability and translation ability, etc. There are evidences of alternative polyadenylation being implicated in different developmental processes and human diseases (1-3). Additionally, there are indication of links between polyadenylation and oxidative stress signaling in plants (4, 5).
The current project delves into the role of alternative polyadenylation in the tall fescue-endophyte symbiotic system. Tall fescue is a cool season perennial forage grass, which forms a symbiotic association with endophytic fungi, Epichloe sp. Fescue plants provide shelter, nutrition and mode of dissemination to the fungi, while the fungi produce toxic alkaloids to deter herbivores and also confer resistance to various stresses. Endophyte infected (E+) and free (E-) tall fescue clone pairs were subjected to drought stress for two days, tissue samples in triplicates were collected from leaves and pseudostems, followed by RNA extraction, poly (A) tag library preparation and sequencing in Illumina platform (6). Global gene expression analysis using the poly (A) tags showed over representation of certain GO categories, namely, secondary metabolism, programmed cell death, reproductive processes, amine metabolism and post translational protein modification, etc. between E+ and E- plants under stress, but not between E+ and E- control plants. Comparison of global poly (A) profiles of E+ and E- plants under drought and control conditions indicates that in presence of endophyte there is some difference in poly (A) profile between drought stressed and control plants. Deep sequencing of the samples is underway to obtain more read coverage to substantiate preliminary findings. Additionally, confirmation of candidate genes displaying altered poly (A) profile between E+ and E- plants under drought is being carried out using 3ʹ RACE.

References:
1. Liu et al., Science, 2009. 327 (5961): 94-97.
2. Simpson et al., Cell, 2003. 113 (6): 777–787.
3. Mayr et al., Cell. 2009. 138 (4): 673-684.
4. Zhang et al., PLoS One. 2008. 3 (6): e2410.
5. Delaney et al., Plant Physiology. 2006. 140 (4): 1507-1521.
6. Ma et al., Methods.2014. 67 (1): 74-83.

Keywords: Alternative polyadenylation, Tall fescue, Drought