Investigating the functions of polycomb group proteins in potato development

Abstract

Phenotypic plasticity enables plants to cope with ever changing environmental conditions This often involves regulated gene expression mediated by chromatin modifiers such as Polycomb PcG and Trithorax TrxG group proteins Previous studies in Arabidopsis have shown the involvement of PcG proteins in controlling the several developmental transitions in plants however their role in other important crops is still unexplored S tuberosum ssp andigena is a photoperiod sensitive cultivar of potato in which stolon to tuber development is under the strict control of short day SD photoperiodic conditions Previous studies have identified several transcription factors mobile RNAs and plant growth hormones involved in controlling stolon to tuber development Interestingly many of these factors also control floral transition in Arabidopsis In this study we aimed to understand the role of selective PcG members StMSI1 StE z 2 and StBMI1 in controlling tuber development under different photoperiodic conditions Our investigation revealed differential expression of these genes in stolon under short day versus long day photoperiod condition We further show that overexpression of PRC members StMSI1 StE z 2 or knockdown of StBMI1 resulted in pleiotropic effects including altered leaf architecture and reduced below ground tuber yield Interestingly these lines exhibited enhanced miRNA156 accumulation accompanied by aerial tubers from axillary nodes similar to miRNA156 OE lines Through RNA sequencing analysis we found that these lines had decreased expression of auxin and brassinosteroid signaling transport genes whereas increased expression of cytokinin related genes possibly leading to reduced apical dominance and axillary stolon development Using ChIP sequencing we have identified the genes targeted by a PRC group histone methyltransferase StE z 2 during tuber development In addition to this we also investigated the genome wide occupancy of two important histone modification H3K27me3 and H3K4me3 from SD induced stolon tis newline newline