Differential Effects of High-Temperature Stress on Nuclear Topology and Transcription of Repetitive Noncoding and Coding Rye Sequences

摘要

The plant stress response has been extensively characterizedat the biochemical and physiological levels. However, knowledgeconcerning repetitive sequence genome fraction modulationduring extreme temperature conditions is scarce. Westudied high-temperature effects on subtelomeric repetitivesequences (pSc200) and 45S rDNA in rye seedlings submittedto 40 ° C during 4 h. Chromatin organization patterns wereevaluated through fluorescent in situ hybridization and transcriptionlevels were assessed using quantitative real-timePCR. Additionally, the nucleolar dynamics were evaluatedthrough fibrillarin immunodetection in interphase nuclei.The results obtained clearly demonstrated that the pSc200sequence organization is not affected by high-temperaturestress (HTS) and proved for the first time that this noncodingsubtelomeric sequence is stably transcribed. Conversely, itwas demonstrated that HTS treatment induces marked rDNAchromatin decondensation along with nucleolar enlargementand a significant increase in ribosomal gene transcription.The role of noncoding and coding repetitive rye sequencesin the plant stress response that are suggested bytheir clearly distinct behaviors is discussed. While the hetero-chromatic conformation of pSc200 sequences seems to beinvolved in the stabilization of the interphase chromatin architectureunder stress conditions, the dynamic modulationof nucleolar and rDNA topology and transcription suggesttheir role in plant stress response pathways