Abstract
BackgroundDue to their sessile life style, plant survival is dependent on the ability to build up fast and highly adapted responses to environmental stresses by modulating defense response and organ growth. The phytohormone jasmonate plays an essential role in regulating these plant responses to stress.ResultsTo assess variation of plant growth responses and identify genetic determinants associated to JA treatment, we conducted a genome-wide association study (GWAS) using an original panel of Vietnamese rice accessions. The phenotyping results showed a high natural genetic variability of the 155 tested rice accessions in response to JA for shoot and root growth. The level of growth inhibition by JA is different according to the rice varieties tested. We conducted genome-wide association study and identified 28 significant associations for root length (RTL), shoot length (SHL), root weight (RTW), shoot weight (SHW) and total weight (TTW) in response to JA treatment. Three common QTLs were found for RTL, RTW and SHL. Among a list of 560 candidate genes found to co-locate with the QTLs, a transcriptome analysis from public database for the JA response allows us to identify 232 regulated genes including several JA-responsive transcription factors known to play a role in stress response.ConclusionOur genome-wide association study shows that common and specific genetic elements are associated with inhibition of shoot and root growth under JA treatment suggesting the involvement of a complex JA-dependent genetic control of rice growth inhibition at the whole plant level. Besides, numerous candidate genes associated to stress and JA response are co-located with the association loci, providing useful information for future studies on genetics and breeding to optimize the growth-defense trade-off in rice.
Highlights
Due to their sessile life style, plant survival is dependent on the ability to build up fast and highly adapted responses to environmental stresses by modulating defense response and organ growth
After 7 days of exposure to JA, root length (RTL), shoot length (SHL), root weight (RTW), shoot weight (SHW) and total weight (TTW) were evaluated as parameters to analyze the dose-effect of JA on rice growth
To confirm whether the variation exhibited in a certain trait could be attributed to genetic variation, the heritability coefficient was calculated according to the formula given by (Wray and Visscher 2008)
Summary
Due to their sessile life style, plant survival is dependent on the ability to build up fast and highly adapted responses to environmental stresses by modulating defense response and organ growth. In response to the developmental cues or stress signals, JA-Ile is accumulated and percieved by the COI1 receptor, the JAZ repressors is recruited for ubiquitination and degradation through the 26S proteasome manner, thereby relieving the repression of transcription factors and enabling the expression of JAresponsive genes and JA responses (Wasternack and Hause 2013). Besides these main components, the JAZ repressor interact with other proteins, such as TOPLESS and NINJA (NOVEL INTERACTER of JAZ), to repress the transcription factor MYC2 (Pauwels et al 2010; Gasperini et al 2015). It is interesting to identify specific genes that could optimize the defense system of plants with less impact on growth
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