title: Pre-symptomatic transcriptome changes during cold storage of chilling sensitive and resistant peach cultivars to elucidate chilling injury mechanisms.
abstract: BACKGROUND
  Cold storage induces chilling injury (CI) disorders in peach fruit (woolliness/mealiness, flesh browning and reddening/bleeding) manifested when ripened at shelf life. To gain insight into the mechanisms underlying CI, we analyzed the transcriptome of 'Oded' (high tolerant) and 'Hermoza' (relatively tolerant to woolliness, but sensitive to browning and bleeding) peach cultivars at pre-symptomatic stages. The expression profiles were compared and validated with two previously analyzed pools (high and low sensitive to woolliness) from the Pop-DG population. The four fruit types cover a wide range of sensitivity to CI. The four fruit types were also investigated with the ROSMETER that provides information on the specificity of the transcriptomic response to oxidative stress.
  
  
  RESULTS
  We identified quantitative differences in a subset of core cold responsive genes that correlated with sensitivity or tolerance to CI at harvest and during cold storage, and also subsets of genes correlating specifically with high sensitivity to woolliness and browning. Functional analysis indicated that elevated levels, at harvest and during cold storage, of genes related to antioxidant systems and the biosynthesis of metabolites with antioxidant activity correlates with tolerance. Consistent with these results, ROSMETER analysis revealed oxidative stress in 'Hermoza' and the progeny pools, but not in the cold resistant 'Oded'. By contrast, cold storage induced, in sensitivity to woolliness dependant manner, a gene expression program involving the biosynthesis of secondary cell wall and pectins. Furthermore, our results indicated that while ethylene is related to CI tolerance, differential auxin subcellular accumulation and signaling may play a role in determining chilling sensitivity/tolerance. In addition, sugar partitioning and demand during cold storage may also play a role in the tolerance/sensitive mechanism. The analysis also indicates that vesicle trafficking, membrane dynamics and cytoskeleton organization could have a role in the tolerance/sensitive mechanism. In the case of browning, our results suggest that elevated acetaldehyde related genes together with the core cold responses may increase sensitivity to browning in shelf life.
  
  
  CONCLUSIONS
  Our data suggest that in sensitive fruit a cold response program is activated and regulated by auxin distribution and ethylene and these hormones have a role in sensitivity to CI even before fruit are cold stored.
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, CSIC-Universidad Politecnica de Valencia, E-48022, Valencia, Spain. cpons@upvnet.upv.es.
authors.forename: Clara
authors.initials: C
authors.lastname: Pons Puig
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel. anuragdagar@gmail.com.
authors.forename: Anurag
authors.initials: A
authors.lastname: Dagar
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, CSIC-Universidad Politecnica de Valencia, E-48022, Valencia, Spain. cmarti@ibmcp.upv.es.
authors.forename: Cristina
authors.initials: C
authors.lastname: Marti Ibanez
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel. vikram.s.viking@gmail.com.
authors.forename: Vikram
authors.initials: V
authors.lastname: Singh
authors.affiliation: Plant Sciences Department, University of California Davis, 1 Shields Ave, Davis, CA, 95616, USA. chcrisosto@ucdavis.edu.
authors.forename: Carlos H
authors.initials: CH
authors.lastname: Crisosto
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel. hayafr@agri.gov.il.
authors.forename: Haya
authors.initials: H
authors.lastname: Friedman
authors.affiliation: Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, Volcani Center, P.O. Box 6, Bet Dagan, 50250, Israel. slurie43@agri.gov.il.
authors.forename: Susan
authors.initials: S
authors.lastname: Lurie
authors.affiliation: Instituto de Biología Molecular y Celular de Plantas, CSIC-Universidad Politecnica de Valencia, E-48022, Valencia, Spain. agranell@ibmcp.upv.es.
authors.forename: Antonio
authors.initials: A
authors.lastname: Granell
mesh_terms: D000079:Acetaldehyde / Q000378:metabolism; D002473:Cell Wall / Q000378:metabolism; D003080:Cold Temperature; D005030:Ethylenes / Q000378:metabolism; D007210:Indoleacetic Acids / Q000378:metabolism; D010368:Pectins / Q000096:biosynthesis; D000068239:Prunus persica / Q000235:genetics* / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D059467:Transcriptome
chemical_list: D005030:Ethylenes; D007210:Indoleacetic Acids; D017382:Reactive Oxygen Species; D010368:Pectins; C036216:ethylene; D000079:Acetaldehyde