Developmental, transcriptome, and genetic alterations associated with parthenocarpy in the grapevine seedless somatic variant Corinto bianco

  1. Royo, C. 3
  2. Carbonell-Bejerano, P. 3
  3. Torres-Pérez, R. 3
  4. Nebish, A. 2
  5. Martínez, Óscar. 1
  6. Rey, M. 1
  7. Aroutiounian, R. 2
  8. Ibáñez, J. 3
  9. Martínez-Zapater, J.M. 3
  1. 1 Universidade de Vigo
    info

    Universidade de Vigo

    Vigo, España

    ROR https://ror.org/05rdf8595

  2. 2 Yerevan State University
    info

    Yerevan State University

    Ereván, Armenia

    ROR https://ror.org/00s8vne50

  3. 3 Instituto de Ciencias de la Vid y del Vino
    info

    Instituto de Ciencias de la Vid y del Vino

    Logroño, España

    ROR https://ror.org/01rm2sw78

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Journal:
Journal of Experimental Botany

ISSN: 0022-0957

Year of publication: 2016

Volume: 67

Issue: 1

Pages: 259-273

Type: Article

DOI: 10.1093/JXB/ERV452 SCOPUS: 2-s2.0-84954561692 WoS: WOS:000367816300019 GOOGLE SCHOLAR

More publications in: Journal of Experimental Botany

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Abstract

Seedlessness is a relevant trait in grapevine cultivars intended for fresh consumption or raisin production. Previous DNA marker analysis indicated that Corinto bianco (CB) is a parthenocarpic somatic variant of the seeded cultivar Pedro Ximenes (PX). This study compared both variant lines to determine the basis of this parthenocarpic phenotype. At maturity, CB seedless berries were 6-fold smaller than PX berries. The macrogametophyte was absent from CB ovules, and CB was also pollen sterile. Occasionally, one seed developed in 1.6% of CB berries. Microsatellite genotyping and flow cytometry analyses of seedlings generated from these seeds showed that most CB viable seeds were formed by fertilization of unreduced gametes generated by meiotic diplospory, a process that has not been described previously in grapevine. Microarray and RNA-sequencing analyses identified 1958 genes that were differentially expressed between CB and PX developing flowers. Genes downregulated in CB were enriched in gametophyte-preferentially expressed transcripts, indicating the absence of regular post-meiotic germline development in CB. RNA-sequencing was also used for genetic variant calling and 14 single-nucleotide polymorphisms distinguishing the CB and PX variant lines were detected. Among these, CB-specific polymorphisms were considered as candidate parthenocarpy-responsible mutations, including a putative deleterious substitution in a HAL2-like protein. Collectively, these results revealed that the absence of a mature macrogametophyte, probably due to meiosis arrest, coupled with a process of fertilization-independent fruit growth, caused parthenocarpy in CB. This study provides a number of grapevine parthenocarpy-responsible candidate genes and shows how genomic approaches can shed light on the genetic origin of woody crop somatic variants. © 2015 The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved.