Molecular mapping and candidate gene analysis for fruit epidermal structure in cucumber

Abstract

Firmness of skin is an important quality of processing cucumbers, which is a feature of the palisade epidermis in these types compared to flat epidermis in fresh cucumbers. This study was conducted to map the Pe (palisade epidermis) and analyse the candidate gene. Populations derived from the cross of two inbred lines, NCG122 with fruit flat epidermis and NCG121 with fruit palisade epidermis, were used to identify the inheritance of palisade epidermis and to map the gene involved in its development. The results showed that the palisade epidermis trait is controlled by a single gene, Pe, that is dominant over flat epidermis. Seven simple sequence repeat (SSR) and five insertion deletion (Indel) markers were identified to be linked to the Pe gene. It was mapped to cucumber chromosome 5 (Chr.5) between SSR14611 and Indelpe12 with genetic distances of 0.3 cM and 0.2 cM, respectively. The physical distance of the genomic region harbouring the gene was 227.5 kb with 26 predicted candidate genes. The accuracy of marker‐assisted selection using the molecular markers, Indelpe12 and SSR14611, was 68% and 88%, respectively.

QTL and Transcriptomic Analyses Implicate Cuticle Transcription Factor SHINE as a Source of Natural Variation for Epidermal Traits in Cucumber Fruit

“…This variation is likely due to multiple factors controlling epidermal cell shape, including the Pe gene on chromosome 5. Pe has been localized to a 0.23 Mb region and exhibits tight, but not unbreakable, linkage to several fruit surface related traits such as dull ( D ), uniform fruit color ( u ) and tuberculate ( Tu ), suggesting a cluster of genes modulating cucumber exocarp characteristics (Yang et al, 2014a, Yang et al, 2014b, Yang et al, 2014c; Chen et al, 2016; Zhang et al, 2017; Yang et al, 2019). The QTL for epidermal cell width identified on chromosome 5 in this study is consistent with the location of Pe .…”

Genetics and marker-assisted breeding for sex expression in cucumber

“…Moreover, a gene belonging to the BZR1-BES1 family (brassinosteroid signaling pathway gene family) was highly expressed in hermaphrodite flowers (Guo et al, 2010). Shoot tips of gynoecious cucumbers treated with gibberellic acid exhibited high expression of genes SAUR32, WRKY41, CYP450, MYB21, NAC2, NAC72, SAUR21, 1AA13, CKX1, and ETR1, as identified through transcriptome and qRT-PCR analysis (Zhang et al, 2017;Zhang et al, 2019). Pan et al (2018) performed the transcriptome analysis of apical shoots of near-isogenic lines of cucumber, which included gynoecious, monoecious, and hermaphrodite, and revealed that B-class floral homeotic genes CsPI and CsAP3 were highly expressed in monoecious lines but suppressed in gynoecious lines.…”

“…Moreover, a gene belonging to the BZR1-BES1 family (brassinosteroid signaling pathway gene family) was highly expressed in hermaphrodite flowers ( Guo et al, 2010 ). Shoot tips of gynoecious cucumbers treated with gibberellic acid exhibited high expression of genes SAUR32 , WRKY41 , CYP450 , MYB21 , NAC2 , NAC72 , SAUR21 , 1AA13 , CKX1 , and ETR1 , as identified through transcriptome and qRT-PCR analysis ( Zhang et al, 2017 ; Zhang et al, 2019 ).…”