Identification and mapping of ts (tender spines), a gene involved in soft spine development in Cucumis sativus

Abstract

Using map-based cloning of ts gene, we identified a new sort of gene involved in the initiation of multicellular tender spine in cucumber. The cucumber (Cucumis sativus L.) fruit contains spines on the surface, which is an extremely valuable quality trait affecting the selection of customers. In this study, we elaborated cucumber line NC072 with wild type (WT) hard fruit spines and its spontaneous mutant NC073, possessing tender and soft spines on fruits. The mutant trait was named as tender spines (ts), which is controlled by a single recessive nuclear gene. We identified the gene ts by map-based cloning with an F segregating population of 721 individuals generated from NC073 and WT line SA419-2. It was located between two markers Indel6239679 and Indel6349344, 109.7 kb physical distance on chromosome 1 containing fifteen putative genes. With sequencing and quantitative reverse transcription-polymerase chain reaction analysis, the Csa1G056960 gene was considered as the most possible candidate gene of ts. In the mutant, Csa1G056960 has a nucleotide change in the 5' splicing site of the second intron, which causes different splicing to delete the second exon, resulting in a N-terminal deletion in the predicted amino acid sequence. The gene encodes a C-type lectin receptor-like tyrosine-protein kinase which would play an important role in the formation of cucumber fruit. This is firstly reported of a receptor kinase gene regulating the development of multicellular spines/trichomes in plants. The ts allele could accelerate the molecular breeding of cucumber soft spines.

Genome-wide identification and characterization of lectin receptor-like kinase gene family in cucumber and expression profiling analysis under different treatments

“…In addition, some LecRLKs affect the development and growth of plant, for instance, two L-type LecRLKs, LecRK-IX.1 and LecRK-IX.2 will induce cell death, thereby increasing plant survival, when infected with phytophthora (Wang et al, 2015). A C-type LecRLK mutant changed cell stacking pattern of trichome in cucumber, resulting fruit spines being easy to fall off from pericarp (Guo et al, 2017). It is similar to previous study (Yang et al, 2016), through the RNA-Seq data, we also found drastic number of CsLecRLKs may be expression in root (Fig.…”

“…Although there is only one subfamily member in Arabidopsis and rice, the C-type LecRLKs had not been reported involving any speci c biological traits for a long time. Until 2017, a C-type LecRLK was identi ed that may affect morphogenesis of trichome in cucumber (Cucumis sativus) (Guo et al, 2017).…”

Comparative transcriptome analysis of hard and tender fruit spines of cucumber to identify genes involved in morphological development of fruit spines

“…The mutant (Csts) used in this study was initially de ned as having a tender fruit spines [29]. With continuous tracking of the developmental stage of the fruit spines, we found that the most direct reason for the fruit spines being more easily bent was their developmental deformity in the mutant, which made the combination of the base and epidermis unstable (Fig.…”

“…In the mutant, the expression levels of a series of calcium sensors were downregulated, which was closely related to the function of CsTs. CsTs is a C-type lectin receptor-like kinase located on the cell membrane [29]. The extracellular domain function of CsTs is serving as a calcium-dependent carbohydrate binding module.…”

“…CsTs (tender spines), a C-type lectin receptor-like kinase (LecRLK), can affect the structure of trichomes. Mutations in CsTs will cause cells from the basal part of trichomes to be arranged out of order from the normal style of the wild type (Wt) [29], but do not affect the density and size of trichomes, which indicates that CsTs is a key gene determining the differentiation of cucumber trichomes. To the best of our knowledge, there has been no detailed characterization of the developmental regulation of cucumber trichomes.…”