A New Glabrous Gene (csgl3) Identified in Trichome Development in Cucumber (Cucumis sativus L.)

Abstract

Spines or trichomes on the fruit of cucumbers enhance their commercial value in China. In addition, glabrous mutants exhibit resistance to aphids and therefore their use by growers can reduce pesticide residues. Previous studies have reported two glabrous mutant plants containing the genes, csgl1 and csgl2. In the present study, a new glabrous mutant, NCG157, was identified showing a gene interaction effect with csgl1 and csgl2. This mutant showed the glabrous character on stems, leaves, tendrils, receptacles and ovaries, and there were no spines or tumors on the fruit surface. Inheritance analysis showed that a single recessive gene, named csgl3, determined the glabrous trait. An F2 population derived from the cross of two inbred lines 9930 (a fresh market type from Northern China that exhibits trichomes) and NCG157 (an American processing type with glabrous surfaces) was used for genetic mapping of the csgl3 gene. By combining bulked segregant analysis (BAS) with molecular markers, 18 markers, including two simple sequence repeats (SSR), nine insertion deletions (InDel) and seven derived cleaved amplified polymorphism sequences (dCAPs), were identified to link to the csgl3 gene. All of the linked markers were used as anchor loci to locate the csgl3 gene on cucumber chromosome 6. The csgl3 gene was mapped between the dCAPs markers dCAPs-21 and dCAPs-19, at genetic distances of 0.05 cM and 0.15 cM, respectively. The physical distance of this region was 19.6 kb. Three markers, InDel-19, dCAPs-2 and dCAPs-11, co-segregated with csgl3. There were two candidate genes in the region, Csa6M514860 and Csa6M514870. Quantitative real-time PCR showed that the expression of Csa6M514870 was higher in the tissues of 9930 than that of NCG157, and this was consistent with their phenotypic characters. Csa6M514870 is therefore postulated to be the candidate gene for the development of trichomes in cucumber. This study will facilitate marker-assisted selection (MAS) of the smooth plant trait in cucumber breeding and provide for future cloning of csgl3.

A fragment substitution in the promoter of CsHDZIV11/CsGL3 is responsible for fruit spine density in cucumber (Cucumis sativus L.)

“…This hypothesis was supported by data from the present study, with no observed difference in leaf trichome density but a significant difference in fruit spine density between fs1 and WT (Fig. Neighbor-joining phylogenetic tree was generated after a complete protein sequence alignment with Clustal X (1.81) Table 3 of trichomes on foliage or fruit were mapped on chromosomes 2, 3 and 6, respectively (Yang et al 2011;Li et al 2015;Pan et al 2015;Wang et al 2016;Zhao et al 2015;Cui et al 2016). In cucumber, a number of genes related to fruit spines have been identified: B for black spine, ns for numerous spines, ss for small spines, s or s1 for spine size and frequency, s2 and s3 for dense and small spines, and gl (glabrous) and tril (trichome-less) for trichomes formation (Call and Wehner 2010;Wang et al 2016).…”

“…2c, d), which might cause increased expression level of CsH-DZIV11 in the fs1 mutant (Fig. Interestingly, CsHDZIV11 in this study, TRIL/CsGL3 found by Wang et al (2016), Pan et al (2015) and Cui et al (2016) are the same gene, Csa6M514870. 4).…”

“…The predicted functions and associated information of all 25 genes are presented in Table S3. Csa6G514870 was named CsHDZIV11 by Fu et al (2013), but named CsGL3 by Pan et al (2015) and Cui et al (2016), and encoded a PROTODERMAL FACTOR 2 (PDF2) protein (Table S3) that belonged to the HD-Zip IV subfamily, sharing high similarity with AtPDF2, AtML1 and AtHDG2 from Arabidopsis and SlWO (which participates in trichome formation) from tomato (Tables 1, 2; Yang et al 2011). We found that a 10-bp fragment from −833 to −823 bp before the start codon of Csa6G514870 was replaced with 812 bp in fs1 compared with WT; and the whole genomic DNA sequence of Csa6G514870 was no different between fs1 and WT (Fig.…”

“…Moreover, the existence of cucumber fruit spines is a precondition for the formation of fruit tubercules, as genetic analysis indicated that cucumber glabrous 1 (csgl1), a gene controlling fruit spine formation, was epistatic to the Tuberculate fruit (Tu) (Cao and Guo 1999;Cao et al 2001;Yang et al 2014;Li et al 2015). Genes gl-2, csgl1 and tril/ csgl3 controlling presence or absence of trichomes on the foliage or fruit were mapped in chromosomes 2, 3 and 6, respectively; and csgl1, tril and csgl3 were recently cloned, and both Tril and CsGL3 were found to be the same gene, Csa6M514870, in three different labs (Yang et al 2011;Li et al 2015;Pan et al 2015;Wang et al 2016;Zhao et al 2015;Cui et al 2016). Several genes related to fruit spine size and density have been identified through genetic analysis (Tkachenko 1935;Hutchins 1940;Poole 1944;Caruth 1975;Fanourakis and Simon 1987).…”

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…Five trichome-related mutants of the genes CsGL3, TRIL, MICT, TBH, and CsGL1, all of them encoding homeodomain-Leu zipper transcription factors from different subfamilies, have been reported in C. sativus (Chen et al, 2014;Li et al, 2015;Pan et al, 2015;Zhao et al, 2015;Cui et al, 2016;Wang et al, 2016b). Based on the observed phenotypes, a molecular mechanism underlying the development of multicellular trichomes in this species has been proposed in a recent review and seems to confirm that the transcriptional control of multicellular trichomes in C. sativus differs from the one observed in Arabidopsis.…”