Fine mapping and candidate gene analysis of the dominant glandless gene Gl 2 e in cotton (Gossypium spp.)

Abstract

Dominant glandless gene Gl 2 (e) was fine-mapped to a 15 kb region containing one candidate gene encoding an MYC transcription factor, sequence and expression level of the gene were analyzed. Cottonseed product is an excellent source of oil and protein. However, this nutrition source is greatly limited in utilization by the toxic gossypol in pigment glands. It is reported that the Gl 2 (e) gene could effectively inhibit the formation of the pigment glands. Here, three F2 populations were constructed using two pairs of near isogenic lines (NILs), which differ nearly only by the gland trait, for fine mapping of Gl 2 (e) . DNA markers were identified from recently developed cotton genome sequence. The Gl 2 (e) gene was located within a 15-kb genomic interval between two markers CS2 and CS4 on chromosome 12. Only one gene was identified in the genomic interval as the candidate for Gl 2 (e) which encodes a family member of MYC transcription factor with 475-amino acids. Unexpectedly, the results of expression analysis indicated that the MYC gene expresses in glanded lines while almost does not express in glandless lines. These results suggest that the MYC gene probably serves as a vital positive regulator in the organogenesis pathway of pigment gland, and low expression of this gene will not launch the downstream pathway of pigment gland formation. This is the first pigment gland-related gene identification in cotton and will facilitate the research on glandless trait, cotton MYC proteins and low-gossypol cotton breeding.

The gland localized CGP1 controls gland pigmentation and gossypol accumulation in cotton

“…Studies on glandless mutants showed that a Val for Ala amino acid substitution at residue 43 of Gl 2 results in the dominant Gl 2 e allele, while single nucleotide insertions into Gl 2 and Gl 3 introduce premature stop codons and generate the recessive gl 2 and gl 3 alleles (Ma et al , ). Later, Cheng et al () confirmed the identity of GoPGF using near‐isogenic lines (NILs) at the Gl 2 e locus. Comparative transcriptome analysis of glanded and glandless cotton embryos identified three Cotton Gland Formation ( CGF ) genes that participate in gland formation (Janga et al , ).…”

Map-based cloning of a recessive gene v1 for virescent leaf expression in cotton (Gossypium spp.)

“…T582 serves as a basic tool for scientific study into the mechanism of cotton metabolism, inheritance and development due to its multiple recessive marker stocking with cu, fg, cl 1 , gl 1 , and v 1 (Kohel et al 1965). The candidate gene of the pigment glands which related gene gl 1 would provide the prospects of fabricating gossypol-free cotton seeds (Cheng et al 2016). In addition, many important genes were subdivided into different linkage groups through T582 (Percival and Kohel 1974;Endrizzi et al 1984).…”

“…, 15 s at 95°C (Cheng et al 2016). qRT-PCR was carried out by the gene-specific primers (5′-ATTGCCACT GTCATCCCCAACTGCT-3′, 5′-TCAGCTGAAAACCT CATAGAATTTC-3′) and actin (Genbank ID: AY305733) (5′-ATCCTCCGTCTTGACCTTG-3′, 5′-TGTCCGTCA GGCAACTCAT-3′) was employed as an internal control.…”

“…Functional analysis of the v 1 gene was performed in CCRI 12-Dgl (Cheng et al 2016) using VIGS to validate its role in the formation of virescent leaf in cotton. The 250 bp interference fragment was inserted into a TRV2 (tobacco rattle virus) vector to construct the VIGS vector.…”

Recent insights into cotton functional genomics: progress and future perspectives

“…Therefore, it is also crucial to fine map the genomic regions with large number of markers that will enhance the efficiency of selection, which ultimately helps to clone the genes present at the target loci. In cotton, fine mapping of few important genes and QTLs has been reported, that is fine mapping of glandless gene (Cheng et al ., ), leaf shape (Andres et al ., ) and fibre quality‐related QTLs (Fang et al ., ; Liu et al ., ; Xu et al ., ).…”