Genetic basis for glandular trichome formation in cotton

Abstract

Trichomes originate from epidermal cells and can be classified as either glandular or non-glandular. Gossypium species are characterized by the presence of small and darkly pigmented lysigenous glands that contain large amounts of gossypol. Here, using a dominant glandless mutant, we characterize GoPGF, which encodes a basic helix-loop-helix domain-containing transcription factor, that we propose is a positive regulator of gland formation. Silencing GoPGF leads to a completely glandless phenotype. A single nucleotide insertion in GoPGF, introducing a premature stop codon is found in the duplicate recessive glandless mutant (gl2gl3). The characterization of GoPGF helps to unravel the regulatory network of glandular structure biogenesis, and has implications for understanding the production of secondary metabolites in glands. It also provides a potential molecular basis to generate glandless seed and glanded cotton to not only supply fibre and oil but also provide a source of protein for human consumption.

Genes regulating gland development in the cotton plant

“…Interestingly, the CGF3 gene that we have identified and sequenced from the glanded cotton, GVS4, is the same gene designated as GoPGF by Ma et al . (). However, the underlying cause of mutation responsible for glandless phenotype in each case is different, as discussed later.…”

“…The other two glandless cotton lines (NM‐13P1115 and NM‐13P1117) had a total of three SNPs in the coding region of ACGF3 gene, including two synonymous and one nonsynonymous, at residue 43, which alters an alanine to valine. Thus, these two lines have the same dominant mutation Gl e 2 obtained through irradiation to create the Egyptian glandless cotton cultivar ‘Bahtim 110’, as reported previously (Kohel and Lee, ; Ma et al ., ). Their pedigrees show that the glandless parent for both NM‐13P1115 and NM‐13P1117 was an experimental line that had Bahtim 110 as one of its parents.…”

“…As mentioned above, the underlying cause for the glandless trait in the recessive, G. hirsutum mutant as proposed by Ma et al . () was the insertion of a single nucleotide in the coding sequence of each of the two GoPGF homeologs. However, the GoPGF (synonym CGF3 ) gene identified in this study showed a 5.1 kb, copia‐like, retrotransposon in the A subgenome homeolog and several SNPs, insertions and deletions in the promoter of the D subgenome homeolog of the glandless mutant GVS5 (Figures , S8 and S9).…”

Plant Glandular Trichomes: Natural Cell Factories of High Biotechnological Interest

“…Several transcription factors belonging to different protein families and playing a role in glandular trichome development have indeed been identified: AmMIXTA, a MYB transcription factor from A. majus whose ectopic expression in tobacco induces the development of additional long glandular trichomes (Glover et al, 1998); GoPGF, a basic helix-loop-helix (bHLH) transcription factor from Gossypium spp., acting as a positive regulator of glandular trichome formation, its silencing leading to a completely glandless phenotype (Ma et al, 2016); AaHD1, a homeodomain-Leu zipper transcription factor required for jasmonate-mediated glandular trichome initiation in A. annua ; AtGIS, a C2H2 zinc-finger transcription factor from Arabidopsis whose ectopic expression in tobacco regulates glandular trichome development through GA 3 signaling (Liu et al, 2017); AaMYB1, a MYB transcription factor from A. annua whose overexpression induces the formation of a greater number of trichomes (Matías-Hernández et al, 2017); and CsGL3, an HD-Zip Figure 1. Glandular trichome initiation and development, a process with many unknowns.…”

Phenological, morphological and agronomic characterization of sixteen genotypes of cotton plant (Gossypium hirsutum L.) in rainfed condition in Benin

“…This high amount of protein permits the production of cakes occupying an important place in animal feed (12% of world production) and places cotton flour in 2nd place of world plant protein after soybeans (Yue et al, 2012;Camara, 2015). With varieties without gossypol or "glandless", cotton might even become progressively a food plant (Ma et al, 2016;Zhang et al, 2016).…”