Location: Crop Genetics ResearchTitle: Genes regulating gland development in the cotton plant
|Janga, Madhusudhana - Texas A&M University|
|Pandeya, Devendra - Texas A&M University|
|Campbell, Leanne - Texas A&M University|
|Konganti, Kranti - Texas A&M University|
|Toinga, Stephany - Texas A&M University|
|Pepper, Alan - Texas A&M University|
|Stipanovic, Robert - Bob|
|Rathore, Keerti - Texas A&M University|
Submitted to: Plant Biotechnology Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/20/2018
Publication Date: 11/22/2018
Citation: Janga, M.R., Pandeya, D., Campbell, L.M., Konganti, K., Toinga, S., Puckhaber, L.S., Pepper, A., Stipanovic, R.D., Scheffler, J.A., Rathore, K. 2018. Genes regulating gland development in the cotton plant. Plant Biotechnology Journal. 16:1-12. https://doi.org/10.1111/pbi.13044.
Interpretive Summary: Cotton belongs to a unique group of plants that possess glands throughout the plant, including the seed. The glands contain gossypol and related compounds that protect the cotton plants from pests and diseases. Although the seed contains ~23% protein (>10 million tons produced per year), the presence of gossypol in the seed makes it unsafe as feed for non-ruminants such as pigs and chickens as well as humans. This study identified and characterized genes that control gland development. Deactivating of one of these genes resulted in plants with no glands. Inactivating this gene in the seed while expressing it in rest of the plant would provide an additional safe source of seed protein for animals and humans as well as cotton with stronger self defense mechanisms.
Technical Abstract: In seeds and most plant parts of cultivated tetraploid cotton, multicellular groups of cells lysigenously form dark glands containing toxic terpenoids such as gossypol that help defend against pests and pathogens. Using RNA-seq analysis of near-isogenic glanded (Gl2Gl2Gl3Gl3) versus glandless (gl2gl2gl3gl3) embryos, we identified 33 genes that expressed exclusively or at higher levels in embryos just prior to gland formation in glanded plants. Using Virus Induced Gene Silencing (VIGS), we assessed the effects of silencing of ten of these genes on gland formation. VIGS against three gene pairs led to significant reductions in the number of glands in the leaves, and significantly lower levels of gossypol and related terpenoids. These genes encode transcription factors (TFs) and have been designated the “Cotton Gland Formation” (CGF) genes. No sequence differences were found between glanded and glandless cotton for CGF1 and CGF2 gene pairs. The glandless cotton has a transposon insertion within the coding sequence of the CGF3 gene of the A subgenome and extensive mutations in its D subgenome homeolog. CRISPR/Cas9 knockout of CGF3 genes resulted in glandless phenotype. Taken collectively, the results show that the CGF3 gene plays a critical role in the formation of glands in the cotton plant. It now becomes possible to target the CGF genes, either individually or in combination, for seed-specific silencing to eliminate the glands, and thus gossypol, from the cottonseed to render it safe as feed for monogastrics, while maintaining the wild-type levels or even increasing glands and terpenoids in rest of the plant.