Institute for Plant Genomics and Biotechnology, Texas A&M University, College Station, TX, USA.
Texas A&M Institute for Genome Sciences and Society, Texas A&M University, College Station, TX, USA.
Plant Biotechnol J. 2019 Jun;17(6):1142-1153. doi: 10.1111/pbi.13044. Epub 2018 Dec 21.
In seeds and other parts of cultivated, tetraploid cotton (Gossypium hirsutum L.), multicellular groups of cells lysigenously form dark glands containing toxic terpenoids such as gossypol that defend the plant against pests and pathogens. Using RNA-seq analysis of embryos from near-isogenic glanded (Gl Gl Gl Gl ) versus glandless (gl gl gl gl ) plants, we identified 33 genes that expressed exclusively or at higher levels in embryos just prior to gland formation in glanded plants. Virus-induced gene silencing 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 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 GoPGF (synonym CGF3) gene of the A subgenome and extensive mutations in the promoter of D subgenome homeolog. Overexpression of GoPGF (synonym CGF3) led to a dramatic increase in gossypol and related terpenoids in cultured cells, whereas CRISPR/Cas9 knockout of GoPGF (synonym CGF3) genes resulted in glandless phenotype. Taken collectively, the results show that the GoPGF (synonym CGF3) gene plays a critical role in the formation of glands in the cotton plant. Seed-specific silencing of CGF genes, either individually or in combination, could eliminate glands, thus gossypol, from the cottonseed to render it safe as food or feed for monogastrics.
在栽培的四倍体棉花（Gossypium hirsutum L.）的种子和其他部位，多细胞细胞溶酶体形成深色腺体，含有毒的三萜类化合物，如棉酚，以抵御害虫和病原体。我们通过对近等基因有腺（Gl Gl Gl Gl）和无腺（gl gl gl gl）植株胚胎的 RNA-seq 分析，鉴定了 33 个在有腺植株的腺体形成前仅在胚胎中表达或表达水平更高的基因。针对三个基因对的病毒诱导基因沉默导致叶片中的腺体数量显著减少，棉酚和相关三萜类化合物的水平显著降低。这些基因编码转录因子，被命名为“棉花腺体形成”（Cotton Gland Formation，CGF）基因。在有腺和无腺棉花中，CGF1 和 CGF2 基因对之间没有发现序列差异。无腺棉花在 A 亚基因组的 GoPGF（同义 CGF3）基因的编码序列内有一个转座子插入，而 D 亚基因组同源基因的启动子有广泛的突变。过表达 GoPGF（同义 CGF3）导致培养细胞中的棉酚和相关三萜类化合物显著增加，而 CRISPR/Cas9 敲除 GoPGF（同义 CGF3）基因则导致无腺表型。总的来说，这些结果表明，GoPGF（同义 CGF3）基因在棉花植株腺体的形成中起着关键作用。CGF 基因的种子特异性沉默，无论是单独还是组合，都可以消除腺体，从而消除棉籽中的棉酚，使其作为单胃动物的食物或饲料安全。
