Cotton roots are the major source of gossypol biosynthesis and accumulation

Abstract

Background: Gossypol is a specific secondary metabolite in Gossypium species. It not only plays a critical role in development and self-protection of cotton plants, but also can be used as important anti-cancer and male contraceptive compound. However, due to the toxicity of gossypol for human beings and monogastric animals, the consumption of cottonseeds was limited. To date, little is known about the gossypol metabolism in cotton plants. Results: In this study, we found that cotyledon was the primary source of gossypol at the seed germination stage. But thereafter, it was mainly originated from developing roots. Grafting between glanded and glandless cotton as well as sunflower rootstocks and cotton scion revealed that gossypol was mainly synthesized in the root systems of cotton plants. And both glanded and glandless cotton roots had the ability of gossypol biosynthesis. But the pigment glands, the main storage of gossypol, had indirect effects on gossypol biosynthesis. In vitro culture of root and rootless seedling confirmed the strong gossypol biosynthesis ability in root system and the relatively weak gossypol biosynthesis ability in other organs of the seedling. Expression profiling of the key genes involved in the gossypol biosynthetic pathway also supported the root as the major organ of gossypol biosynthesis. Conclusions: Our study provide evidence that the cotton root system is the major source of gossypol in both glanded and glandless cottons, while other organs have a relatively weak ability to synthesize gossypol. Gossypol biosynthesis is not directed related to the expression of pigment glands, but the presence of pigment glands is essential for gossypol accumulation. These findings can not only clarify the complex regulation network of gossypol metabolism, but it could also accelerate the crop breeding process with enhanced commercial values.

Identification and characteristics of a novel gland‐forming gene in cotton

“…Comparing the expression profiles of gossypol genes in stem and root, we observed much higher expression in roots, indicating gossypol biosynthesis to mainly occur in the root (Figure 4 and Table S9); this conclusion is consistent with previous reports (Smith, 1961;Zhao et al, 2020).…”

Interspecific grafting between Gossypium hirsutum, G. barbadense and G. herbaceum lines

“…However, when rootstock and scion belong to different family the grafting was not successful. In the present study, none of the four grafting approaches was successful between G. hirsutum and Helianthus annuus , as previously reported 19 . Previous studies revealed that intra familial grafts are rarely compatible, and inter familial grafts are essentially always incompatible 27 .…”

“…In cotton, grafting experiments have been conducted for different purposes including transfer of root-knot nematode resistance 11 , recovery of plants from in vitro culture 12 , transgenic recovery 13 , transfer of cytokinins and abscisic acid hormones 14 , transfer of Verticillium dahlia resistance 15 , identification of the role of shoot on premature leaf senescence induced by potassium nutrition 16 , increased cryotolerance 17 , and resistance to leaf curl disease 18 . In a study of grafting experiments, Zhoa et al 19 concluded that the major source of gossypol was root system in glanded and glandless cotton. However, our unpublished data does not confirm this finding instead; we found that gossypol is also synthesized from other tissues in cotton.…”

Identification of the WRKY Group I Genes and the Functional Analysis of GhWRKY138 in Cotton Pigment Gland Development

“…Similarly, since gossypol is an important component of cotton glands, genes associated with gossypol was also studied. We also performed qRT-PCR analysis on 6 key enzyme genes in the gossypol synthesis pathway [42]. In GhWRKY138-silenced leaves, the expression levels of 4 genes decreased and 2 genes increased conversely ( Fig.…”