Insulin regulates plant immunity and induces polyploids
Insulin, a 6 kDa peptide hormone, produced by beta cells of the pancreatic islets is one of the main anabolic hormones of the body. It is considered to regulate the metabolism of carbohydrates, fats and protein. Decrease in insulin sensitivity causes metabolic disorders such as type Ⅱ diabetes and metabolic syndrome (Yaribeygi, Farrokhi, Butler, & Sahebkar, 2019).
There are insulin-like materials in several plants which play essential role in multiple physiological processes. They have the same molecular masses, immunological and bioactive properties with insulin, such as bovine insulin which was reported to stimulate growth and DNA synthesis in the radicles and the coleoptiles of the embryonic axis in 200 μU ml-1 (Avila-Alejandre et al., 2013). Chemically, insulin has a great potential to affect physiology in plant, such as increases of root length and weight in barley (Csaba, & Katalin, 1982). It was reported that insulin (10−8 M) enhanced the increase of root in lengths and weights significantly, and had a similarly strong influence on the increase of coleoptile (Oliveira et al., 2004). Qualitative cytological studies even indicated that insulin may induce a polyploidism, associated with the Feulgen-positive bodies in the cytoplasm (Csaba, & Katalin, 1982). Moreover, the regulation of the cell-cycle restart by bovine insulin is demonstrated in germinating embryonic axes (Avila-Alejandre et al., 2013). This suggests that plant cells also have potential receptors to which hormones of vertebrates could bind (Csaba, & Katalin, 1982). Molecular mechanism of insulin would be worthwhile avenues to explore.