Morphological, anatomical, physiological, and cytological studies in diploid and tetraploid plants of Ispaghul (Plantago ovata Forsk.)

Ispaghul (Plantago ovata Forsk.) as an important medicinal plant has obtained a remarkable reputation due to therapeutic applications of seed mucilage. To determine the effect of in vitro-induced polyploidy on various characteristics of P. ovata, the terminal bud of two true leaves seedlings were separately treated with colchicine [0.1, 0.3 and 0.5% (w/v) for 6, 12 and 24 h] and trifluralin [7.5, 15 and 22.5% (w/v) for 24, 48 and 72 h] solutions. The ploidy level of induced tetraploids was determined via chromosome counting of root tip cells, and then confirmed through flow-cytometric analysis. Comparison the morphological, physiological, anatomical features of intact diploids and induced tetraploids revealed that tetraploids had considerable more height, thicker leaf, larger spike and seed, larger pollen grain and more seeds per spike. Moreover, the amount of chlorophyll (a, b, and total) and carotenoids, as well as chloroplast number in guard cells was further in tetraploids than diploids. Unlike density, stomata size in tetraploids was bigger than that one in diploids. It was also observed that seeds of tetraploids had more mucilage than diploids. In summary, we firstly developed the P. ovata tetraploids and suggested 0.3% colchicine for 24 h and 22.5% trifluralin for 72 h as the optimum treatments for inducing tetraploidy in P. ovata.