Plantago ovata: genetic diversity, cultivation, utilization and chemistry

Abstract

Plantago ovata is the cultivated and economically important species in the monotypic genus Plantago. P. ovata is a short-stemmed annual herb, 10–45 cm tall. The species is generally an in-breeder. The seed husk of this plant is commonly called Psyllium or Isabgol (in Hindi), which is a very effective laxative. Other usages of Isabgol are in ice cream making, cosmetics, printing and finishing. The intake of husk also reduces blood cholesterol levels. Isabgol is commercially very important as its export earns India foreign exchange worth INR 2.5 billion (US$1=44 INR). The plant is cultivated on a large scale in western India. In Gujarat, it is cultivated in about 144,000 ha of land, yielding 720 kg/ha. P. ovata has a narrow genetic base, and the lack of variability is on account of low chromosome number, small chromosome size, presence of high heterochromatin in the chromosomes, low chiasmata frequency and low recombination index. The genome size of the species is ∼500 Mb. Different breeding methods, namely selection, hybridization, induced mutations, polyploidy and tissue culture, have been used for genetic improvement of this plant. Except selections, which have led to isolation of a few varieties, the results of other methods have not been encouraging. P. ovata has about 200 wild allies, some of which are medicinally important. These wild species constitute a rich resource of important genes, which if transferred to cultivated species could revolutionize the production of Isabgol. The present paper highlights various aspects of genetic diversity, cultivation and utilization of this important medicinal plant, and suggests the prospects of genetic manipulation.