Ginger (Zingiber officinale Roscoe), a monocot of the Zingiberaceae, is an important spice and medicinal plant known since time immemorial. Ginger is intimately associated with the food habits of India, China, Vietnam, Thailand, Japan, and other Southeast Asian countries. The potential of ginger in the culinary, non-culinary and medicinal fields is based on the chemistry of volatile oil and non-volatile pungent principles. The origin of ginger is not certain but evidences indicate that it must have originated in South Asia to South East Asia. It was in cultivation in China in antiquity and in India since Vedic times. Global production is over US $ 913 million and global trade from top 20 countries is around US$247 million. Nigeria has the largest area under ginger accounting for nearly a half the total world area while India ranks first in production contributing to 30% of global production. Australia leads the world in production of ginger confectionary products. Ginger never sets seed and sexual recombination has never been reported. Cultivars have evolved by unconscious selection and are generally known by the name of the region. The major crop improvement objectives in ginger are high yield, wide adaptability, resistance to diseases (such as rhizome rot, bacterial wilt, and Fusarium yellows), improvement in quality parameters (oil, oleoresin), and low fiber.
Mango ginger is a unique spice having morphological resemblance with ginger but imparts raw mango flavor. It is also distributed in China, Bangladesh, Myanmar, Thailand, Burma, Japan and Australia. Curcuma amada is a perennial, rhizomatus, aromatic herb, belongs to the family Zingiberaceae. The plant grows to a height of 1 m. The leaves are long, oblong, lanceolate, radical, sheathed, petiolate in tufts. Rhizomes are fleshy, buff coloured, 5-10 com long, 2-5 cm in diam, demarcated into nodes and internodes. Rhizomes are branched and branching is sympodial.
Ginger is affected by many diseases among which, bacterial wilt is one of the most important production constraints in the tropical, sub tropical and warm temperature regions of the world. It inflicts serious economic losses to small and marginal farmers who depend on this crop for their livelihood. Geographical distribution of this pathogen is expanding in recent years due to unintentional transmission of the bacterium through infected rhizomes, which are the primary propagules. None of the germplasm accessions or released varieties are resistant to bacterial wilt. This is due to lack of genetic variability among the accessions for disease resistance, which is one of the bottlenecks in ginger genetic improvement. The search for resistance has been extended to other closely related genera in the family, Zingiberaceae. Among the Zingiberaceae members such as Curcuma amada, C. longa, C. zedoria, C. aromatica, Kaempferia galanga, Elettaria cardamomum, Zingiber zerumbet and Z. officinale evaluated for their reaction to Ralstonia solanacearum (causal agent of bacterial wilt) biovar 3 (ginger specific strain), and Pythium species, the Indian Mango Ginger, C. amada Roxb., exhibited significant resistance to both pathogens, while Z. zerumbet is resistant to P. aphanidermatum.
The C. amada plants hold promise for developing bacterial wilt resistant plants of ginger if the exact mechanism of resistance is understood. A thorough genetic analysis would unravel the factors (genes) governing the resistance in Curcuma amada against Ralstonia solanacearum and Pythium sp.