Changes in key traits occurring during the process of plant domestication are mostly inferred by reference to wild relatives or to primitive land races, especially for those crops outside western Eurasia, and therefore are subject to continuous debate (Ladizinsky, 1998
; Diamond, 2002
). Only in the case of genetic analysis (e.g. Doebley et al., 1997
) or with extensive plant remains (e.g. Zohary and Hopf, 2000
) can specific sets of changes be documented. Historical details of the plant domestication processes are rare and other evidence of morphological change can be difficult to obtain, especially for those vegetables that lack a substantial body of archaeological data.
With potato (Solanum tuberosum
) and tomato (Solanum lycopersicum
= Lycopersicon esculentum
), eggplant or aubergine (Solanum melongena
) is one of the three most important cultivated crops in the Solanaceae (FAO, 2007
). The origin and domestication of eggplant, however, is still a challenging question. Hypotheses about the origins and evolution of eggplants have in the past been based on inference (Lester and Hasan, 1991
; Choudhury, 1995
) owing to the lack of archaeological evidence for origins and early domestication. Lester and Hasan (1991)
suggested that the eggplant was derived from the subtropical species S. incanum
, native to north Africa and the Middle East. They suggested that the wild progenitor developed as a garden weed, and through human selection in south-east Asia, progressively more advanced cultivars were selected. They divided S. melongena
into a series of morphological types or gene pools, identified as A (putative wild progenitors) to G (advanced cultivars), and suggested eastwards movement of cultivated forms, with subsequent movement westwards complicating patterns of character change (Lester and Hasan, 1991
). AFLP (Mace et al., 1999
) and DNA sequence (T. Weese and L. Bohs, University of Utah, USA, pers. comm.) data sets support the broad relationships between S. incanum
and its African relatives and the eggplants, but the data sets used were relatively small and did not include Chinese samples. None of the S. incanum s.s.
group as currently understood is present in China or adjacent south-east Asia; Lester and Hasan (1991)
hypothesized that the true wild progenitor of the eggplant was an undiscovered species in the savanna ecosystems of the region. No Asian prickly solanums have been included in any phylogenetic analyses of relationships in Solanum
, making this a priority for understanding not only evolution in Solanum
in general, but the origin of the eggplant in particular.
Several candidate areas for eggplant domestication have been proposed: India and south-east China (Doganlar et al., 2002a
), China, India and Thailand (Doganlar et al., 2002b
), Burma to Indo-China (Daunay et al., 2001
) and south-east Asia (Lester and Hasan, 1991
). Evidence for each of these is based on presence of weedy forms (putative progenitors for many authors) and literature references. The authors' field work in recent years has revealed the presence of wild, weedy forms of eggplants in southern China, supporting a south-east Asian origin, but the possibility of multiple domestication events has not yet been investigated.
Evidence for an Indian domestication has been drawn from examination of the Sanskrit literature. Khan (1979)
cited common names for the eggplant from various works, with the oldest dated between the 3rd century bc
and the 3rd century ad.
His citation of the oldest Sanskrit work from 300 bc
, however, was based on a secondary source (Monier-Williams, 1899
), and the time range he estimated cannot be substantiated, due to the many revisions of the work in question over the centuries (S. Y. Ye, Peking University, China, pers. comm.). It is essential that the primary sources of exact dates be re-examined in order to explore this further. These Sanskrit names have been regarded as evidence that the eggplant was first cultivated in India, although no more detailed and continuous evidence about the domestication process can be gleaned from the Indian ancient literature. In contrast, in depth examination of the ancient Chinese literature has revealed a rich set of references to many cultivated plants (Li, 1969
; Keng, 1974
; Walters, 1989
), including the eggplant. The Chinese literature is especially characterized by its antiquity, continuity and coherence (Needham, 1986
). Much written evidence about the eggplant can be found in this vast reservoir. It is a treasure trove of information about plant domestication (Brestschneider, 1871
; Li, 1969
) and has previously usually only been referenced from secondary sources. The purpose of the present study is to use primary sources to document as many of these historical data as possible and, by piecing them together, to draw a relatively authentic picture of the process of the domestication and evolution of the eggplant in China.