The eggplant research programs started in 1962 at INRA. The researcher who was in charge of these programs at the time was Edmond Pochard. His goal was varietal improvement, for both yield and fruit quality. In order to understand the genetic potential of eggplants usable in breeding, he put together a first collection illustrating the genetic and phenotypical diversity of Solanum melongena, that was accessible to him through communication and collaboration at the time. He began by introducing French varieties that were commercialised at the time by many seed merchants, some of which were incorporated into still active establishments (Gautier Seeds, Vilmorin, and the company HM-Clause), and some of whom have now disappeared (Garcin Mistral, Cayeux). He also introduced varieties from gene banks (Institut für Pflanzenforschung de Gatersleben-DDR, USDA -USA, Institut Vavilov then named the All Union Institute of Plant Industry-USSR) or provided by foreign geneticist breeders (Greece, Italy, Spain, Czechoslovakia, Bulgaria, Turkey, Japan, etc.).
INRAE crossed certain introductions from different geographical origins, presenting complementary and complimentary phenotypical characteristics to the French market and selected lines in the resulting offspring. These lines, combined with INRAE breeding into traditional populations, allowed the creation of the first French F1 hybrids, registered in the official catalog in 1973: F1 Bonica with purple globular fruits and F1 Baluro with half long purple fruits. Both hybrids, early and productive, are still available in some commercial catalogs. The INRAE variety Dourga, a very early variety, with a semi-long white fruit and a soft taste, registered in the catalogue in 1975, originated from selection following a cross between Violette of Barbentane and an introduced white Indian, Kanto Ao.
Eggplant collection Solanum melongena
The introduction of the Solanum melongena varieties into the collection has been a continuous but irregular activity because it has fluctuated according to opportunities (Figure 1), with two peaks corresponding firstly (1962) with the opening of the research program on this species and secondly (2004) to the transfer of the eggplant collection of the University of Birmingham to INRAE within the framework of the EGGNET (GENRES PL 98-113) project, funded by Europe.
1061 varieties were introduced between 1962 and 2013 but 150 were eliminated for reasons related generally to a lack of germination or interest or because of duplicating varieties already in the collection. The collection includes 911 varieties, originating from about 60 countries in Europe, the Middle East, Central Asia, Asia, Africa, the Americas (and some miscellaneous). A hundred accessions in this collection are from breeding programs conducted from 1960 to 2000 in plant breeding stations of INRAE in the Caribbean and in Montfavet.
Collection of Solanum related to eggplant
The establishment of the collection of the Solanum species, cultivated or wild, and related to the eggplant actually began during the expansion of the eggplant research team in 1978 with the recruitment of M.C. Daunay (Figure 2). The two introductory peaks correspond to one (1991) being the formalisation of the scientific collaboration with the taxonomist Richard N. Lester of the University of Birmingham, UK (AEGIS program “ALLIANCE”). The second (2004) corresponds to the transfer of the collection of Solanum species related to the eggplant from the University of Birmingham (UK) to INRA within the framework of the EGGNET project.
The nomenclature used in this collection is the one used by R.N. Lester and in particular for the group of S. incanum and S. melongena spontaneous (wild or primitive). 1293 accessions were introduced over the period 1962 to 2013 but 171 were eliminated mainly due to problems of germination and seed production during regeneration. The collection currently includes 1122 accessions, originating mostly from Africa, the continent where the majority of the species related to S. melongena are found.
The collection includes three cultivated species, Solanum aethiopicum or “scarlet eggplant” (324 accessions), S. macrocarpon or “Gboma eggplant” (81 accessions), and S. scabrum (9 accessions). These species are leafy vegetables and/or indigenous African fruits. S. aethiopicum and S. macrocarpon are a part of the usable secondary gene pool to improve S. melongena (and conversely, S.melongena is a part of the usable secondary gene pool used to improve S. aethiopicum and S. macrocarpon).
Spontaneous or primitive forms of S. melongena (a hundred accessions) are currently included in this collection.
Nearly 500 accessions belonging to a hundred wild species, for the vast majority related to cultivated eggplants, complete the collection, as well as a few samples of other kinds of Solanaceae (Atropa, Datura, Lycium, Nicandra, Physalis and Withania).
The characterisation and regeneration of this collection generates several difficulties. A number of problems in determining names of species have not been resolved. Many species cannot be regenerated in short cycles of greenhouses or fields available to the GAFL station of INRA in Montfavet (eg. the majority of species of the Lasiocarpa and Torva sections, all species native to Australia). The problems of germination of introduced seed lots are very frequent: thus sixty accessions are still not regenerated nor identified botanically, due to a lack of germination thus far. Moreover, in order to reduce the frequency of poor germination of wild species (slow, low or very spread out over time), we almost always use GA3 (500 ppm) Gibberellin seed pretreatment during planting.
Maintenance of collections
The eggplant and related species collections have been maintained with the help of the technique of Daniel Chambonnet and Georges Breuils (1962-1970), Augustine Florent (1962-1978), Evelyne Jullian (1978-2010) and David Savio (2011-2016).
Importance of the collections
These collections have underpinned a great many research programmes at INRAE and outside INRAE for the last 55 years. These collections represent an informative and unique sample of intra- and interspecific diversity used for the genetic improvement of cultivated eggplants (and their rootstocks).