UC Davis UC Davis Previously Published Works
Total Page：16
File Type：pdf, Size：1020Kb
UC Davis UC Davis Previously Published Works Title Distribution, ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile Permalink https://escholarship.org/uc/item/1k34z2qm Journal Euphytica: International Journal of Plant Breeding, 167(1) ISSN 1573-5060 Authors Chetelat, Roger T. Pertuzé, Ricardo A. Faúndez, Luis et al. Publication Date 2009-05-01 DOI 10.1007/s10681-008-9863-6 Peer reviewed eScholarship.org Powered by the California Digital Library University of California Euphytica (2009) 167:77–93 DOI 10.1007/s10681-008-9863-6 Distribution, ecology and reproductive biology of wild tomatoes and related nightshades from the Atacama Desert region of northern Chile Roger T. Chetelat Æ Ricardo A. Pertuze´ Æ Luis Fau´ndez Æ Elaine B. Graham Æ Carl M. Jones Received: 16 September 2008 / Accepted: 8 December 2008 / Published online: 25 December 2008 Ó The Author(s) 2008. This article is published with open access at Springerlink.com Abstract Over the past 20 years, several expeditions pollen size, and flower scent—suggest S. sitiens and were made to northern Chile to collect populations of S. lycopersicoides attract different pollinators than S. wild tomatoes (Solanum chilense, S. peruvianum) and chilense and S. peruvianum. The four Solanum spp. allied nightshades (S. lycopersicoides, S. sitiens), and native or endemic to Chile provide a variety of novel obtain information about their geographic distribution, traits which, through hybridization and introgression ecology and reproductive biology. Restricted mainly to with cultivated tomato, could facilitate development of drainages of the Andean and the coastal cordillera, improved varieties, as well as research on a variety of populations are geographically fragmented. The two basic topics, including plant-pollinator interactions, nightshade species are rare and threatened by human abiotic stress responses, and evolution of reproductive activities. Adaptation to extreme aridity and soil barriers. salinity are evident in S. chilense and S. sitiens (the latter exhibits several xerophytic traits not seen in the Keywords Solanum sitiens Á tomatoes) and to low temperatures in S. lycopersico- Solanum lycopersicoides Á Solanum chilense Á ides and S. chilense. All tested accessions are self- Solanum peruvianum Á Tomato Á incompatible, with the exception of one S. peruvianum Germplasm collecting population collected at the southern limit of its distribution. Several distinguishing reproductive traits—anther color, attachment, and dehiscence, Introduction R. T. Chetelat (&) Á E. B. Graham Á C. M. Jones C. M. Rick Tomato Genetics Resource Center, Department of Plant Sciences, University of California, The cultivated tomato and its wild relatives form a One Shields Ave., Davis, CA 95616, USA small clade of 13 closely related species, comprising e-mail: [email protected] Solanum sect. Lycopersicon, formerly recognized as the genus Lycopersicon (Peralta et al. 2008). Four R. A. Pertuze´ Á L. Fau´ndez Depto. Produccio´n Agrı´cola, Universidad de Chile, other Solanum spp. are the closest outgroup species to Casilla 1004, Santiago, Chile the tomato clade: S. ochranthum and S. juglandifo- lium in Solanum sect. Juglandifolia, and S. sitiens and Present Address: S. lycopersicoides in sect. Lycopersicoides. E. B. Graham Á C. M. Jones Seminis Vegetable Seeds, 37437 State Highway 16, The wild tomatoes and related nightshades are Woodland, CA 95695, USA native to the Andean region of South America, 123 78 Euphytica (2009) 167:77–93 including parts of Ecuador, Peru and Chile. In Chile, there remained large geographic gaps between these they are found only in the northernmost three known populations. administrative Regions (Arica-Parinacota, Tarapaca´, The principal goal of the 2005 visit was to collect and Antofagasta). They include representatives of additional populations of S. chilense from the coastal sect. Lycopersicon, S. peruvianum, S. chilense, and of cordillera, and to fill in gaps in existing collections of sect. Lycopersicoides, S. lycopersicoides and S. the other taxa. Our studies of genetic diversity and sitiens. Endemic to Chile, S. sitiens is limited to arid relationships in S. chilense (Graham 2005) had slopes to the NW and S of the city of Calama. Its indicated that populations at the northern and south- sister species, S. lycopersicoides, is found in just a ern ends of the distribution are genetically diverged handful of steep drainages near the Peru/Chile and isolated by partial reproductive barriers from frontier. The natural range of S. peruvianum is each other and from populations in the center of the primarily in Peru, where it is widespread along the distribution. Yet there were relatively few accessions West coast and in the Andes, and extends into of S. chilense collected from coastal sites in the northern Chile. It overlaps with S. chilense—wide- TGRC or other genebanks. spread in northern Chile but extending into southern Among the reasons for thoroughly collecting the Peru—as well as with S. lycopersicoides. available wild populations are that (a) some are Prior to 1985, relatively few ex situ accessions of threatened or have already been extirpated by over- wild tomatoes from Chile were available in national or grazing or other activities, and (b) each of these four international genebanks. The holdings of the C. M. species possesses unique traits that could lead to Rick Tomato Genetics Resource Center at UC-Davis further improvement of the tomato crop (reviewed by were limited to a few collections made by Charles M. Rick and Chetelat 1995). In the past, breeders have Rick (UC-Davis) in 1957, and by Carlos Ochoa tapped S. chilense and S. peruvianum for disease (Centro Intl. de la Papa) in 1982. During the period resistance traits that were unavailable within the 1985–1988, Rick, Andres Contreras (University of genepool of cultivated tomato. For instance, S. Austral, Chile), Rudolf Thomann, Miguel Holle (Cen- peruvianum is the source of several widely deployed tro Intl. de la Papa) and their associates made several R genes, including Mi for resistance to root knot trips to northern Chile to collect wild tomatoes nematodes (Meloidogyne spp.), Tm-2 for Tobacco (Thomann et al. 1987). Sponsored by the IBPGR Mosaic Virus resistance, and Sw-5 for tomato spotted (International Board for Plant Genetic Resources), wilt virus (TSWV) resistance. Novel traits bred from these expeditions benefited from favorable climatic S. chilense include resistances to TYLCV (tomato conditions, particularly in the normally hyperarid yellow leaf curl virus) and other gemini viruses, coastal mountains, and resulted in a thorough sampling cucumber mosaic virus (CMV), TSWV, as well as of the geographic area. Still, a number of ‘gaps’ in the fruit quality traits such as elevated antioxidant collections remained, prompting two additional expe- compounds. The nightshades S. lycopersicoides and ditions in 2001 and 2005, which were sponsored by the S. sitiens possess other potentially unique character- USDA Plant Exchange Office. istics not found among the Lycopersicon clade The primary objective of the 2001 trip was to collect species (Rick 1988). The former is known for its additional populations of S. lycopersicoides and broad suite of disease resistance (summarized in S. sitiens, both underrepresented in the TGRC and Chetelat et al. 1997), including Botrytis cinerea, all other ex situ collections. The natural range of each races of Xanthomonas campestris, Phytophthora species is confined to small areas within the Atacama parasitica, cucumber mosaic virus (CMV), tomato Desert region. Previous observations suggested some yellow leaf curl virus (TYLCV), and the tomato populations were threatened in situ by human-associ- criniviruses TICV and ToCV (William Wintermantel, ated factors, such as grazing, mining, and other persersonal communication), as well as tolerance to activities. The number of collections of these species low temperatures. The second nightshade, S. sitiens, was limited: for S. sitiens, only five populations were has not been thoroughly tested for economic traits, known, all but one of which originated from a small but its ability to thrive in the Atacama Desert area around the mining town of Chuquicamata. More certainly indicates a high level of drought tolerance. accessions of S. lycopersicoides had been collected, yet Our tests of soil samples taken at sites where this 123 Euphytica (2009) 167:77–93 79 species grow also indicate a high level of salt herbarium records included GIS coordinates, which tolerance. In addition, S. sitiens could be a source allowed us to navigate to relatively remote popula- of novel fruit textural properties—its fruit mature via tions. GIS-based maps of currently held accessions a unique desiccation process, rather than the ripening- were studied for gaps in our existing collections, and to associated softening, color, and odor changes typical identify likely habitat for the tomato species, notably in of the tomatoes. Introgression lines (ILs) and similar the drainages of the Andes. Finally, one of the authors prebreds that capture the genomes of related wild (LF) has conducted botanical surveys in the Atacama species via overlapping chromosome segments in the Desert in the past, and was familiar with the location of genetic background of cultivated tomato, are useful several previously uncollected populations. For the resources for plant breeders (Zamir 2001). A com- 2001 and 2005 trips, these