Conservation and Change: A Comparison of In situ and Ex situ Conservation of Jala Maize Germplasm.

Conservation of agricultural genetic resources, whether in situ (in farmers' fields) or ex situ (in a germplasm repository), provides variation for breeding and selection efforts. In this study, we assayed levels of genetic diversity from in situ and ex situ populations of Jala, a very tall, large-eared race of maize (Zea mays L. subsp. mays), using 22 simple sequence repeat (SSR) loci. For comparison, we also analyzed diversity in reference populations of other maize races and wild relatives of maize, the teosintes (both Zea spp. and Z. mays subsp.). As expected, both the in situ and ex situ Jala populations were not as diverse as the teosintes (gene diversity, He, ≈0.60 and 0.7, respectively), but they were surprisingly more diverse than the populations representing other maize races (He = 0.55). The older ex situ Jala populations were less diverse and more differentiated than more recently collected accessions. Despite this fact, we observed similar levels of overall genetic diversity in the ex situ and in situ populations (He = 0.62 and 0.61, respectively), and little differentiation between these groups (Fst = 0.01). Therefore, the ex situ Jala collections, as a whole, contained the diversity found today in the field, even though diversity was under-represented in individual repository populations. [ABSTRACT FROM AUTHOR]