Comparative genetic structure within single-origin pairs of rice (Oryza sativa L.) landraces from in situ and ex situ conservation programs in Yunnan of China using microsatellite markers

The genetic structure and diversity of eight pairs of rice landraces from in situ (collected in 2007) and ex situ (collected in 1980) conservation programs were studied using 20 pairs of microsatellite markers with high polymorphism. Each pair of rice landraces shares a name and origin and has similar seed and plant traits. The number of alleles detected in the populations from in situ conservation ranged from 43 to 88 with the mean number of alleles per locus ranging from 2.15 to 4.40, while the number of alleles detected in the populations from ex situ conservation ranged from 33 to 65, and the mean of alleles per locus ranged from 1.65 to 3.25. Compared to the ex situ populations, the number of alleles, the number of specific alleles and the genetic diversity index showed a significant increase in the in situ populations. Further, the numbers of specific alleles from in situ populations were 2.1–5.0 times greater than in ex situ populations except for rice landrace ‘Qitougu’. An AMOVA showed that the within-landrace genetic structure differed significantly between in situ and ex situ conservation treatments with differences exceeding 20%. The analysis of genetic similarity reached similar conclusions to those of the AMOVA. Compared with ex situ conservation programs, the rice landraces under in situ conservation programs had more alleles and higher genetic diversity in Yunnan of China.