Abstract
Life histories and breeding systems strongly affect the genetic diversity of seed plants, but the genetic architectures that promote outcrossing in Oryza longistaminata, a perennial wild species in Africa, are not understood. We conducted a genetic analysis of the anther length of O. longistaminata accession W1508 using advanced backcross quantitative trait locus (QTL) analysis and chromosomal segment substitution lines (CSSLs) in the genetic background of O. sativa Taichung 65 (T65), with simple sequence repeat markers. QTL analysis of the BC3F1 population (n = 100) revealed that four main QTL regions on chromosomes 3, 5, and 6 were associated to anther length. We selected a minimum set of BC3F2 plants for the development of CSSLs to cover as much of the W1508 genome as possible. The additional minor QTLs were suggested in the regional QTL analysis, using 21 to 24 plants in each of the selected BC3F2 population. The main QTLs found on chromosomes 3, 5, and 6 were validated and designated qATL3, qATL5, qATL6.1, and qATL6.2, as novel QTLs identified in O. longistaminata in the mapping populations of 94, 88, 70, and 95 BC3F4 plants. qATL3, qATL5, and qATL6.1 likely contributed to anther length by cell elongation, whereas qATL6.2 likely contributed by cell multiplication. The QTLs were confirmed again in an evaluation of the W1508ILs. In several chromosome segment substitution lines without the four validated QTLs, the anthers were also longer than those of T65, suggesting that other QTLs also increase anther length in W1508. The cloning and diversity analyses of genes conferring anther length QTLs promotes utilization of the genetic resources of wild species, and the understanding of haplotype evolution on the differentiation of annuality and perenniality in the genus Oryza.
Highlights
Life histories and breeding systems strongly affect the genetic diversity of seed plants
quantitative trait locus (QTL) derived from O. longistaminata in a uniform genetic background, we developed chromosomal segment substitution lines (CSSLs) carrying
Because our objective was to construct a platform from which to analyze the genetic difference between O. sativa and O. longistaminata, we evaluated the phenotypic character anther length, which is a key character in O. longistaminata, and genotyped BC3 populations and W1508ILs
Summary
Life histories and breeding systems strongly affect the genetic diversity of seed plants. Annuals tend to allocate their resources to sexual reproduction to produce as many flowers as possible for the one-time dispersal of seeds. Perennial species tend to show higher heterozygosity when compared with the annual species or domesticated species [2]. Heterozygosity has been found to correlate with fitness-related traits, such as survival probability, reproductive success, and disease resistance [3,4,5,6,7]. Populations of perennials maintain high genetic diversity by producing few but large floral organs, and by promoting relatively high outcrossing rates with mechanisms to prevent self-pollination—such as self-incompatibility
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