Saturated molecular map of the rice genome based on an interspecific backcross population.

Abstract

A molecular map has been constructed for the rice genome comprised of 726 markers (mainly restriction fragment length polymorphisms; RFLPs). The mapping population was derived from a backcross between cultivated rice, Oryza sativa, and its wild African relative, Oryza longistaminata. The very high level of polymorphism between these species, combined with the use of polymerase chain reaction-amplified cDNA libraries, contributed to mapping efficiency. A subset of the probes used in this study was previously used to construct an RFLP map derived from an inter subspecific cross, providing a basis for comparison of the two maps and of the relative mapping efficiencies in the two crosses. In addition to the previously described PstI genomic rice library, three cDNA libraries from rice (Oryza), oat (Avena) and barley (Hordeum) were used in this mapping project. Levels of polymorphism detected by each and the frequency of identifying heterologous sequences for use in rice mapping are discussed. Though strong reproductive barriers isolate O. sativa from O. longistaminata, the percentage of markers showing distorted segregation in this backcross population was not significantly different than that observed in an intraspecific F2 population previously used for mapping. The map contains 1491 cM with an average interval size of 4.0 cM on the framework map, and 2.0 cM overall. A total of 238 markers from the previously described PstI genomic rice library, 250 markers from a cDNA library of rice (Oryza), 112 cDNA markers from oat (Avena), and 20 cDNA markers from a barley (Hordeum) library, two genomic clones from maize (Zea), 11 microsatellite markers, three telomere markers, eleven isozymes, 26 cloned genes, six RAPD, and 47 mutant phenotypes were used in this mapping project. Applications of a molecular map for plant improvement are discussed.

Multi-Environment Quantitative Trait Loci Mapping for Grain Iron and Zinc Content Using Bi-parental Recombinant Inbred Line Mapping Population in Pearl Millet

“…Pollen abortion is most common in pearl millet than abnormalities in female gametes, leading to a comparatively greater loss of male alleles and the subsequent skewness toward the female parent (Kumar et al, 2018). Distortion from expected Mendelian segregation has been observed previously in maize (Wendel et al, 1987;Lu et al, 2002), barley (Graner et al, 1991;Devaux et al, 1995), rice (Causse et al, 1994;Xu et al, 1997), wheat (Blanco et al, 2004;Quarrie et al, 2005), and pearl millet (Supriya et al, 2011). The protogynous nature of pearl millet also contributes to segregation distortion (Liu et al, 1994).…”

An introgression line population of Lycopersicon pennellii in the cultivated tomato enables the identification and fine mapping of yield-associated QTL.

“…such studies must possess sufficient polymorphism for marker analysis and for quantitative traits. For self-pollinated crops, such as rice (CAUSSE et al 1994), soybean (KEIM et al 1990) and tomato (MILLER and TANKSLEY 1990), little variation between cultivated varieties is detectable by DNA markers. To overcome this problem, studies of quantitative trait loci (QTL) were performed on wide crosses between species or races.…”

Identification of QTL for fasciated ear related traits in maize

“…Young leaves were taken from every plant of the parents and F 2 generation. The DNA of these young leaves was extracted according to the method of cetyltrimethyl ammonium bromide (CTAB) (Causse et al., 1994; Murray & Thompson, 1980). Simple sequence repeats (SSRs) were used for molecular marker mapping (Senior, Chin, Lee, Smith, & Stuber, 1996).…”