Orientation and integration of the classical and molecular genetic maps of chromosome 11 in rice

Summary The classical genetic map and molecular map of rice chromosome 11 were oriented to facilitate the use of these maps for genetic studies and rice improvement. Three morphological markers (d-27, z-2, and la) were crossed to a rice breeding line, IRBB21, which has the Xa-21 gene for bacterial blight resistance. Three F₂ populations were analyzed with RFLP markers known to be located on chromosome 11. Segregation analysis of molecular markers and morphological markers was used to construct an RFLP map for each population. The recombination frequency between markers varied from population to population although the marker order on the maps was the same for all three populations. Based on a common set of markers mapped in the three populations, an integrated map was generated consisting of both RFLP and morphological markers. The genetic distance between markers on this map was determined by taking a weighted average of the data from the three populations. The oriented map serves as a bridge to understand the relationship between the classical and molecular linkage maps. Based on this information, the location of several genes on the classical map can be approximated with respect to RFLP markers without having to map them directly.     

Correction to: Genome-wide association study to identify chromosomal regions related to panicle architecture in rice (Oryza spp.)

Genetic Resources and Crop Evolution - A correction to this paper has been published: https://doi.org/10.1007/s10722-021-01185-6     

Genome-wide association study to identify chromosomal regions related to panicle architecture in rice (Oryza sativa)

Panicle architecture directly affects the grain yield of rice; meanwhile, crop domestication has increased the complexity of rice panicle size and branching pattern. Genome-wide association study (GWAS) was performed to investigate the genetic basis underlying panicle architecture using 183 rice accessions from around the world and a 7 K SNP array. Phenotyping was conducted at Texas A&M AgriLife Research Center in Beaumont, TX. GWAS was performed using MLM (Q?+?K) model using GAPIT software. At p-value?<?0.001, a total of 49 GWAS QTLs controlling various panicle architecture traits were mapped. Considering the recurring and linked SNPs across the panicle architecture traits, 42 independent QTL regions were identified. Among these, 27 QTL regions co-localized with known genes or previously reported QTLs or significant SNP markers, while 15 were potentially novel QTL regions. The results of our study offer useful information on genetic bases controlling panicle architecture in rice, which could be further validated and utilized for designing markers for use in markers assisted selection (MAS) in rice breeding programs.

     

Relationship of milled grain percentages and flowering-related traits in rice

The economic value of harvested rice is determined by the grain yield and the percentages of head rice (at least 3/4 the length of a head or kernel) and total milled rice. This study was conducted to determine the effects of flowering-related traits such as duration of flowering, rate of flowering, heading, and duration from heading to maturity on head rice and total milling percentages of rice. Flowering data, gathered for two years from 105 long grain rice genotypes grown in Beaumont, Texas were analyzed for their effects on and relationship with milling traits. A positive linear relationship was obtained for rate of flowering and the duration from heading to maturity but negative for duration of flowering and days to heading. Genotypes with early heading had relatively shorter flowering durations, and genotypes with shorter flowering duration had higher head rice and total milled rice. A faster rate in attaining 100% flowering and more days from heading to maturity were favorable in increasing head rice and total milled grains. The duration from the start of flowering to heading or to 100% flowering can be used in the evaluation and selection for high head rice and total milled rice percentages in rice.