scholarly journals Phylogenetic Differentiation of Cultivated Rice, XX Analysis of the Genetic Basis of Hybrid Breakdown in Rice

1962 ◽  
Vol 37 (1) ◽  
pp. 24-35 ◽  
Author(s):  
Hiko-Ichi OKA ◽  
Yukio DOIDA
Keyword(s):  
Genetic Basis ◽  
Hybrid Breakdown ◽  
Cultivated Rice

scholarly journals Substitution Mapping of a Locus Responsible for Hybrid Breakdown in Populations Derived From Interspecific Introgression Line

2021 ◽  
Vol 12 ◽  
Author(s):  
Nilsa Emilia Munguambe ◽  
Shouta Inoue ◽  
Zita Demeter ◽  
Yoshiyuki Yamagata ◽  
Hideshi Yasui ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Interspecific Cross ◽  
Introgression Line ◽  
Chromosome 4 ◽  
Hybrid Breakdown ◽  
Cultivated Rice ◽  
Lod Score ◽  
Interspecific Introgression ◽  
Oryza Meridionalis ◽  
Weak Growth

Hybrid breakdown, a form of postzygotic reproductive barrier, has been reported to hinder gene flow in many crosses between wild and cultivated rice. Here, the phenomenon of hybrid breakdown was observed as low-tillering (i.e., low tiller number) in some progeny of an interspecific cross produced in an attempt to introduce Oryza meridionalis Ng (W1625) chromosomal segments into Oryza sativa L. ssp. japonica “Taichung 65” (T65). Low-tillering lines were obtained in BC4-derived progeny from a cross between W1625 and “Taichung 65,” but the locus for low-tillering could not be mapped in segregating populations. As a second approach to map the locus for low-tillering, we analyzed an F2 population derived from a cross between the low-tillering lines and a high-yielding indica cultivar, “Takanari.” A major QTL for low-tillering, qLTN4, was detected between PCR-based markers MS10 and RM307 on the long arm of chromosome 4, with a LOD score of 15.6. The low-tillering phenotype was associated with weak growth and pale yellow phenotype; however, low-tillering plant had less reduction of grain fertility. In an F4 population (4896 plants), 563 recombinant plants were identified and the low-tillering locus was delimited to a 4.6-Mbp region between markers W1 and C5-indel3729. This region could not be further delimited because recombination is restricted in this region of qLTN4, which is near the centromere. Understanding the genetic basis of hybrid breakdown, including the low-tillering habit, will be important for improving varieties in rice breeding.

scholarly journals The Genetic Basis of High Resistance to Rice Yellow Mottle Virus (RYMV) in Cultivars of Two Cultivated Rice Species

Plant Disease ◽  
1999 ◽  
Vol 83 (10) ◽  
pp. 931-935 ◽  
Author(s):  
M. N. Ndjiondjop ◽  
L. Albar ◽  
D. Fargette ◽  
C. Fauquet ◽  
A. Ghesquière
Keyword(s):  
Genetic Basis ◽  
Virus Isolate ◽  
Mottle Virus ◽  
F1 Hybrids ◽  
Enzyme Linked Immunosorbent Assay ◽  
Rice Yellow Mottle Virus ◽  
Recessive Resistance ◽  
Cultivated Rice ◽  
Recessive Resistance Gene ◽  
Yellow Mottle

Three cultivars of Oryza sativa (IR64, Azucena, and Gigante) and four cultivars of O. glaberrima (Tog5681, Tog5673, CG14, and SG329) were evaluated for their resistance to two isolates of rice yellow mottle virus (RYMV) by enzyme-linked immunosorbent assay (ELISA) and symptomatology. Cultivars Tog5681 and Gigante were highly resistant, and no symptoms were observed when either virus isolate was inoculated at 10 or 20 days postgermination and assayed by ELISA at 7, 14, 22, 35, 50, or 64 days postinoculation. Azucena showed a partial resistance, whereas the other cultivars were susceptible. Symptom appearance was associated with increase in ELISA absorbance in the systemically infected leaves. The best discrimination among the cultivars occurred when the plants were inoculated at 10 days postgermination. Crosses were made between the highly resistant (Gigante and Tog5681) and the susceptible (IR64) cultivars to determine the genetic basis of resistance to RYMV. Evaluation of F1 hybrids and interspecific progenies, as well as the segregation of resistance in F2 and F3 lines of the IR64 × Gigante cross, provided results consistent with the presence of a single recessive resistance gene common to Tog5681 and Gigante.

scholarly journals Genomic divergence during feralization reveals both conserved and distinct mechanisms of parallel weediness evolution

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Toshiyuki Imaizumi ◽  
Kaworu Ebana ◽  
Yoshihiro Kawahara ◽  
Chiaki Muto ◽  
Hiroyuki Kobayashi ◽  
...  
Keyword(s):  
Crop Production ◽  
Genetic Basis ◽  
Whole Genome Sequence ◽  
Weedy Rice ◽  
Cultivated Rice ◽  
Tropical Japonica ◽  
Adaptive Introgression ◽  
Genomic Signatures ◽  
Genomic Divergence ◽  
Genetic Mechanisms

AbstractAgricultural weeds are the most important biotic constraints to global crop production, and chief among these is weedy rice. Despite increasing yield losses from weedy rice in recent years worldwide, the genetic basis of weediness evolution remains unclear. Using whole-genome sequence analyses, we examined the origins and adaptation of Japanese weedy rice. We find evidence for a weed origin from tropical japonica crop ancestry, which has not previously been documented in surveys of weedy rice worldwide. We further show that adaptation occurs largely through different genetic mechanisms between independently-evolved temperate japonica- and tropical japonica-derived strains; most genomic signatures of positive selection are unique within weed types. In addition, some weedy rice strains have evolved through hybridization between weedy and cultivated rice with adaptive introgression from the crop. Surprisingly, introgression from cultivated rice confers not only crop-like adaptive traits (such as shorter plant height, facilitating crop mimicry) but also weedy-like traits (such as seed dormancy). These findings reveal how hybridization with cultivated rice can promote persistence and proliferation of weedy rice.

scholarly journals The genic nature of gamete eliminator in rice.

Genetics ◽  
1990 ◽  
Vol 125 (1) ◽  
pp. 183-191 ◽  
Author(s):  
Y Sano
Keyword(s):  
Genetic Basis ◽  
Hybrid Sterility ◽  
Oryza Glaberrima ◽  
Male Sterile ◽  
Cultivated Rice ◽  
Sterility Gene ◽  
Wx Locus ◽  
Allelic Interaction ◽  
Different Genetic Background ◽  
Marked Suppression

Abstract The two cultivated rice species, Oryza sativa and Oryza glaberrima, are morphologically alike but are reproductively isolated from each other by hybrid sterility. The hybrid is male sterile but partially female fertile. Backcross experiments were conducted to introduce an alien factor controlling hybrid sterility from O. glaberrima (W025) into O. sativa (T65wx) and examine the genetic basis. An extracted sterility factor, closely linked to the wx locus, induced gametic abortion due to allelic interaction and was tentatively designated as S(t). The segregation patterns for infertility was explained by assuming that W025 and T65wx carried S(t) and S(t)a, respectively, and gametes with S(t)a aborted only in the heterozygote (S(t)/S(t)a) although the elimination of female gametes was incomplete. Thus, S(t) seemed to be intermediate between a gamete eliminator and pollen killer. However, S(t) was proven to be likely the same as S1 which was formerly reported as gamete eliminator in a different genetic background of O. sativa. In addition, a chromosomal segment containing S1 (or S(t] caused a marked suppression of crossing over around it, suggesting the presence of an inversion. Further, female transmission of S1a increased as the segment containing S1 became small by recombination. After S1 was further purified by successive backcrosses up to the BC15 generation, it became pollen killer. The present results give evidence that a profound sterility gene such as gamete eliminator can be made from accumulation of pollen killer and its modifier(s) when pollen killer and modifier(s) are linked, they behave as a gene complex in the hybrid.

scholarly journals Overdominant Epistatic Loci Are the Primary Genetic Basis of Inbreeding Depression and Heterosis in Rice. II. Grain Yield Components

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1755-1771 ◽  
Author(s):  
L J Luo ◽  
Z-K Li ◽  
H W Mei ◽  
Q Y Shu ◽  
R Tabien ◽  
...  
Keyword(s):  
Grain Yield ◽  
Inbreeding Depression ◽  
Yield Components ◽  
Genetic Basis ◽  
Mixed Model ◽  
Gene Action ◽  
Recombinant Inbred Lines ◽  
Hybrid Breakdown ◽  
Multilocus Genotypes ◽  
Grain Yield Components

Abstract The genetic basis underlying inbreeding depression and heterosis for three grain yield components of rice was investigated in five interrelated mapping populations using a complete RFLP linkage map, replicated phenotyping, and the mixed model approach. The populations included 254 F10 recombinant inbred lines (RILs) derived from a cross between Lemont (japonica) and Teqing (indica), two backcross (BC) and two testcross populations derived from crosses between the RILs and the parents plus two testers (Zhong413 and IR64). For the yield components, the RILs showed significant inbreeding depression and hybrid breakdown, and the BC and testcross populations showed high levels of heterosis. The average performance of the BC or testcross hybrids was largely determined by heterosis. The inbreeding depression values of individual RILs were negatively associated with the heterosis measurements of the BC or testcross hybrids. We identified many epistatic QTL pairs and a few main-effect QTL responsible for >65% of the phenotypic variation of the yield components in each of the populations. Most epistasis occurred between complementary loci, suggesting that grain yield components were associated more with multilocus genotypes than with specific alleles at individual loci. Overdominance was also an important property of most loci associated with heterosis, particularly for panicles per plant and grains per panicle. Two independent groups of genes appeared to affect grain weight: one showing primarily nonadditive gene action explained 62.1% of the heterotic variation of the trait, and the other exhibiting only additive gene action accounted for 28.1% of the total trait variation of the F1 mean values. We found no evidence suggesting that pseudooverdominance from the repulsive linkage of completely or partially dominant QTL for yield components resulted in the overdominant QTL for grain yield. Pronounced overdominance resulting from epistasis expressed by multilocus genotypes appeared to explain the long-standing dilemma of how inbreeding depression could arise from overdominant genes.

Overdominant Epistatic Loci Are the Primary Genetic Basis of Inbreeding Depression and Heterosis in Rice. I. Biomass and Grain Yield

Genetics ◽  
2001 ◽  
Vol 158 (4) ◽  
pp. 1737-1753 ◽  
Author(s):  
Zhi-Kang Li ◽  
L J Luo ◽  
H W Mei ◽  
D L Wang ◽  
Q Y Shu ◽  
...  
Keyword(s):  
Grain Yield ◽  
Inbreeding Depression ◽  
Genetic Basis ◽  
Mixed Model ◽  
Recombinant Inbred Lines ◽  
Hybrid Breakdown ◽  
Mixed Model Approach ◽  
Epistatic Qtl ◽  
Main Effect ◽  
Mapping Populations

AbstractTo understand the genetic basis of inbreeding depression and heterosis in rice, main-effect and epistatic QTL associated with inbreeding depression and heterosis for grain yield and biomass in five related rice mapping populations were investigated using a complete RFLP linkage map of 182 markers, replicated phenotyping experiments, and the mixed model approach. The mapping populations included 254 F10 recombinant inbred lines derived from a cross between Lemont (japonica) and Teqing (indica) and two BC and two testcross hybrid populations derived from crosses between the RILs and their parents plus two testers (Zhong 413 and IR64). For both BY and GY, there was significant inbreeding depression detected in the RI population and a high level of heterosis in each of the BC and testcross hybrid populations. The mean performance of the BC or testcross hybrids was largely determined by their heterosis measurements. The hybrid breakdown (part of inbreeding depression) values of individual RILs were negatively associated with the heterosis measurements of their BC or testcross hybrids, indicating the partial genetic overlap of genes causing hybrid breakdown and heterosis in rice. A large number of epistatic QTL pairs and a few main-effect QTL were identified, which were responsible for >65% of the phenotypic variation of BY and GY in each of the populations with the former explaining a much greater portion of the variation. Two conclusions concerning the loci associated with inbreeding depression and heterosis in rice were reached from our results. First, most QTL associated with inbreeding depression and heterosis in rice appeared to be involved in epistasis. Second, most (~90%) QTL contributing to heterosis appeared to be overdominant. These observations tend to implicate epistasis and overdominance, rather than dominance, as the major genetic basis of heterosis in rice. The implications of our results in rice evolution and improvement are discussed.

scholarly journals Genetic-basis analysis of heterotic loci in Dongxiang common wild rice (Oryza rufipogon Griff.)

2012 ◽  
Vol 94 (2) ◽  
pp. 57-61 ◽  
Author(s):  
XIAO-JIN LUO ◽  
XIAO-YUN XIN ◽  
JIN-SHUI YANG
Keyword(s):  
Wild Rice ◽  
Genetic Basis ◽  
Single Point ◽  
Crop Improvement ◽  
Dominant Gene ◽  
Introgression Line ◽  
Oryza Rufipogon ◽  
Cultivated Rice ◽  
Common Wild Rice ◽  
Point Analysis

SummaryHeterosis is widely used in genetic crop improvement; however, the genetic basis of heterosis is incompletely understood. The use of whole-genome segregating populations poses a problem for establishing the genetic basis of heterosis, in that interactions often mask the effects of individual loci. However, introgression line (IL) populations permit the partitioning of heterosis into defined genomic regions, eliminating a major part of the genome-wide epistasis. In our previous study, based on mid-parental heterosis (HMP) value with single-point analysis, 42 heterotic loci (HLs) associated with six yield-related traits were detected in wild and cultivated rice using a set of 265 ILs of Dongxiang common wild rice (Oryza rufipogon Griff.). In this study, the genetic effects of HLs were determined as the combined effects of both additive and dominant gene actions, estimated from the performance values of testcross F1s and the dominance effects estimated from the HMP values of testcross F1s. We characterized the gene action type at each HL. Thirty-eight of the 42 HLs were over-dominant, and in the absence of epistasis, four HLs were dominant. Therefore, we favour that over-dominance is a major genetic basis of ‘wild-cultivar’ crosses at the single functional Mendelian locus level.

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