Quantitative Trait Loci For Flowering Research Articles

Genetic and molecular control of the flowering time in soybean (Glycine max (L.) Merrill)

Photoperiod response to flowering is one of the most vital factors that affect in regional adaptation and yield in soybean. Soybean adaption at high latitude areas (long-day) requires early flowering and low photoperiod sensitive cultivars; adaptation to low latitudes (short-day) areas needs delayed flowering cultivars, which maximize vegetative growth and seed yield. This paper represents a genetic and molecular regulation of flowering time in soybean, which will help broad adaptability across latitudes. It is revealed that one to eleven main genes control the flowering time in soybean. The FT family of flowering integrators plays a central role in controlling the flowering time. The juvenile growth phase (JGP) determines the development rate for flowering; a long JGP results in the lengthening of the vegetative period and increases the soybean production in low latitude areas. This review outlines the JGP-related gene in soybean. We emphasize the interaction between major genes and QTLs for flowering in soybean. Several major genes and quantitative trait loci (QTLs) for flowering interact with one another including the environment to greatly influence flowering time. The molecular ground information of the flowering in Arabidopsis will help to understand the molecular dissection of flowering in soybean. This information could be used for breeding of high‐yielding soybean cultivars in different latitudinal areas.
 Res. Agric., Livest. Fish.9(1): 1-10, April 2022

Disentangling group specific QTL allele effects from genetic background epistasis using admixed individuals in GWAS: An application to maize flowering.

When handling a structured population in association mapping, group-specific allele effects may be observed at quantitative trait loci (QTLs) for several reasons: (i) a different linkage disequilibrium (LD) between SNPs and QTLs across groups, (ii) group-specific genetic mutations in QTL regions, and/or (iii) epistatic interactions between QTLs and other loci that have differentiated allele frequencies between groups. We present here a new genome-wide association (GWAS) approach to identify QTLs exhibiting such group-specific allele effects. We developed genetic materials including admixed progeny from different genetic groups with known genome-wide ancestries (local admixture). A dedicated statistical methodology was developed to analyze pure and admixed individuals jointly, allowing one to disentangle the factors causing the heterogeneity of allele effects across groups. This approach was applied to maize by developing an inbred “Flint-Dent” panel including admixed individuals that was evaluated for flowering time. Several associations were detected revealing a wide range of configurations of allele effects, both at known flowering QTLs (Vgt1, Vgt2 and Vgt3) and new loci. We found several QTLs whose effect depended on the group ancestry of alleles while others interacted with the genetic background. Our GWAS approach provides useful information on the stability of QTL effects across genetic groups and can be applied to a wide range of species.

Earliness per se QTLs and their interaction with the photoperiod insensitive allele Ppd-D1a in the Cutler × AC Barrie spring wheat population

Earliness per se regulates flowering time independent of environmental signals and helps to fine tune the time of flowering and maturity. In this study, we aimed to map earliness per se quantitative trait loci (QTLs) affecting days to flowering and maturity in a population developed by crossing two spring wheat cultivars, Cutler and AC Barrie. The population of 177 recombinant inbred lines (RILs) was genotyped for a total of 488 SSR and DArT polymorphic markers on all 21 chromosomes. Three QTLs of earliness per se affecting days to flowering and maturity were mapped on chromosomes 1B (QEps.dms-1B1 and QEps.dms-1B2) and 5B (QEps.dms-5B1), in individual environments and when all the environments were combined. A QTL affecting flowering time (QFlt.dms-4A1) was identified on chromosome 4A. Two grain yield QTLs were mapped on chromosome 5B, while one QTL was mapped on chromosome 1D. The population segregated for the photoperiod insensitive gene, Ppd-D1a, and it induced earlier flowering by 0.69days and maturity by 1.28days. The photoperiod insensitive allele Ppd-D1a interacted in an additive fashion with QTLs for flowering and maturity times. The earliness per se QTL QFlt.dms-5B.1 inducing earlier flowering could help to elongate grain filling duration for higher grain yield. Hence, chromosome 5B possesses promising genomic regions that may be introgressed for higher grain yield with earlier maturity through marker-assisted selection in bread wheat.

Identification of population-specific QTLs for flowering in soybean

Flowering is an important stage in plant development and crucial for adaptation of plant species to different environments. Two soybean mapping populations were used to identify quantitative trait loci (QTLs) for days to flowering (DF) and days to maturity (DM) by genotyping simple sequence repeat (SSR) markers. Single-factor analysis of variance detected association of phenotypic data with SSR markers in each population. DF QTLs were identified on four chromosomes (chrs.); two QTLs located on chrs. 2 and 13 with Satt041 and Satt206 in the Jinpumkong 2 × SS2-2 population and other two DF QTLs were detected on chrs. 6 and 19 with Satt100 and Satt373 in the Iksannamulkong × SS2-2 population. The major QTLs associated with Satt100 explained 30.3% of maximum phenotypic variation. Especially, all DF QTLs included QTLs for DM, except Satt206 on chr. 13. Moreover, two additional DM QTLs were mapped on chrs. 10 and 11 with Satt243 and Satt359, respectively. DF QTL on chr. 2 with Satt041 was the newly identified QTL only in the Jinpumkong 2 × SS2-2 population and explained 10.3% of the phenotypic variation. The single locus of Satt100 on chr. 6 and Satt373 on chr. 19 were located on soybean genomic regions of the known flowering gene loci E1 and E3, respectively. These population-specific QTLs (Satt100 and Satt373) are the major QTLs for flowering time, putatively, they may be related to maturity QTLs with large effect. Additionally, these QTLs are valuable for marker-assisted approaches and could be widely adopted by soybean breeders.

Genetic resolution and verification of quantitative trait loci for flowering and plant height with recombinant inbred lines of maize

Recombinant inbred (RI) lines offer several advantages for detecting quantitative trait loci (QTLs), including increased precision of trait measurements, power for detection of additive effects, and resolution of linked QTLs. This study was conducted to detect and characterize QTLs in maize for flowering and plant height and to compare QTL detection in an early (F2:3) generation of the same population. One hundred and eighty-six RIs from a cross between inbred lines Mo17 and H99 were evaluated in a replicated field experiment and analyzed at 101 loci detected by restriction fragment length polymorphisms. QTLs were identified by single-factor analysis of variance. A total of 59 QTLs were detected for plant height, ear height, top height, anthesis, silk emergence, and anthesis to silk interval. Individual QTLs explained 2.2-15.4% of trait variation, and multiple models including all QTLs detected for a trait explained up to 52.5% of the phenotypic variation. Comparison of QTLs detected with 150 F2:3 lines from the same population indicated that 16 (70%) of the 23 F2:3 QTLs were also observed in the F6:7 generation. Parental effects were consistent across generations. At 14 of the 16 QTLs detected in both generations, genetic effects were smaller in the F6:7. Also, some QTLs detected in the F2:3 were resolved into multiple linked QTLs in the F6:7, indicating the additional power of RI populations for mapping, with important implications for marker-assisted selection as well as map-based cloning of QTLs. Key words : Zea mays, RFLP, plant breeding, genetics, recombination.

Quantitative Trait Loci for Flowering, Plant and Ear Height, and Kernel Traits in Maize

The inheritance of quantitative traits is not well understood. A study was conducted to determine the number and chromosomal locations of quantitative trait loci (QTL) controlling male anthesis date; plant and ear height; kernel weight; and kernel protein, oil, and starch concentration in maize (Zea mays L.). Two hundred S1 lines were derived from a single F1 plant from a cross of Illinois High Oil (IHO) by lllinois Low Oil (Early Maturity) [ILO(EM)]. Restriction fragment length polymorphism (RFLP) analysis was performed to determine RFLP genotypes of the 200 S1 families at 80 polymorphic loci spaced on average 24 centimorgans throughout the genome. The 200 S1 families were measured for phenotypic traits in replicated field trials during 1992 and 1993. Analysis of variance detected significant (P < 0.05) associations between several RFLP loci and each phenotypic trait. A total of 16 marker loci clustered in eight chromosomal regions were significantly associated with male anthesis date, 18 marker loci clustered in II regions were significantly associated with plant height, 14 marker loci clustered in nine regions were significantly associated with ear height, 27 marker loci clustered in II regions were associated with kernel weight, 16 marker loci clustered in eight regions were associated with protein concentration, 31 marker loci clustered in II regions were associated with oil concentration, and 28 marker loci clustered in 13 regions were associated with starch concentration. A number of QTL were detected in chromosomal regions where known gene loci of biological relevance are located.