QTLs For Plant Height Research Articles

Linkage map construction and QTL identification for yield related traits of rice (Oryza sativa L.)

The study was undertaken to construct a linkage map and to identify the QTLs for heading date, plant height, and culm strength using a F2 population derived from Ayeyarmin/IR 64, two varieties distinctly different in heading date and plant height. A total of 233 F2 individuals were genotyped using 70 SSR primers, and phenotypic data were collected for heading date, plant height and culm strength traits. Fifty-four out of 70 marker loci were mapped across twelve rice chromosomes spanning a total map length of 1592.30 cM with an average distance of 29.49 cM between adjacent marker loci using MAPMAKER/EXP 3. Composite interval mapping for QTL analysis was conducted with 1000 permutation time at 0.05 probability level using WinQTL Cartographer version 2.5. One major QTL for heading date was mapped between marker RM204 and RM50 on chromosome 6. One major QTL for culm strength was mapped between marker RM1003-RM5931, and two major QTLs for plant height were mapped between RM84-RM1003 and RM1003-RM5931 on chromosome 1. The molecular markers linked to the major QTLs could be potentially used in marker-assisted selection for the rainfed rice improvement breeding program.

Identification of QTLs for plant height and branching related traits in cultivated peanut

Plant height (PH), primary lateral branch length (PBL) and branch number (BN) are architectural components impacting peanut pod yield, biomass production and adaptivity to mechanical harvesting. In this study, a recombinant inbred population consisting of 181 individual lines was used to determine genetic controls of PH, PBL and BN across three environments. Phenotypic data collected from the population demonstrated continuous distributions and transgressive segregation patterns. Broad-sense heritability of PH, PBL and BN was found to be 0.87, 0.88 and 0.92, respectively. Unconditional individual environmental analysis revealed 35 additive QTLs with phenotypic variation explained (PVE) ranging from 4.57 to 21.68%. A two-round meta-analysis resulted in 24 consensus and 17 unique QTLs. Five unique QTLs exhibited pleiotropic effects and their genetic bases (pleiotropy or tight linkage) were evaluated. Joint analysis was performed to estimate the QTL by environment interaction (QEI) effects on PH, PBL and BN, which collectively explained phenotypic variations of 10.80, 11.02, and 7.89%, respectively. We identified 3 major and stable QTL regions (uq9-3, uq10-2 and uq16-1) on chromosomes 9, 10 and 16, spanning 1.43-1.53 Mb genomic regions. Candidate genes involved in phytohormones biosynthesis, signaling and cell wall development were proposed to regulate these morphological traits. These results provide valuable information for further genetic studies and development of molecular markers applicable for peanut architecture improvement.

Construction of a high density genetic map between cultivated and semi-wild soybeans and identification of QTLs for plant height

<p id="C3">In this study, 252 plants and their parents of Fengshou 24 × Tongjiao 83-611 were genotyped by SNP160K DNA-chip. A high-density genetic linkage map with a total length of 3661.46 cM was constructed, composing of 5861 SNP markers. Seven QTLs of plant height were detected by inclusive composite interval mapping (ICIM), and each one explained 2.56%-10.41% of the variation in plant height. <italic>qPH-6-1</italic> had the highest contribution rate of phenotypic variation and dominant effect, explaining 10.41% of plant height variation, and the additive and dominant effects are -1.72 and 18.94, respectively. The contribution rate of <italic>qPH-18-1</italic> was the second, explaining 9.64% of plant height variation, but <italic>qPH-18-1</italic> has the highest additive effect, reaching -12.42. 11 plants with <italic>qPH-6-1</italic> and <italic>qPH-18-1</italic> genotypes <italic>Q6Q6/Q18Q18</italic> were screened in F₂ population with an average plant height of 167.00 cm, and 16 plants with 2-locus genotypes <italic>q6q6/q18q18</italic> were screened out with an average plant height of 91.25 cm. The addition of 23 SNP markers inside and outside the <italic>qPH-18-1</italic> locus interval narrowed the locus interval from 766.97 kb to 66.03 kb, containing eight genes. Combined with gene annotation and relative expression difference analysis, it was hypothesized that <italic>Glyma.18G279800</italic> and <italic>Glyma.18G280200</italic> might be associated with plant height of soybean. This study provides a molecular reference base and genetic basis for the improvement of soybean plant architecture.

Five plants per RIL for phenotyping traits of high or moderate heritability ensure the power of QTL mapping in a rice MAGIC population.

Currently, the power of QTL mapping is mainly dependent on the quality of phenotypic data in a given population, regardless of the statistical method, as the quality of genotypic data is easily guaranteed in the laboratory. Increasing the sample size per line used for phenotyping is a good way to improve the quality of phenotypic data. However, accommodating a large-scale mapping population takes a large area of rice field, which frequently results in high costs and extra environmental noises. To acquire a reasonable small sample size without a penalty in mapping power, we conducted three experiments with a 4-way MAGIC population and measured phenotypes of 5, 10, and 20 plants per RIL. Three traits including heading date, plant height, and tillers per plant were focused. With SNP- and bin-based QTL mapping, 3 major and 3 minor QTLs for heading date with high heritability and 2 major QTLs for plant height with moderate heritability were commonly detected across the three experiments, but no QTL for tillers per plant with low heritability were commonly identified. In addition, bin-based QTL mapping was more powerful than SNP-based mapping and able to rank the genetic effects of parental alleles. Thus, 5 plants per RIL for phenotyping ensure the power of QTL mapping for traits of high or moderate heritability, and bin-based QTL mapping is recommended for multiparent populations.

QTL analysis for plant height and fine mapping of two environmentally stable QTLs with major effects in soybean

Plant height is an important agronomic trait, which is governed by multiple genes with major or minor effects. Of numerous QTLs for plant height reported in soybean, most are in large genomic regions, which results in a still unknown molecular mechanism for plant height. Increasing the density of molecular markers in genetic maps will significantly improve the efficiency and accuracy of QTL mapping. This study constructed a high-density genetic map using 4 011 recombination bin markers developed from whole genome re-sequencing of 241 recombinant inbred lines (RILs) and their bi-parents, Zhonghuang 13 (ZH) and Zhongpin 03-5373 (ZP). The total genetic distance of this bin map was 3 139.15 cM, with an average interval of 0.78 cM between adjacent bin markers. Comparative genomic analysis indicated that this genetic map showed a high collinearity with the soybean reference genome. Based on this bin map, nine QTLs for plant height were detected across six environments, including three novel loci (qPH-b_11, qPH-b_17 and qPH-b_18). Of them, two environmentally stable QTLs qPH-b_13 and qPH-b_19-1 played a major role in plant height, which explained 10.56–32.7% of the phenotypic variance. They were fine-mapped to 440.12 and 237.06 kb region, covering 54 and 28 annotated genes, respectively. Via the function of homologous genes in Arabidopsis and expression analysis, two genes of them were preferentially predicted as candidate genes for further study.

Identification of QTLs for stagnant flooding tolerance in rice employing genotyping by sequencing of a RIL population derived from Swarna × Rashpanjor.

The online version contains supplementary material available at 10.1007/s12298-021-01107-x.

Mapping of QTL for agronomic traits using high-density SNPs with an RIL population in maize.

Genome wide association studies (GWAS) have been widely used to identify QTLs underlying quantitative traits in humans and animals, and they have also become a popular method of mapping QTLs in many crops, including maize. Advances in high-throughput genotyping technologies enable construction of high-density linkage maps using SNP markers. High-density genetic mapping must precede to find molecular markers associated with a particular trait. The objectives of this study were to (1) construct a high-density linkage map using SNP markers and (2) detect the QTLs for grain yield and quality related traits of the Mo17/KW7 RIL population. In this study, two parental lines, Mo17 (normal maize inbred line) and KW7 (waxy inbred line) and 80 F7:8 lines in the Mo17/KW7 RIL population were genotyped using the MaizeSNP50 BeadChip, an Illumina BeadChip array of 56,110 maize SNPs. Marker integration and detection of QTLs was performed using the inclusive composite interval mapping (ICIM) method within the QTL IciMapping software. This study was genotyped using the Illumina MaizeSNP50 BeadChip for maize Mo17/KW7 recombinant inbred line (RIL) population. The 2904 SNP markers were distributed along all 10 maize chromosomes. The total length of the linkage map was 3553.7cm, with an average interval of 1.22cm between SNPs. A total of 18 QTLs controlling eight traits were detected in the Mo17/KW7 RIL population. Three QTLs for plant height (PH) were detected on chromosomes 4 and 8 and showed from 16.01% (qPH8) to 19.85% (qPH4a) of phenotypic variance. Five QTLs related to ear height (EH) were identified on chromosomes 3, 4, and 6 and accounted for 3.79% (qEH6) to 27.57% (qEH4b) of phenotypic variance. Five QTLs related to water content (WC) on chromosomes 1, 4, 8, and 9 accounted for 9.55% (qWC8b) to 23.30% (qWC4) of phenotypic variance. One QTL (qAC9) relating to amylose content (AC) on chromosome 9 showed 82.10% of phenotypic variance. The high-density linkage map and putative QTLs of the maize RIL population detected in this study can be effectively utilized in waxy and normal maize breeding programs to facilitate the selection process through marker-assisted selection (MAS) breeding programs.

Mapping consistent additive and epistatic QTLs for plant production traits under drought in target populations of environment using locally adapted landrace in rice (Oryza sativa L.)

ABSTRACT A total of 36 colocated QTLs associated with plant production traits were mapped using IR62266/Norungan recombinant inbred lines under drought and non-stress conditions in target populations of environment. Multi-model composite interval mapping and multi-environment analysis detected seven consistent QTLs for plant production traits on chromosomes 1, 2, 3, 6, 10 and 11. QTLs for plant height, number of tillers, biomass, spikelet fertility and grain yield under drought identified on chr. 1 (RM5389-RM11943-RM5794), chr. 2 (RM324-RM5390 and RM12460-RM423-RM5345), chr. 3 (RM6329-RM5475-RM16030), chr. 6 (RM508-RM585-RM217), chr. 10 (RM7361-RM8207) and chr. 11 (RM209-RM6499) in this study have been reported as meta-QTLs for yield under drought. Consistent positive allelic contribution from the landrace, Norungan was shown at the two QTLs on chr. 2, while IR62266 showed consistent positive allelic effect at the QTL on chr. 10. At other four regions the effect was confounded with the stress condition, for instance the region on chr. 3 identified for straw yield showed additive effect from Norungan in all stress trials, while in the non-stress trials the positive allele came from IR62266. Epistasis for grain yield was detected in the regions of non-additive effects and its relative contribution was small. Relatively small percentage of grain yield variation was explained by additive x environment interaction (0.28 - 1.77%), but was larger than that explained by additive effect QTL across environments (0.05 - 0.35%). These consistent QTLs may have genes evolutionarily conserved in response to drought and could be ideal candidates for rice yield improvement in water-limited environments.

Mapping QTLs for important agronomic traits in an Iniadi-derived immortal population of pearl millet

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a climate-hardy nutricereal and an essential staple for the people living in dry regions. Substantial improvement has been achieved for seed yield stability in pearl millet, the cultivable area under pearl millet reduces. Deployment of early-flowering, bold-seeded and dwarf genotypes in pearl millet is a vital breeding strategy to improve grain production and enhance the adaptability of pearl millet in low-input farms. Therefore, an experiment was performed for mapping agronomically important traits like flowering time (FT), plant height (PH), panicle length (PL), and 1000-grain weight (TGW) in 317 recombinant inbred line (RIL) population derived from ICMS 8511-S1-17-2-1-1-B-P03 × AIMP 92901-S1-183-2-2-B-08 cross. Broad-sense heritability estimates were high to very high, ranging from 0.52 (PL) to 0.86 (PH). FT showed a significant positive correlation with PH. A key QTL for FT was mapped on LG 1, 15 QTLs for PH scattered on 10 chromosomes, five QTLs for PL dispersed on four chromosomes, and two QTLs for TGW spanned linkage groups 3 and 7. One QTL on LG1 was common for FT and PH. Two major QTLs for PH, one each on LG4B/8 cM and LG7/110 cM were detected. The large effect QTL for TGW on LG7 had a phenotypic variance (R2) of 24.3%. The R2 for PH and PL ranged between 5.2 - 24.5% and 5.0–11.5%, respectively. The QTLs mapped for FT and other agronomic traits in the current study can be exploited to develop elite hybrid parental genotypes/cultivars through marker-assisted breeding and genomic selection.

Effect evaluation of QTL &amp;lt;italic&amp;gt;Qph&amp;lt;/italic&amp;gt;&amp;lt;bold&amp;gt;.&amp;lt;/bold&amp;gt;&amp;lt;italic&amp;gt;nau-5B&amp;lt;/italic&amp;gt; controlling plant height in wheat

Plant height affects directly the yield potential of wheat, and constitutes an important component of plant resistance to lodging. Although a large number of QTLs for plant height were detected, most of them have not been evaluated for their genetic effects yet. In the previous study, a major QTL Qph . nau-5B controlling wheat plant height was identified through association mapping in wheat variety collection. To evaluate the dwarfing effect of this QTL, three near-isogenic lines (NILs) with different alleles of Qph . nau-5B were developed using marker-assisted selection with Nanda 2419, Jichun 1016, and Zhengmai 9023 as donor and Zhongyou 9507 as receptor. The recipient genome compositions of these NILs were higher than 93%. Seven independent field trials were conducted and revealed that, compared with the recurrent parent, all NILs indicated a significant decrease in plant height (11.1 cm or 10.3% on average). Three alleles of Qph . nau-5B showed different degrees of dwarfing effects. The alleles coming from Jichun 1016 and Zhengmai 9023 displayed a similar effect on plant height (12.4 cm) in all environments, stronger than that of Nanda 2419 (8.6 cm). However, the relative dwarfism effects of different alleles were affected by different environments. Further analysis elucidated that this QTL had little detrimental influence on other agronomical traits such as spike number per plant, spike length and 1000-grain weight. These results suggested the breeding value of Qph . nau-5B that would be utilized for molecular design breeding of plant architecture in wheat.

Genetic determinants for agronomic and yield-related traits localized on a GBS-SNP linkage map from a japonica x indica cross in rice

Rice is an important cereal for human consumption. Identification of QTLs for important agronomic traits with high resolution is essential to the identification of genes and marker-assisted breeding to improve rice productivity. A genotyping by sequencing (GBS)-based high-resolution SNP linkage developed in a recombinant inbred lines (RIL) population of a japonica (Bengal) × indica (Pokkali) cross was used for QTL analysis of traits such as days to heading, plant height, panicle length, flag leaf length, 1000 kernel weight, number of unfilled grains, number of filled grains, grain width, grain length, and awns using interval mapping and inclusive composite interval mapping approaches. Among the 102 additive QTLs identified for the ten traits, 23 QTLs were major effect QTLs. A chromosomal region flanking the sd-1 gene colocalized the QTLs for plant height, panicle length, and flag leaf length, suggesting possible pleiotropic effects on the expression of these traits. Our study not only reduced confidence intervals of previously identified QTLs but also validated several known genes for heading date (Hd1), panicle length (APO1), grain width (GW2, GW5) and awn length (An-1). Furthermore, candidate genes for several agronomic traits were identified. Annotations of genes within novel QTLs for yield-related traits revealed that RCN4 (LOC_Os06g45460), expansin precursor (LOC_Os02g51040), and RGB1 (LOC_Os03g46650) are promising candidates for yield enhancement. Our study provided genetic insights into the important agronomic and yield enhancing traits through identification of QTLs and candidate genes for future validation and molecular breeding to improve rice yield potential.

Genetic control of maize plant architecture traits under contrasting plant densities

Plant architecture has played an important role in the adaptation of maize (Zea mays L.) hybrids to historical increases in plant density in order to maximize yields per unit area. At high density, a compact plant structure would allow for less interference by light among plants of the row and a deeper penetration of the radiation towards the lowest canopy layers, without compromising the capture of radiation at crop level. The genetic control of plant architecture traits of maize under contrasting plant densities remains poorly understood. In this work, traits related to leaf and stem architecture were phenotypically analyzed and QTLs were mapped using 160 RILs from the IBM B73 × Mo17 Syn4 population cultivated at low density and high density during 2013–2014 and 2014–2015 growing seasons in Buenos Aires province, Argentina. Forty-nine QTLs were detected on chromosomes 1, 3, 4, 5, 9 and 10. Most QTLs of vertical insertion angle of leaves and leaf orientation value (i.e., vertical angle affected by the curvature of leaves) were detected on chromosome 5 at high density and showed a high percentage of co-location. Detected QTLs for plant and ear height, and the relationship between them were concentrated on chromosome 9, with consistent effect under different density × environment combinations. These regions had large-effect QTLs and constitute hot spots that need to be studied in more detail to determine their potential use in breeding programs.

Construction of a high-density genetic map and mapping of QTLs for soybean (Glycine max) agronomic and seed quality traits by specific length amplified fragment sequencing

BackgroundSoybean is not only an important oil crop, but also an important source of edible protein and industrial raw material. Yield-traits and quality-traits are increasingly attracting the attention of breeders. Therefore, fine mapping the QTLs associated with yield-traits and quality-traits of soybean would be helpful for soybean breeders. In the present study, a high-density linkage map was constructed to identify the QTLs for the yield-traits and quality-traits, using specific length amplified fragment sequencing (SLAF-seq).ResultsSLAF-seq was performed to screen SLAF markers with 149 F8:11 individuals from a cross between a semi wild soybean, ‘Huapidou’, and a cultivated soybean, ‘Qihuang26’, which generated 400.91 M paired-end reads. In total, 53,132 polymorphic SLAF markers were obtained. The genetic linkage map was constructed by 5111 SLAF markers with segregation type of aa×bb. The final map, containing 20 linkage groups (LGs), was 2909.46 cM in length with an average distance of 0.57 cM between adjacent markers. The average coverage for each SLAF marker on the map was 81.26-fold in the male parent, 45.79-fold in the female parent, and 19.84-fold average in each F8:11 individual. According to the high-density map, 35 QTLs for plant height (PH), 100-seeds weight (SW), oil content in seeds (Oil) and protein content in seeds (Protein) were found to be distributed on 17 chromosomes, and 14 novel QTLs were identified for the first time. The physical distance of 11 QTLs was shorter than 100 Kb, suggesting a direct opportunity to find candidate genes. Furthermore, three pairs of epistatic QTLs associated with Protein involving 6 loci on 5 chromosomes were identified. Moreover, 13, 14, 7 and 9 genes, which showed tissue-specific expression patterns, might be associated with PH, SW, Oil and Protein, respectively.ConclusionsWith SLAF-sequencing, some novel QTLs and important QTLs for both yield-related and quality traits were identified based on a new, high-density linkage map. Moreover, 43 genes with tissue-specific expression patterns were regarded as potential genes in further study. Our findings might be beneficial to molecular marker-assisted breeding, and could provide detailed information for accurate QTL localization.

QTL mapping uncovers a semi-dwarf 1 (sdw1) allele in the barley (Hordeum vulgare) ND23049 line.

In barley, semi-dwarf varieties are attractive for their superior harvest index and lodging resistance, but many semi-dwarf barley genotypes suffer from poor spike emergence. We performed a genetic characterization of a semi-dwarf line (ND23049) that combines short stature, strong stiff culms, and adequate spike emergence. We developed a doubled haploid (DH) population derived by crossing ND23049 and the cultivar CLE253. A subset of 88 DH lines and parents were characterized for plant height in 2013 and 2014 and genotyped. In total, 1984 SNPs (345 unique loci) were used to produce a linkage map of 1127.1 cM. Three QTLs for plant height were detected in this population and coincided with the HvGA20ox2/Sdw1, HvBRI1/Uzu1, and HvPRR95 gene loci. The phenotypic variation explained by each QTL was 75.8%, 7.7%, and 4.1%, respectively, and jointly explained 83.3% (2013) and 87.7% (2014) of plant height. Our results suggest that ND23049 contributed the "short" allele at the HvGA20ox2/sdw1 locus while CLE253 provided "short" alleles at the HvBRI1/uzu1 and HvPRR95 loci. We identified a large deletion (at least 92.7 Kb), including HvGA20ox2 (Sdw1), as the causal mutation in ND23049. A set of tightly flanked SNP markers will help breeders to develop improved semi-dwarf varieties.

Analysis of the genetic basis of plant height-related traits in response to ethylene by QTL mapping in maize (Zea mays L.).

Ethylene (ET) is critical importance in the growth, development, and stress responses of plants. Plant hormonal stress responses have been extensively studied, however, the role of ET in plant growth, especially plant height (PH) remains unclear. Understanding the genetic control for PH in response to ET will provide insights into the regulation of maize development. To clarify the genetic basis of PH-related traits of maize in response to ET, we mapped QTLs for PH, ear height (EH), and internode length above the uppermost ear (ILAU) in two recombinant inbred line (RIL) populations of Zea mays after ET treatment and in an untreated control (CK) group. Sixty QTLs for the three traits were identified. Twenty-two QTLs were simultaneously detected under both ET treatment and untreated control, and five QTLs were detected at two geographic locations under ET treatment only. Individual QTL can be explained 3.87–17.71% of the phenotypic variance. One QTL (q2PH9-1, q1PH9, q1EH9/q1ILAU9-1, q2ILAU9, and q2EH9) for the measured traits (PH, EH, ILAU) was consistent across both populations. Two QTLs (q2PH2-5, q2ILAU2-2, q1PH2-2, and q1ILAU2-2; q1PH8-1, q1EH8-1, q2PH8-1) were identified for up to two traits in both locations and populations under both ET treatment and untreated control. These consistent and stable regions are important QTLs of potential hot spots for PH, ear height (EH), and internode length above the uppermost ear (ILAU) response to ET in maize; therefore, QTL fine-mapping and putative candidate genes validation should enable the cloning of PH, EH, and ILAU related genes to ET response. These results will be valuable for further fine-mapping and quantitative trait nucleotides (QTNs) determination, and elucidate the underlying molecular mechanisms of ET responses in maize.

Detection of QTLs for Plant Height Related Traits in Brassica napus L. Using DH and Immortalized F 2 Population

Detection of QTLs for Plant Height Related Traits in <i>Brassica napus</i> L. Using DH and Immortalized F ₂ Population

QTL mapping of agronomically important traits in sorghum (Sorghum bicolor L.)

Sorghum is one of the most important cereal crops; it is used to produce feed, sugar, and biofuel. To investigate genetic tradeoffs between grain and stem sugar production, we evaluated plant height, Brix (the percentage of soluble solids in stalk juice), 100-grain weight and flowering time over 3 years in a recombinant inbred line (RIL) population consisting of 189 individuals derived from a cross between the sweet sorghum cultivar ‘Rio’ and grain sorghum ‘BTx623’. We constructed a genetic linkage map (total length, 1418.71 cM; average distance between markers, 11.26 cM), which consisted of 118 simple sequence repeat (SSR) and 8 insertion-deletion (INDEL) markers. A total of 14 QTLs were detected on chromosomes 1, 3, 6, 7, and 9, which included 6 QTLs for plant height; 4 for Brix; and 2 QTLs for each 100-grain weight and flowering time. Eight QTLs were detected at least in 2 years. These results will be useful for future QTL fine mapping and gene mining for these traits, and useful for the improvement of sorghum through molecular marker-assisted selection.

Mapping QTLs for plant height and flowering time in a Chinese summer planting soybean RIL population

Soybean is a primary source of plant oil and protein and has a high nutritional value. Plant height (PH) and flowering time (FT) are two important agronomic traits in breeding programs for soybean. In this study, we mapped QTLs associated with PH and FT in three environments using a population with determinate growth including 236 recombinant inbred lines (NJZY-RIL) derived from a cross between two summer planting varieties, ZXD and NN1138-2. A high-density genetic map with 3255 SLAF-markers was constructed that spanned 2144.85 cM of the soybean genome with an average marker distance of 0.66 cM. Altogether, six QTLs controlling PH and eleven QTLs controlling FT were mapped using mixed-model-based composite interval mapping and composite interval mapping methods. qPH-1-1 and qFT-15-2 were two novel main effect QTLs identified in this study; qFT-6-2, qFT-15-2, qFT-16-1, qPH-1-1, qPH-15-1 and qPH-16-1 were consistently detected across environments and by the two mapping methods. Two pairs of QTLs, qFT-15-2 and qPH-15-1 as well as qFT-16-1 and qPH-16-1, which were located in the same marker interval on chromosomes 15 and 16, respectively, were found to have close linkage or pleiotropy. These results may increase our understanding of the genetic control of PH and FT in soybean and provide support for implementing marker-assisted selection in developing soybean cultivars with high yield and early maturity in summer planting regions.

Quantitative trait loci (QTL) controlling plant architecture traits in a Solanum lycopersicum × S. pimpinellifolium cross

Plant architecture is an important determinant of tomato yield because it affects light distribution within a crop canopy. One hundred and eleven lines of a BC1F8 population developed from Solanum lycopersicum ‘M570018’ and its wild relative Solanum pimpinellifolium (PI124039) were grown in a glasshouse in spring and autumn, and plant architecture traits evaluated at two leaf positions: the last leaf before floral initiation (F leaf) and the largest leaf (L leaf). QTL analysis was performed using QTLNetwork 2.1; 23 additive QTLs and seven epistatic QTLs were detected for 13 of 16 traits measured in this study. On chromosomes 2 and 12, QTLs for the leaf drooping angle (DRAN) of the F leaf (fdran2 and fdran12) co-located with QTLs for canopy size (CAN) at each leaf position of the F and L leaves (fcan2 and lcan2, fcan12 and lcan12). On chromosome 3, QTLs for leaf length (LL) of the F and L leaves (fll3 and lll3) co-located with the epistatic QTL for CAN at the L leaf (lcan3). QTLs for plant height (PH) were detected on chromosome 2, 3, 4, and 6; all of these QTLs (ph2, ph3, ph4, and ph6) decreased PH in the presence of Solanum lycopersicum (SL) alleles. QTLs for total leaf number and internode length were detected on chromosomes 3 and 4; tln3 and int4 mapped in the vicinity of ph3 and ph4, respectively. The co-localization of QTLs associated with CAN, DRAN, and LL suggests canopy size is determined by both leaf length and leaf drooping angle in tomato.

Epistatic Effects and QTL×Environment Interaction Effects of QTLs for Yield and Agronomic Traits in Soybean

Improving seed yield is an important goal of soybean breeding programs.In this investigation,a soybean SSR genetic linkage map constructed by a total of 447 recombinant inbred lines(RILs) derived from a cross between Jindou 23(cultivar,female parent) and ZDD2315(semi-wild,male parent) and the mixed linear model was used to identify the QTLs of yield and other QTLs for major agronomic traits in a two-year experiment.Nine QTLs bearing additive effects for pod position,plant height,node number on main stem,branch number,stem thickness and yield per plot were mapped in the linkage groups J_2,I,and M.The QTLs of yield per plot,stem thickness,plant height,branch number and node number on main stem showed positive additive effects donated by Jindou 23.Seven pairs of epistatic effects QTLs for pod position,plant height and stem thickness were detected,which had an interaction with environments.The results indicated that the epistatic effects and the environmental factors played an important role in yield per plot and agronomic traits in soybean.It will be very important to pay attention to not only QTLs with major effects but also those with epistatic effects in soybean molecular marker-assisted breeding in considering the stability expression and inheritance of the agronomic traits.