Controlling Plant Height Research Articles

DBC1, an allelic OsDRP2B gene, regulating plant height by controlling cell division in Oryza sativa L.

Plant height directly affects the lodging resistance and yield of rice, a staple food for almost half the world’s population. To investigate the molecular mechanism of plant height development, a dwarf and brittle mutant dbc1 was obtained from the progeny of Ethylmethane sulfonate (EMS) treated indica restorer line Jinhui10. Cultivated in the paddy field, the dbc1 had a decreased plant height from the seedling stage through to maturity. All internodes of dbc1 were reduced in length at a highly significant level, compared with those of the wild type. However, paraffin sectioning showed that their cell sizes displayed no obvious difference. Additionally, the dbc1 developed more slowly than the wild type, having a developmental delay of 7 days. Cells at the root apical meristem (RAM) containing two nuclei were much more abundant in dbc1 compared to those of the wild type. The regulated gene of dbc1 was confirmed as encoding a dynamin-related protein 2B (OsDRP2B) by mapped-based cloning strategy. qPCR indicated that the expression of cell cycle related genes decreased in the mutant and was partially restored in DBC1-overexpressed plant. Gibberellin response assay showed that the dbc1 was less sensitive to exogenous GA3, the endogenous bioactive GA1 decreased significantly, and these results agreed with the qPCR analysis. The OsDRP2B/DBC1 was proposed to control plant height by regulating cell division, and the process was partially influenced by the gibberellin pathway.

Fine-mapping and transcriptome analysis of a candidate gene controlling plant height in Brassica napus L.

BackgroundBrassica napus provides approximately 13–16% of global vegetable oil for human consumption and biodiesel production. Plant height (PH) is a key trait that affects plant architecture, seed yield and harvest index. However, the genetic mechanism of PH in B. napus is poorly understood.ResultsA dwarf mutant df59 was isolated from a large-scale screening of an ethyl methanesulphonate-mutagenized rapeseed variety Ningyou 18. A genetic analysis showed that the dwarfism phenotype was controlled by one semi-dominant gene, which was mapped on C9 chromosome by quantitative trait loci sequencing analysis and designated as BnaDwf.C9. To fine-map BnaDwf.C9, two F2 populations were constructed from crosses between conventional rapeseed cultivars (Zhongshuang 11 and Holly) and df59. BnaDwf.C9 was fine-mapped to the region between single-nucleotide polymorphism (SNP) markers M14 and M4, corresponding to a 120.87-kb interval of the B. napus ‘Darmor-bzh’ genome. Within this interval, seven, eight and nine annotated or predicted genes were identified in “Darmor-bzh”, “Ningyou 7” and “Zhongshuang 11” reference genomes, respectively. In addition, a comparative transcriptome analysis was performed using stem tips from Ningyou 18 and df59 at the stem elongation stage. In total, 3995 differentially expressed genes (DEGs) were identified. Among them, 118 DEGs were clustered in plant hormone-related signal transduction pathways, including 81 DEGs were enriched in auxin signal transduction. Combining the results of fine-mapping and transcriptome analyses, BnaC09g20450D was considered a candidate gene for BnaDwf.C9, which contains a SNP that co-segregated in 4746 individuals. Finally, a PCR-based marker was developed based on the SNP in BnaC09g20450D.ConclusionsThe combination of quantitative trait loci sequencing, fine-mapping and genome-wide transcriptomic analysis revealed one candidate gene located within the confidence interval of 120.87-kb region. This study provides a new genetic resource for semi-dwarf breeding and new insights into understanding the genetic architecture of PH in B. napus.

Proteomic analysis in different development stages on SP0 generation of rice seeds after space flight

The space biological effects of plants will drive the development of aerospace science and breeding science. The aim of this study is to reveal changes in the proteome of contemporary plants at different growth and development stages after space flight of rice seeds. We carried the rice seeds (DN416) through the SJ-10 returning satellite and returned to the ground for planting to the three-leaf stage (TLP) and tillering stage (TS) after a 12.5-day orbital flight. We found that the space flight caused the rice germination rate, the TLP plant height, and the number of tillers in the TS decreased by 11.64%, 9.75%, and 9.80%, respectively. In addition, the treatment group ROS and MDA level increased in the TLP and TS. The abundance patterns of proteins in these leaves identified 214 proteins in the TLP and 286 in the TS leaves that were markedly changed. Moreover, our study identified D14 proteins that control plant height and tiller. Our results show that the space environment may affect the downstream signaling mechanism by regulating the level of ROS in the body to achieve a response to the space environment. Meanwhile, the space environment may affect the plant height and tiller of rice by altering the expression of D14 protein and hormone-regulated proteins. Our results reveal changes in the proteome of different growth stages of rice plants, and also reveal the molecular mechanism of space environment regulation of rice plant height and tiller, which provides a new direction for further understanding of space biological effects and space mutation breeding.

Efficacy of botanicals and biofertilizers in sesame seed treatment

Sesame (Sesamum indicum L.) an ancient and third main oilseed crop after Groundnut (Arachis hypogeae L.) and Rape seed (Brassica campestris L.) grown in India. It occupies an area of 24.37 million hectares and total production of 208.71 million tonnes with productivity of 856 kg ha-1. In any crop, seed is the basic input in agriculture and its supply of to the farmers is essential to attain self-sufficiency. Seed pelleting is the easier and a common technique followed in direct sown crops as it needs initial vigour for relentless crop growth and development. Pelleting provide a medium to construct package of materials which will help to influence micro environment of each seed by supplying nutrients from the earlier stages of the crop. This study was aimed to ascertain the outcome of seed pelleting on different sesame varieties and their yield attributes and yield. Usually seeds vary in size, shape and colour, which leads to difficulty in precision seeding and uniform plant spacing. Physical seed enhancement techniques like seed pelleting results in more rapid and synchronous germination across seedbed environment particularly when their seed size is very small. The bio-fertilizers stimulate the growth and there by increased the survival rate of planted seedling. The hike in germination of seeds pelleted with bio-fertilizers might be due to the increased cytokinin production which actively involved in cell division. Pelleting can indirectly improve seed germination and stand establishment, while nutrient pelleting enrich the rhizosphere region with macro and micro nutrient triggering the vegetative growth of seedling as well to the improvement in zone specific microbial activity. From the present study it is revealed that seed pelleted with Neem leaf powder 760 g + Azospirillum 120 g + Phosphobacteria 120 g + 10% Maida gruel registered maximum plant height of 126.7 cm, No. of capsules (58.5), No. of Seeds per capsule (58.5) and seed yield of 530 kg/ha compared to control (Plant height (112.6 cm), No. of capsules (51.3), No. of Seeds per capsule (51.3) and seed yield of 375 kg/ha.

Natural Selection Towards Wild-Type in Composite Cross Populations of Winter Wheat.

Most of our crops are grown in monoculture with single genotypes grown over wide acreage. An alternative approach, where segregating populations are used as crops, is an exciting possibility, but outcomes of natural selection upon this type of crop are not well understood. We tracked allelic frequency changes in evolving composite cross populations of wheat grown over 10 generations under organic and conventional farming. At three generations, each population was genotyped with 19 SSR and 8 SNP markers. The latter were diagnostic for major functional genes. Gene diversity was constant at SSR markers but decreased over time for SNP markers. Population differentiation between the four locations could not be detected, suggesting that organic vs. non-organic crop management did not drive allele frequency changes. However, we did see changes for genes controlling plant height and phenology in all populations independently and consistently. We interpret these changes as the result of a consistent natural selection towards wild-type. Independent selection for alleles that are associated with plant height suggests that competition for light was central, resulting in the predominance of stronger intraspecific competitors, and highlighting a potential trade-off between individual and population performance.

The Role of Brassinosteroids in Controlling Plant Height in Poaceae: A Genetic Perspective.

The most consistent phenotype of the brassinosteroid (BR)-related mutants is the dwarf habit. This observation has been reported in every species in which BR action has been studied through a mutational approach. On this basis, a significant role has been attributed to BRs in promoting plant growth. In this review, we summarize the work conducted in rice, maize, and barley for the genetic dissection of the pathway and the functional analysis of the genes involved. Similarities and differences detected in these species for the BR role in plant development are presented. BR promotes plant cell elongation through a complex signalling cascade that modulates the activities of growth-related genes and through the interaction with gibberellins (GAs), another class of important growth-promoting hormones. Evidence of BR–GA cross-talk in controlling plant height has been collected, and mechanisms of interaction have been studied in detail in Arabidopsis thaliana and in rice (Oryza sativa). The complex picture emerging from the studies has highlighted points of interaction involving both metabolic and signalling pathways. Variations in plant stature influence plant performance in terms of stability and yield. The comprehension of BR’s functional mechanisms will therefore be fundamental for future applications in plant-breeding programs.

Physiology and Yield of Confection Sunflower under Different Application Schemes of Mepiquat Chloride

The use of plant growth regulator mepiquat chloride (MPC) has been a widespread practice for the control of vegetative growth in cotton production for several decades. As a growth retardant, MPC could potentially provide a means of controlling plant height in field sunflower (Helianthus annuus L.), but this possibility has not been studied. Field experiments over two years were conducted in northern Greece to study the influence of MPC at rates of 37.5 plus 37.5 g ha−1 (named double application) and 37.5 plus 37.5 plus 37.5 g ha−1 (named triple application) on sunflower growth and yield. MPC provided a height reduction of 9.5% (25 cm) with the double application and a height reduction of 14.4% (49.2 cm) with the triple application at maturity. The number of nodes was also reduced, indicating shorter plants, whereas stem width did not show a consistent response. Moreover, MPC resulted in increased crop growth rate with the triple application scheme. MPC reduced nitrogen utilization efficiency in both growing seasons. However, a reduction in achene yield per plant by 19.9% was observed with the triple application scheme. The achene yield reduction resulted by the reduction in the 100-achene weight (22.3%), given that the number of filled achenes was similar to control. None of the application schemes reduced seed nitrogen and oil content. The results from testing application schemes could be a basis for further research on the use of MPC in this crop, e.g., different timing of applications could be tested for benefits to height reduction.

Effect of drought stress on morphological, anatomical, and physiological characteristics of Cempo Ireng Cultivar Mutant Rice (Oryza sativa l.) strain 51 irradiated by gamma-ray

Drought stress is a factor that affects plant growth and development, both in terms of morphology, anatomy, and physiology. Mutant Oryza sativa L. strain 51 of Cempo Ireng cultivar as the result of gamma-ray irradiation is superior mutant black rice strain which has a faster planting period of 10-20 days than its control and shorter plant height. This study aims to determine the morphological, anatomical, and physiological responses, especially the proline content inside the leaves of mutant black rice strain 51. The study used a completely randomized design (CRD) with the treatment of drought stress using PEG 6000 in Yoshida liquid media. The seedlings were planted for 21 days in untreated media, then treated for 14 days. Observation of morphological characters was carried out by measuring plant height, root length, leaf area, and plant biomass. Observations of anatomical characters were carried out by observing the cross-section of the root. Observation of physiological character was carried out by measuring leaf proline levels. The results showed that drought stress with PEG 6000 inhibited the growth and development of mutant rice strain 51. Drought stress reduces plant height, root length, leaf area, plant biomass and the area of root aerenchyma. Proline leaf content increased significantly at a PEG concentration of 30%. Mutant rice strain 51 showed a tolerant response to drought stress with the significant increased of proline, the increased of root stele diameter and the constant number of metaxylem.

High resolution genetic mapping and identification of a candidate gene(s) for the purple sheath color and plant height in an interspecific F2 population derived from Oryza nivara Sharma & Shastry × Oryza sativa L. cross

Wild relatives of rice (Oryza sativa L.) represent enormous genetic diversity for many traits. Many domestication related traits found only in wild species that are lost from cultivated species during domestication. In this study, we report high-resolution mapping of two domestications related quantitative trait locus (QTL) controlling purple sheath color and plant height using high-density SNP based linkage map in an interspecific F2 population derived from a cross between O. nivara Sharma & Shastry and O. sativa. The segregation ratio of purple sheath color fit into 3:1 indicated that the presence of a dominant gene. The segregation of plant height trait exhibited a normal distribution in F2 and F2:3 generations. QTL analysis showed the identification of two QTLs controlling purple sheath color (designated as qPsh6.1 and qPsh6.2) on chromosome 6 explaining 27.12% and 14% phenotypic variance, respectively. The only plant height QTL (tentatively designated as qPh1.9) was mapped on chromosome 1 contributing 18.3% phenotypic variance. The qPsh6.1 covers 25.17 Kb region flanked by AX-95928721 and AX-95954573 containing five open reading frames (ORFs) while qPsh6.2 spanned in 118.2 Kb region containing 19 ORFs flanked by markers AX-95956260 and AX-95928295. The qPh1.9 gene controlling plant height was mapped between two SNP markers, AX-95944819 and AX-95964796 co-segregated with the locus LOC_Os01g66690 encoding for ZIP4/SPO22 protein. The detailed genetic study of the location of these genes will be useful for the map-based cloning.

A lipid transfer protein variant with a mutant eight-cysteine motif causes photoperiod- and thermo-sensitive dwarfism in rice.

Plant height is an important trait for architecture patterning and crop yield improvement. Although the pathways involving gibberellins and brassinosteroids have been well studied, there are still many gaps in our knowledge of the networks that control plant height. In this study, we determined that a dominant photoperiod- and thermo-sensitive dwarf mutant is caused by the active role of a mutated gene Photoperiod-thermo-sensitive dwarfism 1 (Ptd1), the wild-type of which encodes a non-specific lipid transfer protein (nsLTP). Ptd1 plants showed severe dwarfism under long-day and low-temperature conditions, but grew almost normal under short-day and high-temperature conditions. These phenotypic variations were associated with Ptd1 mRNA levels and accumulation of the corresponding protein. Furthermore, we found that the growth inhibition in Ptd1 may result from the particular protein conformation of Ptd1 due to loss of two disulfide bonds in the eight-cysteine motif (8-CM) that is conserved among nsLTPs. These results contribute to our understanding of the novel function of disulfide bonds in the 8-CM, and provide a potential new strategy for regulation of cell development and plant height by modifying the amino acid residues involved in protein conformation patterning.

Genetic effects of important yield traits analysed by mixture model of major gene plus polygene in wheat

The important traits represented by yield per plant are the main target traits in high-yield breeding of wheat, and analysing then the quantitative genetic characteristics will provide a basis for further study on the genetic mechanism. In this study, we selected the winter Pingdong 34 as the female parent (P1) and the Barran as the male parent (P2) to configure the hybrid combination, and applied the main gene + polygene mixed genetic model method to analyse the length and number of tillers in the single generation (P1, P2) RIL7:8, RIL8:9 at four environments in two years genetic model and correlation among yield per plant, 1000-grain weight, plant height, internode length, internode length and number of tillers. There were significant or extremely significant condation among all the traits, except for the 1000-grain weight and number of tillers. The average correlation coefficient between the internodes and the upper leaves of the flag was 0.91 ( P ≤ 0.001). The optimal genetic model for yield per plant was four pairs of additive epigenetic gene + polygenic genetic model with the main gene additive effect values of 3.78, 2.89, –6.18, and 0.15, respectively, and the multigene heritability of 86.23%. The optimal genetic model of 1000-grain weight of a mixed genetic model with two pairs of complementary main genes + additive effects. The multi-gene additive effect value was 22.37, the main gene heritability was 66.96%, and the multi-gene heritability was 28.25%. The optimal genetic model of plant height was a mixed genetic model of two pairs of cumulative main genes + additive multigenes. The additive value of the first pair of main genes controlling plant height was 5.15. Additive × additive epistatic interaction value was –9.66, the multigene additive effect value was –9.31, the major gene heritability was 58.57%, and the polygene heritability was 39.71%. The optimal genetic model of the internode length below spike above the flag leaf was the additive-superordinate multi-gene genetic model, and the main gene heritability was 97.65% and 99.14%, respectively. The optimal genetic model of the number of tillers was an additive-superordinate multi-gene mixed genetic model with a genetic rate of 78.89% for primary genes and 19.87% for multiple genes. These traits were mainly dominated by the combination of major gene + polygene in multiple environments. In the process of breeding excellent strains, it is necessary to take into account the important performances adapting to the ecological environment conditions, and further provide a theoretical basis for screening closely linked to target traits markers and promoting molecular marker-assisted selection.

The Role of Dwarfing Traits in Historical and Modern Agriculture with a Focus on Rice.

Semidwarf stature is a valuable agronomic trait in grain crops that reduces lodging and increases harvest index. A fundamental advance during the 1960s Green Revolution was the introduction of semidwarf cultivars of rice and wheat. Essentially, all semidwarf varieties of rice under cultivation today owe their diminished stature to a specific null mutation in the gibberellic acid (GA) biosynthesis gene, SD1 However, it is now well-established that, in addition to GAs, brassinosteroids and strigolactones also control plant height. In this review, we describe the synthesis and signaling pathways of these three hormones as understood in rice and discuss the mutants and transgenics in these pathways that confer semidwarfism and other valuable architectural traits. We propose that such genes offer underexploited opportunities for broadening the genetic basis and germplasm in semidwarf rice breeding.

Effects of plant growth regulators on the plant height and quantitative properties of Narcissus tazetta

The effects of flurprimidol, paclobutrazol, and ethephon treatment as soil drench on plant height and quantitative and other properties of native narcissus (Narcissus tazetta L.) plants grown in pots were investigated. When the plants were 7?10 cm tall, flurprimidol and paclobutrazol at 0, 1, and 2 mg/pot and ethephon at 0, 37.5, and 75 mg/pot were applied as soil drenches. The effects of plant growth retardant treatments on plant height, leaf length, time of flowering, number of flowers, and flower life were determined. In addition, quantitative measurements (leaf area ratio, specific leaf area, leaf thickness, leaf weight ratio, and stem weight ratio) were analyzed in native narcissus. When narcissus grown in pots in the greenhouse reached the sale stage, the plants were taken to the laboratory at 20 °C to evaluate the postproduction life and quality of pot plants. Flurprimidol, paclobutrazol, and ethephon shortened plant height. The shortest plant height was obtained from 2 mg/pot paclobutrazol; plant height was 5.42 cm, 65% shorter than the untreated controls. Chemical applications also shortened leaf length. The shortest leaf length (13.25 cm) was obtained from the 2 mg/pot paclobutrazol treatment. The chemical treatment decreased the leaf area ratio and specific leaf area, but increased the leaf thickness and leaf weight ratio compared to the control plants. The effects of treatments on plant height continued in laboratory (home-office) conditions after production. The shortest plant height (9.5 cm) was obtained from the 2 mg/pot paclobutrazol treatment, whereas the height of untreated control plants was 24.25 cm during the postproduction life of pot plants.

Identification and characterization of a new dwarf locus DS-4 encoding an Aux/IAA7 protein in Brassica napus

A dominant dwarfing gene, ds - 4 , encodes an Aux/IAA protein that negatively regulates plant stature through an auxin signaling pathway. Dwarfism is an important agronomic trait affecting yield in many crop species. The molecular mechanisms underlying dwarfism in oilseed rape (Brassica napus) are poorly understood, restricting the progress of breeding dwarf varieties in this species. Here, we identified and characterized a new dwarf locus, DS-4, in B. napus. Next-generation sequencing-assisted genetic mapping and candidate gene analysis found that DS-4 encodes a nucleus-targeted auxin/indole-3-acetic acid (Aux/IAA) protein. A substitution (P87L) was found in the highly conserved degron motif of the Aux/IAA7 protein in the ds-4 mutant. This mutation co-segregated with the phenotype of individuals in the BC1F2 population. The P87L substitution was confirmed as the cause of the extreme dwarf phenotype by ectopic expression of the mutant allele BnaC05.iaa7 (equivalent to ds-4) in Arabidopsis. The P87L substitution blocked the interaction of BnaC05.iaa7 with TRANSPORT INHIBITOR RESPONSE 1 in the presence of auxin. The BnaC05.IAA7 gene is highly expressed in the cotyledons, hypocotyls, stems and leaves, but weakly in the roots and seeds of B. napus. Our findings provide new insights into the molecular mechanisms underlying dominant (gain-of-function) dwarfism in B. napus. Our identification of a distinct gene locus controlling plant height may help to improve lodging resistance in oilseed rape.

QTL mapping, validation and candidate genes analysis for plant height in maize

Plant height is one of the most important agronomic traits closely associated with biomass, lodging resistance and grain yield in maize. The aim of this study to map QTLs, validate QTL results and analyze candidate genes for plant height based on high density linkage map from a cross between two inbred lines of maize. A set of 199 F2:3 progeny derived from the cross SG5. Thirty two different populations would be the most reliable and stable QTLs. SG7 was studied. Thirty two QTLs associated with plant height (PH) using the least absolute shrinkage selection operator (LASSO) method were identified. QTLs detected in this study were validated to find the stability and consistency in different environments. A total of 12 QTLs detected in this study were similar to earlier reported QTLs, which may be the most reliable and stable. Genes underlying these QTLs (+50 kb from the significant markers) were analyzed and 10 genes were predicted as candidate genes for PH. The work will not only help in underlying the mechanisms that control plant height trait of maize, but also provide a basis for map-based cloning of PH genes and dwarf breeding application in further studies.

RhizobacteriumBacillus subtilisreduces toxic effects of high electrical conductivity in soilless culture of lettuce

Quality of irrigation water is a critical factor for greenhouse production. A high concentration of soluble salts is the main reason for high electrical conductivity (EC) of irrigation water. The low water quality available for agriculture is the main problem in many places of the world. Plant growth-promoting bacteria are free-living soil bacteria that can help plant growth without having pathogenic effects. In the current study, three concentrations of NaCl (0, 40 and 80 mM, which resulted in EC of 1, 4 and 8 mS, respectively) were added to the irrigation water. Half of the salt-treated plants were fed with the rhizobacterium Bacillus subtilis (OD=0.6) to test whether it can reduce the problems of medium and high EC of irrigation water on lettuce plants, cultivated in Perlite medium. Growth parameters, including fresh and dry weights, leaf area, leaf number and plant height of control plants, were considerably improved by application of B. subtilis in the root medium of lettuce plants. Furthermore, the growth of plants exposed to medium and high EC was improved by the presence of B. subtilis in their rhizosphere. Polyphasic chlorophyll fluorescence transient parameters such as absorption flux, trapping flux and quantum yield for energy dissipation were decreased in plants with B. subtilis in their rhizosphere, while electron transport flux per reaction center was increased in B. subtilis-treated plants. In conclusion, B. subtilis can be used in the root medium of greenhouse plants to prevent the toxic effects of high EC of irrigation water.

Rice SDSFL1 plays a critical role in the regulation of plant structure through the control of different phytohormones and altered cell structure

Semi-dwarfism is one of the most important agronomic traits for many cereal crops. In the present study, a mutant with semi-dwarf and short flag leaf 1, sdsfl1, was identified and characterized. The sdsfl1 mutant demonstrated some distinguished structural alterations, including shorter plant height and flag leaf length, increased tiller numbers and flag leaf width, and decreased panicle length compared with those of wild type (WT). Genetic analysis suggested that the mutant traits were completely controlled by a single recessive gene. The SDSFL1 gene was mapped to the long arm of chromosome 3 within a region of 44.6 kb between InDel markers A3P8.3 and A3P8.4. The DNA sequence analysis revealed that there was only a T to C substitution in the coding region of LOC_Os03g63970, resulting in the substitution of Tryptophan (Try) to Arginine (Arg) and encoding a GA 20 oxidase 1 protein of 372 amino acid residues. Photosynthesis analysis showed that the photosynthetic rate (Pn), stomatal conductance (Gs), and intercellular CO2 concentration (Ci) were significantly increased in sdsfl1. Chlorophyll a (Chl a), total Chl, and carotenoid contents were significantly increased in sdsfl1 compared with those in WT. sdsfl1 carried a reduced level of GA3 but reacted to exogenously applied gibberellins (GA). Moreover, the levels of abscisic acid (ABA), indole 3-acetic acid (IAA), and salicylic acid (SA) were notably improved in sdsfl1, whereas there was no noteworthy change in jasmonic acid (JA). The results thus offer a visible foundation for the molecular and physiological analysis of the SDSFL1 gene, which might participate in various functional pathways for controlling plant height and leaf length in rice breeding.

Validation of QTLs for plant ideotype, earliness and growth habit traits in pigeonpea (Cajanus cajan Millsp.).

Pigeonpea productivity is greatly constrained by poor plant ideotype of existing Indian cultivars. Enhancing pigeonpea yield demands a renewed focus on restructuring the ideal plant type by using more efficient approaches like genomic tools. Therefore, the present study aims to identify and validate a set of QTLs/gene(s) presumably associated with various plant ideotype traits in pigeonpea. A total of 133 pigeonpea germplasms were evaluated along with four checks in the augmented design for various ideotype traits i.e. initiation of flowering (IF), days to 50% flowering (DFF), days to maturity (DM), plant height (PH), primary branches (PB), seeds per pod (SP) and pod length (PL). We observed significant genetic diversity in the germplasm lines for these traits. The genetic control of IF, DFF, DM and PH renders these traits suitable for detection of marker trait associations. By using residual maximum likelihood algorithm, we obtained appropriate variance-covariance structures for modeling heterogeneity, correlation of genetic effects and non-genetic residual effects. The estimates of genetic correlations indicated a strong association among earliness traits. The best linear unbiased prediction values were calculated for individual traits, and association analysis was performed in a panel of 95 diverse genotypes with 19 genic SSRs. Out of five QTL-flanking SSRs used here for validation, only ASSR295 could show significant association with FDR and Bonferroni corrections, and accounted for 15.4% IF, 14.2% DFF and 16.2% DM of phenotypic variance (PV). Remaining SSR markers (ASSR1486, ASSR206 and ASSR408) could not qualify false discovery rate (FDR) and Bonferroni criteria, hence declared as false positives. Additionally, we identified two highly significant SSR markers, ASSR8 and ASSR390 on LG 1 and LG 2, respectively. The SSR marker ASSR8 explained up to 22 and 11% PV for earliness traits and PB respectively, whereas ASSR390 controlled up to 17% PV for earliness traits. The validation and identification of new QTLs in pigeonpea across diverse genetic backgrounds brightens the prospects for marker-assisted selection to improve yield gains in pigeonpea.

Dynamic QTL analysis and validation for plant height using maternal and paternal backcrossing populations in Upland cotton

Plant height determines plant biomass yield, harvest index and economic yield. We analyzed quantitative trait loci (QTL) and gene action controlling plant height. We generated the maternal and paternal testcrossing (TC/M and TC/P) populations based on a recombinant inbred line population. Data for plant height at t1, t2, t3, t4 or t5 stages were collected over 2 years from 3 TC/M field trials and 2 TC/P field trials. At single-locus level, 32 QTLs at five stages and 24 conditional QTLs at four intervals were detected, and 14 QTLs shared in different years or populations or stages. Plant height displayed dynamic characteristics through expression of QTLs. A total of 21 novel QTLs were detected and 11 QTLs validated the previous results. And 19 QTLs explained over 10% of phenotypic variation, such as qPH-Chr9-2, qPH-Chr19-4 and qPH-Chr22-4. The region of NAU5330-NAU1269 on chromosome 19 may be a desired target for genetic improvement of plant height in Upland cotton. In addition, five and eight heterotic loci were identified in TC/M and TC/P populations, respectively. Additive, partial dominance and overdominance effects were observed in both TC populations. We also identified 43 epistatic QTLs and QTLs by environment interactions by inclusive composite interval mapping method. Taken together, additive, partial dominance and overdominance effects together with epistasis explained the genetic basis of plant height in Upland cotton.

QTL mapping of seven agronomic traits in maize based on the introgression lines

Maize ( Zea mays L.) is an important crop with great nutrition, fodder and energy values. The yield of maize is dependent on the integration and coordination of a lot of agronomic traits, such as plant height, ear length, grain weight per spike and others, which are controlled by micro-effects of multiple genes. The objective of this study was to identify genes related to agronomic traits in maize inbred line PHB1M and to investigate the correlation between those genes and yield-related traits. An introgression line was constructed using tetra-287 as a donor to improve the backbone maize inbred lines and create new breeding resources. The progenies were grown and evaluated in both Helin and Hohhot, Inner Mongolia of China. With 70 pairs of SSR and 64 pairs of SRAP primers, the constructed introgression materials were genotyped. As a result, a total of 793 polymorphic loci were obtained locating 10 linkage groups. A linkage map was then constructed with a length of 1917.2 cM. By using MQM mapping method, a total of 100 QTLs were identified in both locations, which distributed on 9 linkage groups except the 10th linkage group. Fifty QTLs were detected in single environment, with LOD values ranged from 3.20 to 9.12, and contribution rates ranged from 2.2% to 35.2%. Among the 100 QTLs, 23 for plant height, 16 for ears height, 22 for number of leaves, 10 for ear length, 16 for shafts diameter, 4 for ear rows, and 9 for 100-grain weights were identified; Eight genes controlling 5 traits were consistently expressed from plant of both locations, including 2 QTLs controlling plant height ( qPH1-5 and qPH2-6 , qPH1-6 and qPH2-7 ), 1 for ear height ( qEP1-2 and qEP2-1 ), 1 for leaf number( qLN1-10 and qLN2-4 ), 2 for ear length ( qEL1-2 and qEL2-1 , qEL1-4 and qEL2-4 ), and 2 for shafts diameter( qSD1-3 and qSD2-2 , qSD1-8 and qSD2-5 ). Three QTLs expressed stably for plant height and ear height, and 14 enriched QTL regions were found on 6 linkage groups. This research provided theoretical support for gene cloning and marker-assisted maize breeding.