Traits In Breeding Research Articles

Morphometric frequency and spectrum of gamma-ray-induced chlorophyll mutants identified by phenotype and development of novel variants in lentil (Lens culinaris Medik.).

Genetic variations are a crucial source of germplasm heterogeneity, as they contribute to the development of new traits for plant breeding by offering an allele resource. Gamma rays have been widely used as a physical agent to produce mutations in plants, and their mutagenic effect has attracted much attention. Nonetheless, few studies have examined the whole mutation spectrum in large-scale phenotypic evaluations. To comprehensively investigate the mutagenic effects of gamma irradiation on lentils, biological consequences on the M1 generation and substantial phenotypic screening on the M2 generation were undertaken. Additionally, the study followed the selected mutants into the M3 generation to evaluate the agronomic traits of interest for crop improvement. Seeds of lentil variety Moitree were irradiated with a range of acute gamma irradiation doses (0, 100, 150, 200, 250, 300, and 350 Gy) to induce unique genetic variability. This research focused on determining the GR50 value while considering seedling parameters and examining the status of pollen fertility while comparing the effects of the gamma irradiation dosages. The GR50 value was determined to be 217.2 Gy using the seedling parameters. Pollens from untreated seed-grown plants were approximately 85% fertile, but those treated with the maximum dosage (350 Gy) were approximately 28% fertile. Numerous chlorophyll and morphological mutants were produced in the M2 generation, with the 300 Gy -treated seeds being the most abundant, followed by the 250 Gy -treated seeds. This demonstrated that an appropriate dosage of gamma rays was advantageous when seeking to generate elite germplasm resources for one or multiple traits. Selected mutants in the M3 generation showed improved agronomic traits, including plant height, root length, number of pods per plant, and yield per plant. These investigations will contribute to a comprehensive understanding of the mutagenic effects and actions of gamma rays, providing a basis for the selection and design of suitable mutagens. This will facilitate the development of more controlled mutagenesis protocols for plant breeding and help guide future research directions for crop improvement using radiation-induced mutation breeding techniques.

Study on correlation estimates between carcass traits of sheep breeds of Baluchistan

Study on correlation estimates between carcass traits of sheep breeds of Baluchistan

Effect of animal breed on the different parts of carcass traits of various sheep breeds of Baluchistan

Effect of animal breed on the different parts of carcass traits of various sheep breeds of Baluchistan

Breeding Approaches for Controlled Conditions of Artificial Light Culture for Small Radish and Radish (Raphanus sativus L.)

This paper presents the results of breeding and genetic studies of Raphanus sativus L. under the controlled conditions of the biopoligon of the Agrophysical Research Institute (St. Petersburg, Russia). The aim of this study was to create new R. sativus forms for controlled environments with artificial lightning (CEAL). An original technique for accelerated transgressive plant breeding was used. It is based on the methodology for predicting transgressions by economically valuable plant traits when evaluating breeding traits under controlled conditions. Using it in a short period of time (4–5 years) greatly increases productive accessions of small radish and radish adapted to light culture, and a set of valuable characteristics (resistance to bolting, glabrous leaves, compact leaf rosette) were obtained. The yield of roots of new forms was 4.30–4.98 kg/m2 (small radish) and 5.46–7.66 kg/m2 (radish) for the growing period. Transgression by root mass was observed in plants of three new forms and amounted to 40.7–63.0% in small radish and 40.3% in radish. The breeding of new genotypes of R. sativus is aimed at expanding the range of crops cultivated in plant factories, and ultimately, at a better and more balanced nutrition for the population.

Blocking the Expression of the Nitrate Reductase Gene OsNia3 Confers Early Maturation in Rice

Early flowering is a major contributing factor to early crop maturation and is a prerequisite for the expansion of crop production to high latitudes with short growing seasons as well as for annual double/triple cropping systems. Nitrogen is the mineral element most limiting to plant growth and, consequently, also to crop yield. Nitrogen also plays a role in the regulation of flowering time. Here, we show that OsNia3 is a member of the rice nitrate reductase (NR) gene family. OsNia3 was found to be expressed in stem nodes of rice, while the loss of its function led to a reduction in plant height mainly due to disrupted nitrate metabolism at the site of OsNia3 expression. The expression levels of genes related to nitrate transport, nitrate assimilation, and ammonium assimilation, such as OsNia1, OsNRT2.3A, and OsNGS1, increased in the leaves of osnia3 mutant plants, concomitant with an increase in the activity of the nitrogen metabolism pathway. The ammonium and amino acid contents in the leaves also increased in the osnia3 mutant, as did the chlorophyll content. Phenotypic analysis showed that the osnia3 mutant exhibited a shorter growth period compared with wild-type plants; nevertheless, yield was not significantly affected in mutant plants. The deletion of the OsNia3 gene led to the upregulation of genes related to the photoperiod regulation network (OsGI, OsHd1, and OsHd3a), which likely promoted early flowering. These results indicated that OsNia3 is involved in the floral inhibition pathway (OsGI-OsHd1-OsHd3a) in rice under long-day conditions. Our findings provide a theoretical and material basis for the coordination and improvement of early maturity and high-yield traits in rice breeding.

Fine mapping of qAHPS07 and functional studies of AhRUVBL2 controlling pod size in peanut (Arachis hypogaea L.).

Cultivated peanut (Arachis hypogaea L.) is an important oil and cash crop. Pod size is one of the major traits determining yield and commodity characteristic of peanut. Fine mapping of quantitative trait locus (QTL) and identification of candidate genes associated with pod size are essential for genetic improvement and molecular breeding of peanut varieties. In this study, a major QTL related to pod size, qAHPS07, was fine mapped to a 36.46 kb interval on chromosome A07 using F2 , recombinant inbred line (RIL) and secondary F2 populations. qAHPS07 explained 38.6%, 23.35%, 37.48%, 25.94% of the phenotypic variation for single pod weight (SPW), pod length (PL), pod width (PW) and pod shell thickness (PST), respectively. Whole genome resequencing and gene expression analysis revealed that a RuvB-like 2 protein coding gene AhRUVBL2 was the most likely candidate for qAHPS07. Overexpression of AhRUVBL2 in Arabidopsis led to larger seeds and plants than the wild type. AhRUVBL2-silenced peanut seedlings represented small leaves and shorter main stems. Three haplotypes were identified according to three SNPs in the promoter of AhRUVBL2 among 119 peanut accessions. Among them, SPW, PW and PST of accessions carrying Hap_ATT represent 17.6%, 11.2% and 26.3% higher than those carrying Hap_GAC，respectively. In addition, a functional marker of AhRUVBL2 was developed. Taken together, our study identified a key functional gene of peanut pod size, which provides new insights into peanut pod size regulation mechanism and offers practicable markers for the genetic improvement of pod size-related traits in peanut breeding.

Polymorphism of Genes and Their Impact on Beef Quality.

The single-nucleotide polymorphism (SNP) form of genes is a valuable source of information regarding their suitability for use as specific markers of desirable traits in beef cattle breeding. For several decades, breeding work focused on improving production efficiency through optimizing the feed conversion ratio and improving daily gains and meat quality. Many research teams previously undertook research work on single-nucleotide polymorphism in myostatin (MSTN), thyroglobulin (TG), calpain (CAPN), and calpastatin (CAST) proteins. The literature review focuses on the most frequently addressed issues concerning these genes in beef cattle production and points to a number of relevant studies on the genes' polymorphic forms. The four genes presented are worth considering during breeding work as a set of genes that can positively influence productivity and production quality.

MdIPT1, an adenylate isopentenyltransferase coding gene from Malus domestica, is involved in branching and flowering regulation

Flowering and shoot branching are significant agricultural traits for apple tree breeding. Cytokinin metabolism and signaling pathways play a crucial role in plant development. However, little is known about cytokinin biosynthetic molecular mechanism and function involved in apple flowering and branching. In this study, an adenylate isopentenyl transferase coding gene MdIPT1, homologous to AtIPT3/AtIPT5 in Arabidopsis thaliana, was identified. MdIPT1 was highly expressed in apple floral and axillary buds and was dramatically up-regulated during floral induction and axillary bud outgrowth. The promoter of MdIPT1 showed high activity in multiple tissues and responded to different hormone treatments. The MdIPT1-overexpressing Arabidopsis showed a multi-branching and early-flowering phenotype, with elevated endogenous cytokinin levels and altered expression of genes related to branching and flower formation. Overexpression of MdIPT1 confers the growth vigor of transgenic apple callus on a CKs-deficient medium. Our findings suggest that MdIPT1 is a positive regulator involved in branching and flowering. The data presented herein provide extensive research results on MdIPT1 and will contribute to molecular breeding for new apple varieties.

A posture-based measurement adjustment method for improving the accuracy of beef cattle body size measurement based on point cloud data

Beef cattle body size is an important phenotypic trait for breeding and production. The non-contact automatic calculation of beef cattle body sizes via point cloud data exhibits several disadvantages, such as the inaccurate positioning of measurement points and the sensitivity to postures, heavily restricting commercial applications. To address these issues, an automatic method for key region segmentation, body size calculation, and data calibration to accurately measure the body size parameters of beef cattle in different postures is proposed. Firstly, the body sizes were obtained based on the point cloud data. Then the twelve micro-posture feature parameters were defined and extracted from four categories corresponding to the head, back, torso, and leg regions. Based on those parameters, a Posture-based Measurement Adjustment model was established to reduce the influence of postures on calculation results based on the correlation between measurement errors and micro-posture features. The experimental results show that, after the adjustment model calibration, the average errors of body oblique length, wither height, hip height, chest girth, and abdominal girth were 1.14%, 1.84%, 3.47%, 1.56%, and 2.36%, respectively, whereas the corresponding maximum errors were 4.36%, 8.10%, 11.10%, 7.29%, and 9.26%. The measurement errors of body sizes can be significantly minimised by the adjustment model, which can improve the robustness of different postures. The adjustment model improves the accuracy of the non-contact body size measurement, which could provide guidance and inspirations for future research.

Consensus genomic regions for grain quality traits in wheat revealed by Meta-QTL analysis and in silico transcriptome integration.

Grain quality traits are the key factors that determine the economic value of wheat and are largely influenced by genetics and the environment. In this study, using a meta-analysis of quantitative trait loci (QTLs) and a comprehensive in silico transcriptome assessment, we identified key genomic regions and putative candidate genes for the grain quality traits protein content, gluten content, and test weight. A total of 508 original QTLs were collected from 41 articles on QTL mapping for the three quality traits in wheat published from 2003 to 2021. When these original QTLs were projected onto a high-density consensus map consisting of 14,548 markers, 313 QTLs resulted in the identification of 64 MQTLs distributed across 17 of the 21 chromosomes. Most of the meta-QTLs (MQTLs) were distributed on sub-genomes A and B. Compared with the original QTLs, the confidence interval (CI) of the MQTLs was smaller, with an average CI of 4.47 cM, while the projected QTLs CI was 11.13 cM (2.49-fold lower). The corresponding physical length of the MQTL ranged from 0.45 to 239.01 Mb. Thirty-one of these 64 MQTLs were validated in at least one genome-wide association study. In addition, five of the 64 MQTLs were selected and designated as core MQTLs. The 211 quality-related genes from rice were used to identify wheat homologs in MQTLs. In combination with transcriptional and omics analyses, 135 putative candidate genes were identified from 64 MQTL regions. The findings should contribute to a better understanding of the molecular genetic mechanisms underlying grain quality and the improvement of these traits in wheat breeding.

Identification of genetic loci associated with five agronomic traits in alfalfa using multi-environment trials.

The use of multi-environment trials to test yield-related traits in a diverse alfalfa panel allowed to find multiple molecular markers associated with complex agronomic traits. Yield is one of the most important target traits in alfalfa breeding; however, yield is a complex trait affected by genetic and environmental factors. In this study, we used multi-environment trials to test yield-related traits in a diverse panel composed of 200 alfalfa accessions and varieties. Phenotypic data of maturity stage measured as mean stage by count (MSC), dry matter content, plant height (PH), biomass yield (Yi), and fall dormancy (FD) were collected in three locations in Idaho, Oregon, and Washington from 2018 to 2020. Single-trial and stagewise analyses were used to obtain estimated trait means of entries by environment. The plants were genotyped using a genotyping by sequencing approach and obtained a genotypic matrix with 97,345 single nucleotide polymorphisms. Genome-wide association studies identified a total of 84 markers associated with the traits analyzed. Of those, 29 markers were in noncoding regions and 55 markers were in coding regions. Ten significant SNPs at the same locus were associated with FD and they were linked to a gene annotated as a nuclear fusion defective 4-like (NFD4). Additional SNPs associated with MSC, PH, and Yi were annotated as transcription factors such as Cysteine3Histidine (C3H), Hap3/NF-YB family, and serine/threonine-protein phosphatase 7 proteins, respectively. Our results provide insight into the genetic factors that influence alfalfa maturity, yield, and dormancy, which is helpful to speed up the genetic gain toward alfalfa yield improvement.

Effects of Source Strength and Sink Size on Starch Metabolism, Starch Properties and Grain Quality of Rice (Oryza sativa L.)

The source strength and sink demand as well as their interaction have been demonstrated to co-regulate the synthesis of starch and determine the grain quality, but the knowledge of the underlying physiological mechanisms is limiting. An indica variety, Yangdao 6, and a japonica variety, Jinxiangyu 1, were planted with three treatments, including normal growth plant (CK), leaf-cutting (LC) and spikelet-thinning (ST). The transcript levels of starch metabolic genes, physicochemical characteristics of starch and appearance, milling, cooking and tasting qualities of rice under different treatments were determined. The ST treatment increased the relative expression of genes related to the synthesis of short branch-chains of amylopectin (SSI, BEI, BEIIb) and amylose (GBSSI) and reduced the relative expression of medium-long to long branch-chains of amylopectin synthesis genes (SSIIa, SSIIIa, SSIIIb, ISA1). When comparing ST with the CK treatment, starch granules became smoother with higher contents of short branch-chains and lower ratios of medium-long and long branch-chains of amylopectin; the crystallinity and the value of 1045/1022 cm−1 was decreased; for pasting properties, the setback and pasting temperature were decreased; the peak viscosity, hot viscosity, breakdown and final viscosity were significantly increased. Meanwhile, the ST treatment improved the appearance, milling and cooking and tasting qualities. The opposite results were observed under the LC treatment. These results indicated that source strength and sink size would regulate expression levels of starch metabolic genes, which is pivotal for the contents of amylose and short/long branch chains ratio of amylopectin, thus changing the structure and physicochemical properties of starch and grain quality. Here, we speculated that the improved source strength in terms of higher leaf/canopy photosynthesis and small sink size, such as small panicle size, would be preferred traits in high grain quality rice breeding.

Interrelation of the breeding characteristics of the herd horses of Transbaikal

The results of the study of exterior and constitutional features, the phenotypic correlation of live weight with body measurements and body built indexes in herd horses of the Buryat breed are presented. The research material was full-grown stallions (n = 7) and mares (n = 20), as well as horse colts (n = 20) and fillies (n = 20) aged 1.5 and 2.5 years. It has been established that stud stallions in live weight exceed the breed standard by 25.8%, mares - by 23.8%, colts - by 28.0-28.5% and fillies - by 12.3-25.7%. The measurement of the articles of the body also indicates their superiority in all basic measurements over the standard. The calculation of the body built indexes indicates that individuals are characterized by pronounced meaty forms. At the same time, males are characterized by a more solid build, broad and stretched body of a strong constitution. Analysis of the obtained data shows that the horses of the Buryat breed in terms of live weight and body parts measurements belong to the massive type I of the ecological zone. In adults and young animals at the age of 1.5 and 2.5 years, a positive, at a fairly high level, correlation between live weight and all measurements was revealed. A closer relationship of the live weight in stallions and mares was noted with the cannon bone girth (r = 0.586; r = 0.770), in colts and fillies at the age of 1.5 years - with chest girth (r = 0.903) and height at the withers (r = 0.903), respectively. With age, in colts, the relationship between the live weight and the body length increases (r = 0.902), in fillies - with chest girth (r = 0.623). The revealed relationships of the live weight with exterior and constitutional features in herd horses will allow to increase the pressure on a specific breeding trait during selection.

Novel single nucleotide polymorphisms of insulin-like growth factor-binding protein 7 (IGFBP7) gene significantly associated with growth traits in striped catfish (Pangasianodon hypophthalmus Sauvage, 1878).

Breeding program to improve economically important growth traits in striped catfish (Pangasianodon hypophthalmus) requires effective molecular markers. This study was conducted to identify single nucleotide polymorphisms (SNPs) of Insulin-like Growth Factor-Binding Protein 7 (IGFBP7) gene which plays multiple roles in regulating growth, energy metabolism and development. The association between SNPs in IGFBP7 gene and growth traits in striped catfish was analyzed in order to uncover the SNPs that have potential to be valuable markers for improving growth traits. Firstly, fragments of IGFBP7 gene from ten fast-growing fish and ten slow-growing fish were sequenced in order to discover SNPs. After filtering the detected SNPs, an intronic SNP (2060A > G) and two non-synonymous SNPs (344T > C and 4559C > A) causing Leu78Pro and Leu189Met in protein, respectively, were subjected to further validated by individual genotyping in 70 fast-growing fish and 70 slow-growing fish using single base extension method. Our results showed that two SNPs (2060A > G and 4559 C > A (p. Leu189Met)) were significantly associated with the growth in P. hypophthalmus (p < 0.001), thus being candidate SNP markers for the growth traits of this fish. Moreover, linkage disequilibrium and association analysis with growth traits of haplotypes generated from the 3 filtered SNPs (344T > C, 2060 A > G and 4559 C > A) were examined. These revealed that the non-coding SNP locus (2060A > G) had higher genetic diversity at which the G allele was predominant over the A allele in the fast-growing fish. Furthermore, the results of qPCR showed that expression of IGFBP7 gene with genotype GG (at locus 2060) in fast-growing group was significantly higher than that with genotype AA in slow-growing group (p < 0.05). Our study provides insights into the genetic variants of IGFBP7 gene and useful data source for development molecular marker for growth traits in breeding of the striped catfish.

Identification and characterization of the chalkiness endosperm gene CHALK-H in rice (Oryza sativa L.)

Chalkiness is one of the most important agronomic traits in rice breeding, which directly affects the quality of rice seed. In this study, we identified a chalkiness endosperm mutant, chalk-h, from N-methyl-N-nitrosourea (MNU)-induced japonica rice cultivar Hwacheong (HC). Compared with wild type (WT)-HC, chalk-h showed severe chalkiness in the endosperm, yellowish green leaves, as well as reduced plant height. Scanning electron microscopy (SEM) analysis showed that starch grains in the chalk-h mutant were irregular in size and loosely arranged, with large gaps between granules, forming ovoid or orbicular shapes. MutMap analysis revealed that the phenotype of chalk-h is controlled by a single recessive gene LOC_Os11g39670 encoding seryl-tRNA synthetase, which is renamed as CHALK-H. A point mutation occurs in chalk-h on the sixth exon (at nucleotide 791) of CHALK-H, in which adenine (A) is replaced by thymidine (T), resulting in an amino acid codon change from glutamine (Glu) to valine (Val). The chalk-h mutant exhibited a heat-sensitive phenotype from the 3-leaf stage, including yellow-green leaves and reduced pigment content. The transcriptional expression of starch synthesis-related genes was down-regulated in the chalk-h mutants compared to WT-HC at different grain-filling stages. With an increase in temperature, the expression of photosynthesis-related genes was down-regulated in the chalk-h mutant compared to WT-HC. Overexpression of CHALK-H rescued the phenotype of chalk-h, with endosperm and leaf color similar to those of WT-HC. Our findings reveal that CHALK-H is a causative gene controlling chalkiness and leaf color of the chalk-h mutant. CHALK-H is the same gene locus as TSCD11, which was reported to be involved in chloroplast development under high temperature. We suggest that CHALK-H/TSCD11 plays important roles not only in chloroplast development, but also in photosynthesis and starch synthesis during rice growth and development, so it has great application potential in rice breeding for high quality and yield.

Multi-Year QTL Mapping and RNA-seq Reveal Candidate Genes for Early Floret-Opening Time in Japonica Rice

Floret-opening time (FOT) refers to the time between florets opening and closing within a day, and is a crucial agricultural trait for reproductive development, thermal tolerance and hybrid breeding in rice. However, little is known about the genetic basis and genes controlling FOT in rice. Here, we report the genetic mapping and transcriptome analysis of FOT in the japonica rice cultivar G23. Combining the QTLseqr and GradedPool-seq (GPS) methods, we located a major quantitative trait locus (QTL), qFOT6, on chromosome 6 in multiple years and under different environments. Integrating RNA-seq analysis, we selected 13 potential candidate genes in the qFOT6 interval that might be associated with FOT in G23. Taken together, our work uncovers a major QTL and potential candidate genes for FOT in rice, thus providing invaluable clues for rice breeding.

Molecular and phenotypic markers for pyramiding multiple traits in rice

Abstract Gene pyramiding has been developed for effective resistant genes, such as bacterial blight resistance genes. However, in this report, pyramiding for multiple traits is presented. We evaluated 28 pyramided rice lines derived from 7 hybridizations of valuable parents for high yield potential, early maturity, aroma, high grain quality, and resistance to brown planthopper using both simple-sequence repeat markers and phenotypic markers. Pyramided rice genotypes were evaluated with RM282 molecular marker linked to GW3 gene associated with grain weight, RM259 (number of panicles), RM3600 (length of panicles), RM3701 (short panicles), RM19414 (Hd3), RM7601 (Hd2), RM190, and SSIIa (waxy), IFAP and ESP (aroma), RM586 (Bph3 and Bph4), and RM8213 (Qpbh4 and Bph17(t)). Eight genotypes (i.e., #9, #15, #16, #22, #25, #26, #27, and #28) were confirmed to have desired genes associated with multiple important traits based on molecular markers and morpho-agronomic traits. A strong correlation was found between RM19414 and heading date, between specific markers for aroma and sensory test. Meanwhile, a weak correlation was found between RM259 with panicle number, RM586, and RM8213 with trichome density. As presented in this study, gene pyramiding promises a new hope to combine multiple traits in rice breeding. Promising rice lines will be incorporated in the multiple traits breeding program.

Genetic parameters of husk spot resistance in macadamia breeding families

Husk spot caused by the Pseudocercospora macadamiae fungus induces premature abscission of fruit in many industry standard macadamia cultivars. Fungicides and other management strategies add to farm costs, thus breeding for varietal resistance is important. Genetic parameters of husk spot symptom expression had not previously been estimated. To guide selection methods for field resistance, over 300 open-pollinated seedlings of 32 families and 24 parent genotypes were inoculated, and seven symptom expression traits were evaluated. Narrow-sense and broad-sense heritabilities were estimated, breeding values were predicted, and correlations between breeding values of trait pairs were tested for significance. The traits with the highest heritabilities were necrotic lesion number per fruit (H2 = 0.41–0.59; h2 = 0.21–0.30) and necrotic incidence (H2 = 0.19–0.27; h2 = 0.17–0.24). Breeding values of the two traits were highly correlated (r = 0.98; p < 0.001), suggesting that either trait could be used to indirectly select for the other. All genotypes expressed symptoms to some degree, however, breeding values for necrotic traits and symptom-induced premature abscission were low for clones and progeny of cultivar ‘HAES791’. Necrotic trait breeding values were also promising for progeny of cultivar ‘HAES246’ and clones of Australian Macadamia Breeding Program elite selection, ‘BAM263’. Having been identified as potentially partially resistant, these selections can now be further evaluated and used as parents of new progeny populations.

Variation in mesopredator abundance and nest predation rate of the endangered Strange‐tailed Tyrant (Alectrurus risora)

Nest predation is the main cause of nest failure in passerine birds and thus is a key determinant of breeding traits. Accordingly, nest predator community composition and abundance modulate nest predation rates. When top predators are absent, mesopredator populations may become unchecked, which in turn increases the predation pressure on their prey species. We evaluated whether nest predator abundance and breeding traits of an endangered grassland bird, the Strange‐tailed Tyrant Alectrurus risora, differed between two protected areas: Iberá National Park (INP), where top predators have been extinct for 50 years, and Reserva El Bagual (REB), where Pumas Puma concolor still have a stable population. We measured abundances of potential nest predator species and during the 2015–2018 breeding seasons we monitored Strange‐tailed Tyrant nests and set camera traps to identify nest predators. Mesopredator abundance was higher in INP, and foxes were identified as the main nest predators. Nest predation rate was also higher in INP, where the daily nest predation rate and cumulative probability of nest predation were 0.05 ± 0.006 and 0.81, whereas in REB they were 0.04 ± 0.004 and 0.70, respectively. The 10‐fold higher frequency of fox records in INP could explain the higher nest predation rate observed, suggesting that the extinction of top predators may increase nest predation rates of endangered grassland birds in protected areas through release of native mesopredator species. The lower nest predation observed in REB was compensated for by a higher nest abandonment rate, which resulted in a similar fledgling production in the two study sites. Clutch size, hatching success and number of nestlings did not differ between study sites. The low breeding success recorded for this endangered species despite its populations being in protected areas of high conservation value is alarming given the global decline that grassland bird populations are facing.

Identification of quantitative trait loci and development of diagnostic markers for growth habit traits in peanut (Arachis hypogaea L.)

Key messageQTLs for growth habit are identified on Arahy.15 and Arahy.06 in peanut, and diagnostic markers are developed and validated for further use in marker-assisted breeding.Peanut is a unique legume crop because its pods develop and mature underground. The pegs derive from flowers following pollination, then reach the ground and develop into pods in the soil. Pod number per plant is influenced by peanut growth habit (GH) that has been categorized into four types, including erect, bunch, spreading and prostrate. Restricting pod development at the plant base, as would be the case for peanut plants with upright lateral branches, would decrease pod yield. On the other hand, GH characterized by spreading lateral branches on the ground would facilitate pod formation on the nodes, thereby increasing yield potential. We describe herein an investigation into the GH traits of 521 peanut recombinant inbred lines grown in three distinct environments. Quantitative trait loci (QTLs) for GH were identified on linkage group (LG) 15 between 203.1 and 204.2 cM and on LG 16 from 139.1 to 139.3 cM. Analysis of resequencing data in the identified QTL regions revealed that single nucleotide polymorphism (SNP) or insertion and/or deletion (INDEL) at Arahy15.156854742, Arahy15.156931574, Arahy15.156976352 and Arahy06.111973258 may affect the functions of their respective candidate genes, Arahy.QV02Z8, Arahy.509QUQ, Arahy.ATH5WE and Arahy.SC7TJM. These SNPs and INDELs in relation to peanut GH were further developed for KASP genotyping and tested on a panel of 77 peanut accessions with distinct GH features. This study validates four diagnostic markers that may be used to distinguish erect/bunch peanuts from spreading/prostrate peanuts, thereby facilitating marker-assisted selection for GH traits in peanut breeding.