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Twenty-one quantitative trait loci were discovered across six environments, including three (NS), seven (LS) and eleven (VLS) conditions. The linkage groups 1A, 1B, 2A, 2B, 2D, 3B, 4A, 6A, 6B and 7D spanned quantitative trait loci (QTLs). For canopy temperature (CT), a stable QTL (Qct_rpcau_4A) in the environment E6 has shown a phenotypic variance (PVE) up to 17.85%. The QTL, Qspad_rpcau_2D, was found to be stable for SPAD value, explaining the PVE of 15.05%. Whereas, three stable QTLs viz. Qgy_rpcau_3B, Qgy_rpcau_4A and Qgy_rpcau_6A were associated with the chromosomes 3B, 4A and 6B explaining a PVE of 20.85%, 17.43% and 17.37% respectively for the trait GY. The interaction of genotype and environment has been shown to be useful in determining the best lines for heat-stressed environments. In addition, G X E analysis was performed on the population. In the ranking of genotypes for both mean yield and mean vs. stability, GGE biplot across the six environments, DH 146, 195, 60, 202, 65, 155, 124, 5, 201, 169, 15 and 170 were ranked closest to ideal and winning genotype; these were highly adapted and most stable lines. The goal of the current investigation was to find the best suitable double haploid lines which can withstand heat stress and to find those QTLs which are influential to heat stress for the studied traits. [ABSTRACT FROM AUTHOR]

Vegetables are the richest source of vitamins and minerals and play a major role in nutritional security. The primary objective of vegetable breeding is enhancing production and productivity. Breeders use various conventional and non-conventional breeding approaches for genetic advance. Recent advances in biotechnology helps to enhance the efficiency and shorten the time required to achieve the fixed goals in a breeding program, as well as to address the economic and ecological goals. Among these, haploid (H) and doubled haploid (DH) production through gametic embryogenesis has long been recognized as a valuable tool to help crop improvement. Haploid plants are the sporophytes with a gametophytic chromosome number and doubled haploids (DH) are haploids that have undergone chromosome duplication. Haploids and double haploids occur spontaneously in nature. Haploids can also be induced artificially by various techniques such as wide hybridization, pollination with irradiated pollens androgenesis, gynogenesis and finally further chromosome doubling results in double haploids. Production of double haploids in vegetables will shorten the breeding cycle and also DH technology is useful in reverse breeding, CMS line production, gene stacking and various other genetic studies. [ABSTRACT FROM AUTHOR]

Rapeseed is a significant global source of plant oil. Silique size, particularly silique length (SL), impacts rapeseed yield. SL is a typical quantitative trait controlled by multiple genes. In our previous study, we constructed a DH population of 178 families known as the 158A-SGDH population. In this study, through SL QTL mapping, we identified twenty-six QTL for SL across five replicates in two environments. A QTL meta-analysis revealed eight consensus QTL, including two major QTL: cqSL.A02-1 (11.32–16.44% of PVE for SL), and cqSL.C06-1 (10.90–11.95% of PVE for SL). Based on biparental resequencing data and microcollinearity analysis of target regions in Brassica napus and Arabidopsis, we identified 11 candidate genes at cqSL.A02-1 and 6 candidate genes at cqSL.C06-1, which are potentially associated with silique development. Furthermore, transcriptome analysis of silique valves from both parents on the 14th, 21st, and 28th days after pollination (DAP) combined with gene function annotation revealed three significantly differentially expressed genes at cqSL.A02-1, BnaA02G0058500ZS, BnaA02G0060100ZS, and BnaA02G0060900ZS. Only the gene BnaC06G0283800ZS showed significant differences in parental transcription at cqSL.C06-1. Two tightly linked insertion-deletion markers for the cqSL.A02-1 and cqSL.C06-1 loci were developed. Using these two QTL, we generated four combinations: A02SGDH284C06158A, A02SGDH284C06SGDH284, A02158AC06158A, and A02158AC06SGDH284. Subsequent analysis identified an ideal QTL combination, A02158AC06SGDH284, which exhibited the longest SL of this type, reaching 6.06 ± 0.10 cm, significantly surpassing the other three combinations. The results will provide the basis for the cloning of SL-related genes of rapeseed, along with the development of functional markers of target genes and the breeding of rapeseed varieties. [ABSTRACT FROM AUTHOR]

Sweetpotato (Ipomoea batatas L.) is a strategic crop with both economic and energy value. However, improving sweetpotato varieties through traditional breeding approaches can be a time-consuming and labor-intensive process due to the complex genetic nature of sweetpotato as a hexaploid species (2n = 6x = 90). Double haploid (DH) breeding, based on in vivo haploid induction, provides a new approach for rapid breeding of crops. The success of haploid induction can be achieved by manipulating specific genes. Two of the most critical genes, DMP (DUF679 membrane proteins) and MTL (MATRILINEAL), have been shown to induce haploid production in several species. Here, we identified and characterized DMP and MTL genes in sweetpotato using gene family analysis. In this study, we identified 5 IbDMPs and 25 IbpPLAs. IbDMP5 and IbPLAIIs (IbPLAIIκ, IbPLAIIλ, and IbPLAIIμ) were identified as potential haploid induction (HI) genes in sweetpotato. These results provide valuable information for the identification and potential function of HI genes in sweetpotato and provide ideas for the breeding of DH lines. [ABSTRACT FROM AUTHOR]

To keep pace with the skyrocketing demand of vegetable oil and reduced dependency on import, there is a need to focus on indigenous oilseed crops, such as niger (Guizotia abyssinica L.F. Cass). Niger is a minor oilseed crop that consists of 32 to 40% quality oil and 18 to 24% protein in the seeds. Despite its considerable importance, self-incompatibility and high outcrossing pose difficulty in breeding through conventional methods. Double haploid (DH) technology is one of the alternatives to overcome the problem and develop inbred lines in a shorter time. In context to this, a highly efficient protocol for DH production through anther culture in Indian niger varieties JNS 9 and JNS 28 was developed. The investigation was conducted to identify the suitable microspore stage for anther culture, cold pre-treatment, hormonal combinations for callus induction (T1–T4), shooting (S1–S26), rooting (R1–R3), hardening, ploidy index, and the effect of different colchicine treatments on the efficiency of the developed protocol. Anthers in disc florets of light green to greenish yellow color have uninucleate microspores (7 d of bud initiation). For callus initiation, Murashige and Skoog (MS) medium containing 2.0 mg L−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.3 mg L−1 kinetin (KIN) showed 100% efficiency. For shoot initiation, 37 to 40% greening was observed on MS medium with 0.5 mg L−1 6-benzylaminopurine (BAP) and 0.5 mg L−1 activated charcoal and, subsequently, 19% shoot emergence on MS medium containing 0.5 mg L−1 BAP and 0.5 mg L−1 KIN. Low efficiency of shoot regeneration was addressed by adding 0.2% colchicine for 30 h at the callusing stage which resulted in 90 to 95% increased efficiency in shooting. For rooting, MS medium containing 2.0 mg L−1 indole-3-butyric acid (IBA) was efficient with a frequency of 85 to 90% followed by hardening in 1:1:1 ratio of vermiculite:sand:soil in pots. Ploidy indexing was done using cell size analysis followed by chromosome count using a microscope which confirmed the ploidy level of regenerants as compared to diploid control. Thus, the procedure developed in the study demonstrates the successful development of DH which in turn facilitates the acceleration of the breeding program through the development of homozygous inbreds and new cultivars. [ABSTRACT FROM AUTHOR]

[Objectives]The paper aimed to obtain double haploids of the melon (2n=2x=24) inbred line BPC-4 by distant hybridization, and analyse botanical traits and genomic changes. [Methods]The melon inbred line BPC-4 was used as the maternal parent to cross with eight different materials of the genus Cucumis. F1 generation of the obtained cross was selfed to obtain F2 and F3,which were used for chromosome number observation, SSR molecular marker analysis and plant traits consistency in the same generation to identify their double haploid feature; F2 and F3 were genome resequenced and then purified site distribution and stability of double haploid genome SNP were analyzed. [Results]Among the eight hybrid combinations, three seeds were obtained from the combination of (BPC-4×cucumber inbred line YPJ-6) (2n=2x=14),among which one seed was planted and 50 self-crossing progenies were obtained. The chromosome number of the F2 generation were identified to be 2n=2x=24. SSR identification showed that the PCR bands by 27 SSR markers in F2 generation were the same as those of the maternal parent. The PCR bands of F2 was consistent among single plants and F3 was not separated, indicating that the F2 gene loci were homozygous. Statistical analysis of botanical traits showed that the main changes in F2 were compact and dwarf compared with BPC-4. The average values of internode spacing, stem diameter, leaf length and width, and petiole length in F2 were all lower than those of BPC-4,and F2 individual plants were consistent. The above results proved that the progenies obtained from the distant crosses were double haploid, and thus F1,F2 and F3 were named as DH0,DH1 and DH2,respectively. The data of seed number and seed setting rate of dihaploid showed that fertility of DH0 was low, while fertility of DH1 and DH2 had recovered up to that of BPC-4 and could be used for seed propagation and preserved through self-crossing. The genome resequencing revealed that the double haploid SNP loci were further purified by 0.26% compared with BPC-4,and the new purified loci were distributed on all 12 chromosomes. The difference of purified loci between DH1 and DH2 of the double haploid selfing progeny was 1 016,accounting for only 0.05%,which was smaller than the heterozygosity difference of 3.13% from Mendelian theory conventional self-crossing S4 to S5,indicating that the double haploid genome had been stabilized. [Conclusions]Genome resequencing and botanical trait variation demonstrated that it was still necessary to create a double haploid in melon after four generations of self-crossing, and that the double haploids obtained could be saved by seed for further breeding and theoretical studies.  [ABSTRACT FROM AUTHOR]

Zinc (Zn) deficiency is a common limiting factor in agricultural soils, which leads to significant reduction in both the yield and nutritional quality of agricultural produce. Exploring the quantitative trait loci (QTL) for shoot and grain Zn accumulation would help to develop new barley cultivars with greater Zn accumulation efficiency. In this study, two glasshouse experiments were conducted by growing plants under adequate and low Zn supply. From the preliminary screening of ten barley cultivars, Sahara (0.05 mg/pot) and Yerong (0.06 mg/pot) showed the lowest change in shoot Zn accumulation, while Franklin (0.16 mg/pot) had the highest change due to changes in Zn supply for plant growth. Therefore, the double haploid (DH) population derived from Yerong × Franklin was selected to identify QTL for shoot mineral accumulation and biomass production. A major QTL hotspot was detected on chromosome 2H between 31.91 and 73.12 cM encoding genes for regulating shoot mineral accumulations of Zn, Fe, Ca, K and P, and the biomass. Further investigation demonstrated 16 potential candidate genes for mineral accumulation, in addition to a single candidate gene for shoot biomass in the identified QTL region. This study provides a useful resource for enhancing nutritional quality and yield potential in future barley breeding programs. [ABSTRACT FROM AUTHOR]

Bounteous modern and innovative biotechnological tools have resulted in progressive development in the barley breeding program. Doubled haploids developed (homozygous lines) in a single generation is significant. Since the first discovery of haploid plants in 1920 and, in particular, after discovering in vitro androgenesis in 1964 by Guha and Maheshwari, the doubled haploidy techniques have been progressively developed and constantly improved. It has shortened the cultivar development time and has been extensively used in: genetic studies, gene mapping, marker/trait association, and QTL studies. In barley, the haploid occurrence developed gradually from being a sporadic and random process (spontaneous) to haploid development by in vivo method of modified pollination or by in vitro culture of immature male or female gametophytes. Although significant improvement in DH induction protocols has been made, challenges still exist for improvement in areas such as: low efficiency, albinism, genotypic specificity etc. Here, the paper focuses on: haploidization via different in vitro, in vivo techniques, the recent advances technologies like centromere‐mediated haploidization, hap induction gene, and Doubled haploid CRISPR. The au-courant work of different researchers in barley using these technologies is reviewed. Studies on different factors affecting haploid induction and work on genome doubling of barley haploids to produce DH lines via spontaneous and induced technologies has also been highlighted. [ABSTRACT FROM AUTHOR]

Maize (Zea mays) hybrid breeding programs are increasingly adopting double haploid (DH) technology to enhance efficiency and meet the growing demand for food in the face of population growth and climate change. However, in developing countries such as those in subtropical regions, the utilization of DH technology is still limited. This study aims to evaluate the potential benefits of incorporating this technology into both new and established maize breeding programs. Using a pedigree selfing population from the CIMMYT Genebank, DH lines were developed and compared to the conventional pedigree selfing method through a line-by-tester evaluation. Fifteen DH lines and fourteen lines from each of the S2, S4, and S6 selfing generations were subjected to multilocation yield trials in the subtropics of Mexico. The results showed that it took three years for the S1 population to identify DH lines with 100 % homozygosity and the highest general combining ability (GCA), which was one year earlier than the S6 lines (98,4 % homozygous). DH lines exhibited more genotype-by-environment interactions (GxE) compared to S2 testcrosses but demonstrated similar heritability to the S6 generation. Significant statistical differences were observed between the DH evaluations and the S4 and S6 testcrosses, while no significant difference was found between the S2 and DH evaluations. Based on these findings, a gradual implementation of DH technology in hybrid breeding programs is recommended. However, the conventional pedigree method should not be abandoned entirely, and testing in selfing generations, particularly in S6, remains crucial. This study provides a statistical comparison of DH versus the conventional pedigree method using a line-by-tester approach, contributing valuable insights for plant breeders and researchers in the field of maize breeding. [ABSTRACT FROM AUTHOR]

Ovule number (ON) produced during flower development determines the maximum number of seeds per silique and thereby affects crop productivity; however, the genetic basis of ON remains poorly understood in oilseed rape (Brassica napus). In this study, we genetically dissected the ON variations in a double haploid (DH) population and in natural population (NP) by linkage mapping and genome-wide association analysis. Phenotypic analysis showed that ON displayed normal distribution in both populations with the broad-sense heritability of 0.861 (DH population) and 0.930 (natural population). Linkage mapping identified 5 QTLs related to ON, including qON-A03, qON-A07, qON-A07-2, qON-A10, and qON-C06. Genome-wide association studies (GWAS) revealed 214, 48, and 40 significant single-nucleotide polymorphisms (SNPs) by individually using the single-locus model GLM and the multiple-locus model MrMLM and FASTMrMLM. The phenotypic variation explained (PVE) by these QTLs and SNPs ranged from 2.00–17.40% to 5.03–7.33%, respectively. Integration of the results from both strategies identified four consensus genomic regions associated with ON from the chromosomes A03, A07, and A10. Our results preliminarily resolved the genetic basis of ON and provides useful molecular markers for plant yield improvement in B. napus. [ABSTRACT FROM AUTHOR]

The development of Fusarium head blight (FHB)-resistant winter wheat cultivars using the gene Fhb1 has been conducted in northern China. Sumai 3, a Chinese FHB-resistant spring wheat cultivar, carries three FHB resistance genes: Fhb1, Fhb2 and Fhb5. To better use these genes for increasing FHB resistance in northern China, it is necessary to elucidate the pyramiding effects of Fhb1, Fhb2 and Fhb5 in winter wheat backgrounds. Eight gene combinations involving Fhb1, Fhb2 and Fhb5 were identified in a double haploid (DH) population, and the effects on FHB resistance were evaluated in six tests. At the single gene level, Fhb1 was more efficient than the other two genes in single-floret inoculation tests, whereas Fhb5 showed better resistance than Fhb1 and Fhb2 under a natural infection test. Pyramiding Fhb1, Fhb2 and Fhb5 showed better FHB resistance than the other gene combinations. Forty-nine DH lines showing consistently better resistance than the moderately susceptible control Huaimai 20 in multiple tests were evaluated for main agronomic traits, and no difference in grain yield was found between the mean values of DH lines and the recipient parents Lunxuan 136 and Lunxuan 6, which are higher than those of recipient parent Zhoumai 16 and the donor parent Sumai 3 (p < 0.05). Based on the phenotypic and genomic composition analyses, five promising DH lines fully combined the FHB resistance of donor Sumai 3 and the elite agronomic traits from the recipient parents. This study elucidates the pyramiding effects of three FHB resistance genes and that the promising DH lines with resistance to FHB can be directly applied in wheat production or as parents in winter wheat breeding programs. [ABSTRACT FROM AUTHOR]

Double haploids (DHs) production and utilization is an important aspect of wheat breeding programs in worldwide, because, it provides many advantages over the conventional breeding program. Therefore, in vitro and in vivo responses of anther derived two bread wheat cultivars and their F1 crosses were investigated. Results showed significant genetic variation among the tested bread wheat genotypes. The pre-cold treated anther derived embryonic calli and shoot induction (%) were obtained from all genotypes that ranged 44 - 76% and 32 - 58% respectively. The highest shoot induction from embryonic calli was achieved from F1 cross of Zubkov x Atay-85, whereas, lowest induction was obtained from Atay-85 cultivar. The F1 cross (Zubkov x Atay-85) showed a better response in anther culture in term of shoots per plant and root induction than their respective parental genotypes. The present results indicated positive and significant heterotic effects of F1 crosses for calli and shoot induction that also showed less albino plant regeneration after colchicine treatments. Total number of 114 anthers driven DHs lines from two genotypes and their F1 crosses were regenerated, confirmed by flow-cytometry and evaluated under field condition. Some DHs lines were found to be significantly superior for agronomical traits including seed yield than the parental genotypes as well as local bread wheat (control) cultivars. [ABSTRACT FROM AUTHOR]

Combination breeding and mutation breeding are widely used methods in plant breeding. Intensive studies are carried out on biotechnological methods that will allow obtaining homozygous lines in a short time in populations obtained with these two techniques. Numerous studies have been carried out by different researchers on mutation breeding in wheat. There are few studies on anther culture response in mutagen-treated genotypes. Two different bread wheat promising advanced lines were used as the material in the study, in which the possibilities of combining mutation breeding with anther culture through ionizing radiation in high quality wheat breeding were investigated. In the study, the responses of advanced bread wheat mutant lines to anther culture, to which eight different doses of gamma rays (0, 100, 150, 200, 250, 300, 350, 400 Gy) were applied, including the control, were investigated. There are significant differences between genotypes and irradiation doses for all traits studied. It has been shown that it is possible to decrease albinism and increase the response of anther culture with dose-dependent gamma irradiation depending on bread wheat varieties. In the multiple comparison test to classify the difference between doses; statistically, 150 gray dose 5.60 is in the first statistical class and in the first place with the number of transferred green plants. After that, it ranks second in the same class with the number of green plants transferred with a 300 gray dose of 5.21. In the total number of regenerated green plants excluding controls (888), 635 unit (71.5%) and 205 unit (23.1%) haploids and spontaneous double haploid plants were obtained, respectively. In the study integrated into the bread wheat breeding program, a total of 205 spontaneous double haploid mutant lines were produced. According to the data obtained, it was shown that the gamma ray doses of 150 and 200 Gy had a significant stimulation effect on all parameters studied and ultimately the success index of anther culture in bread wheat compared to control. [ABSTRACT FROM AUTHOR]

Summary: Reactive oxygen species (ROS) play important roles during anther and pollen development. DNA damage may cause chromosome fragmentation that is considered to underlie chromosome elimination for haploid induction by matrilineal pollen, a key step in MATRILINEAL‐based double haploid breeding technology. But when and how DNA damage occurs is unknown.We performed comparative studies of wheat pollens from the wild‐type and the CRISPR/Cas9 edited matrilineal mutant (mMTL).Chemical assays detected a second wave of ROS in mMTL pollen at the three‐nuclei‐stage and subsequently, along with reduced antioxidant enzyme activities. RNA‐seq analysis revealed disturbed expression of genes for fatty acid biosynthesis and ROS homoeostasis. Gas chromatography‐mass spectrometry measurement identified abnormal fatty acid metabolism that may contribute to defective mMTL pollen walls as observed using electron microscopy, consistent with the function of MTL as a phospholipase. Moreover, DNA damage was identified using TdT‐mediated dUTP nick‐end labelling and quantified using comet assays. Velocity patterns showed that ROS increments preceded that of DNA damage over the course of pollen maturation.Our work hypothesises that mMTL‐triggered later‐stage‐specific ROS causes DNA damage that may contribute to chromosome fragmentation and hence chromosome elimination during haploid induction. These findings may provide more ways to accelerate double haploid‐based plant breeding. [ABSTRACT FROM AUTHOR]

The golden berry Physalis peruviana native to the inter-Andean valleys of South America, is currently one of the most relevant exotic fruits for Colombia, its demand for export seeks to possess ideal traits of yield and fruit quality. The objective is to determine the genetic parameters of Combinatory Aptitude of nine inbred lines of Uchuva under conditions of the Andean natural region of the department of Nariño. 36 hybrids of cape gooseberry obtained from nine inbred lines 12U347, 12U350, 12U352, 12U357, 12U360, 12U368, 12U374, 12U377, and 12U39, in four localities of the department of Nariño: Gualmatán, Puerres, Pasto, and Ipiales, in order to determine the effects of general (GCA) and specific (SCA) combining ability on performance. The commercial yield (CY) and the agronomic yield (AY) are evaluated in a dialellic under method IV of Griffing (1956). The combined analysis of variation indicates significant differences in the genotype-environment interaction for CY and AY across all localities. The Combinatorial Aptitude analysis reported that additive and nonadditive effects are important in AY and CY. The best hybrids in Gualmatán were 7x8, 3x5 and 3x7, in Ipiales 2x9, 1x3 and 4x8, in Pasto 1x7, 1x3 and 7x8, and in Puerres 2x5, 2x8 and 2x3, which can be taken into account to be used as commercial hybrids high yield. [ABSTRACT FROM AUTHOR]

The experiments were conducted during kharif (June to September) 2018 and 2019 to screen 7 aromatic rice double haploid (DH) lines developed against Bacterial Leaf Bligh (BLB) and blast disease. Three genes Xa21, xa13, xa5 for BLB resistance and two genes Pi1, Pi2 for blast resistance was introgressed into a local aromatic rice variety Dubraj from Chhattisgarh State of India. Dubraj is extremely popular aromatic short medium grain variety in Chhattisgarh and Madhya Pradesh region and hence used in this study. RPBIO-226 and PR122 rice variety is used as donor for BLB and blast resistance respectively. 7 DH lines (L-1 to L-7) were developed from the crosses (Dubraj X RPBIO-226 X PR122) in the year 2017. Phenotypic evaluation for BLB diseases resistance has shown that L-1, L-6 and L-7 (score 1) has a similar resistance as the control check RPBIO-226(score-1) and 3 lines with moderate resistance (L-3 score 2) (L-4 score 3) (L-5 score 3). For blast disease, three lines (L-4, L-6 and L-7) were identified as resistance with the disease score of 1, whereas three were grouped under the section moderately resistant (L-1, L-3 and L-5) with a disease score of 3. Sensory test (1.7% KOH) was conducted for the estimation of presence / absence of aroma. Moderately strong aroma was present in four lines (L-1, L-3, L-6 and L-7). On the basis of yield and presence of aroma in grain, L-3 has been selected with moderately resistant to BLB and blast for further advancement and subsequently evaluated under State Initial Evaluation Trial (SIET) during kharif 2020. Within 3 years of development of DH line, L-3 is under varietal developmental trail, which itself indicate the efficacy of anther culture in fixing homozygosity and speedy development of desired variety within short period of time. [ABSTRACT FROM AUTHOR]

Background: Alfalfa (Medicago Sativa), a perennial cross-pollinated plant, is one of the most important forage crops in the world with commercial value and ecological significance. However, due to the complexity of its genome, varietal improvement is difficult. Therefore, generating genetically homozygous materials have greater significance for breeding. In the current study, we aimed to identify the best tissue culture conditions to obtain haploid plants and double haploid plants. Methods: In this study, the haploid plants of alfalfa were obtained by combining tissue culture regeneration system with Flow cytometry. Different concentrations of colchicine were applied to the haploid plants using solid and liquid cultivation methods to determine the optimum conditions to obtain double haploid plants of Medicago Sativa L. cv. 'XinJiangDaYe'. Result: Among the two colchicine cultivation methods tested, the doubling rate of regenerated plants obtained by liquid cultivation method was higher and the leaves developed under this system have the best doubling effect among the three explants tested. Optimal doubling conditions for alfalfa haploid (Medicago Sativa L. cv. 'XinJiangDaYe') were identified. The double haploid plant material generated from the current study could serve as a genetic resource for developing the hybrid combinations and for analyzing genetic linkage in alfalfa improvement programs. [ABSTRACT FROM AUTHOR]

Drought leads to serious yield losses and followed by increasing food prices. Thereby, drought tolerance is one of most important, pivotal issues for plant breeding and is determined by the very complex genetic architecture, which involves a lot of genes engaged in many cell processes. Within genomes of currently cultivated sugar beet forms, the number of favourable allelic variants is limited. However, there is a potential to identify genes related to drought tolerance deposited in genomes of wild or fodder relatives. Therefore, the goal of our study, was to identify the source of allelic variants involved in drought tolerance using a large spectrum of sugar or fodder beets and their wild relatives for analyses. Based on the drought tolerance index, calculated for morphophysiological traits, it was demonstrated that some of selected fodder beets showed the highest level of drought tolerance. The most drought tolerant fodder beet genotype did not show differences in the level of expression of genes engaged in osmoprotection and the antioxidative system, between control and drought condition, compared to sugar and wild beets. The genetic distance between selected beet forms was broad and ranged from 18 to 87%, however the most drought tolerant sugar, fodder and wild beets showed high genetic similarity and formed the common clade. Based on obtained results we propose that an adequate broad source of genes related to drought tolerance occurs in fodder beets, the crossing with which is easier, less time-consuming and more cost-effective than with wild forms of beets. • Some of fodder beets showed the higher drought tolerance than wild and sugar beets. • Genes engaged in osmoprotection and the antioxidant system are not involved in the response of fodder beet to drought. • The total genetic distance between Beta accessions was broad and ranged from 18 to 87%. • The most drought tolerant sugar, fodder and wild beets showed high genetic similarity and formed the common clade. • Appropriate source of genes related to drought tolerance for sugar beet might be fodder beet. [ABSTRACT FROM AUTHOR]

Haploids and doubled haploids are critical components of plant breeding. This review is focused on studies on haploids and double haploids inducted in cucurbits through in vitro pollination with irradiated pollen, unfertilized ovule/ovary culture, and anther/microspore culture during the last 30 years, as well as comprehensive analysis of the main factors of each process and comparison between chromosome doubling and ploidy identification methods, with special focus on the application of double haploids in plant breeding and genetics. This review identifies existing problems affecting the efficiency of androgenesis, gynogenesis, and parthenogenesis in cucurbit species. Donor plant genotypes and surrounding environments, developmental stages of explants, culture media, stress factors, and chromosome doubling and ploidy identification are compared at length and discussed as methodologies and protocols for androgenesis, gynogenesis, and parthenogenesis in haploid and double haploid production technologies. [ABSTRACT FROM AUTHOR]

Abstract: Sugar beet (Beta vulgaris L.) is the second largest sugar-producing crop (following sugarcane), accounting around 40% of total global sugar output. It has been reckoned with huge contribution in sugar, ethanol, and fodder industries. Since sugar beet is recalcitrant in nature, to address the multifaceted difficulties associated with its conventional propagation, several biotechnological tools and techniques aiming with in vitro–based mass regeneration-cum-genetic enhancement are becoming popular. The implementation of effective methodology for in vitro regeneration from ex vitro explant sources becomes the necessity for successful commercial-scale clonal propagation and genetic modification. Substantial research achievements have been made in the past few decades in connection to the optimization of in vitro protocols for direct and callus-mediated regeneration, homozygous line production, somatic hybridization, and genetic transformation of sugar beet. The current review summarizes several reported findings on various physio-chemical factors responsible for direct, indirect organogenesis, somatic embryogenesis, protoplast culture, haploid culture, acclimatization accountable for plantlet mass multiplication, assessing the genetic integrity of in vitro–cultured plantlets, and, finally, successful transgenic approaches to remediate biotic and abiotic stresses. Furthermore, this study highlights undiscovered regions, research gaps, and major bottlenecks that might be considered in developing significant innovative ideas related to sugar beet biotechnology in the near future.• Sugar beet, the second largest sugar producer, is a major contributor in sugar, ethanol, and fodder industries.• Current review comprehensively evaluates diverse factors influencing the success of in vitro biotechnological interventions.• This review further highlights the research gaps and offers way outs to attain comprehensive genetic improvement.Key points: Sugar beet (Beta vulgaris L.) is the second largest sugar-producing crop (following sugarcane), accounting around 40% of total global sugar output. It has been reckoned with huge contribution in sugar, ethanol, and fodder industries. Since sugar beet is recalcitrant in nature, to address the multifaceted difficulties associated with its conventional propagation, several biotechnological tools and techniques aiming with in vitro–based mass regeneration-cum-genetic enhancement are becoming popular. The implementation of effective methodology for in vitro regeneration from ex vitro explant sources becomes the necessity for successful commercial-scale clonal propagation and genetic modification. Substantial research achievements have been made in the past few decades in connection to the optimization of in vitro protocols for direct and callus-mediated regeneration, homozygous line production, somatic hybridization, and genetic transformation of sugar beet. The current review summarizes several reported findings on various physio-chemical factors responsible for direct, indirect organogenesis, somatic embryogenesis, protoplast culture, haploid culture, acclimatization accountable for plantlet mass multiplication, assessing the genetic integrity of in vitro–cultured plantlets, and, finally, successful transgenic approaches to remediate biotic and abiotic stresses. Furthermore, this study highlights undiscovered regions, research gaps, and major bottlenecks that might be considered in developing significant innovative ideas related to sugar beet biotechnology in the near future.• Sugar beet, the second largest sugar producer, is a major contributor in sugar, ethanol, and fodder industries.• Current review comprehensively evaluates diverse factors influencing the success of in vitro biotechnological interventions.• This review further highlights the research gaps and offers way outs to attain comprehensive genetic improvement. [ABSTRACT FROM AUTHOR]

Using seeds of inbred progenies of Cucurbita pepo L. DH12-11409 double haploids as experimental materials, the effects of different hormone combinations, explant types and seedling ages on adventitious bud regeneration and rooting of C. pepo L. were investigated. According to the results, inoculating cotyledonary nodes of yellow-green cotyledons from 5-d-old C. pepo L. double haploids to MS + 30 g/L Sue + 8 g/L Agar + 2.0 mg/L 6-BA +0.1 mg/L NAA led to the best results with the induction frequency of 90.0% and differentiation coefficient of 8.5. MS medium with addition of 0.05 or 0.1 mg/L NAA led to the highest rooting rate. Regenerated seedlings with 5-6 true leaves exhibited the highest survival rate of 90.0%, which was the optimal period for domestication and transplanting of regenerated seedlings. This study laid a solid foundation for high-efficiency utilization of heterosis of C. pepo L. [ABSTRACT FROM AUTHOR]

Highlights: [•] The inheritance of tolerance to high temperature stress was investigated using QTL analysis on a doubled haploid population. [•] Seven stable QTL were identified for HSI of traits, mapping to chromosomes 1D, 6B, 2D and 7A. [•] Three QTLs related to HSI of grain filling duration, two to thousand grain weights and one each to grain yield and canopy temperature. [•] The QTL analysis for the direct traits GY, TGW, GFD and CT led to detection of 22 QTLs spread over to 17 chromosomal regions. [•] A QTL for TGW on chromosome 6B under normal sown co-located with HSI (TGW) QTL QHTgw.bhu-6BL. [Copyright &y& Elsevier]

Microspore embryogenesis involves reprogramming of the pollen immature cell towards embryogenesis. We have identified and characterized a collection of 14 genes induced along different morphological phases of microspore-derived embryo development in wheat ( Triticum aestivum L.) anther culture. SERKs and FLAs genes previously associated with somatic embryogenesis and reproductive tissues, respectively, were also included in this analysis. Genes involved in signalling mechanisms such as TaTPD1- like and TAA1b, and two glutathione S-transferase ( GSTF2 and GSTA2) were induced when microspores had acquired a 'star-like' morphology or had undergone the first divisions. Genes associated with control of plant development and stress response ( TaNF- YA, TaAGL14, TaFLA26, CHI3, XIP- R; Tad1 and WALI6) were activated before exine rupture. When the multicellular structures have been released from the exine, TaEXPB4, TaAGP31- like and an unknown embryo-specific gene TaME1 were induced. Comparison of gene expression, between two wheat cultivars with different response to anther culture, showed that the profile of genes activated before exine rupture was shifted to earlier stages in the low responding cultivar. This collection of genes constitutes a value resource for study mechanism of intra-embryo communication, early pattern formation, cell wall modification and embryo differentiation. [ABSTRACT FROM AUTHOR]

This review provides a summary of haploid induction methods and factors affecting the efficacy of specific methodologies as applied to cucumber (Cucumis sativus L.), melon (Cucumis melo L.), watermelon (Citrullus lanatus (Thunb.) Matsum. & Nakai), winter squash (Cucurbita maxima Duch. ex Lam.), summer squash (Cucurbita pepo L.) and other cucurbits. This report is focused on studies that were carried out during the last 20 years. The main objective of the research on the production of haploid cucurbit plants is to accelerate breeding programs through the use of homozygous double haploid lines (DHL) and to facilitate the selection of desired (e.g. disease-resistant) genotypes for breeding. Unfortunately, currently used protocols result in a low number of double haploids (DH). The most common and best-known method of obtaining haploid cucurbit plants is via pollination with irradiated pollen, which induces parthenogenetic development of haploid embryos in planta. The embryos are extracted from immature seeds and cultured in vitro to facilitate the maturation and development of plants. The studies described below were primarily aimed at the determination of an appropriate dose of radiation and the evaluation of the impact of the genotype and the time of year on the number of haploid embryos and plants obtained. A less popular method of haploid production - ovule and ovary culture - is based on in vitro gynogenesis. The studies related to this method concentrated on optimising the composition of the medium and pre-treatment conditions (primarily temperature) to which the flower buds were subjected. Recently, increasing attention has been paid to anther and microspore culture. As in the case of in vitro ovule and ovary culture, the medium composition and flower bud pre-treatment conditions were optimised. The most recent studies suggest that anther culture is comparable in effectiveness to the irradiated pollen technique. [ABSTRACT FROM AUTHOR]

With 2 figures and 4 tables Abstract Net type net blotch (NTNB) is an important barley disease in Australia and elsewhere, inducing significant yield reduction. 'WPG8412' was resistant against Australian NTNB isolates 97NB1 and NB73, whereas 'Pompadour' and 'Stirling' showed differential responses to these isolates. Using these lines, three F1-derived double haploid populations that comprised 194 double haploid lines (DHLs) of 'WPG8412' ×'Stirling', 116 DHLs of 'WPG8412' × 'Pompadour' and 206 DHLs of 'Pompadour' × 'Stirling' were tested against these two isolates. Bimodal segregation indicated a major gene for resistance was operative: in 'WPG8412' × 'Stirling' against 97NB1; in 'WPG8412'×'Pompadour' against NB73; and in 'Pompadour' × 'Stirling' against either of the isolate. This major gene was mapped using simple sequence repeat (SSR) markers on chromosome 6H in the centromeric region in all three populations. This work demonstrated that 6H region controlling NTNB is a complex locus, where at least three alleles or closely linked genes are possible in these parents against these isolates. This is a first report of 6H complexity for NTNB resistance against Australian isolates. [ABSTRACT FROM AUTHOR]

Background: Brassica rapa is an economically important crop and a model plant for studies concerning polyploidization and the evolution of extreme morphology. The multinational B. rapa Genome Sequencing Project (BrGSP) was launched in 2003. In 2008, next generation sequencing technology was used to sequence the B. rapa genome. Several maps concerning B. rapa pseudochromosome assembly have been published but their coverage of the genome is incomplete, anchoring approximately 73.6% of the scaffolds on to chromosomes. Therefore, a new genetic map to aid pseudochromosome assembly is required. Results: This study concerns the construction of a reference genetic linkage map for Brassica rapa, forming the backbone for anchoring sequence scaffolds of the B. rapa genome resulting from recent sequencing efforts. One hundred and nineteen doubled haploid (DH) lines derived from microspore cultures of an F1 cross between a Chinese cabbage (B. rapa ssp. pekinensis) DH line (Z16) and a rapid cycling inbred line (L144) were used to construct the linkage map. PCR-based insertion/deletion (InDel) markers were developed by re-sequencing the two parental lines. The map comprises a total of 507 markers including 415 InDels and 92 SSRs. Alignment and orientation using SSR markers in common with existing B. rapa linkage maps allowed ten linkage groups to be identified, designated A01-A10. The total length of the linkage map was 1234.2 cM, with an average distance of 2.43 cM between adjacent marker loci. The lengths of linkage groups ranged from 71.5 cM to 188.5 cM for A08 and A09, respectively. Using the developed linkage map, 152 scaffolds were anchored on to the chromosomes, encompassing more than 82.9% of the B. rapa genome. Taken together with the previously available linkage maps, 183 scaffolds were anchored on to the chromosomes and the total coverage of the genome was 88.9%. Conclusions: The development of this linkage map is vital for the integration of genome sequences and genetic information, and provides a useful resource for the international Brassica research community. [ABSTRACT FROM AUTHOR]

With 2 figures and 5 tables Net type net blotch (NTNB) is an important barley disease in Australia and elsewhere, with significant yield reduction. This trait is important in selection along with other traits of quality and agronomic value. Two-hundred doubled-haploid lines were generated through anther culture from a cross between ‘Pompadour’ and ‘Stirling’. Quantitative trait loci (QTL) were identified against five isolates of Pyrenophora teres f. teres, which represent virulences across Australia. QTL were mapped on chromosomes 3H and 6H using simple sequence repeat (SSR) markers. The resistance locus on 6H was detected with all isolates while the 3H locus was detected with two isolates. The 6H QTL from ‘Pompadour’ contributed resistance to isolates 97NB1, 95NB100 and NB81, whereas 6H QTL from ‘Stirling’ contributed resistance to isolates NB50 and NB52B. The 3H QTL from ‘Pompadour’ contributed resistance to NB50 and NB52B. Significant epistatic interactions were detected between QTL on 3H and 6H. These resistance QTL are a useful resource and identifying closely linked SSR markers with allelic combinations will facilitate in marker-assisted selection to develop NTNB resistant breeding lines. [ABSTRACT FROM AUTHOR]

A doubled-haploid (DH) population, obtained by anther culture of F1 plants from a cross between a highly susceptible rice cultivar Lijiangxintuanheigu and the resistant somaclone (SC09), of the cultivar Araguaia, was used to identify RAPD markers linked to the blast resistance gene Pi-ar. The 86 DH plants, inoculated with the race IB-9 of Magnaporthe oryzae, segregated in 1:1 ratio of resistant and susceptible plants. Of the 67 primers used 31 produced DNA profiles that differentiated resistant and susceptible bulks as well as the parental cultivars. The resistance gene was found linked to the primer OPS162072 ('AGGGGGTTCC') at a distance of 3.6 cM. The selection efficiency of this primer was assessed in a BC3 F1 population derived from another cross between a susceptible cultivar IAC 201 and SC09. The marker OPS16 showed efficiency of 86.9%, when six resistant and two susceptible plants were considered as negatives in RAPD analysis. [ABSTRACT FROM AUTHOR]

Although barley is extensively grown in the Peruvian highlands as a food crop, agricultural and quality performance have historically been poor. A double-haploid technique was used to obtain barley varieties better suited to this environment. Three crosses were constructed: Ya/LM94, B16/LM94 and B12/LM94. From all crosses, F1 anthers were cultured in vitro to produce double-haploid lines. At DH6, promising materials were evaluated in the Peruvian highlands, along with their parents and two commercial controls (PPch, UNA80). Expert agronomic criteria for the ideal barley cultivar for this region were defined and Euclidean distance was used for simultaneous selection of the recorded agricultural traits. Ya/LM94-PC27 exhibited the shortest Euclidean distance to the expert criteria (0.41), higher yield than controls, and low plant height. Periods from first rain to flowering and maturity suited growth during the rainy season. Ya/LM94-PC27 was resistant to stripe rust, and its grain protein content suited the malting-brewing industry. Hectoliter and 1,000-grain masses met or surpassed industry requirements. [ABSTRACT FROM AUTHOR]

Blackleg, caused by Leptosphaeria maculans, is a major disease of oilseed rape ( Brassica napus), worldwide, including Australia and France. The aims of these studies were first, to determine if higher levels of resistance to L. maculans could be generated in double haploid (DH) lines derived from spring-type B. napus cv. Grouse, which has a good level of field resistance to blackleg; and second, to determine whether the resistance to blackleg disease of individual DH lines responds differentially to different L. maculans field populations within and between the two countries. DH lines were extracted from cv. Grouse and tested in field experiments carried out in both France and Australia against natural L. maculans populations. Extracting and screening DH lines were an effective means to select individual lines with greatly improved expression of resistance to blackleg crown canker disease in comparison with the original parental population. However, relative disease resistance rankings for DH lines were not always consistent between sites. The higher level of resistance in France was shown to be because of a high expression level of quantitative resistance in the French growing conditions. Big differences were observed for some DH lines between the 2004 and the 2005 field sites in Australia where the L. maculans populations differed by their virulence on single dominant gene-based resistant lines derived from Brassica rapa ssp. sylvestris. This differential behaviour could not be clearly explained by the specific resistance genes until now identified in these DH lines. This investigation highlights the potential to derive DH lines with superior levels of resistance to L. maculans compared with parental populations. However, in locations with particularly high pathogen diversity, such as in southern Australia, multiyear and multisite evaluations should be performed to screen for the most efficient material in different situations. [ABSTRACT FROM AUTHOR]

A genetic linkage mapping study was conducted in 93 doubled-haploid lines derived from a cross between Triticum aestivum L. em. Thell 'Arina' and a Norwegian spring wheat breeding line, NK93604, using diversity arrays technology (DArT), amplified fragment length polymorphism (AFLP), and simple sequence repeat (SSR) markers. The objective of this study was to understand the distribution, redundancy, and segregation distortion of DArT markers in comparison with AFLP and SSR markers. The map contains a total of 624 markers with 189 DArTs, 165 AFLPs and 270 SSRs, and spans 2595.5 cM. All 3 marker types showed significant (p < 0.01) segregation distortion, but it was higher for AFLPs (24.2%) and SSRs (22.6%) than for DArTs (13.8%). The overall segregation distortion was 20.4%. DArTs showed the highest frequency of clustering (27.0%) at < 0.5 cM intervals between consecutive markers, which is 3 and 15 times higher than SSRs (8.9%) and AFLPs (1.8%), respectively. This high proportion of clustering of DArT markers may be indicative of gene-rich regions and (or) the result of inclusion of redundant clones in the genomic representations, which was supported by the presence of very high correlation coefficients (r > 0.98) and multicollinearity among the clustered markers. The present study is the first to compare the utility of DArT with AFLP and SSR markers, and the present map has been successfully used to identify novel QTLs for resistance to Fusarium head blight and powdery mildew and for anther extrusion, leaf segment incubation, and latency. [ABSTRACT FROM AUTHOR]

Background: Farmed Atlantic salmon are one of the most economically significant global aquaculture products. Early sexual maturation of farmed males represents a significant challenge to this industry and has been linked with the vgll3 genotype. However, tools to aid research of this topic, such as all-male and clonal fish, are still lacking. The present 6-year study examined if all-male production is possible in Atlantic salmon, a species with heteromorphic sex chromosomes (males being XY, females XX), and if all-male fish can be applied to further explore the vgll3 contribution on the likelihood of early maturation. Results: Estrogen treatment of mixed sex yolk sac larvae gave rise to one sexually mature hermaphrodite with a male genotype (XY) that was used to produce both self-fertilized offspring and androgenetic double haploid (dh) offspring following egg activation with UV treated sperm and pressure shock to block the first mitotic division. There were YY supermales among both offspring types, which were crossed with dh females. Between 1 and 8% of the putative all-male offspring from the eight crosses with self-fertilized supermales were found to have ovaries, and 95% of these phenotypic females were also genetically female. None of the offspring from the one dh supermale cross had ovaries. When assessing the general contribution of the vgll3 locus on the likelihood of early post-smolt sexual maturation (jacking) in the all-male populations we found individuals that were homozygous for the early maturing genotype (97%) were more likely to enter puberty than individuals that were homozygous for the late maturing genotype (26%). However, the likelihood of jacking within individuals with an early/late heterozygous genotype was higher when the early allele came from the dam (94%) compared to the sire (45%). Conclusions: The present results show that supermale Atlantic salmon are viable and fertile and can be used as a research tool to study important aspects of sexual maturation, such as to further explore the sex dependent parental genetic contribution to age at puberty in Atlantic salmon. In addition, we report the production of viable double haploid supermale fish. [ABSTRACT FROM AUTHOR]

• Responsive and recalcitrance lines of triticale differ with respect to phenotypic, genetic and epigenetic features. • There is a link between the formation of DNA damage and cytidine-analogs induced DNA de-methylation. • The application of 5-azacytidine increases the efficiency of microspore embryogenesis in the highly-responsive line. Microspores exposed to some stress factors may display cell totipotency and could be reprogrammed towards embryogenic development. Plant breeding and genetic engineering widely use haploids/doubled haploids (DHs) derived from in vitro -cultured microspores, but the mechanism of this process remains poorly understood. Recently published data suggest that microspore embryogenesis (ME) is accompanied by changes in DNA methylation and chromatin reorganization. Here, we used two triticale DH lines (DH19 and DH28), significantly different with respect to embryogenic potential. To change DNA methylation levels, we applied two cytosine-analogs: 5-azacytidine (AC) and 2′-deoxy-5-azacytidine (DAC) treatments. We found that chemically-induced DNA demethylation caused chromatin relaxation and dysregulation of marker genes (TaTPD1-like, GSTF2, GSTA2, CHI3, Tad1, TaNF-YA7, SERK2, TaME1) related to ME. Both drugs showed significant cytotoxicity in a dose-dependent manner. We noticed that lines varied in terms of overall DNA methylation levels and responded in a different way to hypomethylation caused by the drugs. DH19 (low embryogenic) after inhibitors treatment, showed higher microspore viability, but its recalcitrancy was not overcome. For highly embryogenic DH28, we noted significantly higher effectiveness of embryo-like structure production and plant regeneration. In summary, our study provides new insight into the role of DNA methylation in ME initiation. They suggest potential benefits resulting from the utilization of epigenetic inhibitors to improve the process of DHs production. [ABSTRACT FROM AUTHOR]