Conventional Breeding Programs Research Articles

Citrus Genetic Transformation: An Overview of the Current Strategies and Insights on the New Emerging Technologies.

Citrus are among the most prevailing fruit crops produced worldwide. The implementation of effective and reliable breeding programs is essential for coping with the increasing demands of satisfactory yield and quality of the fruit as well as to deal with the negative impact of fast-spreading diseases. Conventional methods are time-consuming and of difficult application because of inherent factors of citrus biology, such as their prolonged juvenile period and a complex reproductive stage, sometimes presenting infertility, self-incompatibility, parthenocarpy, or polyembryony. Moreover, certain desirable traits are absent from cultivated or wild citrus genotypes. All these features are challenging for the incorporation of the desirable traits. In this regard, genetic engineering technologies offer a series of alternative approaches that allow overcoming the difficulties of conventional breeding programs. This review gives a detailed overview of the currently used strategies for the development of genetically modified citrus. We describe different aspects regarding genotype varieties used, including elite cultivars or extensively used scions and rootstocks. Furthermore, we discuss technical aspects of citrus genetic transformation procedures via Agrobacterium, regular physical methods, and magnetofection. Finally, we describe the selection of explants considering young and mature tissues, protoplast isolation, etc. We also address current protocols and novel approaches for improving the in vitro regeneration process, which is an important bottleneck for citrus genetic transformation. This review also explores alternative emerging transformation strategies applied to citrus species such as transient and tissue localized transformation. New breeding technologies, including cisgenesis, intragenesis, and genome editing by clustered regularly interspaced short palindromic repeats (CRISPR), are also discussed. Other relevant aspects comprising new promoters and reporter genes, marker-free systems, and strategies for induction of early flowering, are also addressed. We provided a future perspective on the use of current and new technologies in citrus and its potential impact on regulatory processes.

An insight into the reproductive success in an interspecific cross of sesamum

Sesame viz., Sesamum indicum (CO 1) and Sesamum alatum. The wild species are the potential source for biotic and abiotic stress-resistant genes and therefore high crossability with the cultivated variety is very essential for the transfer of genes through a conventional breeding programme. The pollen images obtained and the number of colpi counted from Light Microscope and Scanning Electron Microscope assisted in differentiating the pollen of Sesamum indicum from Sesamum alatum. The pollen fertility assessment by Acetocarmine test proved that Sesamum indicum (CO 1) was more fertile than Sesamum alatum and hence the former was presumed to be the better pollen-producing parent in terms of fertility. The pollen pistil interaction by aniline blue technique between direct and reciprocal crosses of two species of Sesamum reported higher and lower germination per cent at 2 HAP and 8 HAP, respectively. The mean pollen germination per cent of the direct and reciprocal cross was observed to be 69.99 and 58.59, respectively. In the direct cross, the pollen tube managed to reach the ovary but did not set seeds and hence is claimed to possess a post-zygotic fertilization barrier. In the reciprocal cross, the growth of the pollen tube stopped before reaching the ovary apparently, no seed set was observed and therefore designated to have pre zygotic fertilization barriers. Direct and reciprocal crosses were compared and ways to mitigate fertilization barriers are discussed. Key words: Sesame, interspecific cross, pollen pistil interactions, aniline blue technique, fertilization barriers

In-Vivo Pollination; A Better Option for Longevity Test of Pollen Viability of Cowpea (Vigna unguiculata L. Walp)

Abstract: A quick and trusted method for evaluating pollen quality and viability is essential in a conventional breeding program. Techniques used in evaluating pollen viability can be classified into in vivo and in vitro tests. Harrison, Heslop, Harrison and Shivanna (2004) categorize the in vitro test into (a) test of germinability, (b) test of stainability, (c) test for enzyme activity and (d) fluorochromatic procedure (FCR). Using pollen of different age crossability can be suitable in testing pollen viability in the field. This research work was conducted in 2007 and 2008 at the screen house of the Institute for Agricultural Research (IAR) of Ahmadu Bello University Samaru Zaria to study pollen viability and its implication for outcrossing in cowpea. Four genotypes, IT86D1010, IT93K452-1, B301 and kanannado were used in the study. Completely Randomized Design (CRD) was used where each cultivar was sown in four labeled pots containing topsoil mixed with manure and sand. This set of planting was repeated three times but staggered to synchronize the flowering of the genotypes. Pollen grains were collected early in the morning (6:00- 6:30 am) from a matured pollen and kept in a well-labeled Petri dish in a filter paper. The crossing was done immediately after pollen collection at 0 hours, then after 3 hours of collection and 6 hours. The crossing was done in all forms, including reciprocals. Record of successful and failed crosses was taken when pods started to form. A regression analysis of pollen age on percent successful cross was carried out to determine the crossability, pollen viability, and relationships. The study shows that the three varieties, IT86D1010, IT93K452-1 and B301 were readily crossable both as paternal and maternal parents. Kanannado was crossable as a paternal parent only, but no seed was recorded when used as a maternal parent. Regression analysis shows a significant effect of pollen age on pollen viability and crossability. The experiment suggests that pollen from neighboring plants can threaten breeding materials if transferred by an efficient vector since pollen can be viable under ambient temperature for up to three hours. Keywords: In-Vivo, pollen, longevity, cowpea, viability

Genomic-Assisted Marker Development Suitable for CsCvy-1 Selection in Cucumber Breeding.

Cucumber is a widely grown vegetable crop plant and a host to many different plant pathogens. Cucumber vein yellowing virus (CVYV) causes economic losses on cucumber crops in Mediterranean countries and in some part of India such as West Bengal and in African countries such as Sudan. CVYV is an RNA potyvirus transmitted mechanically and by whitefly (Bemisia tabaci) in a semipersistent manner. Control of this virus is heavily dependent on the management of the insect vector and breeding virus-resistant lines. DNA markers have been used widely in conventional plant breeding programs via marker-assisted selection (MAS). However, very few resistance sources against CVYV in cucumber exist, and also the lack of tightly linked molecular markers to these sources restricts the rapid generation of resistant lines. In this work, we used genomics coupled with the bulked segregant analysis method and generated the MAS-friendly Kompetitive allele specific PCR (KASP) markers suitable for CsCvy-1 selection in cucumber breeding using a segregating F2 mapping population and commercial plant lines. Variant analysis was performed to generate single-nucleotide polymorphism (SNP)-based markers for mapping the population and genotyping the commercial lines. We fine-mapped the region by generating new markers down to 101 kb with eight genes. We provided SNP data for this interval, which could be useful for breeding programs and cloning the candidate genes.

Conceptual review on the conventional and genome-wide association analysis towards developing salinity tolerance in rice

Salinity is the major abiotic stress which predominantly affects the productivity of rice worldwide. Conventional breeding programs to develop stress-tolerant varieties showed only marginal success. Marker-assisted selection can improve the efficiency of salinity tolerance as they are growth stage and environment independent. However, physiological response due to ionic and osmotic stresses caused by salt accumulation in the soil hinders plant growth and development. Genetic engineering strategy was adopted to tailor the selection and incorporation of candidate salt-tolerant genes in rice. Understanding the genomics of salinity tolerance remains a complex phenomenon since several genes and pathways control them. Genome-wide association studies revealing the information of SNP's variants and functional effects appear to be a future for breeding salinity-tolerant rice. Therefore, this review provides scientific insights into the mechanisms and approaches to enhance salinity tolerance, genome-wide association analysis, and the CRISPR/Cas technology as an efficient tool for genome modifications. Genome-wide association analysis showed the presence of major QTL region SalTol in chromosome 1, containing potential salt tolerant responsive genes in indica varieties. The distribution of SNP and InDels was highest in the Chromosome 1 of Godawee, Pokkali, and Nona Bokra. The SNP and InDels density was not consistent among the varieties. Genome-wide association analysis of SNPs and InDels data highlighted the importance of genomic variants in regulating the salinity tolerance that could be useful for future crop improvements.

In vitro tetraploidy induction creates enhancements in morphological, physiological and phytochemical characteristics in the fig tree (Ficus Carica L.)

Fig tree (Ficus carica L.) is a precious fruit tree in semi-arid and arid areas worldwide which has difficulties in its conventional breeding programs. This study was carried out to make new genotypes with superior features based on the ploidy induction method. Thus, in vitro tetraploidization in two fig cultivars, namely ‘Sabz’ and ‘Torsh’, was successfully established using shoot tip explants and colchicine as the antimitotic agent in MS medium. The flow cytometry and chromosome counting techniques were used to verify tetraploid plants. The results revealed that, in comparison to the original diploid plants of both cultivars, tetraploid plants significantly had taller stems, larger leaves, a greater number of chloroplasts in guard cells, and higher chlorophyll content and photosynthesis rate. UPLC-MS analysis revealed that the level of growth stimulator phytohormones, including ZR, IAA, GA3, SA, and JA in the tetraploid plants of both cultivars were significantly higher than their diploid controls. In contrast, they had less accumulated growth inhibitor phytohormone (ABA) than their diploid explant source. Moreover, tetraploid plants had significantly accumulated a higher content of phenolic compounds, total soluble sugars, and total soluble proteins, but showed a significantly less total antioxidant activity. Consequently, it is concluded that the growth advantages of tetraploid figs created in this study are substantial in terms of phytohormonal, physiological, and phytochemical superiorities, as compared to their corresponding diploid plants. Polyploidization proves as a promising breeding tool for future breeding programs of the fig tree.

Effect of abiotic stresses and mitigation strategy associated with their tolerance in wheat

Global warming influences environmental factors which directly and indirectly affects agricultural crop production by exposing to several new biotic and abiotic stresses. The abiotic stresses like heat, drought, moisture, salinity and pre harvest sprouting stresses are most common whose effect became more severe due to climate change. Globally wheat is the most widely cultivated and used crops due to its economic and social values. Its production and productivity are highly vulnerable to these abiotic stresses. The development of wheat varieties tolerant to these abiotic stresses is a very challenging assignment for wheat researchers. The conventional breeding program is being practiced for such objectives but it will not be sufficient to achieve the target production and more advanced research is needed for better understanding the mechanism of these stresses and how plants became more tolerant. The progress made in the understanding of these abiotic stress tolerances is due to advances in three main research areas: physiology, genetic, and breeding research. Identifying morphological traits, physiological and biochemical traits for précised phenotyping and associated genes contributing to particular stress tolerance is very important under mitigation strategy. Previous studies showed that some abiotic stress tolerance is controlled by a polygene and its genetic constitution will help to analyze the gene network(s) controlling stress tolerance. Furthermore, stress mitigation options particularly through the application of plant hormones, several agronomic interventions, genetic and biotechnological management strategy are convenient for improving plant performances under various abiotic stresses are also essential to stabilize the wheat productivity.

Forecasting rice latitude adaptation through a daylength-sensing-based environment adaptation simulator.

Global climate change necessitates crop varieties with good environmental adaptability. As a proxy for climate adaptation, crop breeders could select for adaptability to different latitudes, but the lengthy procedures for that slow development. Here, we combined molecular technologies with a streamlined in-house screening method to facilitate rapid selection for latitude adaptation. We established the daylength-sensing-based environment adaptation simulator (DEAS) to assess rice latitude adaptation status via the transcriptional dynamics of florigen genes at different latitudes. The DEAS predicted the florigen expression profiles in rice varieties with high accuracy. Furthermore, the DEAS showed potential for application in different crops. Incorporating the DEAS into conventional breeding programmes would help to develop cultivars for climate adaptation.

Competitive gene flow does not necessarily maximize the genetic gain of genomic breeding programs in the presence of genotype-by-environment interaction

National and international across-population selection is often recommended and fairly common in the current breeding practice of dairy cattle, with the primary aims to increase genetic gain and genetic variability. The aim of this study was to test the hypothesis that the strategy of truncation selection of sires across populations [i.e., competitive gene flow strategy (CGF)] may not necessarily maximize genetic gain in the long term in the presence of genotype-by-environment interaction (G×E). Two alternative strategies used to be compared with CGF were forced gene flow (FGF) strategies, with 10 or 50% of domestic dams forced to be mated with foreign sires (FGF10%, FGF50%). Two equal-size populations (Ndams = 1,000) that were selected for the same breeding goal trait (h2 = 0.3) under G×E correlation (rg) of either 0.9 or 0.8 were simulated to test these 3 different strategies. Each population first experienced either 5 or 20 differentiation generations (Gd), then 15 migration generations. Discrete generations were simulated for simplicity. Each population performed a within-population conventional breeding program during differentiation generations and the 3 across-population sire selection strategies based on joint genomic prediction during migration generations. The 4 Gd_rg combinations defined 4 different levels of differentiation degree between the 2 populations at the start of migration. The true rate of inbreeding over the last 10 migration generations in each scenario was constrained at 0.01 to provide a fair basis for comparison of genetic gain across scenarios. Results showed that CGF maximized the genetic gain after 15 migration generations in 5_0.9 combination only, the case of the lowest differentiation degree, with a superiority of 0.4% (0.04 genetic SD units) over the suboptimal strategy. While in 5_0.8, 20_0.9, and 20_0.8 combinations, 2 FGF strategies had a superiority in genetic gain of 2.3 to 12.5% (0.21-1.07 genetic SD units) over CGF after 15 migration generations, especially FGF50%. The superiority of FGF strategies over CGF was that they alleviated inbreeding, introduced new genetic variance in the early migration period, and improved accuracy in the entire migration period. Therefore, we concluded that CGF does not necessarily maximize the genetic gain of across-population genomic breeding programs given moderate G×E. The across-population selection strategy remains to be optimized to maximize genetic gain.

Improved response to selection in dairy goat breeding programme through reproductive technology and genomic selection in the tropics

• Incorporation of reproductive technologies improved response to selection in dairy goats breeding programme in the tropics. • AI-Liquid semen realised high response to selection compared to natural mating and AI-Frozen dairy goats breeding programme. • Genomic selection improved response to selection compared to conventional scheme in dairy goats breeding programme. It was reasoned that, incorporating reproductive technologies and genomic selection in the current dairy goats breeding programme would generate higher response to selection compared to use of natural mating in the current conventional breeding programme. This premise was tested by deterministic simulation approach and compared to the current breeding programme where natural mating and conventional breeding programme is used in the tropics. Two breeding schemes with three breeding strategies were simulated. The first scheme was conventional breeding scheme (CS) which represented the current dairy goat-breeding programme in the tropics. An alternative scheme was genomic breeding scheme (GS). Each scheme was evaluated with three mating strategies. They include; conventional scheme using natural mating (CNM), AI-Liquid semen (CLS) and AI-Frozen semen (CFS), and genomic scheme using natural mating (GNM), AI-Liquid semen (GLS) and AI-Frozen semen (GFS) strategies, with 5% of the total population in the nucleus and 95 % in the commercial. The current study found that CLS and GLS were superior compared to CFS and GFS, and CNM and GNM strategies in terms of annual genetic gain, returns and profit per doe per year. The CLS realised additional Kenya Shillings (KES) 3.00 and 3.61, 151.31 and KES 46.72, 148.89 and 47.81, in genetic gain, returns and profitability compared to CNM and CFS, respectively. The CLS incurred low costs KES 23.38 compared to CFS with KES 24.47 but higher than CNM with KES 20.96. On the other hand, CFS strategy has generated additional returns KES 104.59 and profit KES 101.08 but lower by KES 0.61 in genetic gain compared to CNM strategy. Implementation of genomic scheme has generated additional improvement across the three mating strategies in all the parameters measured compared to the conventional scheme. The GS realised additional KES 11.54, 10.80 and 10.21 in genetic gain, KES 161.30, 183.48 and 175.90 returns, and 136.30, 158.48 and 150.90 profit in the GNM, GLS and GFS, respectively, compared to those realised in CNM, CLS and CFS. Genetic gain increased with increased nucleus population size up to 15 % and thereafter, it declines in both CS and GS schemes with optimal nucleus size ranging between 14 % and 16 %. In conclusion, the current study demonstrated that adoption of reproductive technologies such as AI would optimize response to selection in dairy goat breeding programs in the tropics. The response to selection in such breeding programmes could be maximized in combination with genomic selection.

Developing Climate-Resilient, Direct-Seeded, Adapted Multiple-Stress-Tolerant Rice Applying Genomics-Assisted Breeding.

There is an urgent need to breed dry direct-seeded adapted rice varieties in order to address the emerging scenario of water–labor shortage. The aim of this study was to develop high-yielding, direct-seeded adapted varieties utilizing biparental to multiparental crosses involving as many as six different parents in conventional breeding programs and 12 parents in genomics-assisted breeding programs. The rigorous single plant selections were followed from the F2 generation onwards utilizing phenotypic selection and quantitative trait locus (QTL)/gene-based/linked markers for tracking the presence of desirable alleles of targeted QTL/genes. In conventional breeding, multiparent lines had significantly higher yields (2,072–6,569 kg ha−1) than the biparental lines (1,493–6,326 kg ha−1). GAB lines derived from multiparent crosses had significantly higher (3,293–6,719 kg ha−1) yields than the multiparent lines from conventional breeding (2,072–6,569 kg ha−1). Eleven promising lines from genomics-assisted breeding carrying 7–11 QTL/genes and eight lines from conventional breeding with grain-yield improvement from 727 to 1,705 kg ha−1 and 68 to 902 kg ha−1, respectively, over the best check were selected. The developed lines may be released as varieties/parental lines to develop better rice varieties for direct-seeded situations or as novel breeding material to study genetic interactions.

Genomic dissection of widely planted soybean cultivars leads to a new breeding strategy of crops in the post-genomic era

Soybeans specially the widely planted cultivars have been dramatically improved in agronomic performance and is well adapted to local planting environments after long-time domestication and breeding. Uncovering the unique genomic features of popular cultivars will help to understand how soybean genomes have been modified through breeding. We re-sequenced 134 soybean cultivars that were released and most widely planted over the last century in China. Phylogenetic analyses established that these cultivars comprise two geographically distinct sub-populations: Northeast China (NE) versus the Huang-Huai-Hai River Valley and South China (HS). A total of 309 selective regions were identified as being impacted by geographical origins. The HS sub-population exhibited higher genetic diversity and linkage disequilibrium decayed more rapidly compared to the NE sub-population. To study the association between phenotypic differences and geographical origins, we recorded the vegetative period under different growing conditions for two years, and found that clustering based on the phenotypic data was closely correlated with cultivar geographical origin. By iteratively calculating accumulated genetic diversity, we established a platform panel of cultivars and have proposed a novel breeding strategy named “Potalaization” for selecting and utilizing the platform cultivars that represent the most genetically diversity and the highest available agronomic performance as the “plateau” for accumulating elite loci and traits, breeding novel widely adapted cultivars, and upgrading breeding technology. In addition to providing new genomic information for the soybean research community, the “Potalaization” strategy that we devised will also be practical for integrating the conventional and molecular breeding programs of crops in the post-genomic era.

Yield estimation of soybean breeding lines under drought stress using unmanned aerial vehicle-based imagery and convolutional neural network

Crop yield is a primary trait to select superior genotypes and evaluate breeding efficiency in breeding programs. Crops with high yield potential are usually selected from numerous breeding lines in multiple years and locations. However, the efficiency of conventional breeding programs is limited by the capacity of field phenotyping, which can be improved by developing high-throughput field phenotyping systems using emerging technologies, including Unmanned Aerial Vehicle (UAV) imagery and deep learning technologies. The goal of this study was to evaluate the performance of a UAV imaging system and convolutional neural network (CNN) in estimating yield of soybean breeding lines. In this study, 972 soybean breeding lines in three maturity groups were planted under rainfed conditions for testing their drought tolerance. Aerial images were taken at the late vegetation (V6), early (R1), and late reproductive (R6-R8) growth stages. Seven image features associated with plant height, canopy colour, and canopy texture were selected to estimate the yield of each breeding line. A mixed CNN model was built to estimate soybean yield by taking the seven image features and two categorical factors, i.e. maturity group and drought tolerance, as predictors. Results show that image features collected at the early and late reproductive growth stages are comparably promising in estimating soybean yield. The prediction model could explain 78% of the measured yield with a root mean square error of 391.0 kg·ha−1 (33.8% to the average yield), indicating that the UAV imagery and deep learning models are promising in estimating yield for soybean breeding purposes.

Application Techniques of Molecular Marker and Achievement of Marker Assisted Selection (MAS) in Three Major Crops Rice, Wheat and Maize

With the discovery of new genetic technology, the researcher focuses on using DNA molecular markers to improve new varieties worldwide. Such as resistance to biotic and abiotic stresses and enhancing quality and quantity at different plant breeding fields. Conventional breeding selection is based on phenotype data selection, time-consuming, and has a high chance of linkage drag. Thus, DNA molecular marker method usage is faster, easy, and not expensive than conventional breeding programs. This review focused on applying molecular markers such as genetic diversity analysis, the genotype of identification and fingerprinting, gene tagging and mapping, QTL analysis, and marker-assisted selection. In another part of this review, we focused on MAS's achievements related to improving agronomic traits, quality traits, and biotic/abiotic stresses for three major cereal crops like Wheat, Rice, and Maize.

Assessment of Tomato Recombinant Lines in Conventional and Organic Farming Systems for Productivity and Fruit Quality Traits

It is estimated that more than 95% of organic agriculture is based on crop cultivars that were bred for the conventional high-input sector. Most selections were made through conventional breeding programs and lack important traits required under organic and low-input conditions. Hybrids are the most common type of cultivars used in tomato because of heterosis. In tomato, continuous selfing enabled homozygosity to exploit favorable additive genes, resulting in the so-called inbred vigor. This paper presented the possibility to express inbred vigor at a level equal to or greater than hybrid vigor in tomato when cultivated under organic low input conditions. The evaluation of the recombinant lines produced through classical reverse breeding from four F1 single cross hybrids was done at low- and high-input farming systems. The results show that, following the appropriate breeding process in early generation selection and under low-input conditions, it is possible to produce recombinant lines, demonstrating inbred vigor in yield potential and fruit quality. These genetic materials can stand as new dynamic cultivars intended for cultivation in organic, low-input, or high-input conditions, depending on their performance in different farming systems at the later stages of evaluation.

Impact of colchicine on leaf morphology and stomatics of Kalanchoe tubiflora (Harv.) Raym.-Hamet (Crassulaceae)

The demand of medicinal plants for consumption is greatly increasing worldwide. The conventional breeding programs are generally dependent on the environment prone to biotic and abiotic stresses. These added to the low content of secondary metabolites at harvest, bring the need for artificial development of polyploid individuals as an alternative to increase productivity. Consequently, the present study evaluated the effect of different colchicine concentrations and exposure time, on Kalanchoe tubiflora leaf morphology and stomata. Initially, K. tubiflora seedlings were harvested and submitted to colchicine concentrations of 0, 0.025, 0.05 and 0.1 % and at two exposure times (24 and 48 hours). Subsequently, morphological measurements such as plant height, leaf width, leaves number, leaf length, leaf thickness and leaf volume every 15 days were made for 16 weeks after planting. Then, the stomata were characterized, taking into account the width, length, stomatal index and the number of chloroplasts per stoma. A significant increase in leaf morphology was found in colchicine treatments of 0.025 % at 48 h and 0.1 % at 24 h. A significant increase in stomatal morphology with the treatment of 0.025 % at 24 h was also recorded. This shows that the correct application of colchicine in term of quantity and time could produce greater growth in a short period and increase the biomass of K. tubiflora medicinal plant.

Development of Shading Tolerant Rice Varieties Suitable for Intercropping Cultivation in Agroforestry Systems

The Indonesian government continuously strives to increase rice production in an effort to meet the staple food needs of almost 270 million people and to turn Indonesia to become a rice exporter country. One of the strategic efforts is to expand the planted area of rice outside irrigated rice areas. Upland is one of the potential areas that continues to be developed to support the increase of national rice production. While upland is not an ideal ecosystem for rice plants to grow, the opportunity to produce rice in this ecosystem is promising, especially using rice as an intercropping in plantation. This effort requires the availability of adaptive varieties to low light intensity conditions. The breeding program to develop shade-tolerant rice varieties has been carried out by the Indonesian Center for Rice Research (ICRR) through the conventional breeding program. Breeding populations were produced by crossing local varieties, national leading varieties and introduced varieties. The selection of shading adaptive lines was carried out using both artificial shading and natural shading in the target plantation areas. New shade tolerant rice varieties have been recently released, namely Rindang 1 Agritan and Rindang 2 Agritan which have the potential to be utilized by farmers for intercropping rice cultivation in the agroforestry systems.

In Vitro Anther Culture for Doubled Haploid Plant Production in Spelt Wheat.

Doubled haploid (DH) plant production belongs to modern biotechnology methods of plant breeding. The main advantage of DH plant production methods is the development of genetically homozygous lines in one generation, whilst in conventional breeding programmes, the development of homozygous lines requires more generations. The present chapter describes an efficient protocol for DH plant production in spelt wheat genotypes using in vitro anther culture.

The Toolbox for Fiber Flax Breeding: A Pipeline From Gene Expression to Fiber Quality.

The goal of any plant breeding program is to improve quality of a target crop. Crop quality is a comprehensive feature largely determined by biological background. To improve the quality parameters of crops grown for the production of fiber, a functional approach was used to search for genes suitable for the effective manipulation of technical fiber quality. A key step was to identify genes with tissue and stage-specific pattern of expression in the developing fibers. In the current study, we investigated the relationship between gene expression evaluated in bast fibers of developing flax plants and the quality parameters of technical fibers measured after plant harvesting. Based on previously published transcriptomic data, two sets of genes that are upregulated in fibers during intrusive growth and tertiary cell wall deposition were selected. The expression level of the selected genes and fiber quality parameters were measured in fiber flax, linseed (oil flax) cultivars, and wild species that differ in type of yield and fiber quality parameters. Based on gene expression data, linear regression models for technical stem length, fiber tensile strength, and fiber flexibility were constructed, resulting in the identification of genes that have high potential for manipulating fiber quality. Chromosomal localization and single nucleotide polymorphism distribution in the selected genes were characterized for the efficacy of their use in conventional breeding and genome editing programs. Transcriptome-based selection is a highly targeted functional approach that could be used during the development of new cultivars of various crops.

Transgenic Approaches in Groundnut (Arachis hypogaea L.)

Groundnut (Arachis hypogaea L.) is one of the primary oilseed crops that has a rich source of protein. The geocarpic nature of crop growth hinders the overall yield performance of groundnut by several biotic and abiotic stress factors. Several attempts were undertaken to overcome these factors by developing superior varieties, however many of the conventional approaches were unsuccessful. An alternative to this is by biotechnological intervention like transformation of alien genes, either directly or indirectly that ultimately enhances the yield. Several genes were detected, cloned and transformed as major parts of transgenic programmes. Application of modern molecular biological techniques, in designing biotic and abiotic stress tolerant/resistant groundnut varieties that exhibited mechanisms of resistance, relied on the expression of specific genes associated to particular stress. The genetically transformed stress tolerant groundnut varieties could be utilized as donor parents in conventional breeding programmes. The present article emphasizes on the prospects of genetic transformation tools, implemented for the enhancement of groundnut varieties against key biotic and abiotic stress factors.