Biobreeding Open Access

Biobreeding, a Bridge between Fundamental Research and Agricultural Application

Study on the Alleviative Effect of Diethyl Aminoethyl Hexanoate (DA-6) on Pepper Seed Germination under Salt Stress

Diethyl aminoethyl hexanoate (DA-6) is a broad-spectrum high-energy plant growth regulator with multiple functions similar to auxin, gibberellin, and cytokinin. Research on crops such as corn, rice, peanuts, flowers, and vegetables has shown that it can increase the activity of plant peroxidase (POD) and nitrate reductase, promote plant cell division and elongation, and facilitate seed germination and seedling growth. This experiment used the seeds of the chili variety “Changxian Tianxia” as research materials. The experiment was conducted by designing DA-6 soaking experiments with different concentration gradients to determine physiological indicators of pepper growth, screen a suitable DA-6 concentration for pepper seed germination, and study the alleviating effect of DA-6 on pepper seed growth under salt stress. The aim is to provide a scientific basis for high-yield cultivation of chili in saline alkali soil. In the seed germination experiment, five DA-6 concentration treatment groups were set up, namely 0, 0.1 mmol/L, 0.5 mmol/L, 1 mmol/L, and 5 mmol/L. Three biological replicates were set up for each treatment group to screen for the most suitable DA-6 concentration for pepper seed germination. The germination and growth effects of pepper seeds under salt stress were then studied using this concentration. The growth physiological indicators were measured to investigate the alleviating effect of aminobutyric acid on pepper seed germination under salt stress. The experimental results showed that the appropriate concentration of aminobutyric acid ester (DA-6) promoted the germination of pepper seeds under salt stress. Under the treatment of soaking seeds in DA-6 at a concentration of 1 mmol/L, the activities of catalase (CAT) and POD increased by 8.6% and 14.6%, respectively, while inhibiting the accumulation of MDA (reducing it by 11.4%), improving the antioxidant effect of plant cell membranes, and enhancing the salt tolerance of pepper seeds. This experiment shows that soaking pepper seeds in 1 mmol/L DA-6 can effectively improve the antioxidant capacity of pepper seeds under salt stress environment, enhance seed germination rate and growth effect, and alleviate the damage caused by salt stress to pepper seedling growth to a certain extent.

Fast Backcross Breeding for Climate-Resilient Cereals: Integrating Speed Breeding, Marker-Assisted Backcrossing and Genomic Selection

Abiotic stresses, including drought, heat, salinity, waterlogging, and acidic soils, are increasingly inhibiting the consistency of global food production, valued at USD 3.26 trillion during the last three decades. Although backcrossing efficiently transfers large-effect loci into elite backgrounds, conventional pipelines remain slow and vulnerable to linkage drag and unreliable genotype-to-phenotype translation. Here, we synthesize an operational fast backcross (FB) breeding framework that integrates (i) rapid generation advance (speed breeding), (ii) embryo culture to shorten generation intervals and unlock wide crosses, (iii) marker-assisted backcrossing with coordinated foreground, recombinant, and genome-wide background selection, and (iv) genomic selection to capture residual polygenic adaptation. We propose practical approaches to prioritize stress-adaptive loci and to validate yield and quality neutrality under non-stress conditions before pyramiding. Case studies in rice (SUB1, Saltol, Pup1 and DRO1), wheat (Nax1/Nax2) and barley (aerenchyma formation and HvAACT1 loci) illustrate how FB pipelines can compress variety development timelines from 8–10 years to 3–5 years while maintaining farmer-preferred agronomic and end-use traits; however, they also underscore the constraints of relying on whole-plant phenotyping alone. We show that FB succeeds only when early locus prioritisation, recombinant selection to minimise linkage drag, and pre-pyramiding neutrality testing are enforced, explaining why many accelerated pipelines underperform despite advanced genotyping tools. Further, we propose AI-enabled selection and targeted editing to scale FB breeding for climate-resilient agriculture.

Three New Synthetic Algal Culture Media to Grow Them All ^†

Three new synthetic algal culture media are described that have been used to cultivate ~12,000 diverse strains of (micro)algae, one culture medium for marine and brackish-water algae (ASP-MEL (Artificial Seawater Provasoli-MELKONIAN)), and two culture media for freshwater/terrestrial algae (SFM (Synthetic Freshwater Medium) and W-MEL (Waris-MELKONIAN)). The genesis of the three media since their original formulation and the rationale for modifications of these media over the past 50 years are outlined. A complex trace element mix derived from an enriched natural seawater culture medium (L1) is used in all three media, and allows the omission of soil water extract from one freshwater culture medium (W-MEL). It is suggested that the inclusion of selenite renders soil extract in algal culture media superfluous. Prospects and limitations of the three synthetic algal culture media as general-purpose media for large collections are discussed.

In Vitro Bulb‑Scale Propagation of Lilium leichtlinii var. maximowiczii for Urban Landscaping

This study was conducted to establish an efficient in vitro mass-propagation system for the Korean native bulbous plant Lilium leichtlinii var. maximowiczii and to lay the foundation for supplying the produced bulbs for use in flowerbeds. Although this species is a promising native bulbous lily for urban flowerbeds, its use has been limited by the lack of an efficient system for large-scale propagation. L. leichtlinii var. maximowiczii is distributed in the northern part of Gyeonggi-do, Gangwon-do, and the eastern region of Gyeongsangbuk-do in South Korea, and is a native lily species with very high ornamental value. Among the tested disinfection protocols, a 0.1% (w/v) benomyl solution pretreatment for 1 h, followed by 70% (v/v) ethanol (EtOH) for 30 s and sequential surface sterilization in 1% (v/v) sodium hypochlorite (NaOCl) for 20 min and 2% (v/v) NaOCl for 10 min, was the most effective for in vitro introduction of bulb scales. As a result of bulblet induction using combinations of plant growth regulators, the medium containing 2.2 µM BAP + 5.7 µM IAA produced the highest number of bulblets (2.5 ± 0.12 per survived explant; total 38), followed by 4.4 µM BAP + 2.7 µM NAA (2.0 ± 0.00 per survived explant; total 24). Following a total culture period consisting of introduction (3 weeks), formation (3 weeks), and expansion (7 weeks), the regenerated plantlets were acclimatized for 1 week without mortality. These results revealed distinct roles for different plant growth regulators (PGRs) combinations in the regeneration process. The medium supplemented with BAP + IAA was optimal for initial bulblet induction, yielding the highest proliferation efficiency. The in vitro propagation technique established in this study is expected to provide a practical technical basis for the nursery production of uniform L. leichtlinii var. maximowiczii plantlets and to promote their wider use as native flowerbed plants.

Validation of Thymidylate Synthase as a Key Gene Inhibiting WSSV Proliferation in Procambarus clarkii

White spot syndrome virus (WSSV) is a highly pathogenic agent that poses a significant constraint on the sustainable aquaculture of the red swamp crayfish (P. clarkii). Thymidylate synthase (TS) and ribonucleotide reductase (RR), two genes involved in viral DNA replication, are potential targets for RNAi-based control, but their functional validation and low-cost use remain limited. Bioinformatics analysis revealed that WSSV TS differs evolutionarily from crustacean TS but shares 64% homology with P. clarkii TS, suggesting potential virus-host substrate competition. In vitro-synthesized dsRNA-TS and dsRNA-RR both significantly suppressed WSSV replication in infected P. clarkii. TS was selected for further study due to its evolutionary profile and potential compatibility with molecular breeding approaches. The dsRNA-TS injection eliminated detectable virus within 3 days and reduced cumulative mortality by 10%. Under simulated transport stress conditions, dsRNA-TS did not enhance survival rates, likely due to immunosuppressive effects; however, it sustained the suppression of WSSV replication from 7 to 14 days post-infection. The dsRNA-TS expressed in Escherichia coli HT115 (DE3) had no significant effect, probably because of low purity, low concentration, and poor delivery. The findings provide a sustainable biological control strategy against WSSV in P. clarkii aquaculture, and lay the foundation for the optimization of prokaryotic dsRNA production systems as well as the integration of RNAi with molecular breeding techniques.

Progress and Prospects in Breeding Research on Key Aromatic Species of the Lamiaceae Family

Aromatic herbs of the family Lamiaceae are mainly represented by several economically important genera in the subfamily Nepetoideae, including Mentha, Ocimum, Origanum, Rosmarinus, Thymus, Lavandula, and Perilla. These plants originated mainly in the Mediterranean region, Southwest Asia, and tropical America, and are now widely distributed throughout Europe, Asia, Africa, and the Americas. This paper systematically reviews the global history of breeding within this taxonomic group of, key aromatic genera of Lamiaceae synthesizes the patterns of its utilization and dissemination, and divides its development and evolution into four key phases: The first phase is the pre-breeding stage (before 1000 BCE), driven primarily by basic human survival needs, during which wild resources were utilized directly without the development of artificial cultivation or directed selection; The second stage is the early introduction and preliminary domestication stage (1000–500 BCE), during which the expansion of ancient trade facilitated the cross-regional dissemination of species, and the domestication of germplasm began through simple phenotypic selection under artificial cultivation; The third phase is the conventional breeding stage, from 500 BCE to the late 20th century, which was driven by increasing commercial demand. During this period, clonal selection, phenotypic selection, and hybridization were gradually developed and widely applied, enabling the stable retention of desirable traits and the formation of diverse regionally distinctive local germplasm. The fourth phase is the modern molecular breeding stage, from the 21st century to the present, which has developed alongside scientific and technological advances. This stage includes molecular breeding strategies based on genome sequencing, identification of genes associated with essential oil biosynthesis and stress tolerance, and marker-assisted selection. However, despite significant progress in the breeding of these key aromatic plant genera of Lamiaceae, the commercialization process still faces multiple bottlenecks: low genetic conversion efficiency in most species, scarcity of genomic resources for niche groups, lengthy traditional breeding cycles, and the lack of a comprehensive germplasm evaluation system, as well as the fragmentation of phenotype-genotype association databases. Future research priorities include: (1) establishing a globally standardized database of Lamiaceae aromatic germplasm resources; (2) integrating multi-omics approaches, including transcriptomics, metabolomics, and proteomics, to elucidate the genetic regulatory networks underlying essential oil biosynthesis and stress resistance; and (3) optimizing gene-editing and genetic transformation protocols for both major and underutilized aromatic Lamiaceae species. This review provides a historical and theoretical framework for the genetic improvement, germplasm utilization, and industrial development of key aromatic genera of Lamiaceae.

Biobreeding, a Bridge between Fundamental Research and Agricultural Application

Progress and Prospects in Breeding Research on Key Aromatic Species of the Lamiaceae Family

Aromatic herbs of the family Lamiaceae are mainly represented by several economically important genera in the subfamily Nepetoideae, including Mentha, Ocimum, Origanum, Rosmarinus, Thymus, Lavandula, and Perilla. These plants originated mainly in the Mediterranean region, Southwest Asia, and tropical America, and are now widely distributed throughout Europe, Asia, Africa, and the Americas. This paper systematically reviews the global history of breeding within this taxonomic group of, key aromatic genera of Lamiaceae synthesizes the patterns of its utilization and dissemination, and divides its development and evolution into four key phases: The first phase is the pre-breeding stage (before 1000 BCE), driven primarily by basic human survival needs, during which wild resources were utilized directly without the development of artificial cultivation or directed selection; The second stage is the early introduction and preliminary domestication stage (1000–500 BCE), during which the expansion of ancient trade facilitated the cross-regional dissemination of species, and the domestication of germplasm began through simple phenotypic selection under artificial cultivation; The third phase is the conventional breeding stage, from 500 BCE to the late 20th century, which was driven by increasing commercial demand. During this period, clonal selection, phenotypic selection, and hybridization were gradually developed and widely applied, enabling the stable retention of desirable traits and the formation of diverse regionally distinctive local germplasm. The fourth phase is the modern molecular breeding stage, from the 21st century to the present, which has developed alongside scientific and technological advances. This stage includes molecular breeding strategies based on genome sequencing, identification of genes associated with essential oil biosynthesis and stress tolerance, and marker-assisted selection. However, despite significant progress in the breeding of these key aromatic plant genera of Lamiaceae, the commercialization process still faces multiple bottlenecks: low genetic conversion efficiency in most species, scarcity of genomic resources for niche groups, lengthy traditional breeding cycles, and the lack of a comprehensive germplasm evaluation system, as well as the fragmentation of phenotype-genotype association databases. Future research priorities include: (1) establishing a globally standardized database of Lamiaceae aromatic germplasm resources; (2) integrating multi-omics approaches, including transcriptomics, metabolomics, and proteomics, to elucidate the genetic regulatory networks underlying essential oil biosynthesis and stress resistance; and (3) optimizing gene-editing and genetic transformation protocols for both major and underutilized aromatic Lamiaceae species. This review provides a historical and theoretical framework for the genetic improvement, germplasm utilization, and industrial development of key aromatic genera of Lamiaceae.utf-8

Study on the Alleviative Effect of Diethyl Aminoethyl Hexanoate (DA-6) on Pepper Seed Germination under Salt Stress

Diethyl aminoethyl hexanoate (DA-6) is a broad-spectrum high-energy plant growth regulator with multiple functions similar to auxin, gibberellin, and cytokinin. Research on crops such as corn, rice, peanuts, flowers, and vegetables has shown that it can increase the activity of plant peroxidase (POD) and nitrate reductase, promote plant cell division and elongation, and facilitate seed germination and seedling growth. This experiment used the seeds of the chili variety “Changxian Tianxia” as research materials. The experiment was conducted by designing DA-6 soaking experiments with different concentration gradients to determine physiological indicators of pepper growth, screen a suitable DA-6 concentration for pepper seed germination, and study the alleviating effect of DA-6 on pepper seed growth under salt stress. The aim is to provide a scientific basis for high-yield cultivation of chili in saline alkali soil. In the seed germination experiment, five DA-6 concentration treatment groups were set up, namely 0, 0.1 mmol/L, 0.5 mmol/L, 1 mmol/L, and 5 mmol/L. Three biological replicates were set up for each treatment group to screen for the most suitable DA-6 concentration for pepper seed germination. The germination and growth effects of pepper seeds under salt stress were then studied using this concentration. The growth physiological indicators were measured to investigate the alleviating effect of aminobutyric acid on pepper seed germination under salt stress. The experimental results showed that the appropriate concentration of aminobutyric acid ester (DA-6) promoted the germination of pepper seeds under salt stress. Under the treatment of soaking seeds in DA-6 at a concentration of 1 mmol/L, the activities of catalase (CAT) and POD increased by 8.6% and 14.6%, respectively, while inhibiting the accumulation of MDA (reducing it by 11.4%), improving the antioxidant effect of plant cell membranes, and enhancing the salt tolerance of pepper seeds. This experiment shows that soaking pepper seeds in 1 mmol/L DA-6 can effectively improve the antioxidant capacity of pepper seeds under salt stress environment, enhance seed germination rate and growth effect, and alleviate the damage caused by salt stress to pepper seedling growth to a certain extent.utf-8

Fast Backcross Breeding for Climate-Resilient Cereals: Integrating Speed Breeding, Marker-Assisted Backcrossing and Genomic Selection

Abiotic stresses, including drought, heat, salinity, waterlogging, and acidic soils, are increasingly inhibiting the consistency of global food production, valued at USD 3.26 trillion during the last three decades. Although backcrossing efficiently transfers large-effect loci into elite backgrounds, conventional pipelines remain slow and vulnerable to linkage drag and unreliable genotype-to-phenotype translation. Here, we synthesize an operational fast backcross (FB) breeding framework that integrates (i) rapid generation advance (speed breeding), (ii) embryo culture to shorten generation intervals and unlock wide crosses, (iii) marker-assisted backcrossing with coordinated foreground, recombinant, and genome-wide background selection, and (iv) genomic selection to capture residual polygenic adaptation. We propose practical approaches to prioritize stress-adaptive loci and to validate yield and quality neutrality under non-stress conditions before pyramiding. Case studies in rice (SUB1, Saltol, Pup1 and DRO1), wheat (Nax1/Nax2) and barley (aerenchyma formation and HvAACT1 loci) illustrate how FB pipelines can compress variety development timelines from 8–10 years to 3–5 years while maintaining farmer-preferred agronomic and end-use traits; however, they also underscore the constraints of relying on whole-plant phenotyping alone. We show that FB succeeds only when early locus prioritisation, recombinant selection to minimise linkage drag, and pre-pyramiding neutrality testing are enforced, explaining why many accelerated pipelines underperform despite advanced genotyping tools. Further, we propose AI-enabled selection and targeted editing to scale FB breeding for climate-resilient agriculture.utf-8

In Vitro Bulb‑Scale Propagation of Lilium leichtlinii var. maximowiczii for Urban Landscaping

This study was conducted to establish an efficient in vitro mass-propagation system for the Korean native bulbous plant Lilium leichtlinii var. maximowiczii and to lay the foundation for supplying the produced bulbs for use in flowerbeds. Although this species is a promising native bulbous lily for urban flowerbeds, its use has been limited by the lack of an efficient system for large-scale propagation. L. leichtlinii var. maximowiczii is distributed in the northern part of Gyeonggi-do, Gangwon-do, and the eastern region of Gyeongsangbuk-do in South Korea, and is a native lily species with very high ornamental value. Among the tested disinfection protocols, a 0.1% (w/v) benomyl solution pretreatment for 1 h, followed by 70% (v/v) ethanol (EtOH) for 30 s and sequential surface sterilization in 1% (v/v) sodium hypochlorite (NaOCl) for 20 min and 2% (v/v) NaOCl for 10 min, was the most effective for in vitro introduction of bulb scales. As a result of bulblet induction using combinations of plant growth regulators, the medium containing 2.2 µM BAP + 5.7 µM IAA produced the highest number of bulblets (2.5 ± 0.12 per survived explant; total 38), followed by 4.4 µM BAP + 2.7 µM NAA (2.0 ± 0.00 per survived explant; total 24). Following a total culture period consisting of introduction (3 weeks), formation (3 weeks), and expansion (7 weeks), the regenerated plantlets were acclimatized for 1 week without mortality. These results revealed distinct roles for different plant growth regulators (PGRs) combinations in the regeneration process. The medium supplemented with BAP + IAA was optimal for initial bulblet induction, yielding the highest proliferation efficiency. The in vitro propagation technique established in this study is expected to provide a practical technical basis for the nursery production of uniform L. leichtlinii var. maximowiczii plantlets and to promote their wider use as native flowerbed plants.utf-8

Three New Synthetic Algal Culture Media to Grow Them All ^†

Three new synthetic algal culture media are described that have been used to cultivate ~12,000 diverse strains of (micro)algae, one culture medium for marine and brackish-water algae (ASP-MEL (Artificial Seawater Provasoli-MELKONIAN)), and two culture media for freshwater/terrestrial algae (SFM (Synthetic Freshwater Medium) and W-MEL (Waris-MELKONIAN)). The genesis of the three media since their original formulation and the rationale for modifications of these media over the past 50 years are outlined. A complex trace element mix derived from an enriched natural seawater culture medium (L1) is used in all three media, and allows the omission of soil water extract from one freshwater culture medium (W-MEL). It is suggested that the inclusion of selenite renders soil extract in algal culture media superfluous. Prospects and limitations of the three synthetic algal culture media as general-purpose media for large collections are discussed.utf-8

Validation of Thymidylate Synthase as a Key Gene Inhibiting WSSV Proliferation in Procambarus clarkii

White spot syndrome virus (WSSV) is a highly pathogenic agent that poses a significant constraint on the sustainable aquaculture of the red swamp crayfish (P. clarkii). Thymidylate synthase (TS) and ribonucleotide reductase (RR), two genes involved in viral DNA replication, are potential targets for RNAi-based control, but their functional validation and low-cost use remain limited. Bioinformatics analysis revealed that WSSV TS differs evolutionarily from crustacean TS but shares 64% homology with P. clarkii TS, suggesting potential virus-host substrate competition. In vitro-synthesized dsRNA-TS and dsRNA-RR both significantly suppressed WSSV replication in infected P. clarkii. TS was selected for further study due to its evolutionary profile and potential compatibility with molecular breeding approaches. The dsRNA-TS injection eliminated detectable virus within 3 days and reduced cumulative mortality by 10%. Under simulated transport stress conditions, dsRNA-TS did not enhance survival rates, likely due to immunosuppressive effects; however, it sustained the suppression of WSSV replication from 7 to 14 days post-infection. The dsRNA-TS expressed in Escherichia coli HT115 (DE3) had no significant effect, probably because of low purity, low concentration, and poor delivery. The findings provide a sustainable biological control strategy against WSSV in P. clarkii aquaculture, and lay the foundation for the optimization of prokaryotic dsRNA production systems as well as the integration of RNAi with molecular breeding techniques.utf-8