Broad Genetic Base Research Articles

Peculiarities of the genetic nature of CMS lines of Beta vulgaris L. and the nature of adaptability to biotic and abiotic factors

Purpose. Study of the genetic nature of CMS lines as female components in the hybridization process; selection of the best breeding genotypes with high adaptive potential; establishment of the productivity of the obtained monogerm triploid hybrids on a sterile basis. Methods. The original forms were breeding genotypes from the collection of Verkhniaky Experimental Breeding Station: monogerm SM and CMS lines, obtained through individual selections from recombinant forms of foreign germplasm and aboriginal SM. Modern selection methods were used, specifically recombination, hybridization, and selection. Saturation, analysis and top crossings were carried out. Breeding genotypes were tested according to generally accepted methods. Results. According to the results of long-term research, the possibility of development of breeding lines from the cleavage products of foreign hybrids has been established. Based on the application of modern breeding methods, promising materials with a significant share of valuable genotypes with high adaptive potential and a broad genetic base were developed and selected. Using donors of recombinant initial forms, new CMS lines were developed, which, even under stressful environmental conditions, demonstrate high performance indicators when crossed with multi-germ pollinators of different genetic origin. Conclusions. The selection of the best CMS lines was carried out by the combination value and tolerance to biotic and abiotic factors. In the framework of research, with the aim of obtaining a higher effect of heterosis, new hybrids were developed with the use of female hybrid components of the CMS1 line and male multi-germ SM component of different origins. They are characterized by resistance to biotic and abiotic factors in different regions of the country. According to the results of ecological variety testing, experimental hybrids STs280823 and STs280828 with a sugar yield of 104.5 and 113.5% to the standard are recommended for state variety testing.

Estimation of standard heterosis and heterotic grouping of elite sorghum [Sorghum bicolor (L) Moench] inbred lines under moisture stress conditions

The development and selection of appropriate parents are prerequisites for sorghum hybrid variety development. The lack of a broad genetic base is the most significant constraint to sorghum crop improvement. The assignment of sorghum germplasm lines to appropriate heterotic groups is critical for increasing sorghum productivity. The experiment was conducted to determine the amount of standard heterosis and to categorize sorghum inbred lines into distinct heterotic groups. In the 2019 main cropping season, 42 sorghum genotypes were tested using an alpha-lattice design with two replications. Combined analysis of variance showed that there was a highly significant difference (p < 0.01) among the genotypes for all studied traits. The maximum grain yield was obtained from the hybrids 4x14 (6.32 tha-1), followed by the hybrids 8x15 (5.92 tha-1), 1x15 (5.88 tha-1), 13x14 (5.78 tha-1) and 6x15 (5.57 tha-1), with an average value of 5.0 tha-1. Similarly, the 4x14 hybrid exhibited a maximum grain yield with 30.71 % heterosis, which was greater than the standard check (ESH-4) for grain yield. The two heterotic (A and B) groups were identified based on their specific combining ability effects, whereas three heterotic groups were identified based on their general combining ability effects to develop superior hybrids from broad base and suitable parents. Finally, based on yield performance, heterotic response and combining ability estimates for grain yield and its components, the hybrid crosses 4x14, 8x15, 1x15, 11x14, 11x15, 13x14, and 6x15 were found to be the most promising and potential hybrids that could be exploited commercially after critical evaluation for their superiority and yield stability across locations over the years.

Breeding Strategies for Simultaneous Improvement in Anthracnose Disease Resistance and Economically Important Traits in French Bean

Background: French bean (Phaseolus vulgaris L.) production in the tropics is threatened by heavy incidence of anthracnose disease causing substantial crop loss when infection is at the early growth stages. Breeding strategies for tolerance against anthracnose disease along with enhanced productivity, and high pod protein content are to be formulated. Methods: Genotypes having broad genetic base and phenotypic diversity in 5 bush and 1 pole types were crossed in a 6 × 6 half diallel mating design to estimate combining ability, mode of gene action, and extent of heterosis for 11 quantitative traits. Result: The additive genetic effect was evident for percent disease index (PDI) of anthracnose and 10 pod weight. Rapid genetic gain can be achieved due to predominance of additive gene action in their control and can therefore be selected in early generation through simple breeding methods. Rest of the economic traits controlled by additive and non-additive gene effects could be improved through biparental mating, reciprocal recurrent selection, or diallel selective mating. Anthracnose disease tolerant and high yielding cultivars of might be developed utilizing parents, ‘Laxmi’, ‘Arka Sharath’ and ‘Vaishnavi-264’ with high gca effects. Although two cross combinations ‘Arka Sharath × Lakshmi’ and ‘Arjun × Arka Sharath’ showed significant heterobeltiosis in desired direction for PDI of anthracnose and other desirable horticultural traits but could not be exploited at commercial level due to complexity in hybridization. Identifying pure lines with tolerance against anthracnose disease and favorable horticultural attributes could be accomplished in segregating generations of the prospective hybrids.

Phenotypic variability in the US upland cotton core set for root traits and water use efficiency at the late reproductive stage

AbstractTo incorporate root traits that improve water use efficiency (WUE) in cotton (Gossypium hirsutum L.) variety development, harnessing the genetic variability for root traits is essential. The objectives of this study were to characterize the US upland cotton core set for root traits and WUE and determine the traits associated with WUE. The core set includes 23 of the 381 accessions of the cotton diversity panel and represents 74% of the allelic diversity in US upland cotton. Plants were grown in polyvinyl chloride columns (125‐cm height, 15‐cm diameter) in a greenhouse in 2021–2022 and 2022–2023. Half of the columns contained a synthetic hardpan (1 cm thickness, 300 PSI penetration resistance) at a depth of 25 cm. Plants were harvested when &gt;50% of the population opened bolls. Based on 16 root‐ and shoot‐traits, water use, and WUE, Deltapine 14, Station Miller, and Southland M1 were the best performers, and Toole, Paymaster HS200, Western Stormproof, CD3HCABCUH‐1‐89, and PD 2164 were the poor performers irrespective of the presence or absence of hardpan stress to root growth. The WUE of the core set genotypes was positively correlated with very fine root (diameter &lt;0.25 mm) length, surface area, and volume and total root weight (correlation coefficient ≥0.45). These traits serve as beneficial root traits for developing new varieties with enhanced WUE. The identified genotypes and traits will be valuable for developing the next generation of water‐use‐efficient cotton varieties with a broad genetic base through advanced breeding techniques involving genomic tools and genetic diversity.

Enhancing stress resilience in rice (Oryza sativa L.) through profiling early-stage morpho-physiological and molecular responses to multiple abiotic stress tolerance.

Under changing climatic conditions, crop plants are more adversely affected by a combination of various abiotic stresses than by a single abiotic stress. Therefore, it is essential to identify potential donors to multiple abiotic stresses for developing climate-resilient crop varieties. Hence, the present study was undertaken with 41 germplasm accessions comprising native landraces of Tamil Nadu, Prerelease lines and cultivars were screened independently for drought, salinity, and submergence at the seedling stage during Kharif and Rabi 2022-2023. Stress was imposed separately for these three abiotic stresses on 21-day-old seedlings and was maintained for 10 days. The studied genotypes showed a significant reduction in plant biomass (PB), Relative Growth Index (RGI), relative water content (RWC), leaf photosynthesis, chlorophyll fluorescence, and Chlorophyll Concentration Index (CCI) under drought followed by salinity and submergence. Stress-tolerant indices for drought, salinity, and submergence revealed significant variation for plant biomass. Furthermore, a set of 30 SSR markers linked to drought, salinity, and submergence QTLs has been used to characterize 41 rice germplasm accessions. Our analysis suggests a significantly high polymorphism, with 28 polymorphic markers having a 93.40% in 76 loci. The mean values of polymorphic information content (PIC), heterozygosity index (HI), marker index (MI), and resolving power (RP) were 0.369, 0.433, 1.140, and 2.877, respectively. Jaccard clustering grouped all the genotypes into two major and six subclusters. According to STRUCTURE analysis, all genotypes were grouped into two major clusters, which are concurrent with a very broad genetic base (K = 2). Statistically significant marker-trait associations for biomass were observed for five polymorphic markers, viz., RM211, RM212 (drought), RM10694 (salinity), RM219, and RM21 (submergence). Similarly, significant markers for relative shoot length were observed for RM551 (drought), RM10694 (salinity), and ART5 (submergence). Notably, the genotypes Mattaikar, Varigarudan samba, Arupatham samba, and APD19002 were identified as potential donors for multiple abiotic stress tolerance. Thus, identifying the genetic potential of germplasm could be useful for enhancing stress resilience in rice.

Assessing Genetic Diversity in Bread Wheat (Triticum aestivum L.) using D2 Statistical Analysis

Background: Genetic diversity is one of the potent components used to develop improved cultivars with a broad genetic base and wider adaptability. Genetic diversity between two parents of diverse origin generally displays greater heterosis and yields transgressive segregants. Therefore, knowledge of genetic diversity is the prerequisite for the genetic improvement of crop plants including wheat. D2 statistical analysis is one of the potent biometrical techniques used for the assessment of genetic diversity. Methods: The essence of the current experiment involved 40 providential bread wheat lines that were arranged and laid down in a randomized block design (RBD) with three replications at the experimental research farm of Suresh Gyan Vihar University, Jagatpura, Jaipur, during the rabi crop season (2020-21). The bread wheat lines of the same geographical range were assessed to determine the genetic diversity using D2 statistical analysis and heritability estimate in apropos to ten quantitative/qualitative characters. Result: Based on D2 analysis, the 40 promising wheat strains were lined up into ten different clusters to estimate the average distance at intra and inter-cluster levels. The uttermost intra-cluster distance was recorded in cluster X, whereas, the appreciative inter-cluster distance pertained among cluster-VI and cluster-X pursued by cluster-IX and cluster-X. Entrenched to the mean or average performance, most of the bread wheat lines were spotted to disclose appreciable distinctions concerning to their cluster means. It was perceived that the maximum percent contribution towards total divergence was exhibited by grain yield plant-1, followed by spike length, effective tiller plant-1, 1000 grain weight and plant height. Moreover, the number of effective tillers plant-1, spike length, harvest index ,1000 grain weight, number of grains spike-1 and protein content were quite substantial since these traits exhibit high heritability estimate together with high genetic advance as percent of mean.

THE STRUCTURE OF THE WORLD COLLECTION OF WINTER SOFT WHEAT IN TERMS OF DISEASE RESISTANCE IN THE SOUTHERN FOREST-STEPPE OF UKRAINE

To prevent crop losses from pathogens, new varieties with a broad genetic basis of group resistance should be introduced into the production process. The purpose of research was to describe the collection of soft winter wheat in terms of resistance to the most common diseases in the conditions of the southern forest-steppe of ukraine. 1406 samples of soft winter wheat (Triticum aestivum L.) From 33 countries were taken for research. The significant influence of the amount of precipitation and the level of hydrothermal coefficient (HTC) on the indicator of the number of susceptible samples of wheat to specific pathogens of soft winter wheat was established. Selection work has significantly influenced the creation of more stable varieties in recent years compared to the 70's of the twentieth century. The method of remote hybridization using foreign genes helps to obtain lines more resistant to specific pathogens of soft winter wheat. Creating a special collection of samples resistant to the most common diseases of soft winter wheat allows you to systematize the selection of parental lines on specific grounds.

Prebreeding and genetic enhancement of cultivated sunflower (Helianthus annuusL.) using diploid wild Helianthus species in India

Pre-breeding activities using promising diploid wild Helianthus like Helianthus annuus (wild), H. argophyllus, H. praecox, H. debilis and H. petiolaris and popular cultivar (ARM-243B) have been initiated at ICAR Indian Institute of Oilseeds Research, Rajendranagar, Hyderabad to increase the frequency of desirable genes, wider adaptability and a broad genetic base. Wider variability was observed for yield and yield contributing traits besides disease reactions within and between species. Evaluation of a few populations for biotic stresses and yield related traits resulted in the identification of desirable introgression lines. The highest seed yield (42.5 g/plant) was reported in combinations with H. annuus (wild), H. petiolaris (40.2 g/plant) and H. debilis (39.8 g/plant). Interspecificderivatives derived from H. praecox were found resistant to powdery mildew. Interspecific derivatives of H. argophyllus, namely PB-1001, PB-1003, PB-1005, PB-1007, PB-1008, PB-1014, and PB-1019 were resistant to leafhoppers, while PB-1003, PB-1005, and PB-1007 exhibited resistant reactions to downy mildew under sick plot conditions. H. debilis derivatives viz., PB-120, PB-127, PB-128, PB-129 and PB-130 recorded &gt;40% oil content. The pre-breeding lines derived from these interspecific cross combinations serve as an invaluable reservoir of genes for carrying out basic studies on the key traits as well as the exploitation of agronomically desirable traits in the AICRP sunflower breeding programmes.

Development of trait-specific genetic stocks derived from wild Cicer species as novel sources of resistance to important diseases for chickpea improvement

AbstractLow level of resistance to major diseases such as ascochyta blight (AB), botrytis grey mould (BGM) and dry root rot (DRR) in the cultivated chickpea genepool necessitates harnessing wild Cicer species. Sixty-eight accessions belonging to eight annual wild Cicer species and seven chickpea cultivars were screened for AB, BGM and DRR under controlled environmental conditions over the years. Intra-accession variability was observed among wild Cicer accessions for each disease. Hence, progenies of single resistant plants were selected for further evaluations and the trait-specific genetic stocks (TGS) were developed for each disease after re-screening following the single seed descent method. For AB, a high level of resistance was identified in four accessions belonging to tertiary genepool species, ICC 17334 (Cicer judaicum), ICC 17302, ICC 17308 and ICC 20177 (C. bijugum). Nine accessions, ICC 17160, ICC 17264, ICC 17270, ICC 20170, ICC 20186, ICC 20225, ICC 20247, ICC 20251 and IG 72941 of primary (C. reticulatum) and one accession, ICC 20190 of secondary (C. echinospermum) genepool species were resistant to BGM whereas, four accessions, ICC 20187 (C. reticulatum) and ICC 20218, ICC 20244 and ICC 20257 (C. echinospermum) were resistant to DRR. Development and utilization of these TGS in chickpea pre-breeding will assist in developing disease-resistant chickpea cultivars with broad genetic base.

Genetic variability of Tachigali vulgaris trees based on seed morphophysiological traits

Tachigali vulgaris is a tree with high potential for energy purposes in Brazil. However, there is little information about genetic variability that can be applied to plant breeding. Here, we quantified genetic variability based on biometric and emergence traits of T. vulgaris seeds from the native population of the Brazilian Amazon. The biometric aspects, moisture content, emergence, emergence speed index, and average emergence time of the seeds were evaluated. Genotypic values and genetic parameters were analysed using the mixed model methodology in a completely randomised design with 12 genotypes and four replications of 25 seeds. All biometric and emergence traits of seeds showed phenotypic and genetic variabilities. Heritability was high for all traits evaluated (0.66 to 0.97), and genetic accuracy showed high experimental precision and reliable results (≥ 0.90). Grouping by the Tocher, unweighted pair group with arithmetic mean and principal component analysis methods based on genetic traits returned four groups: Group 1 by Genotypes 1, 4, 5, 6, 7, 8, 9, 10 and 12; Group 2 by Genotype 3; Group 3 by Genotype 2; and Group 4 by Genotype 11. In addition, Genotypes 1, 3–10 and 12 displayed seeds with superior physical and physiological traits and a high probability of genetic gain. Our findings can be used in the selection and marking of trees with a broad genetic base for seed production and plant breeding of this species.

Lessons from insect and disease impacts on radiata pine (Pinus radiataD. Don) plantations in New Zealand over the last hundred years

The imp acts of past and potential insect pests and diseases in New Zealand's radiata pine plantations are reviewed. Invariably their impacts have decreased with time or can be easily managed. Despite past biotic impacts. growth rates have increased over the last 100 years. Pitch pine canker (PPC) is perceived as the greatest new threat. PPC's impact in California, Spain, Portugal, South Africa and Chile suggests that in New Zealand it would become a nursery problem. Radiata pine remains the best medium-density softwood for New Zealand although climate change may alter the site limits. While a biotic catastrophe, despite its low probability, remains an important risk, this risk is outweighed by the opportunity costs and risks associated with diversifying into alternative species. A strong biosecurity infrastructure is vital, as is maintaining a broad genetic base from which to breed resistance. Large plantation estates should develop defensive strategies against new biotic invasions.

MAGIC Populations Improved Traits and Provided Different Accomplishments

Plant breeding is a crucial aspect while ensuring food security by applying updated techniques and utilizing available resources to the fullest extent possible. For instance, the development of the Multi-parent Advanced Generation Intercrosses (MAGIC) population is a prominent example of this. This population uses a wide range of parents from different regions of the world and produces a population with a broad genetic base and significant phenotypic differentiation. Using quantitative trait loci (QTL), certain traits can be identified that can be used for the development of breeding lines for use in a breeding program for the development of advance varieties. As part of this review, we provided some examples of improved traits and different accomplishments achieved through the use of MAGIC populations.

Diversity of Linum genetic resources in global genebanks: from agro-morphological characterisation to novel genomic technologies - a review.

Linseed or flaxseed is a well-recognized nutritional food with nutraceutical properties owing to high omega-3 fatty acid (α-Linolenic acid), dietary fiber, quality protein, and lignan content. Currently, linseed enjoys the status of a 'superfood' and its integration in the food chain as a functional food is evolving continuously as seed constituents are associated with lowering the risk of chronic ailments, such as heart diseases, cancer, diabetes, and rheumatoid arthritis. This crop also receives much attention in the handloom and textile sectors as the world's coolest fabric linen is made up of its stem fibers which are endowed with unique qualities such as luster, tensile strength, density, bio-degradability, and non-hazardous nature. Worldwide, major linseed growing areas are facing erratic rainfall and temperature patterns affecting flax yield, quality, and response to biotic stresses. Amid such changing climatic regimes and associated future threats, diverse linseed genetic resources would be crucial for developing cultivars with a broad genetic base for sustainable production. Furthermore, linseed is grown across the world in varied agro-climatic conditions; therefore it is vital to develop niche-specific cultivars to cater to diverse needs and keep pace with rising demands globally. Linseed genetic diversity conserved in global genebanks in the form of germplasm collection from natural diversity rich areas is expected to harbor genetic variants and thus form crucial resources for breeding tailored crops to specific culinary and industrial uses. Global genebank collections thus potentially play an important role in supporting sustainable agriculture and food security. Currently, approximately 61,000 germplasm accessions of linseed including 1,127 wild accessions are conserved in genebanks/institutes worldwide. This review analyzes the current status of Linum genetic resources in global genebanks, evaluation for agro-morphological traits, stress tolerance, and nutritional profiling to promote their effective use for sustainable production and nutrition enhancement in our modern diets.

Farmers’ Preferences and Agronomic Evaluation of Dynamic Mixtures of Rice and Bean in Nepal

Field trials of rice and bean dynamic mixtures were carried out in low input and hill farming systems of Nepal from 2019 to 2021 to improve productivity and resilience. The rice trials were conducted in two locations (Jumla and Lamjung) and those on bean in Jumla, using a randomized complete block design with three replications. Dynamic mixtures were constructed from landraces, improved varieties and breeding lines for both crops. A total of 48 bean entries were used in Jumla, whereas 56 and 66 rice entries were used to make location-specific dynamic mixtures in Lamjung and Jumla, respectively. They were formed by mixing diverse varieties as a strategy to maintain a broad genetic base. Farmers (men and women) and technicians selected from the most complex mixture and the selections were added to the trials starting from second year. In rice, some mixtures and selections from the mixtures gave grain yield comparable to the improved check and higher than the local checks. In the case of bean, differences between entries were not significant but some of the selections received a high preference score. Overall, the dynamic mixtures appear as a reliable material for sustainable increase in yield in the low input and hill farming system of Nepal.

Genetic Variability of Floral and Agronomic Characteristics that Influence Outcrossing Rate Percentage of Cytoplasmic Male Sterile Rice

Developing high-yielding hybrid rice varieties is much needed to ensure food security to meet the requirement of the increasing population across the world. Cytoplasmic male genetic sterility system is a valuable technology for the exploitation of heterosis and production of high-yielding hybrid rice with better grain quality. Large-scale commercial exploitation of hybrid vigor in rice largely depends on the availability of good CMS (Cytoplasmic Male Sterile) lines. A total of eighteen traits of five CMS lines of rice were evaluated to study the variability and correlation between floral and other yield-contributing traits with outcrossing rate using Randomized Complete Block Design with three replications. High significant variation was observed among the genotypes for all the studied traits. High GCV (Genotypic Coefficient of Variance) and PCV (phenotypic Coefficient of Variance) coupled with high heritability and high genetic advance in percent of mean were observed for number of panicles per plant, filled grain, flag leaf breadth, stigma length and breadth, filament length and outcrossing rate which indicated the broad genetic base, less environmental influence, and these traits are under the control of additive gene action. character association and path analysis indicated that number of grains per panicle, filled grains per panicle, stigma length, and breadth possessed both positive significant correlation and positive direct effects on outcrossing rate therefore, selection for the traits mentioned above will certainly bring in the improvement of the outcrossing percentage of the lines, which in turn enhances the seed quantity of the hybrid.

Policy Gaps and Practices on Genetic Diversity, The Heterogenous and Localized Evolutionary Population as well as Native Landraces in Agriculture of Nepal

Formal breeding strategies and processes focus on developing uniform and non-evolutionary populations. However, many farmers continue to cultivate heterogenous cultivars and populations. To understand the recognition of genetic diversity (heterogenous cultivars and populations) in policies and the fields, a literature survey along with field survey, interaction and field action research were carried out in 15 districts of Nepal. Existing policies demand varieties to go through DUS (distinctness, uniformity, stability) testing and be registered in National Seed Board (NSB) for commercial production and sale. This means all native landraces and other broad genetic-based genotypes cannot be marketed without registration. A formal agriculture system accelerates the cultivation of a single genotype in a large area, leading to a lack of pollinators and the loss of many genetic diversities.&#x0D; Legal agricultural systems have focused mainly on modernizing agriculture through exotic resources, giving less priority to making native landraces and technologies globally competitive. In contrast, the informal seed system deals with polymorphic and evolutionary populations. Therefore, policies should consider the strategies that favor and increase genetic diversity, evolutionary population, site-specific genotypes and staple food, self-seed production system, ecological services, insects/birds/ microorganism-friendly systems, etc. Native agricultural genetic resources (AGRs) with broad genetic bases are essential for food, nutrition, health, environment, and business security. Therefore, native landraces of all six components of agrobiodiversity (namely crops, forages, livestock, aquatic genetic resources, insects, and microorganisms) should receive priority in research, development, extension, and education. Additionally, a favorable policy for the commercialization of such native landraces and/ or their products without registration should be established. Alternatively, a registration system should be developed for broad genetic base genotypes and heterogenous and evolutionary populations.

Yield of starch and its content in the grain of corn hybrids

The article presents the results of assessing the content of starch in hybrid combinations of corn and the yield of starch per unit area. As a result of the study of experimental hybrids created on the basis of the VIR collection material, the selection and combination value of the initial material was revealed in terms of content in grain and yield per hectare of starch. The experiment included simple hybrids (30 combinations) obtained by a complete topcross cross scheme. Instead of crossbreeding the lines with each other, crosses were carried out with three common testers with a broad genetic basis (line, synthetic population). In the study, lines RSK 7, B 293 and a synthetic population of RNIISK 1 were used as testers. The interval of variation in the starch content in grain for the study period varied from low values to an average value and amounted to: in 2020 – 60,9 % to 65,2 %, in 2021 - from 59,3 % to 66,1 %. Lines with a high effect of GCA on the content of starch in the grain (H 46, Vz 6, Om 12, YuV 106), as well as hybrid combinations of YuV 25 / RSK 7 (63,3-64,2 %), KS 75 / RSK 7 (62,7-64,4 %), HLG 948 / RSK 7 (63,5-64,1 %), Kin 073 / RSK 7 (63,4-63,8 %), YuV 106 / RSK 7 (63,6-66,1 %), KS 25 / B 293 (63,0-63,5 %), HLG 182 / B 293 (63,5-63,6 %), KS 75 / B 293 (63,1 -63,5 %), HLG 182 / RNIISK 1 (62,9-63,6 %). The results of the study made it possible to identify experimental hybrids that form the highest yield of starch per unit area: HLG 182 / RSK 7 (3,12-3,58 t/ha), YuV 106 / RSK 7 (2,77-3,11 t/ha ), H 46 / B 293 (3,22-3,39 t/ha), Om 12 / B 293 (2,72-3,85 t/ha).

Genetic diversity and structure of the 4th cycle breeding population of Chinese fir (Cunninghamia lanceolata (lamb.) hook).

Studying population genetic structure and diversity is crucial for the marker-assisted selection and breeding of coniferous tree species. In this study, using RAD-seq technology, we developed 343,644 high-quality single nucleotide polymorphism (SNP) markers to resolve the genetic diversity and population genetic structure of 233 Chinese fir selected individuals from the 4th cycle breeding program, representing different breeding generations and provenances. The genetic diversity of the 4th cycle breeding population was high with nucleotide diversity (Pi ) of 0.003, and Ho and He of 0.215 and 0.233, respectively, indicating that the breeding population has a broad genetic base. The genetic differentiation level between the different breeding generations and different provenances was low (Fst < 0.05), with population structure analysis results dividing the 233 individuals into four subgroups. Each subgroup has a mixed branch with interpenetration and weak population structure, which might be related to breeding rather than provenance, with aggregation from the same source only being in the local branches. Our results provide a reference for further research on the marker-assisted selective breeding of Chinese fir and other coniferous trees.

Molecular characterization of sweet potato (Ipomoea batatas [L.] Lam) germplasms for desirable traits by using simple sequence repeats markers

Every breeding program that aims to create new and improved cultivars with desired traits mostly relies on information related to genetic diversity. Therefore, molecular characterization of germplasms is important to obtain target cultivars with desirable traits. Sweet potato [Ipomoea batatas (L.) Lam] is widely considered the world’s most important crop, with great diversity in morphological and phenotypic traits. The genetic diversity of 20 sweet potato germplasms originating from Bangladesh, CIP, Philippines, Taiwan, and Malaysia were compared, which was accomplished by genetic diversity analysis by exploring 20 microsatellite DNA markers for germplasm characterization and utilization. This information was effective in differentiating or clustering the sweet potato genotypes. A total of 64 alleles were generated using the 20 primers throughout the 20 germplasm samples, with locus IBS97 having the highest number of alleles (5), whereas locus IbU33 had the fewest alleles (2). The alleles varied in size from 105 (IbU31) to 213 base pairs (IBS34). The Polymorphism Information Content (PIC) values for the loci IbL46 and IBS97 varied from 0.445 to 0.730. IBS97 has the highest number of effective alleles (3.704), compared to an average of 2.520. The average Shannon’s diversity index (H) was 1.003, ranging from 0.673 in IbU3 to 1.432 in IBS97. The value of gene flow (Nm) varied between 0.000 and 0.005, with an average of 0.003, whereas genetic differentiation (FST-values) ranged between 0.901 and 1.000. The sweet potato germplasm included in this study had a broad genetic base. SP1 vs. SP9 and SP12 vs. SP18 germplasm pairings had the greatest genetic distance (GD = 0.965), while SP1 vs. SP2 germplasm couples had the least genetic diversity (GD = 0.093). Twenty genotypes were classified into two groups in the UPGMA dendrogram, with 16 genotypes classified as group “A” and the remaining four genotypes, SP10, SP18, SP19, and SP20, classified as group “B.” According to cluster analysis, the anticipated heterozygosity (gene diversity) of Nei (1973) was 0.591 on average. In summary, SSR markers successfully evaluated the genetic relationships among the sweet potato accessions used and generated a high level of polymorphism. The results of the present study will be useful for the management of germplasm, improvement of the current breeding strategies, and the release of new cultivars as varieties.

Genotypic diversity and abiotic stress response profiling of short-grain aromatic landraces of rice (Oryza sativa L. Indica)

This study evaluated the physiological responses and genetic diversity of selected short-grain aromatic rice landraces of Northern Eastern Ghats of India to multiple abiotic stresses. Results revealed that drought, salt and flooding stress remarkably declined plant biomass, relative growth index (RGI), relative water content (RWC), leaf photosynthesis, PSII activity, SPAD relative index, and elevated effect was found in susceptible IR64 (susceptible check) variety. We employed molecular marker analysis to characterize 21 rice genotypes using 32 SSR primers related to drought, flooding and salinity tolerance QTLs. Our analysis suggests significantly high polymorphism (93.12%) in 96 loci. The mean value of polymorphism information content (PIC), marker index (MI) and resolving power (RP) and heterozygosity index (HI) were 0.326, 1.037, 1.558 and 0.420 respectively. The Jaccard’s similarity coefficient ranged from 0.158 to 0.846 with a mean genetic dissimilarity of 0.647. According to neighbor-joining method of clustering, all genotypes were grouped into two major and five sub-clusters which is concurrent with a very broad genetic base (K = 5) obtained with STRUCTURE analysis. Taken together, six aromatic genotypes Basubhoga, Dudhamani, Kalajeera, Laktimachi, Kuyerkuling and Tulasi are genetically very close to drought-tolerant (N22) and flooding tolerant (FR13A) cultivar whereas, salt-tolerant (Pokkali) very close to Sapuri and Muktabali. The degree of genetic variants obtained from this profiling could be useful for landrace conservation, selection and global implications for multiple abiotic stress tolerance.