Multiple Desirable Traits Research Articles

Manipulating hormones to mitigate trade-offs in crops.

Summary statementAddressing trait coupling due to gene pleiotropy presents challenges in conventional breeding system. However, targeted hormonal manipulation and precise genetic engineering designs hold promise to alleviate trade‐offs and unlock the potential of crops for multiple desirable traits.

Identification of High Erucic Acid Brassica carinata Genotypes through Multi-Trait Stability Index

Brassica carinata is an important and native oilseed crop in Ethiopia. The seed oil from B.carinata attracts global attention for its various industrial applications, mainly due to its high erucic acid levels and its superior agronomic traits. Since the demand for high erucic acid from oilseed brassica has been increasing in the world market due to its wider applications in bio-industries, the breeding target of B. carinata has recently been focused on enhancing its erucic acid. Several high erucic acid B. carinata genotypes have been screened from the pre-breeding activities. Such genotypes, however, need to be tested for their stable performance, for their erucic acid level, and other desirable traits under different environments. The aim of this study was to identify high erucic acid B. carinata genotypes with stable performance in multiple desirable traits. Thirty-two B. carinata genotypes were grown in a randomized complete block design with three replications at three locations for two years. The genotypes were evaluated for nine desirable traits related to seed oil quality (erucic acid and oil content), seed yield, and other agronomic traits. The results showed that the proportion of genotype by environment interaction (GEI) was clearly observed in erucic acid, which led to a stability and mean performance analysis for selecting the most stable and best-performing genotypes for the desired traits. For such an analysis, we used the multi-trait stability index (MTSI) along with the weighted average of absolute score BLUPs (WAASB). As revealed from the MTSI, five genotypes (G13, G18, G10, G22 and G5) were identified as the most stable in erucic acid, oil content, seed yield, and other agronomic traits. The selected genotypes showed on average 45.7% erucic acid, 3185 kg ha−1 seed yield and 45.1% oil content with 4.3%, 25.8% and 6.9% positive selection gain, respectively. The negative selection gain of phenological traits and the plant height of the selected genotypes revealed their early maturity and their lower probability of being affected by lodging. Our findings demonstrated MTSI can be used to select high erucic acid B. carinata with a set of desirable traits, which would facilitate breeding efforts in developing novel and high erucic acid B. carinata varieties. Our results also showed that MTSI is an effective tool for selecting genotypes across different environments due to its unique ability to select multiple traits simultaneously.

Unlocking Multifunctional Advantages with Nanocomposites Coatings for Solar Cells: A Comprehensive Review

Abstract: Nanocomposite coatings have garnered considerable attention as a versatile and innovative solution for addressing the challenges faced by solar cell technologies. This review article provides a comprehensive overview of the multifunctional advantages that nanocomposite coatings offer in the realm of solar cell technology. Furthermore, it delves into the myriad benefits that nanocomposite coatings bring to the table, including enhanced light absorption, improved charge carrier dynamics, and augmented protection against environmental factors such as moisture, UV radiation, and thermal stress. The review also discusses the diverse materials and fabrication methods employed in the development of nanocomposite coatings, highlighting their unique properties and practical applications with multifunctional benefits. Moreover, this comprehensive review explores recent advances in the field, encompassing the integration of novel nanomaterials, smart coatings, and multifunctional strategies that enable solar cells to simultaneously exhibit multiple desirable traits. Besides, the review offers insights into future prospects and challenges, presenting a roadmap for harnessing the full potential of nanocomposite coatings in solar cell technology. By unlocking the multifunctional advantages of nanocomposite coatings, this review aims to catalyze further research and innovation, ultimately advancing the prospects of sustainable and efficient solar energy generation.

Unveiling Diversity for Quality Traits in the Indian Landraces of Horsegram [Macrotyloma uniflorum (Lam.) Verdc.

Horsegram (Macrotyloma uniflorum [Lam.] Verdc.) is an underutilized pulse crop primarily cultivated in South Asian countries like India, Nepal, and Sri Lanka. It offers various nutraceutical properties and demonstrates remarkable resilience to both biotic and abiotic stresses. As a result, it has emerged as a promising crop for ensuring future food and nutritional security. The purpose of this study was to assess the nutritional profile of 139 horsegram germplasm lines obtained from 16 Indian states that were conserved at the National Gene Bank of India. Standard analytical methods, including those provided by the Association of Official Analytical Chemists (AOAC), were used for this investigation. The study revealed substantial variability in essential nutrients, such as protein (ranging from 21.8 to 26.7 g/100 g), starch (ranging from 26.2 to 33.0 g/100 g), total soluble sugars (TSSs) (ranging from 0.86 to 12.1 g/100 g), phenolics (ranging from 3.38 to 11.3 mg gallic acid equivalents (GAEs)/g), and phytic acid content (ranging from 1.07 to 21.2 mg/g). Noteworthy correlations were observed, including a strong positive correlation between sugars and phenols (r = 0.70) and a moderate negative correlation between protein and starch (r = -0.61) among the studied germplasm lines. Principal component analysis (PCA) highlighted that the first three principal components contributed to 88.32% of the total variability, with TSSs, phytates, and phenols emerging as the most significant contributors. The cluster analysis grouped the accessions into five clusters, with cluster III containing the accessions with the most desirable traits. The differential distribution of the accessions from north India into clusters I and III suggested a potential geographical influence on the adaptation and selection of genes. This study identified a panel of promising accessions exhibiting multiple desirable traits. These specific accessions could significantly aid quality breeding programs or be directly released as cultivars if they perform well agronomically.

RNA-Seq Provides Novel Genomic Resources for Noug (Guizotia abyssinica) and Reveals Microsatellite Frequency and Distribution in Its Transcriptome.

Genomic resources and tools are essential for improving crops and conserving their genetic resources. Guizotia abyssinica (noug), an outcrossing edible oilseed crop, has highly limited genomic resources. Hence, RNA-Seq based transcriptome sequencing of 30 noug genotypes was performed to generate novel genomic resources and assess their usefulness. The genotypes include self-compatible and self-incompatible types, which differ in maturity time, photoperiod sensitivity, or oil content and quality. RNA-Seq was performed on Illumina HiSeq 2500 platform, and the transcript was reconstructed de novo, resulting in 409,309 unigenes. The unigenes were characterized for simple sequence repeats (SSRs), and served as a reference for single nucleotide polymorphism (SNP) calling. In total, 40,776 SSRs were identified in 35,639 of the 409,309 unigenes. Of these, mono, di, tri, tetra, penta and hexanucleotide repeats accounted for 55.4, 20.8, 21.1, 2.3, 0.2, and 0.2%, respectively. The average G+C content of the unigenes and their SSRs were 40 and 22.1%, respectively. The vast majority of mononucleotide repeat SSRs (97%) were of the A/T type. AG/CT and CCA/TGG were the most frequent di and trinucleotide repeat SSRs. A different number of single nucleotide polymorphism (SNP) loci were discovered in each genotype, of which 1,687 were common to all 30 genotypes and 5,531 to 28 of them. The mean observed heterozygosity of the 5,531 SNPs was 0.22; 19.4% of them had polymorphism information content above 0.30 while 17.2% deviated significantly from Hardy-Weinberg equilibrium (P < 0.05). In both cluster and principal coordinate analyses, the genotypes were grouped into four major clusters. In terms of population structure, the genotypes are best represented by three genetic populations, with significant admixture within each. Genetic similarity between self-compatible genotypes was higher, due to the narrow genetic basis, than that between self-incompatible genotypes. The genotypes that shared desirable characteristics, such as early maturity, and high oil content were found to be genetically diverse, and hence superior cultivars with multiple desirable traits can be developed through crossbreeding. The genomic resources developed in this study are vital for advancing research in noug, such as genetic linkage mapping and genome-wide association studies, which could lead to genomic-led breeding.

Selection-enriched genomic loci (SEGL) reveals genetic loci for environmental adaptation and photosynthetic productivity in Chlamydomonas reinhardtii

This work demonstrates an approach to produce and select hybrid algal strains exhibiting increased photosynthetic productivity under multiple environmental conditions. This simultaneously addresses two major impediments to improving algal bioenergy production: 1) generating new genetic variants with improved performance; and 2) disentangling complex interactions between genetic and physiological factors contributing to these improvements. We pooled progeny generated from mating two environmental isolates of the green alga Chlamydomonas reinhardtii and cultured the pools under multiple environmental conditions. Strains from the outcompeting populations showed substantial (in some cases over 3 fold) increases in productivity over the parental lines under certain environments related to biomass production, including laboratory conditions as well as hyperoxia, fluctuating light, high salinity and high temperature. The results indicate that C. reinhardtii has remarkable, untapped, directed evolution capacity that may be harnessed using breeding and competition approaches. The populations were deep sequenced at multiple time points to identify “Selection-Enriched Genomic Loci” (SEGL) that accumulated in the populations, and thus likely confer increased fitness under the respective environmental conditions. With improved resolution, SEGL mapping can identify allelic combinations used for targeted breeding approaches, generating elite algal lines with multiple desirable traits, as well as to further understand the genetic and mechanistic bases of photosynthetic productivity.Increasing the photosynthetic efficiency of algae during biomass production is perhaps the most critical hurdle for economically sustainable algal based biofuels. This presents unique challenges because modifications designed to increase photosynthesis often result in decreased fitness, due to production of toxic reactive oxygen species when photosynthesis is not adequately regulated. These problems are exacerbated under natural and outdoor production environments because of the complex nature of photosynthesis and the multifaceted interactions between genetic, environmental and physiological factors. Here, we demonstrate a high throughput biotechnological screening approach that simultaneously produces algal strains with highly increased autotrophic productivity and identifies genomic loci contributing to these improvements. Our results demonstrate that Chlamydomonas reinhardtii exhibits high directed evolutionary capacity readily accessed through breeding and selection.

Multivariate selection index of acerola genotypes for fresh consumption based on fruit physicochemical attributes

Acerola (Malpighia emarginata DC.) is one of the most important fruit produced in the São Francisco Valley, a Semi-arid region in the Northeast of Brazil. This study aimed to evaluate the physicochemical quality of thirty-five acerola genotypes produced during two growing seasons in a Semi-arid region and to identify the best ones with potential for fresh consumption based on a multivariate selection index. Fruit of each genotype were harvested during two growing seasons at the maturity stage red-ripe, characterized by full red skin color. After harvest, the fruit were evaluated for diameter, mass, flesh firmness, soluble solids (SS), titratable acidity (TA), SS/TA ratio, ascorbic acid content and skin color. A multivariate selection index (SI) was applied for scoring and ranking the genotypes for fresh consumption based on red-ripe fruit physicochemical quality. According to the results, all physicochemical attributes had high variability among genotypes. The SI was a powerful tool for identifying genotypes with high potential for fresh consumption, since it allowed selecting genotypes with multiple desirable traits. In the first and second growing seasons, the SI identified the genotypes PROG 052 (SI = 76.1 and 78.9), BRS Rubra (SI = 74.1 and 99.5), Cabocla (SI = 72.3 and 70.7), Costa Rica (SI = 61.2 and 73.8) and PROG 069 (SI = 68.1 and 72.4) as the most promising ones for fresh consumption due to the presence of multiple desirable traits such as high diameter, mass, flesh firmness, SS, and SS/AT ratio, as well as lower acidity.

Selection of Suitable Genotypes of Lentil (Lens culinaris Medik.) under Rainfed Conditions in South Italy Using Multi-Trait Stability Index (MTSI)

Lentil (Lens culinaris Medik.) is a popular legume crop in the Mediterranean region, widely grown for its nutritious seeds and improving soil fertility. Lentil yield is a critical and challenging trait for crop genetic improvement because it is influenced by various factors that have detrimental effects on seed yields and seed quality traits. This research was carried out in Italy between 2017 and 2019 to identify high-performing stable genotypes presenting multiple desirable traits and to assess the seed quality of 13 lentil accessions in the field. According to the results of the multi-trait stability index (MTSI), (1) only three accessions (Altamura, Easton, and Caltagirone) fared better in various environmental conditions, and (2) the selected accessions had strength toward seed yield (SY), above-ground biomass (AGB), and 1000-seed weight (THS). The genotype × environment interaction (GEI) effects were highly significant for all traits. During the third growing season, most lentil accessions were sensitive to frost. There was no correlation between lentil seed yield and protein concentration. The MTSI is a useful tool for breeders interested in selecting accessions based on their mean performance and stability, as well as desirable traits and minimum multicollinearity issues.

Refined mapping of stripe rust resistance gene YrP10090 within a desirable haplotype for wheat improvement on chromosome 6A.

A large genomic region spanning over 300 Mb on chromosome 6A under intense artificial selection harbors multiple loci associated with favorable traits including stripe rust resistance in wheat. The development of resistance cultivars can be an optimal strategy for controlling wheat stripe rust disease. Although loci for stripe rust resistance have been identified on chromosome 6A in previous studies, it is unclear whether these loci span a common genetic interval, and few studies have attempted to analyze the haplotype changes that have accompanied wheat improvement over the period of modern breeding. In this study, we used F2:3 families and F6:7 recombinant inbred lines (RILs) derived from a cross between a resistant CIMMYT wheat accession P10090 and the susceptible landrace Mingxian 169 to improve the resolution of the QTL on chromosome 6A. The co-located QTL, designated as YrP10090, was flanked by SNP markers AX-94460938 and AX-110585473 with a genetic interval of 3.5cM, however, corresponding to a large physical distance of over 300Mb in RefSeq v.1.0 (positions 107.1-446.5Mb). More than 1,300 SNP markers in this genetic region were extracted for haplotype analysis in a panel of 1,461 worldwide common wheat accessions, and three major haplotypes (Hap1, Hap2, and Hap3) were identified. The favorable haplotype Hap1 associated with stripe rust resistance exhibited a large degree of linkage disequilibrium. Selective sweep analyses were performed between different haplotype groups, revealing specific genomic regions with strong artificial selection signals. These regions harbored multiple desirable traits associated with resilience to environmental stress, different yield components, and quality characteristics. P10090 and its derivatives that carry the desirable haplotype can provide a concrete foundation for bread wheat improvement including the genomic selection.

A look-ahead Monte Carlo simulation method for improving parental selection in trait introgression

Multiple trait introgression is the process by which multiple desirable traits are converted from a donor to a recipient cultivar through backcrossing and selfing. The goal of this procedure is to recover all the attributes of the recipient cultivar, with the addition of the specified desirable traits. A crucial step in this process is the selection of parents to form new crosses. In this study, we propose a new selection approach that estimates the genetic distribution of the progeny of backcrosses after multiple generations using information of recombination events. Our objective is to select the most promising individuals for further backcrossing or selfing. To demonstrate the effectiveness of the proposed method, a case study has been conducted using maize data where our method is compared with state-of-the-art approaches. Simulation results suggest that the proposed method, look-ahead Monte Carlo, achieves higher probability of success than existing approaches. Our proposed selection method can assist breeders to efficiently design trait introgression projects.

Identification of novel genetic sources for agronomic and quality traits in soybean using multi-trait allele specific genic marker assays

Natural allelic variation among the genes governing various agronomic and quality traits of plant provides opportunity to develop desirable plant type in crops. In soybean [Glycine max (L.) Merr.], natural allelic variation is known for many functionally characterized genes conferring superior phenotype for their respective governing trait. Exploring this natural allelic variation in germplasm pool through gene based allele specific multiplex marker genotyping is one way to identify and combine the alleles of multiple traits in desired genetic background. Using known alleles of 15 genes governing 10 different agronomic and quality traits, we have developed two multi-trait allele specific genic marker assays of 22-plex and 7-plex alleles. These two multi-trait allele specific genic marker assays were used to genotype a large set of diverse soybean germplasm accessions, which identified several novel genetic sources of rare alleles conferring superior or desirable phenotype. Selected genetic sources of rare alleles for days to flowering and maturity, hard-seededness, pod shattering and oleic acid content were validated phenotypically. Genotyping and phenotyping in a multi-parent advanced generation intercross population validated the utility of multi-trait allele specific genic marker assays in marker assisted selection of multiple traits from multiple parents. The novel genetic sources identified in this study will help in the selection of parents with multiple desirable traits for hybridization. The multi-trait allele specific genic marker assays developed will speed up selection of multiple traits in routine soybean breeding programmes for cultivar development and improvement.

Identification and stacking of crucial traits required for the domestication of pennycress

The oilseed species Thlaspi arvense (pennycress)—a weed that was only recently removed from the wild—has the potential to provide new sources of food and bioproducts when grown as a winter cover crop. Domestication of wild species has historically taken hundreds to thousands of years, but by making use of large-scale high-throughput comparative gene and phenotype analyses, along with recently developed technological tools, it has been possible to greatly accelerate this process. By taking advantage of extensive gene and phenotype knowledge in the related plant Arabidopsis, mutations for early maturity, reduced pod shatter, reduced seed glucosinolates and improved fatty acid composition were identified. Progress has been made to rapidly stack these traits in order to domesticate the plant, allowing it to fit within current crop cycles and to have improved seed harvestability and nutritional content. Pennycress, domesticated as a winter cover crop, may provide new sources of food, animal feed and bioproducts—and solutions to food security. Thlaspi arvense (pennycress) has the potential to provide new sources of food and bioproducts when grown as a winter cover crop. Here, Chopra et al. demonstrate that multiple desirable traits can be stacked to rapidly domesticate pennycress. The resulting crop integrates into current crop rotations and produces seeds with improved nutritional qualities, easier harvesting and suitability for human consumption.

Screening of the High-Rhizosphere Competent Limoniastrum monopetalum' Culturable Endophyte Microbiota Allows the Recovery of Multifaceted and Versatile Biocontrol Agents.

Halophyte Limoniastrum monopetalum, an evergreen shrub inhabiting the Mediterranean region, has well-documented phytoremediation potential for metal removal from polluted sites. It is also considered to be a medicinal halophyte with potent activity against plant pathogens. Therefore, L. monopetalum may be a suitable candidate for isolating endophytic microbiota members that provide plant growth promotion (PGP) and resistance to abiotic stresses. Selected for biocontrol abilities, these endophytes may represent multifaceted and versatile biocontrol agents, combining pathogen biocontrol in addition to PGP and plant protection against abiotic stresses. In this study 117 root culturable bacterial endophytes, including Gram-positive (Bacillus and Brevibacillus), Gram-negative (Proteus, Providencia, Serratia, Pantoea, Klebsiella, Enterobacter and Pectobacterium) and actinomycete Nocardiopsis genera have been recovered from L. monopetalum. The collection exhibited high levels of biocontrol abilities against bacterial (Agrobacterium tumefaciens MAT2 and Pectobacterium carotovorum MAT3) and fungal (Alternaria alternata XSZJY-1, Rhizoctonia bataticola MAT1 and Fusarium oxysporum f. sp. radicis lycopersici FORL) pathogens. Several bacteria also showed PGP capacity and resistance to antibiotics and metals. A highly promising candidate Bacillus licheniformis LMRE 36 with high PGP, biocontrol, metal and antibiotic, resistance was subsequently tested in planta (potato and olive trees) for biocontrol of a collection of 14 highly damaging Fusarium species. LMRE 36 proved very effective against the collection in both species and against an emerging Fusarium sp. threatening olive trees culture in nurseries. These findings provide a demonstration of our pyramiding strategy. Our strategy was effective in combining desirable traits in biocontrol agents towards broad-spectrum resistance against pathogens and protection of crops from abiotic stresses. Stacking multiple desirable traits into a single biocontrol agent is achieved by first, careful selection of a host for endophytic microbiota recovery; second, stringent in vitro selection of candidates from the collection; and third, application of the selected biocontrol agents in planta experiments. That pyramiding strategy could be successfully used to mitigate effects of diverse biotic and abiotic stresses on plant growth and productivity. It is anticipated that the strategy will provide a new generation of biocontrol agents by targeting the microbiota of plants in hostile environments.

Breeding Differently—the Digital Revolution: High-Throughput Phenotyping and Genotyping

A conventional potato breeding strategy uses targeted outcrossing, followed by phenotypic recurrent selection over a series of generations to identify improved cultivars. This paper reviews recent research in Australia aimed at improving the efficiency of such breeding. To develop marker-assisted selection (MAS) for traits of interest, our initial targets were qualitative disease resistances for potato cyst nematode (Globodera rostochiensis Ro1), Potato virus Y and Potato virus X. We undertook a cost analysis comparison between MAS and conventional screening, confirming that MAS would be cost-effective within a breeding programme. Then, as the majority of target traits are quantitative in nature, we also looked at methods to address these traits, including progeny testing and a quantitative genetic analysis technique to develop estimated breeding values (EBVs). We found the markers were useful for detecting the disease resistance characters, while the EBVs improved the analysis of the complex traits. Using a combination of MAS, EBVs and conventional screening methods, we then designed a breeding scheme for rapid selection of cultivars with multiple desirable traits, reducing the breeding cycle from over 10 to 4 years. We then explored the factors that will affect the application of genomic selection in potato and investigated strategies to incorporate genomic selection in potato breeding, as we found that it would accelerate genetic gain as the breeding cycle can be reduced to 1 year. Improvements in computational power are also flowing on to research capabilities such as sequencing, high-throughput phenotyping and data analysis, which will accelerate germplasm improvement and breeding. High-throughput phenotyping facilities are being developed that include automated glasshouse systems equipped with imaging sensors and in-field high-throughput phenotyping systems with sensors mounted on ground- or aerial-based vehicles. Using these technological improvements in phenotypic and genotypic analysis will reduce the breeding cycle in a cost-effective manner and means that we can now breed differently.

High-Efficiency Semitransparent Organic Solar Cells with Non-Fullerene Acceptor for Window Application

Organic solar cells possess multiple desirable traits, such as low cost, flexibility, and semitransparency, which opens up potential avenues unavailable to other solar technologies, a prime example of this being window applications. For this specific application, a delicate balance between the transmission of light through the device and power conversion efficiency (PCE), dependent on the amount of light absorbed, must be optimized. Here, we report a high-efficiency semitransparent device based on a novel fullerene-free material system. Using an active layer based on the material system PBDB-T:ITIC, optimized devices exhibited PCEs exceeding 7% while also achieving an average visible transmittance (AVT) of 25%. The concurrent demonstration of high efficiency with an AVT of 25% represents a notable step forward for semitransparent organic solar cells. Additionally, the influence of the active layer thickness on the color rendering properties of these cells was studied. Optimization of the active layer thic...

Improving the selection efficiency in potato breeding

Current Australian potato cultivars suffer from a number of production and quality issues. Commercial cultivar development within Australia used a conventional potato breeding strategy, with outcrossing, and then screening of derived lines to identify improved cultivars, although we have been investigating methods to make the program more efficient. Implementation of marker-assisted selection (MAS) is highly desirable to increase efficiency, and our initial targets for MAS have been qualitative disease resistances. Two diseases of concern within the Australian potato industry are potato cyst nematode (PCN) (Globodera rostochiensis Ro1) and Potato virus Y (PVY), so we investigated markers for these diseases, including a potentially diagnostic marker, 57R, for PCN Ro1. As the majority of the target traits for the breeding program are quantitative and controlled by multiple to many genes, we have also investigated a quantitative genetic analysis technique used in livestock breeding for these complex traits to develop estimated breeding values (EBVs) for them. The breeding program has now developed a breeding scheme using a combination of MAS, EBVs and conventional screening methods for early-generation selection of cultivars with multiple desirable traits. The application of these new techniques, alongside conventional screening, will see a reduction in the breeding cycle and the cost of breeding, as well as improving genetic gain in a range of traits.

Employing the GGE SREG model plus Elston index values for multiple trait selection in sweetpotato

Sweetpotato is a good source of energy, easy-to-grow and hardy and thus useful in contributing to food security. The current study aimed at identification of the best sweetpotato varieties for multiple desirable traits such as good yield, adaptability (including vine vigor) and tastiness (high dry mass content; taste). Ten South African sweetpotato varieties were evaluated during the period 2002/3–2007/8 at six locations each over two seasons. The sites regression model (SREG) of the genotype plus genotype by environment interaction (GGE) biplot analysis was performed with GenStat to determine stability and adaptability of the varieties. Subsequently, multiple trait selection was performed by using the ranking from Elston index selection. To enable inclusion of varietal stability in multiple trait selection, a stability value was calculated. High yielding varieties included Blesbok, Monate, Ndou and Letlhabula, of which Monate and Letlhabula had stable performance. The advantage, particularly for resource-poor farmers, of a specifically adapted, responsive variety such as Ndou, is the ability to respond to changes in the environment. Based on multiple trait selection varieties Ndou and Monate were recommended for production. The results present an innovative use of Elston index selection, including a stability value, in combination with GGE SREG for recommending varieties with multiple desirable traits. The recommended varieties are of significance for future use to improve food security.

New Technologies, Tools and Approaches for Improving Crop Breeding

New Technologies, Tools and Approaches for Improving Crop Breeding

Gamete Selection for Simultaneous Improvement of Multiple Traits in Common Bean

A successful crop improvement program depends upon the ability of breeders and geneticists to effectively and efficiently create, identify, and select recombinant genotypes with a maximum number of desirable traits in the shortest time possible. Therefore, alternative methods of gene recombination and selection need to be studied. My objective is to describe a method of gamete selection for simultaneous improvement of multiple traits in common bean (Phaseolus vulgaris L.). Gametes election is based on the premise that (i) multiple‐parent crosses are required for simultaneous improvement of multiple traits; (ii) the male parents of the final crosses are heterozygous and hence heterogametic;( iii) each zygotic seed is a product of a separate, independent fertilization event; (iv) further chromosomal and genic recombination is limited to genetic material contained within each initial zygote; and (v) early generation (i.e., F1, F2, F3, and F4) testing and selection are an essential part of the methodology. Thus, eventually, plant‐to‐plant pairwise pollination is done between the elite female and beterogametic male parents (selected a priori for desirable dominant and codominant alleles), followed by harvesting and sowing resultant hybrid seeds from each hybridization event in separate plots to obtain F1‐derived families. These are subsequently evaluated in separate, replicated complementary nurseries for seed yield and other agronomic traits, including reactions to diseases and insects, low soil fertility, and/or drought. This permits identifying promising populations and families within populations possessing genes for multiple desirable traits in early generations for further evaluation, selection, and development of improved cultivars.

White Pine Blister Rust in British Columbia III. Effects on the Gene Pool of Western White Pine

Cluster analyses of relative terpene abundance in foliage of western white pine (Pinus monticola Dougl.) trees from throughout the Pacific Northwest geographic range of the species were produced. Terpene patterns were randomly distributed among populations; no geographic or site trends were evident. Although blister rust is devastating to stands, the gene pool is widely distributed and may well be preserved without establishing gene banks.About 40-50 trees selected at random would yield offspring with nearly all possible terpene patterns characteristic of the species and would thus constitute a broad genetic base. Therefore seed orchards do not necessarily need to be composed of many individuals, rather, they should contain highly selected individuals with multiple desirable traits including multiple blister rust resistance mechanisms. Key words: terpenes, dendrogram