Additive Gene Effects Research Articles

Unravelling genetic variability for yield and contributing characteristics in green gram [vigna radiata (L.) wilczek] germplasm

Mungbean [Vigna radiata (L.) Wilczek] is an essential crop for food, feed, and income generation in rice-based farming systems across Southeast Asia and other regions. Its popularity stems from its good taste, high nutritional value, and ease of digestion, making it a promising crop for enhancing livelihoods. However, despite its significance, mungbean productivity remains low, primarily due to environmental stresses and a lack of sufficient genetic variability. This study examines the variability, heritability, phenotypic and genotypic coefficient of variation, and genetic advance among yield-contributing traits in green gram germplasm. A total of 450 germplasm lines were evaluated alongside check varieties, revealing significant variation, with the analysis of variance showing notable differences across nearly all traits. The mean sum of squares for the germplasm was highly significant for all phenotypic traits. Several traits exhibited high estimates of heritability and genetic advance, viz., the number of branches/ plants, number of clusters/ plants, number of pods/ clusters, pod length, test weight, and seed yield/plant, indicating their potential for direct selection in breeding programs. These findings suggest that additive gene effects play a dominant role in controlling these traits, with minimal environmental influence, making simple phenotypic selection an effective approach. The results provide valuable insights for advancing green gram breeding programs focused on improving yield and quality through targeted hybridization and trait selection.

Morpho-molecular Genetic Diversity Analysis of Basmati and Non-basmati Rice (Oryza sativa L.) Germplasm

This study evaluated genetic variability and relatedness among 34 rice genotypes, encompassing basmati and non-basmati varieties using morphological and molecular data. The findings revealed significant variability across all traits assessed. High phenotypic and genotypic coefficients of variation (PCV and GCV) were observed for traits such as days to 50% flowering, days to maturity, biological yield, grain yield, test weight, flag leaf length, and number of effective tillers. Notably, high heritability and genetic advance indicated that these traits are likely influenced by additive gene effects, making them suitable for selection in breeding programs. D2 analysis confirmed substantial genetic diversity among the genotypes and five clusters were formed based on the morphological data. Molecular analysis using 13 SSR primers, out of 13 primers 11 primers are showed the banding pattern, with the highest polymorphism information content (PIC) value recorded at 0.79 for marker HvSSR04-46. Clustering based on Jaccard’s dissimilarity coefficient revealed two distinct clusters. Based on the dendrogram pattern molecular data is divided into two clusters, cluster I and Cluster II, cluster I is subdivided into Cluster Ia and Cluster Ib. This research was conducted at Sardar Vallabhbhai Patel University of Agricultural & Technology, Modipuram, Meerut, Uttar Pradesh, highlights the potential for selecting diverse rice genotypes to enhance breeding programs.

Agronomic Performance and Resistance to Maize Lethal Necrosis in Maize Hybrids Derived from Doubled Haploid Lines

Maize (Zea mays L.) is one of the most widely cultivated grain crops globally. In sub-Saharan Africa (SSA), it plays an important role in ensuring both food and income security for smallholder farmers. This study was conducted to (i) assess the performances of testcross hybrids constituted from maize lethal necrosis (MLN) tolerant doubled haploid (DH) lines under various management conditions; (ii) estimate the combining ability effects and determine the nature of gene action in the DH lines; and (iii) identify DH lines and testcross hybrids for resistance to MLN, high grain yield, and other important traits. Eleven DH lines were crossed with 11 single-cross testers using the line-by-tester mating design, and 115 successful testcross hybrids were generated. These hybrids, along with five commercial check hybrids, were evaluated across four optimum management conditions, two MLN artificial inoculations, and one managed drought environment in Kenya. Under each management condition, the effects of genotypes, environments, and genotype-by-environment interactions were significant for grain yield (GY) and most other traits. Hybrids T1/L3, T10/L3, and T11/L3 exhibited higher grain yields under at least two management conditions. A combining ability analysis revealed that additive gene effects were more important than non-additive effects for GY and most other traits, except for leaf senescence (SEN) and MLN disease severity score. DH line L3 exhibited a desirable general combining ability (GCA) effect for GY, while L5 was the best general combiner for anthesis date (AD) and plant height (PH) across all management conditions. DH lines L2, L6, and L7 showed negative GCA effects for MLN disease severity. Single-cross testers T11 and T10 were good general combiners for GY under all management conditions. Hybrids T2/L11, T9/L10, and T2/L10 demonstrated high specific combining ability (SCA) effects for GY under all conditions. This study identified DH lines and testers with favorable GCA effects for grain yield, MLN resistance, and other agronomic traits that can be used in breeding programs to develop high-yielding and MLN-resistant maize varieties. Better-performing testcross hybrids identified in the current study could be verified through on-farm testing and released for commercial production to replace MLN-susceptible, low-yield hybrids grown in the target ecologies.

Genetic analysis of late blight (Phytophthora infestans (mont.) de Bary) resistance in tomato

ABSTRACT Diallel analysis provides basic genetic information that is critically important to identify parents involved in hybridization breeding programs. This study was initiated to estimate combining ability effects and determine the type of gene action involved in inheritance of late blight resistance. Five tomato lines and 10F1 progenies produced by crossing of parents in a 5 × 5 half-diallel fashion were assessed for late blight resistance in field conditions. The combining ability ratio was greater than unity for all traits considered in this stud. At the same time, the degree of dominance was less than unity for all the traits, indicating a greater importance of additive gene effects for the inheritance of late blight resistance. The parents ’Eshete’ and ’Roma VF’ were general combiners, exhibiting significantadverse general combining ability effects for all studied traits. Specific combining ability effects of ’Roma VF × Eshete’ and ’Melkashola × Eshete’ were significantly negative for disease incidence, with all the lines exhibiting significant negative general combining ability effects for the trait, indicating transgressive segregants that are late blight resistant could be produced from crossing of these parental lines. These results, accordingly, indicated that the parents could be utilized in the crossing programme to develop late blight resistant transgressive segregant varieties.

Unveiling genetic basis of yield and salinity tolerance in rice (Oryza sativa L.) through insights from generation mean analysis

Abstract Rice (Oryza sativa L) serves as a primary food source for over a billion people worldwide and is encountering challenges in yield due to the increasing global population and climate changes. Understanding the genetic variations that underlie complex traits is crucial for its enhancement and this can be accomplished through generation mean analysis. In this study, investigation was made to study the genetic mechanisms governing important quantitative traits, specifically yield and salinity tolerance in rice. The study involved six generations (P1, P2, F1, F2, B1 and B2) resulting from two crosses between three parents. The investigation specifically focused on generation mean analysis, assessing twelve traits includes days to flowering, plant height , total number of tillers , number of productive tillers , panicle length, flag leaf length, flag leaf width, number of filled grains per panicle, total number of grains per panicle, spikelet fertility, thousand-grain weight and single plant yield in the two crosses. In Cross I (ADT 45 × APD 19002), traits such as plant height, days to fifty percent flowering, total number of tillers and total number of grains per panicle exhibited opposing signs for dominance × dominance (l) and dominance (h), indicating a prevalence of duplicate epistasis. At the same time, additive and additive × additive gene effects influenced total number of tillers, plant height, total number of grains per panicle, number of filled grains per panicle and spikelet fertility. In Cross II (CO 54 × APD 19002), total number of tillers, plant height, flag leaf length, total number of grains per panicle, spikelet fertility and single plant yield suggested a predominance of duplicate epistasis. Further, the total number of grains per panicle, total number of tillers per plant, spikelet fertility and thousand-grain weight were primarily governed by additive and additive × additive gene effects. These observations show the feasibility of enhancement through selection in subsequent generations, emphasizing the necessity of integrating selection with salinity tolerance screening for the development of high-yield, salinity-tolerant rice varieties. Keywords: Scaling test, genetic effects, salinity tolerance

Genetic Analysis for Seed Yield and Yield‐Related Traits in Tepary Bean (Phaseolus acutifolius A. Gray) Under Drought‐Stress and Non‐stress Conditions

ABSTRACTTepary bean (Phaseolus acutifolius A. Gray) is an under‐utilized genetic resource with significant potential for food security and stress tolerance breeding. Expanding its cultivation in southern Africa requires high‐yielding, locally adapted and drought‐tolerant varieties. This study determined the combining ability and genetic components for seed yield and related traits in tepary bean genotypes under non‐stress (NS) and drought‐stress (DS) conditions. Seven parents were selected through rigorous phenotyping and crossed using a half‐diallel design. The 7 parents and 21 F2 progenies were evaluated in 2021/2022 season at Kasinthula and Bunda sites in Malawi under NS and DS conditions using a 4 × 7 lattice design with three replications. The specific combining ability (SCA) × location interaction effect was significant (p < 0.05) for DTF, NPP, and SY, suggesting that the genetic effects of crosses were influenced by the test locations. General combining ability (GCA) and SCA mean squares were significant for the number of seeds per pod (NSP) and SY under DS conditions, indicating both additive and non‐additive gene effects. Baker's ratio (BR) > 0.50 for NPP and NSP under DS conditions suggested a preponderance of additive gene effects. G40145, G40148 and G40150 parental lines were good combiners for NPP and SY. The F2 families from crosses such as Zimbabwe landrace/G40138, Zimbabwe landrace/G40150, G40059/G40145, G40059/G40148, G40138/G40150 and G40145/G40150 were identified as best specific combiners, with enhanced SY of 1.67 t/ha under DS conditions. The study recommends advancing high‐performing early‐generation families for selection across representative environments to facilitate variety release and commercialization.

Heritability and Genetic Advance Studies on Fruit Yield and It’s Attributes Traits in Brinjal (Solanum melongena L.)

The present investigation was conducted at the Main Vegetable Research Station, Anand Agricultural University, Anand during the period of 2023-2024. The experimental material comprised twelve generations viz., P1, P2, F1, F2, B1, B2, B11, B12, B21, B22, B1S and B2S of four families involving eight diverse cultivars of brinjal (Solanum melongena L.) used to study the heritability and genetic advance of brinjal for yield and shoot and fruit borer incidence. The experiment was laid out in a compact family block design with three replications. Higher magnitude of heritability along with a higher value of genetic advance as per cent mean was estimated for day to first flowering in family 2, plant height in family 1 and family 4, leaf blade length in family 4, leaf blade width in family 2, fruit length in all families, fruit girth in family 3 and 4, fruit weight in all families expect to family 2, fruits per plant in family 2, fruit yield per plant in all families expect family 4 and shoot and fruit borer incidence in family 2 which suggested preponderance of additive gene effect. The higher value of heritability coupled with the higher value of genetic advance shows higher selection efficiency, permitting plant breeders to efficiently select individuals or groups of individuals. In crops like brinjal, high narrow sense heritability estimates are particularly beneficial for developing enhanced varieties through the fixation of additive gene effects.

Selection of superior Brassica napus L. hybrids by integrated graphical and numerical diallel analysis by yield×traits: Using hayman and biplot diallel approaches

Improving yield via assessment of different yield-related genetic parameters specifically with the challenges of yield × traits combination is a prominent issue for plant breeders. A graphical and numerical description of diallel analysis by yield × traits with the novelty of the parent selection with desirable genetic architecture in rapeseed was illustrated via Hayman and biplot approaches. Eleven divers' parents and their F1 offspring, achieved via a complete diallel mating fashion, were evaluated under field conditions based on randomized complete block design replicated thrice throught 2018–2020. Integrated yield × traits analysis revealed highly significant additive and non-additive gene effects which were confirmed by the meaningful general and specific combining ability of evaluated multi-traits. Graphical Wr-Vr analysis, depicted partial dominance gene action for yield × traits, except yield × thousand grain yield which is governed by over-dominance gene action.The biplot polygon panorama identified the most desirable heterotic parents with higher general and specific combining ability, and more dominant genes including [(P9) × (P4, P6, P10) for yield × pod]; [(P9) × (P7), (P6) × (P11) and (P7) × (P10) for yield × thousand grain yield] and [(P10 × P3) for yield/flowering, yield/physiological maturity, yield/plant height]. These findings suggested that a breeder should consider superior parents with high × high general and specific combining ability according to combining their yield and its related genetic parameters as important traits with all other target characters via descripted approaches.

Unraveling Promising Genetic Variability Associated with Strong Culm and Yield Parameters in Inter Sub-Specific Cross Derived Recombinant Inbred Lines in Rice (Oryza sativa L.)

Strengthening the rice culm through genetic improvement has been an important target in breeding to abate the lodging problem in rice. The present investigation was attempted to study the variability, genetic parameters and trait association in recombinant inbred lines (RILs) derived from inter sub-specific cross of elite indica mega variety ‘Swarna’ and Tropical japonica strong culm accession ‘IRGC 39111’. Analysis of Variance (ANOVA) displayed significant variation in RILs for all the traits studied. The investigation revealed high estimates of GCV and PCV along with high heritability and genetic advance as percent of mean (GAM) for all culm strength (CS) traits revealing the role of additive gene effect and selection of these traits shall be effective in rice improvement. Correlation studies revealed that the internode breaking weight (IBW) and bending moment at breaking(M) had a high significant positive correlation with all the CS traits, panicle weight and grain yield. Thus, the direct selection of positively associated traits can improve the lodging resistance in rice. The principal component analysis (PCA) showed that, seven principal components (PCs) out of 23 traits attributed approximately 92.9% of the total cumulative variability. The traits culm thickness (CT), Internode breaking weight (IBW), section modulus (SM), bending stress (BS), Bending moment at breaking (M) contributed maximum to the total diversity and the lines with higher trait values for the aforementioned traits could be utilized as donors to improve the culm strength and its attributing traits in future breeding programs. From this study, it is evident that tropical japonica lines can be a great source of genetic diversification for rice improvement.

Genetic Analysis to Estimate Components of Genetic Variances in Indian Mustard (Brassica juncea L.)

The current investigation on Brassica juncea L. genotypes focuses on exploring variations through hybridization to enhance genetic diversity. Additionally, it aims to gather genetic insights into yield and related traits essential for selecting superior varieties in subsequent generations. Using a half diallel design, eight potential genotypes were selected and crossed in every imaginable way. All of the qualities had substantial differences according to analysis of variance; these differences were further examined using Hayman's technique, which revealed that all of the traits are dominated by both additive and dominant gene effects. The findings suggested that dominance and additive genetic variations play a significant role in regulating these features. The magnitude of dominance (H1 and H2) was highly significant higher than additive components (D) for all traits. Positive alleles were not equally distributed among parents (H2/4H1 ≠ 0.25) for all the studied traits. The estimates of environmental variance (E) were significantly positive for all studied traits, except for biological yield per plant suggests that environmental factors exert a notable influence on all examined traits. Narrow sense heritability was less than (0.50) for all traits. The graphical analysis Wr/Vr indicated the importance of over dominance gene effects in controlling all traits. Thus suggesting that selection could be effective in latter generations.

Gene action and hybrid vigour for yield, yield components and tolerance to the Two-Spotted Spider mite in summer squash

An investigation was conducted at Kaha Vegetable Research Farm in the Kaliobia Governorate from 2021 to 2023 with an aim to evaluate the performance of six inbred lines of summer squash and their fifteen crosses in both open field and plastic greenhouse conditions. The study spanned two successive summer seasons (2022 and 2023) and focused on assessing horticultural traits and resistance levels to the two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae). Significant variations were observed in the mean performance of all traits among different genotypes. Analysis revealed significant differences in both general (GCA) and specific (SCA) combining abilities for all studied traits, except for the number of days to anthesis of the first female flower, indicating the presence of both additive and non-additive gene effects in traits inheritance. In the plastic greenhouse, genotype P3 exhibited the highest resistance with an average of 10.6 mites per 2 inches², while the cross P2 × P6 showed tolerance with an average of 4.4 mites per 2 inches². This study highlights the potential of new summer squash hybrids with desirable horticultural traits and resistance to the two-spotted spider mite. Additionally, parent 222/2 (P1) demonstrated the best combining ability for all traits, while parents 264 (P5) and 240/3 (P4) were the most effective combiners for total yield. Breeders may leverage these parents for genetic enhancement and the production of hybrids with superior horticultural qualities. Overall, this research provides valuable insights for researchers, breeders and farmers involved in the cultivation, breeding and utilization of summer squash in Egypt.

Variability, Mean Performance Evaluation, Trait Relationship and Principal Component Analysis of Sunflower Genotypes

Forty nine sunflower genotypes evaluated for mean performance and Variability parameters of yield contributing traits at Kulumsa in simple lattice design. The aim is to identify desired characters of the crop, information of nature and genetic variability for seed yield improvement. The traits revealed presence of highly significant genotypic differences at P≤0.01 for yield contrbuting traits: head diameter, number of seed head<sup>-1</sup>, thousand seed weight and seed yield ton ha<sup>-1</sup>. Among the studied genotypes mean performance evaluation indicates that the highest seed yield ton ha<sup>-1 </sup>recorded for genotypes SHRS-2020#18 (3.06ton ha<sup>-1</sup>), followed by SHRS-2020#4 (2.95tonha<sup>-1</sup>) and SHRS-2020#16 (2.84t ha<sup>-1</sup>) and the lowest average seed yield ton ha<sup>-1 </sup>recorded for genotype SHRS-2020#13 (1.15tonha<sup>-1</sup>). Genotypes SHRS-2020#46 (83.5) and SHRS-2020#38 (84.5) the early flowered whereas, the late flowered recorded for the genotype SHRS-2020#43 (107.5) after the date of sowing. Seed yield ton ha<sup>-1</sup> (YTPH), is the most economic trait, was positively and significantly associated with number seed head<sup>-1</sup> and plant height. The characters indicating significantly positively correlation among seed yield and important traits would be highly effective and efficient improving respective traits. Higher estimates of heritability coupled with higher genetic advance were observed for seed yieldtonha<sup>-1</sup> (46.49) and number of seed head<sup>-1</sup> (42.46). This indicated that heritability of the trait is mainly due to additive gene effect and selection is effective for such traits. Principle component analysis (PCA) is usually used to identify the most significant variables in the data. In this study the principle component analysis result showed that accumulative variability original data accounted about 100% for the traits. The first Principal component which accounted for 38.5% total variation were observed through agronomic traits such as: SD, DFF, HD, days to maturity, number of seed head<sup>-1</sup>. Similarily the second principal components which accounted for 17.4% of the total variations among the genoypes were attributed to differently from traits such as: yield ton ha<sup>-1</sup>, number of seed head<sup>-1 </sup>and head diameter were the most important of seed yield positive contributors in the second Principal component. Whereas the third and fourth PCA accounted 14.4% and 14% of variations for agronomic traits such as: TSW, HD and SD in PCA 3 and for PCA 4 TSW, seed yield ton ha<sup>-1</sup>, PH and DNM were the most important positive contributors traits for seed yield. Thus, these variation of traits observed in this experiment can help further as a selection index in genetic improvement of sunflower seed yield and its components.

Genetic Variability Studies for Yield and its Attributing Traits in Rice F4 Mapping Population (Oryza sativa L.)

An experiment was conducted at ICAR-IIRR during the wet season of 2023 in a mapping population derived from the cross TI-128 X BPT-5204, along with five checks in an augmented block design with eight blocks. This study revealed that, significant variability was present among the population for all the traits examined. High genotypic coefficient of variation was observed for number of tillers per plant (29.68), number of productive tillers per plant (30.56) and total number of grains per panicle (29.66). High phenotypic coefficient of variation and genotypic coefficient of variation was observed for the trait grain yield per plant. High heritability coupled with high genetic advance as percent of mean was recorded for number of tillers per plant, number of productive tillers per plant, total number of grains per panicle and grain yield per plant showing that these traits are regulated by additive gene effects, making them suitable for selection criteria in rice breeding programs. The traits viz., number of tillers per plant (0.42***), number of productive tillers per plant (0.41***), filled grains per panicle (0.20**), total number of grains per panicle (0.18**) and test weight (0.18**) exhibited significantly positive association with grain yield per plant.

Generation Mean Analysis for Estimating Gene Action, Heterosis and Inbreeding Depression in Yield and Foliar Disease Resistance in Three Faba Bean (Vicia faba L.) Crosses

This study was conducted at the Sakha Agricultural Research Station farm over three growing seasons (2019/20, 2020/21, and 2021/22) to introduce new faba bean genotypes possessing high yield potential and increased resistance to foliar diseases. The research involved six populations (P1, P2, F1, F2, BC1, and BC2) from three crosses (Cross-1: Santamora x Foal Sbai Labiade, Cross-2: Santamora x Misr 3, and Cross-3: Cairo 4 x Misr 3), analyzed using a randomized complete block design with three replications. Generation mean analysis revealed significant mid and better parent heterosis for most traits, indicating over-dominance. Inbreeding depression manifested negatively for chocolate spot and rust diseases but positively for seed count and seed yield per plant across all crosses. Non-allelic interactions were present for all traits, and dominance gene effects were more influential than additive gene effects for most traits. Mean performance analysis showed that F1 populations had lower disease reactions, but higher yields compared to the better parent, while F2 populations displayed greater genetic variability due to segregation. Heterosis was significant for yield and its components across all crosses but less beneficial for disease resistance. Inbreeding depression was significant and negative for disease reactions but positive for yield traits. The study found high broad-sense heritability for all traits, suggesting potential for phenotypic selection. Narrow-sense heritability values were moderate for qualitative traits and lower for quantitative traits. Genetic advance under selection indicated the highest gains were associated with moderate heritability values. Significant non-allelic interactions suggested the need for specific breeding strategies, with dominance gene effects more pronounced than additive effects. These findings support the feasibility of selecting high-yielding, disease-resistant faba bean genotypes through targeted breeding methods, aligning with previous research on the genetic inheritance of these traits.

Assessment of Genetic Variability in Okra (Abelmoschus esculentus L. Moench) Genotypes

The present investigation was carried out at New Orchard, Main Agricultural Research Station, UAS, Raichur, during late Kharif 2021-22 using thirty-one genotypes and laid out in Randomized Block Design (RBD) with three replications. High magnitude GCV and PCV were reported for the traits viz., fruit yield per hectare, fruit yield per plant, number of fruits per plant, plant height, leaf area per plant, number of ridges on fruit surface, fruit girth and fibre content indicates that maximum variability exists in these traits. The traits viz., number of nodes per plant, fruit length, ten fruits weight, shelf-life, stem girth, harvesting period and first flowering node recorded the medium GCV and PCV values. While, low GCV and PCV values were observed for the characters viz., number of leaves per plant, chlorophyll content, days to 50 per cent flowering and days to first flowering showing little variability for these characters. High heritability accompanied by high genetic advance over per cent mean was observed for number of ridges on fruit surface, number of fruits per plant, fruit yield per plant, fruit yield per hectare, fruit girth, leaf area per plant, plant height, number of nodes per plant, fruit length, fibre content, stem girth and ten fruits weight which indicates additive gene effects and selection based on these characters may be effective. Hence, characters showing high to moderate values of PCV, GCV and high estimate of heritability and genetic advance as per cent mean were considered as most important characters and selection of these traits will be more effective in improvement of fruit yield per plant.

Exploring intra-allelic and inter-allelic gene interactions influencing seed yield and its components in inter-varietal crosses of Mungbean (Vigna radiata (L.) Wilczek)

Mungbean (Vigna radiata (L.) Wilczek) is a versatile legume widely cultivated for its nutritional value and adaptability. Meeting the increasing global demand for nutritious food requires the development of high-yielding varieties. Therefore, understanding the inheritance of yield and component traits is crucial for defining effective breeding strategies. In the present study, we aimed to investigate the genetic effects and interactions governing inheritance through generation mean analysis. The four crosses viz., IPM409-4×VGG18-002, IPM409-4×WGG42, COGG13-39×VGG16-058 and COGG13-39×VGG18-002 and their five generations (P1, P2, F1, F2, and F3) were evaluated for nine yield and yield component traits during 2023 summer season. The significance of additive, dominance, and epistatic components viz.,additive×additive [i] and dominance×dominance [l] of each trait was found to be different among all the crosses. Mungbean is a self-pollinated crop, so only fixable gene effects can be exploited for trait improvement. In the IPM409-4×VGG18-002 cross, all the traits exhibited additive or additive × additive gene action except for plant height and seed yield per plant (dominance). The scaling test was significant in IPM409-4×WGG42 cross for all the traits, except for the number of pods per cluster. Except for the number of branches per plant in which the dominance effect was evident, additive or additive×additive gene effects were observed for the other traits. In COGG13-39×VGG16-058 and COGG13-39×VGG18-002 crosses, all the yield traits recorded fixable (additive and additive×additive) gene effects except for number of pods per plant in COGG13-39×VGG18-002. Considering the results of all four crosses, gene actions that exhibit consistency across crosses revealed that epistatic interaction (additive×additive) significantly influenced the expression of various mung bean traits. Therefore, the later generation selection of short-duration segregants with high yield, bold seeds, and resistance to yellow mosaic disease from the above populations can be carried out to develop commercially valuable mung bean varieties.

Dominant suppressor genes of p53-induced apoptosis in Drosophila melanogaster.

One of the major functions of programmed cell death (apoptosis) is the removal of cells that suffered oncogenic mutations, thereby preventing cancerous transformation. By making use of a Double-Headed-EP (DEP) transposon, a P element derivative made in our laboratory, we made an insertional mutagenesis screen in Drosophila melanogaster to identify genes that, when overexpressed, suppress the p53-activated apoptosis. The DEP element has Gal4-activatable, outward-directed UAS promoters at both ends, which can be deleted separately in vivo. In the DEP insertion mutants, we used the GMR-Gal4 driver to induce transcription from both UAS promoters and tested the suppression effect on the apoptotic rough eye phenotype generated by an activated UAS-p53 transgene. By DEP insertions, 7 genes were identified, which suppressed the p53-induced apoptosis. In 4 mutants, the suppression effect resulted from single genes activated by 1 UAS promoter (Pka-R2, Rga, crol, and Spt5). In the other 3 (Orct2, Polr2M, and stg), deleting either UAS promoter eliminated the suppression effect. In qPCR experiments, we found that the genes in the vicinity of the DEP insertion also showed an elevated expression level. This suggested an additive effect of the nearby genes on suppressing apoptosis. In the eukaryotic genomes, there are coexpressed gene clusters. Three of the DEP insertion mutants are included, and 2 are in close vicinity of separate coexpressed gene clusters. This raises the possibility that the activity of some of the genes in these clusters may help the suppression of the apoptotic cell death.

Unravelling the biochemical traits of traditional rice landraces of Kerala

Biochemical characterisatics of 70 traditional landraces of rice (Oryza sativa L.) of Kerala including various micronutrients, rice bran oil and oryzanol content were analyzed. Traditional varieties have demonstrated their potential as valuable reservoirs of nutrients, indicating their suitability for incorporation into future breeding programmes aimed to develop nutritionally enriched rice varieties. Among the genotypes studied Oorkayama and Thekkan were identified with highest rice bran oil content and γ oryzanol content respectively. Fe, Zn, Na, K, carotene and anthocyanin content showed a wide range of variation among the genotypes. The GCV estimates were high for rice bran oil content and oryzanol content indicating higher magnitude of variability due to genotypes for these characters. The investigation suggests preponderance of additive gene effects for all the biochemical constituents under study as indicated by the high heritability coupled with high genetic advance.

Genetic Variability and Heritability of Morpho-Agronomic Traits, Oil Yield and Fatty Acid Components in Linseed (<i>Linumusitatissimum</i> L.) Germplasm in Ethiopia

Comprehensive information on genetic variability and selection parameters is very crucial to design breeding strategies. However, very limited information is available in Ethiopian linseed germplasm. Therefore, the present study was conducted to estimate genetic variability, broad sense heritability and genetic advance; and determine selection for 19 quantitative traits using 126 genotypes (120 Ethiopian linseed accessions and six released varieties). The analysis of variance showed highly significant (P < 0.01) differences for all of the traits demonstrating the presence of high genetic diversity among the studied linseed genotypes. Higher differences between PCV and GCV estimates were observed for seed yield per plant and biological yield per plant, signifying the importance of environmental factors influence. High heritability coupled with high genetic advance was observed for seed yield per plant and biological yield per plant, indicating that this high heritability is due to additive gene effects and therefore, selection can be effective for the improvement of linseed for these traits. In addition, moderate heritability coupled with moderate genetic advance was recorded for oil yield per hectare, number of capsules, number of secondary branches, days to maturity, seed yield per hectare and plant height. These results indicated the existence of intermediate expression in these traits for both additive and dominance gene effect. In the present study, high heritability coupled with high GAM was observed for seed yield per plant and biological yield per plant, indicating greater contribution of additive gene action for the expression of these traits; and therefore, improvement can be achieved through selection in these traits.

Exploring Gene Action Underlying Post-Harvest Water Loss in Fresh Market Peppers

The objective of this study was to evaluate the genetic effects involved in post-harvest water loss of C. baccatum fruits and to correlate fruit morphological characteristics. Fruits of eight landraces of C. baccatum and their twenty-eight hybrids were evaluated in a randomized, complete block design. Analysis of variance, diallel analysis, phenotypic and genotypic correlation, and path analysis for eight fruit traits were performed. Fruit width, fruit length, dry matter content, and fruit wall thickness were determined by additive gene effects. On the other hand, the non-additive effects played more important role than additive ones, including water loss, cuticle thickness, exocarp thickness, and total soluble solids. The relationship of fruit traits suggested that indirect selection can be carried out from field experiments under different environmental conditions. Overall, genitors 4, 24, 50, and 56 should be selected to form new populations to improve these traits. The Brazilian pepper landraces of C. baccatum species are a source of genetic variability for plant breeders, and the new segregating populations emerging through the crossing of pepper lines with reduced water loss should be developed, opening new ways for conventional breeding.