Development of high yield and tomato yellow leaf curl virus TYLCV resistance using conventional and molecular approaches: a review

Tomato (Solanum lycopersicum L.) belonging to the family Solanaceae is the second most consumed and cultivated vegetable globally. Since the ancient time of its domestication, thousands of cultivated tomato varieties have been developed targeting an array of aspects. Among which breeding for yield and yield-related traits are mostly focused. Cultivated tomato is extremely genetically poor and hence it is a victim for several biotic and abiotic stresses. Among the biotic stresses, the impact of viral diseases is critical all over tomato cultivating areas. Improvement of tomato still largely rely on conventional methods worldwide while molecular approaches, particularly Marker Assisted Selection (MAS) has become popular across the globe as a fast, low cost and precise tool which is essential in present day plant breeding. In this review paper, breeding tomato for high yield and viral disease resistance, particularly to tomato yellow leaf curl virus disease (TYLCVD) using conventional and molecular approaches will be discussed. Lining up of this set of information will be useful to those who are interested in tomato variety development with high yielding and TYLCVD resistance

Genotypic character relationship and phenotypic path coefficient analysis in chilli pepper genotypes grown under tropical condition

Background: Studies on genotypic and phenotypic correlations among characters of crop plants are useful in planning, evaluating and setting selection criteria for the desired characters in a breeding program. The present study aimed to estimate the phenotypic correlation coefficients among yield and yield attributed characters and to work out the direct and indirect effects of yield-related characters on yield per plant using path coefficient analysis. Twenty-six genotypes of chili pepper were laid out in a randomized complete block design with three replications. Results: Yield per plant showed positive and highly significant (P≤0.01) correlations with most of the characters studied at both the phenotypic and genotypic levels. By contrast, disease incidence and days to flowering showed a significant negative association with yield. Fruit weight and number of fruits exerted positive direct effect on yield and also had a positive and significant (P≤0.01) correlation with yield per plant. However, fruit length showed a low negative direct effect with a strong and positive indirect effect through fruit weight on yield and had a positive and significant association with yield. Conclusion: Longer fruits, heavy fruits and a high number of fruits are variables that are related to higher yields of chili pepper under tropical conditions and hence could be used as a reliable indicator in indirect selection for yield

Genetic analysis and selection criteria in Bambara groundnut accessions based yield performance

The knowledge of genetic variability and breeding techniques is crucial in crop improvement programs. This information is especially important in underutilized crops such as Bambara groundnut, which have limited breeding systems and genetic diversity information. Hence, this study evaluated the genetic variability and established the relationship between the yield and its components in Bambara groundnut based on seed weight using multivariate analysis. A field trial was conducted in a randomized complete block design with three replications on 28 lines. Data were collected on 12 agro-morphological traits, and a statistical analysis was conducted using SAS version 9.4 software, while the variance component, genotypic and phenotypic coefficient variation, heritability, and genetic advance values were estimated. A cluster analysis was performed using NT-SYS software to estimate the genetic relations among the accessions. The results showed significant variability among the accessions based on the yield and yield component characteristics. The evaluated lines were grouped into seven primary clusters based on the assessed traits using the UPGMA dendrogram. Based on the overall results, G5LR1P3, G1LR1P3, G4LR1P1, G2SR1P1 and G3SR1P4 performed the best for the yield and yield components. These improved lines are recommended for large-scale evaluation and utilization in future breeding programs to develop high-yield Bambara groundnut varieties

Genotype × Environment interaction and stability analyses of yield and yield components of established and mutant rice genotypes tested in multiple locations in Malaysia

Genotypes evaluation for stability and high yielding in rice is an important factor for sustainable rice production and food security. These evaluations are essential especially when the objective of the breeding program is to select lines with high adaptability and stability. This study was conducted to investigate G × E interaction over ten environments across the peninsular Malaysia for yield stability in fifteen rice genotypes comprising twelve mutant lines and three established varieties. The experiment was laid out in a randomized complete block design with three replications across the environments. Yield component traits were evaluated over multiple harvests and measured as number of tillers per hill, filled grains per panicle, grain weight per hill and yield per hectare. Data analyses were through analyses of variance and stability analyses were conducted for univariate and multivariate stability parameters. The pooled analysis of variance showed highly significant differences among genotypes, locations, seasons, and genotypes by environment (G × E interaction) for all the traits. Based on univariate (bi, , σi2, Wi2, YSi) and multivariate (AMMI and GGE biplot) stability parameters, rice genotypes were classified into three main groups. The first group are genotypes having high stability along with high yield. These genotypes are widely adapted to diverse environmental conditions. The second group is a genotype that exhibited high yield but low stability, this genotype is suitable for specific environments. The last group is genotypes with low yield and high stability. Genotypes in this class are more suitable for breeding specific traits or yield component compensation such as the capacity to recover rapidly from stresses. Significant rank correlations were measured for regression slope (bi), deviation from regression (), Shukla stability variance (), Wricke’s ecovalence (), and Kang stability statistic (YSi) for all the traits

Physicochemical characteristics and nutritional compositions of MR219 mutant rice and their effects on glycaemic responses in BALB/c mice

The awareness of the general public on healthy foods has been a major concern and people are looking for the right variety of rice for diabetic patients. High amylose content rice with low glycaemic index (GI), which is an indicator of sugar release in the blood, is beneficial for human health. The present work was aimed to determine the physicochemical characteristics and nutritional compositions of MR219 mutant rice, and the effects of amylose content to blood glucose response and glycaemic index in field condition. A total of 31 M4 mutant lines (ML1 to ML31) were evaluated for physicochemical characteristics and nutritional compositions in comparison with the parental variety, MR219. In glycaemic response study, 48 female BALB/c mice were fed with glucose (a baseline), saline water, two check varieties (MR219 and MRQ74) and four selected mutant lines with different amylose contents. The physicochemical and proximate analysis revealed highly significant differences among the mutant lines. Some mutant lines improved amylose content and nutritional composition. Mutant ML3 had slightly higher amylose content than the parental variety and was recommended for glycaemic responses. However, the field experiment results showed two mutant lines namely; ML3 and ML30, having significantly lower glucose reading (5.49 mmol/L and 5.47 mmol/L, respectively) as compared to the parental variety and other mutant lines. The glucose level was found highest at 60 min after feeding but significantly dropped at 120 min. The normal glucose reading in ML3 and ML30 also resulted in moderate GI values (65% and 66%, respectively). As low and moderate GI foods are recommended for diabetic patients, ML3 and ML30 had high potential for their consumption, and can be suggested for further breeding program to develop low GI rice

Blast disease intimidation towards rice cultivation: a review of pathogen and strategies to control

Rice blast is the most destructive disease to rice production globally. The objective of this review is to know the fundamentals of rice blast disease and to know the different methods for controlling blast disease. Rice blast disease has been recognised in more than 85 rice-producing countries worldwide. Currently, more than 100 R genes for blast resistance have been identified in rice. These resistance genes can be introgressed into a susceptible variety through marker-assisted backcrossing. Infested residues and seeds are the primary inoculum sources to spread the disease. Considering the importance of this disease, various management approaches have been practiced to control blast disease. The use of resistant varieties is an important measure to manage the disease. This review will provide use fulfacts about the pathogen and its epidemiology, assessment of resistance genes and effective control measure of rice blast disease through breeding and management. This update information will be helpful and guide to the research students and rice breeders to develop durable blast resistant rice varieties. So farmers will able to manage the blast disease in future

Half diallel analysis for biochemical and morphological traits in cultivated eggplants (Solanum melongena L.)

Eleven morphologically diverse cultivated eggplant accessions were used for hybridization following half diallel mating design to obtain 55 hybrids. Evaluation of hybrids along with the parents was conducted over two locations followed by randomised complete block design with three replications to study gene action and combining ability of 15 morphological and biochemical traits. The analysis of variance indicated highly significant differences among the environments and interaction of genotype and environment, except for fruit length to width ratio. Additive gene effects were significant for the inheritance of these traits and expression of these additive genes were greatly affected by environments. The general combining ability (GCA) was greater than their respective specific combining ability (SCA) for all traits except for fruit yield per plant. High values of GCA and SCA effects for characters of interest were dispersed among different genotypes. From this study it was observed that the best parental line was BT15 based on days to first flowering, total number of fruits per plant, total soluble solids and total phenol content. Besides, the parent BM5 showed good general combining ability effects for fruit yield per plant, fruit length and fruit length to width ratio and the parent BB1 performed good general combining ability for fruit diameter, fruit girth and fruit weight. Besides, other parents showed the best performance for only one trait. On the other hand, the hybrid BT6 × BT15 was reported bearing early flowering with high total phenol content and the hybrid BM9 × BB26 has high fruit yield with high soluble solids. Besides, the hybrid BM9 × BB1 has a high fruit diameter and fruit weight. All other hybrids except for these three (BT6 × BT15, BM9 × BB26 and BM9 × BB1) were shown the best performance for only one trait. Hence, based on the desired trait, the hybrid can be selected for future use after large scale evaluation

Determination of lethal (LD) and growth reduction (GR)doses on acute and chronic gamma- irradiated Bambara groundnut [Vigna subterranea (L.) Verdc.]varieties

Bambara groundnut is a highly nutritious underutilized legume with enormous potential to sustain food security in resource-poor countries. However, its potential for improvement through conventional breeding (< 2% success rate) limitation due to the nature of the flowers. Thus, the most viable method of improving this crop is by creating genetic variability through induced mutagenesis. The present study was conducted to evaluate the radiosensitivity of two Bambara groundnut varieties irradiated with acute and chronic gamma irradiations to determine the lethal dose (LD) and growth reduction dose (GR). Healthy seeds of both varieties were exposed to acute gamma irradiation using Cesium-137 at 0, 25, 50, 75, 100, 125, 150, 175, 200, 250, and 300 Gy. For chronic irradiation, two-week-old seedlings of the two genotypes were exposed to accumulated doses of 0, 8.52, 17.04, 35.56, 34.09, 42.61, 59.65, 93.74, 144.87, 255.64, and 570.94 Gy, respectively, in Gamma Green House (GGH) for 60 days. The result from the variance analysis indicated highly significant differences (P < 0.01) for all evaluated traits except for internode length. A linear regression model was developed to determine the mean LD and GR of both genotypes. The established lethal doses (LD25, 50, 75) for acute gamma irradiation on Ex-Sokoto variety were 75, 160, and 250 Gy while 68, 148, and 227 Gy were recorded for Karo variety, respectively. For chronic irradiation, the established growth reduction doses for Ex-Sokoto were 47, 250, and 444 Gy, whereas 70, 264, and 452 Gy were observed in Karo. Variations were observed between the gamma-irradiated genotypes and the methods of irradiations. Generally, the growth, development, and survival rate of Bambara groundnut increase with a decrease in gamma-irradiation doses. The established LD and GR doses from this study can be utilized in large-scale mutagenesis breeding programs for generating a wide range of mutants in Bambara groundnut

Development of anthracnose disease resistance and heat tolerance chili through conventional breeding and molecular approaches: a review

Chili (Capsicum annuum L.) is the popular spicy vegetable crops belonging to family Solanaceae. Chili peppers are known for their pungency characteristic due to the presence of capsaicinoids that classifies them into hot or sweet pepper. Chili is used as spices, folk remedies for diseases, vegetables, and coloring agent showing a diverse role in human’s life. However, its production is hampered by different biotic stress and abiotic factors. Similarly, the unavailability of high yielding varieties, high temperature, and disease incidence, particularly, anthracnose disease, are the major constraints responsible for the low production of chili pepper. The advents of molecular markers, advancement in quantitative trait loci by classical genetic analysis, and conventional breeding have shown the number of genes for many important and major traits. While the newly developed genotyping technologies and next generation sequencing have led to the discovery of molecular basis for economic important characters in the chili genome and generate large scale data for genomic resources. Based on this background, this review summarizes progress in the development of anthracnose disease-resistant and heat-tolerant chili genotypes through conventional breeding and molecular approaches. This review would help plant breeders in understanding the phenotypic and genetic make-up of capsicum genotypes and provides opportunities for pyramiding two respected genes with the help of diversified phenotypic and molecular marker evaluation

Genetic diversity, heritability and genetic advance of Solanum melongena L. from three secondary centers of diversity

Indo-Birmanian is considered as the domesticated region and primary center of eggplant diversity from where it spread to other secondary centers of diversity. In this study, the genetic diversity among 56 eggplant genotypes from three secondary centers of diversity (Bangladesh, Malaysia and Thailand) was assessed using 11 morphological traits. The experiment was laid in a complete randomized block design with three replications. A wide significant variation was observed for all the morphological traits, and highly significant differences among the three centers of diversity. High heritability and genetic advance was found for different traits i.e. fruit length, fruit diameter, fruit girth, fruit length to width ratio, average fruit weight, number of fruits per plant, fruit yield per plant, plant height and number of primary branches per plant. The selected best traits i.e. number of fruits per plant, average fruit weight and fruit yield per plant showed high heritability along with high genetic advance and less environmental influence but the high value of PCV and GCV. So these traits could be useful for selection criteria in the future breeding program. These results are relevant for evolutionary studies, breeding programs, and management of eggplant genetic resources