Varietal Improvement Research Articles

An innovative natural speed breeding technique for accelerated chickpea (Cicer arietinum L.) generation turnover

BackgroundThe slow breeding cycle presents a significant challenge in legume research and breeding. While current speed breeding (SB) methods promise faster plant turnover, they encounter space limitations and high costs. Enclosed environments risk pest and disease outbreaks, and supplying water and electricity remains challenging in many developing nations. Here, we propose an innovative natural speed breeding (nSB) approach to achieve two generation cycles per rabi season under natural open field conditions in chickpea. This cost-effective, environmentally friendly method offers a location-specific alternative to prevalent SB techniques.ResultsTwo field experiments were conducted. First, 11-day-old fresh immature green (FIG) seeds exhibited an 80% germination rate, reducing the duration of the breeding cycle by 14%. In second, abiotic stresses such as atmospheric, nutrient, soil, and water stresses reduced the duration of the breeding cycle by 40%, 18%, 15%, and 18%, respectively. Despite the shortened generation time, we consistently obtained a minimum of 4–6 pods plant-1, ensuring continuity in the subsequent breeding cycle without compromising the nSB process.ConclusionOur investigation revealed that the combination of this location advantage (40%) with the sowing of FIG seeds (14%) enables Baramati to achieve progress from F2 to F5 in 1.5 years, with two generation cycles per rabi (cool) season. Using the nSB method can save 3 years, marking a notable reduction from the conventional six-year timeline. Moreover, incorporating the additional abiotic stresses mentioned above will further reduce the generation advancement time. Therefore, nSB accelerates generation turnover and reduces varietal improvement time at a low cost.

Rapid transfer of the leaf rust resistance gene Lr52 for the improvement of bread wheat cultivar HD3086

For varietal improvement, parental genotypes are crossed and advanced to generate homozygous lines with selection for desirable traits like disease resistance and yield. In the current study, leaf rust resistance gene Lr52 from Lr52/Yr47/2*Mace, the donor parent (DP), transferred to the recurrent parent (RP) HD3086, a popular Indian wheat cultivar, which has become susceptible to leaf rust. During the backcross breeding, the plants were grown sequentially under natural field conditions during the winter season and under controlled environmental conditions to take two crop generations during the summer season. Generations comprising F1, BC1F1, and BC2F1-3 plants were developed by crossing and successive backcrossing with RP HD3086 and further selfing to generate homozygous resistant lines. Plants with leaf rust resistance in backcross generations were selected phenotypically to identify the superior or similar plants as of RP HD3086. The Lr52/Yr47-linked SSR marker icg16c004_2 was initially utilised to confirm hybridity and foreground analysis in the BC1F1 generation but was found to be recombinant. Homozygous resistant (HR) lines in BC2F3 generation were selected based on leaf rust disease score and phenome recovery. Finally, the SSR markers unveiling parental polymorphism across the genome were employed to estimate the background recovery of phenotypically selected superior plants, revealing a recovery of 91.48 to 94.81 % of RP genome. The selected improved lines of HD3086+Lr52 displayed similar performance for most agro-morphological traits, and a few lines were also found to yield significantly superior to that of RP HD3086. Overall, the study shows the practical utility of phenotypic selection with intermittent selection under controlled and natural field conditions for improving popular cultivars with relatively higher speed and precision.

Rapid screening for resistance to Sitobion avenae (F.) and Rhopalosiphum padi (L.) in winter wheat seedlings and selection of efficient assessment methods.

Sitobion avenae (F.) and Rhopalosiphum padi (L.) are harmful pests of wheat [Triticum aestivum (L.)]. No genetic resistance against the aphids has been identified in commercial wheat varieties and resistance phenotyping can be time-consuming and laborious. Here, we tested a high-throughput phenotyping method to screen 29 commercial winter wheat varieties for alate antixenosis and antibiosis. We validated this method using comprehensive behavioural analyses, including alate attraction to volatile organic compounds (VOCs) and a feeding bioassay using an electrical penetration graph (EPG), subsequently highlighting possible sources of resistance. We observed differences in alate behaviour upon assessing alate settlement on wheat seedlings and attraction towards VOCs, revealing the importance of visual and early post-alighting cues for alate host selection. Aphid settlement was four times higher on the most preferred variety than on the least preferred variety. Using an EPG bioassay, we identified phloem feeding and stylet derailment parameters linked to resistance. We found antibiosis assessment on detached leaves to be an inadequate screen because it produced results inconsistent with intact leaves assessment. Alate and nymph mortality were identified as key traits signifying antibiosis, showing significant positive relationships with alate reproduction and nymph mean relative growth rate. Overall, antixenosis and antibiosis varietal responses were consistent for both aphid species. Alate settlement on wheat seedlings was a more efficient antixenosis screen than an olfactometer assay using VOCs. In addition to assessing alate and nymph survival for antibiosis, this allows for more rapid phenotyping of large numbers of genotypes to identify novel aphid resistance genes for varietal improvement. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Unravelling the physiological and molecular mechanisms of leaf color change in Acer griseum through multi-omics analysis

Paperbark maple (Acer griseum), an endemic and endangered wild plant in China, has red-colored autumn leaves of high ornamental and garden application value. Leaf color change serves as a crucial indicator for evaluating garden tree aesthetics; however, research on A. griseum's leaf color change remains limited. This study aims to elucidate the physiological and molecular mechanisms underlying leaf color change in maple leaves through physiological, transcriptional, and metabolic assays. Data analysis encompasses gene expression levels and metabolite changes in three distinct states of maple leaves: green, half-red, and red. The progessive decrease of chlorophyll and carotenoids and the continuous accumulation of anthocyanidins caused a sharp change in leaf coloration, which was most drastic in the green to half-red period. Subsequently, targeted metabolomics analysis was performed, and a total of 71 anthocyanidins were detected, and the content of eight types of anthocyanidins increased significantly in the half-red and red periods, compared with that in the green period; of which the multiplicative difference was the largest for cyanidin-3,5-O diglucoside, delivering the largest multiplicative difference. Thus, it was plausible that cyanidin-3,5-O-diglucoside-dominated compoundswere likely to be the main metabolites associated with leaf reddening. Correlation analysis revealed that 12 key transcription factors (TFs) were significantly correlated with the anthocyanin-related metabolites and structural genes, which play important regulatory roles during the biosynthesis of anthocyanosides in A. griseum. These findings offered useful insights into the molecular basis of leaf color variation in A. griseum; providing valuable information to guide targeted genetic breeding and varietal improvement strategies.

Genome-Wide Association Studies for Key Agronomic and Quality Traits in Potato (Solanum tuberosum L.)

Deciphering the genetic mechanisms underlying key agronomic and quality traits in potato (Solanum tuberosum L.) is essential for advancing varietal improvement. Phenotypic instability in early clonal generations and inbreeding depression, coupled with the complexity of tetrasomic inheritance, pose significant challenges in constructing mapping populations for the genetic dissection of complex traits. Genome-wide association studies (GWASs) offer an efficient method to establish trait–genome associations by analyzing genetic recombination and mutation events in natural populations. This review systematically examines the application of GWASs in identifying agronomic traits in potato, such as plant architecture, yield components, tuber shape, and resistance to early and late blight and nematodes, as well as quality traits including dry matter, starch, and glycoalkaloid content. Some key chromosomal hotspots identified through GWASs include chromosome 5 associated with tuber yield, starch content, and late blight resistance; chromosome 4 and 10 associations with tuber shape and starch content; chromosomes 1, 9, and 11 associated with plant height, tuber number, glycoalkaloid content, and pest resistance. It elucidates the advantages and limitations of GWASs for genetic loci identification in this autotetraploid crop, providing theoretical insights and a reference framework for the precise localization of key genetic loci and the discovery of underlying genes using GWASs.

Genetic Diversity Assessment of Brinjal Germplasm for Varietal Improvement

Forty-one (41) brinjal (Solanum melongena L.) germplasm of were evaluated at the field of Plant Genetic Resources Centre, BARI, Gazipur to identify the salient features and to assess genetic divergence of germplasm in the time of rabi season 2021-22. Distinct variation was observed in qualitative characters among the germplasm except two characters i.e. fruit cross section and fruit position. For the characters length breath ratio and calyx prickles of fruit, the topmost variation was found. In case of quantitative characters, variation was noticed maximum in the length of fruit (CV-43.79%), afterwards individual weight of fruit (CV-32.91%) and yield plant-1 (CV-30.12%). The highest number of germplasm was dispersed into cluster I. Among the clusters, cluster II and cluster III were occupied by ten germplasm, respectively. Cluster mean value was noted maximum in cluster II for the characters days required for 50% flowering (67.90%), plant height (97.97 cm), individual fruit weight (107.35 g), and yield plant-1 (2.51%). Among the principal components, 27.28% of the total variation interpreted by the first PC and the second PC clarified 22.36% of the variation. In the biplot, germplasm NF-15, NF-20, NF-13, NF-7, NF-4, NF-25, NF-16, and NF-2 etc. were independently far away from the studied germplasm by keeping a distance from the centroid. These results displayed distinctiveness and divergence of germplasm as regards of the studied traits. Populations with high values for the first eigen vectors are individual fruit weight (0.642), yield plant-1 (0.564), and width of fruit (0.313), these characters were the utmost significant contributors towards the diversity of germplasm in PC1. The germplasm NF-4 (3.45 kg), NF-30 (3.38 kg), and NF-25 (3.08 kg) were higher yielders among the tested germplasm and may be used for future varietal improvement of brinjal. J. of Sci. and Tech. Res. 5(1): 21-29, 2023

SOIL PROPERTIES AND AGRONOMIC EVALUATION OF TOMATO LINES (SOLANUM LYCOPERSICUM L.) IN THE NORTHWEST REGION OF GABON

The availability of tomato seeds adapted to local production conditions remains one of the major constraints for a sustainable tomato industry in Gabon. An agro-morphological characterization of ten tomato lines enabled us to assess their potential on the soil of the north-western region of Gabon. At this end, the properties of the soil were analyzed on the one hand, then, agronomic parameters of the tomato lineswere assessed on the other. Univariate and multivariate analyses of agronomic data were carried out using R software. Granulometric analysis revealed that the soil had a silty-sandy structure (29% coarse silt, 28.71% coarse sand). The mineralogical composition shows an assimilable phosphorus content of 15.51ppm and concentrations (in meq/100g) of potassium, calcium, sodium and magnesium of 0.41, 0.99, 0.32 and 0.60 respectively. For agronomic results, flowering time ranged from 26 to 36 DAS and first harvests from 70 to 84 DAS. Line L1 was the earliest and L9 the latest. For the yield, lines L4 (26.7 t/ha) and L8 (20.5 t/ha) were the most productive. The fruits with the best sizes were those of lines L2 (87.7 g) and L4 (86.6 g). Lines L1, L4, L5 and L8 were the firmest. The various diseases observed were downy mildew, spoon yellows and apical necrosis, with a moderate severity index (23,08 %) for all lines. These results show the agronomic performance of certain tomato lines on the sandy-loam soils of Gabon and for varietal improvement programs to increase tomatoes productivity in Gabon.

Genetic assessment of diverse rice germplasm for yield-related and stress tolerance traits

AbstractThe development of stress-resistant crops without compromising their yield and nutritional quality is one of the major challenges in plant biology. Plant breeders have made considerable effort in developing cultivars with high yield and tolerance to biotic and abiotic stresses. This research aimed to evaluate pre-breeding resources for favorable genes conferring good yield and resistance to biotic and abiotic stresses for rice varietal improvement. Two hundred forty diverse rice cultivars from top countries with which the United States imports and exports rice were selected from the Germplasm Resource Information Network (GRIN) collection, and these were characterized using molecular markers for various desirable traits. Among the cultivars, 16 were used as checks. The genes of various traits evaluated were grain number (Gn1a), panicle weight (WFP), cold stress tolerance (qSCT-11 and qCTS-12), anaerobic germination (AG1 and AG2), rice blast disease resistance (PiB, Pi-ta, Ptr, and Piz), wide compatibility (S5-n), and restoring ability (Rf4). Out of these 240 accessions, 192 have the Gn1a gene, 168 possess the qSCT-11 cold tolerance gene, 139 carry the Rf4 gene, 152 have the qCTS12 cold tolerance gene, 87 have blast resistance genes, and 44 possess the WC gene. None of the 240 accessions possess the WFP (Wealthy Farmer’s Panicle) gene. The selections with favorable genes can be used by breeders as potential donor parents for varietal improvement programs to produce new and promising cultivars with desired specific traits that may contribute towards alleviating global issues related to food security.

An Analytical Study on Growth Performance of Major Food Grain and Oilseed Crops in Context of Food Security: Rajasthan, India

Background: Productivity, as a source of growth has been a significant premise of analytical investigation in economics all along, however it gained an empirical momentum in the recent years only and has become a necessary index to growth. Present paper estimates growth rate of area, production and productivity of food grain and oilseed crops in Rajasthan. Methods: To analyse growth performance of food grain and oilseed crops Rajasthan time series, data on area, production and yield were collected from 1976-77 to 2018-19. The time-series data were collected on area, production and yield of selected crops from the Directorate of Economics and Statistics (DES), Directorate of Agriculture (DOA) and Rajasthan State Agriculture Department. The compound growth rates (CGRs) of area, production and productivity of selected crops in Rajasthan were calculated using the exponential function. Result: The study revealed that production, productivity and area of total food grains was recorded a positive and highly significant annual growth at the rate of 3.18%, 2.19% 0.63% per annum, respectively. The production, productivity and area of total oilseed was observed a positive and highly significant annual growth rate of 7.63%, 2.07% and 4.27% per annum, respectively. The area under barley, gram and sesamum reduced during the study period. Therefore, the technological support through the varietal improvement and extension support is required.

Genetic Enhancement of Blast and Bacterial Leaf Blight Resistance in Rice Variety CO 51 through Marker-Assisted Selection

The increased use of chemicals in rice farming poses significant issues regarding the emergence of pesticide/fungicide resistance and environmental sustainability concerns. This study was aimed at the genetic improvement of blast, bacterial leaf blight (BB) and gall midge resistance in a popular rice variety CO 51 which already harbours a blast resistance gene Pi54. Efforts were made to pyramid an additional blast resistance gene Pi9 along with two BB resistance genes (xa13 and Xa21) and two gall midge resistance genes (Gm1 and Gm4) into an elite rice variety CO 51 to enhance the resistance level to biotic stresses. The superior lines were selected using functional markers conferring resistance to blast (NBS4 and Pi54MAS linked to Pi9 and Pi54 genes, respectively) and BB [(xa13Prom (xa13) and pTA248 (Xa21)] and SSR markers linked to Gm1 (RM1328) and Gm4 (RM22550) for phenotypic screening and agronomic evaluation. The genotyping and phenotyping of F6 and BC2F6 progenies of CO 51 X 562-4, for agronomic traits and resistance to BB and blast, identified ten superior progenies in F6 and five superior progenies in BC2F6. The breeding lines harbouring both xa13+Xa21 exhibited high levels of resistance to BB (score ≤ 1 cm) and Pi9+Pi54 exhibited strong resistance to blast (score ≤ 2). Identified lines can be evaluated further for varietal improvement or utilised as genetic stocks in breeding programs.

Characterization based on colorimetry, physiology and sensory attributes among traditional jujube cultivars of Sindh, Pakistan

Jujube (Ziziphus spp.) fruit is attaining incredible attention in current global climatic changing scenario as the fruit has significant nutritional value but remained unexplored in past. Fifteen Jujube cultivars were selected at Jujube Research Station Tandojam, Sindh Pakistan, to exploit their morphological, physiochemical, color and sensory attributes. Measured traits like tee shape diverged as semi erect, erect and spreading whereas leaf shape was also found highly variable. Thorn attachment differed as cadoucous, partial and persistent and fruit shape was set as round, oblong, oval and ovate. Maximum leaf blade length was counted by Soofi sanghar (9.0cm) while lowest was found in Gola soghat (5.1cm). Maximum fruit mass was recorded in cultivar Late gola (31.57 g) whereas least was observed in Khirol mukkhri (5.63 g). Maximum stone weight was estimated in Early gola (10.55 g) whereas minimum was recorded in Khirol desi (6.4 g). Highest glucose level was observed in Soofi local (4.46 g 100 mL−1) while lowest glucose level was recorded in Khirol desi and Khirol Ratam (3.53g 100 mL−1). Best cultivars by appearance were Late gola and Early gola followed by Gola saffina, Gola soghat, Soofi sanghar and Soofi local. Findings of this study are useful for varietal improvement and to run successful breeding programmes. Commercially relevant features evaluated in this study are highly beneficial for jujube varietal identification and germplasm conservation

Resistance response of yellow maize inbreds and F1 crosses against Philippine downy mildew [Peronosclerospora philippinensis (Weston) C.G. Shaw]

Maize is one of the world's most important staple crops, yet various pests and diseases impede its optimal production. Philippine maize downy mildew disease (PDM) caused by Peronosclerospora philippinensis (Weston) Shaw is one of the most devastating diseases in corn-growing areas in Asia. Breeding for resistant varieties is the most cost-effective and environmentally safe alternative for controlling the disease. In this study, we evaluated the resistance responses of yellow maize inbreds and hybrids against PDM to select promising genotypes for genetic analysis and varietal improvement. Resistance trials under greenhouse conditions were conducted to investigate the PDM resistance response of 14 selected CIMMYT lines (CMLs) and IPB Var 6 (susceptible check) to select potential parents prior to hybridization. CML 431 and CML 452 were identified to have significantly low disease incidence among the test genotypes. Subsequently, disease evaluation of the two inbred lines with putative DM resistance, four experimental hybrids derived from these inbred lines, and checks was performed in the field. Across three validation trials, inbred CML 431, and hybrid CML 452 × CML 431 showed degrees of resistance to PDM. This study's findings enabled the identification of resistant lines to downy mildew for the generation of mapping populations for genetic association studies, as well as the establishment of experimental units for transcriptomics research.

Diversity, conservation and utilization of grain legumes: A potential source for food and nutritional security in Nepal

Grain legumes are precious crops of Nepal in terms of the dietary protein supplement ample concentration of micronutrients, and role in crop intensification and ameliorating soil fertility. About 11% of the cultivated area is occupied by grain legumes that include lentil, chickpea, grasspea, fieldpea, fababean, pigeonpea, soybean, blackgram, horsegram, ricebean, cowpea, and mungbean. About 100 genera and 379 species of legumes are distributed in diverse agroecological zones ranging from terai to the alpine region of Nepal, with growth habits ranging from annual to perennial shrubs. Out of the 379 species of legumes which include grain, vegetable, and forage legumes, 262 are native, and 20 species belonging to the sub-group Papilionacae are used as food legumes. Highest food legume species diversity has been recorded in Macrotyloma (34 spp.), followed by Crotalaria (18 spp.), Vigna (15 spp.), Lathyrus (7 spp.), Vicia (6 spp.), Cajanus (5 spp.), Trigonella (5 spp.) and Phaseolus (4 spp.). Other genus having 1-3 species includes Cicer (3 spp.), Mukuna (3 spp.), Glycine (2 spp.), Canavila (2 spp.), Pisum (2 spp.), Lablab (2 spp.), Pachyrrhizus (1 sp.), Psophocarpus (1 sp.), Lens (1 sp.) and Cyamopsis (1 sp.). Research on grain legumes was initiated in 1976 and a systematic collection of grain legume landraces was done in 1987 by the Grain Legumes Research Program (GLRP). Past collection missions organized in collaboration with the International Development Research Centre (IDRC), the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), the International Center for Agricultural Research in the Dry Areas (ICARDA), and other institutes have resulted in the collection of 1107 landraces and provided an opportunity for their inclusion in the variety improvement program. National Agricultural Genetic Resources Center (NAGRC) has conserved 2936 landraces of different legumes, 951 landraces have been kept in gene banks of ICARDA center, while GLRP Khajura has active collections of 218 landraces and 627 exotic germplasm of various legume crops. Varietal improvement programs resulted in the development of 51 varieties, while 6 varietes were registered and two varieties were de-notified in food legumes (lentil, chickpea, soybean, cowpea, black gram, mungbean, pigeon pea, rice bean, faba bean, grass pea, and kidney bean).

Exploring the glycaemic impact and culinary qualities of rice through Genome-Wide Association studies on starch composition and viscosity profiles

Starch is the major component in rice grain that determines not just the cooking and eating quality of rice but also the nutritive value of a particular rice variety. It also plays a key role in determining the consumer acceptance of a variety, its trade and market value. Thus, it is essential to assess the available genetic variation for starch composition in the rice germplasm and its effective utilization in varietal improvement programmes. In assessing the nutritional value of rice, resistant starch has received a lot of attention lately. It plays vital roles in reducing glycaemic index and post prandial glucose. The study evaluated a set of 192 rice genotypes of diverse origins for starch composition and viscosity parameters and observed significant variation for these traits. Genome-wide association studies (GWAS) using the multi-locus models BLINK and FarmCPU in GAPIT software resulted in the identification of 45 significant Marker Trait Associations (MTAs) distributed in 11 of the 12 chromosomes except chromosome 8. A total of 15 annotated genes in the 250 kb LD region flanking the significant SNP were identified as putative candidates through insilico analysis. Some of the important genes underlying the MTAs found were GBSSI, OsACS, SSG6, RSR1 and OsPUL which are known to be associated with starch synthesis in rice. The significant MTAs could be deployed in manipulating the starch composition and developing tailored rice varieties for various consumer needs.

Effect of Gamma Irradiation on Embryogenic Calli of Rice and Subsequent Shoot and Regeneration

This study was carried out during May 2021 to January 2022 at the Tissue Culture Laboratory of Biotechnology Division, Bangladesh Institute of Nuclear Agriculture (BINA), Mymensingh, Bangladesh for callus induction and regeneration ability of plantlet from low doses irradiated embryogenic calli of Binadhan-13 and BR5 (Dulabhog). The effect of low gamma rays such as 4, 6 and 8 Gy were observed in vitro shoot, root and plantlet formation. Two different incubation conditions such as light and dark incubation were maintained. Between two varieties, Binadhan-13 showed the highest ability of callus induction in both conditions. Callus induction was significantly higher under dark condition (77.14%) than light condition (67.14%) ‍at 21 days. Data revealed that gamma rays affect both shoot and root regeneration ability of embryogenic callus. Shoot regeneration ability was the highest at 4 Gy in Binadhan-13 (60%) and gradually decreased with the increased doses of gamma rays. Among the treatments, shoot regeneration ability (60% in Binadhan-13 and 50% in BR5) was higher at 4 Gy dose of gamma ray followed by 6 Gy where shoot regeneration ability was 55% and 45% in Binadhan-13 and BR5 respectively. In root induction, the highest root induction ability (80%) was observed in the cultivar Binadhan-13 at control condition. Like shoot regeneration, 4 Gy gamma ray showed better root induction in both the varieties (70% in Binadhan-13, 60% in BR5). The in vitro regenerated plantlets from irradiated embryogenic calli were successfully transferred to soil in pots. The regeneration protocol could be further used for varietal improvement of rice varieties using nuclear technique (60Co gamma ray). Bangladesh J. Nuclear Agric, 37(2): 29-42, 2023

Evaluation of cultivated gladiolus varieties of Bangladesh and radio sensitivity test for varietal improvement

The study was conducted at the research field of Nalitabari Sub-station, BINA, Sherpur during the period November 2019 to May 2020 to characterize, evaluate and select promising gladiolus varieties suitable for Bangladesh and to determine the optimum dose of radiation for LD50 for varietal improvement. The parameters studies were plant height, days to 1st flowering, number of leaves per plant, leaf length, leaf breadth, length of spike, length of rachis, number of flower per spike, flower diameter, number of corms per plant, weight of single corm, vase life, per cent germination, per cent survivability, shoot length and root length. The longest plant (154.2 cm) was observed in White Prosperity, while the shortest plant (101.7 cm) was in Regency. The longest leaf (70.3 cm) was found in Red Cascade and the shortest leaf (48.0 cm) was found in Her Majesty. The highest number of floret per spike was produced by Red Cascade (17.3) followed by White Prosperity (17.0). The Regency produced the lowest number (8.0) of floret per spike. The longest vase life (9.3 days) was observed in American Beauty followed by (8.7 days) Red Cascade, while the shortest vase life (5.7 days) was recorded in Wine and Roses. In radio sensitivity test, 30-40 Gy of gamma irradiation would be the optimal dose for inducing useful mutation in gladiolus. Bangladesh J. Nuclear Agric, 37(2): 43-56, 2023

Genome wide association study reveals key genic regions controlling oil palm vegetative characters in wild population of Cameroon

Cameroon’s oil palm germplasm is contributing a lot towards the improvement of genetic variation in the base oil palm population used in breeding programs around the world. There is a new oil palm germplasm collection at Dibamba constituted of 169 wild accessions but whose genomic study was not implemented before now. Genome-wide-association study is considered as a powerful tool to identify genomic specific allele variants controlling the expression of important agronomic traits in crops. This approach could potentially accelerate varietal improvement in plant breeding programs. The objective of this study was to identify genic regions across the investigated oil palm genomes which are conferred to control natural variation for oil palm vegetative traits such as leaflet width and leaf area. The allele and genotype frequencies were significantly detected to be in Hardy-Weinberg equilibrium (P<0.01) for these vegetative traits. Across the genome, important numbers of single nucleotide polymorphisms were associated with the oil palm leaflet width and leaf area characters. This suggests that the considered regions may contain genes controlling the phenotype variation expression of the trait of interest and should be useful under positive selection in subsequent breeding of the oil palm.

Evaluation of Sugarcane Families and Identification of Promising Families for Cane Yield and Juice Quality Traits in Early Selection Stages

The utilization of superior parental lines and identification of promising families enhance the genetic gain in sugarcane. To identify the promising families, 1620 progenies derived from twenty two crosses involving genetically diverse historical parents were evaluated for cane yield and juice quality attributing traits. The mean number of millable canes per clump (9.00), cane girth (2.32 cm), millable cane height (217.00 cm) and Brix% in juice (20.79%) were recorded. The significant variance, high broad-sense heritability and genetic advance over mean suggested that number of millable canes per clump, single cane weight, millable cane height, Pol% in juice and Brix% in juice are suitable for family evaluation. Based on progeny performance, families of Co 86032 × CoVC 14061 and Co 0312 GC, were found significantly superior compared to most popular clonal check, Co 86032 for number of millable canes per clump, similarly, CoVC 14062 × Co 89003 and Co 86002 × ISH 69 for cane girth, and CoVC 14062 × Co 89003, Co 11015 and Co 87015 for CCS% in juice content at early selection stages. Among 22 families studied, the four families viz., Co 86032 × CoVC 14061, CoVC 14062 × Co 89003, CoVC 14062 GC, Co 87015 GC and Co 11015 GC, produced higher percentage of population selection with acceptable range for commercially important traits (Brix% in juice, cane yield components). These identified promising families can be further exploited in sugarcane varietal improvement.

Genome-wide association analysis to identify genomic regions and predict candidate genes for bunch traits in grapes (Vitis vinifera L.)

Grape quality traits like bunch and berry size are important as they influence consumer acceptance and marketability of the produce. Therefore, a deeper understanding of their genetic determinant is crucial for varietal improvement. In this study, association mapping was performed using SNP marker data and three season phenotyping data of 122 diverse grapevine genotypes. Genotyping by sequencing (GBS) identified 1,08,777 high quality SNPs distributed on all the chromosomes. A good correlation was observed across three seasons for berry size and bunch length. Genome-wide association analysis using six different models identified significantly associated SNPs for each of the traits. We identified 13 significant SNPs associated with bunch length, seven of them were located on linkage groups (LGs) 9 and 15. For berry diameter, 18 significantly associated markers located on LGs 4, 5, 17 and six other LGs were identified. Fourteen SNPs mainly on linkage groups 3 and 5 were identified for berry weight. Three closely linked markers on LG3 explaining about 20-25 % variation suggested presence of major QTL for berry weight on LG3. Candidate genes were mined in the genomic regions containing significant SNPs explaining large phenotypic variation. Twenty-one genes for bunch length, 28 genes for berry length, 22 genes for berry diameter and 25 genes for berry weight were predicted. Several predicted genes were found to have function related to cell enlargement, cell morphogenesis and other physiological processes required for cell growth and development.

Phenotypic diversity analysis of Polygala tenuifolia Willd germplasm resources in China

AbstractPolygala tenuifolia Willd is a perennial herb in the family Polygalaceae and is used as an expectorant and stimulant in traditional Chinese medicine. There is a large demand for P. tenuifolia, while the good cultivars of P. tenuifolia are not enough. In this study, we collected 157 germplasm resources of P. tenuifolia from different regions in China, and 12 phenotypic traits of these samples were analyzed using correlation analysis, principal component analysis (PCA), and cluster analysis methods. The correlation analysis showed the associations between different traits, and the first four principal components contributed 62.63% of the total variation. They contained most of the information of five above-ground traits and eight root traits. Phylogenetic clustering divided materials divided into four taxa, with characteristics of high-yielding specific material, long-rooted specific material, multi-branching specific material, and high plant height specific material, respectively. Our study provides the material and theoretical basis for the utilization of germplasm resources, parental selection, and varietal improvement of P. tenuifolia.