Endosperm Color Research Articles

The sugary enhancer1 (se1) Allele Is Associated with Significant Decreases in Carotenoids and Tocotrienols in Yellow (Y1) sugary1 (su1) Sweet Corn

A distinctive phenotype of homozygous sugary enhancer1 (se1) sweet corn (Zea mays) inbreds and hybrids is a light-yellow color in mature kernels. Carotenoid pigments contribute to yellow endosperm color in maize and are of nutritional importance in the human diet along with the related tocochromanols, the E vitamins. Tocochromanols, including both tocopherols and tocotrienols, are antioxidants important in human nutrition and cardiovascular health. Effects of the presence of sugary enhancer1 allele on carotenoid and tocochromanol levels in homozygous su1, Y1 endosperm were evaluated in the Wisconsin Sweet Corn Diversity Panel. Although population structure was present in the panel, the majority of variation in carotenoid levels was explained by genotype at the se1 locus. se1 was associated with significant decreases in the amount of lutein (34%) and zeaxanthin (36%) and decreases of tocotrienols by 12% to 65%. There were no significant differences in β-carotene and tocopherol levels between the two groups. Given that the biosynthesis pathways for carotenoids and tocochromanols are well defined, these differences in carotenoids and tocotrienols between su1Se1 and su1se1 inbreds point to a broader role of se1 alleles in metabolic pathways beyond endosperm starch production.

Taxonomic significance of seeds and seedling morphology in the threatened Indian endemic palm genus Bentinckia (Arecaceae)

A comparative morphological study was carried out to evaluate the taxonomic significance of seed and seedling traits of Bentinckia condapanna and B. nicobarica (Arecaceae), the threatened endemic palm species. Both species are unique and have specific requirements for seedling recruitment. An effort was made to cultivate these species ex situ at the Botanical Survey of India’s National Orchidarium and Experimental Garden (NOEG) in Yercaud, Tamil Nadu, and Dhanikhari Experimental Garden cum Arboretum (DEGCA), in Andaman & Nicobar Islands. The seeds and seedlings of the two species differ in the beak and ridges on the seed, endosperm colour and the shape of the eophyll.

Kernel Trait and Genetic Variability Analysis in BC2F1 Maize Lines Derived from Zea nicaraguensis Crosses

Maize (Zea mays L.) is an important cereal crop with significant applications in food, feed and industrial applications. This study aimed to increase maize yield and quality by evaluating core traits in introgressed Zea nicaraguensis individual’s recipients of LM13 and LM14 maize inbred lines. Kernel type, shape, color, dimensions and weight were assessed in 35 BC2F1 plants using standardized descriptor guidelines. Analysis of genotypic and phenotypic coefficients of variation, heritability and genetic progress showed significant genetic diversity and the influence of environmental factors. Significant sources of variability highlighted by principal component analysis were kernel color, endosperm color, and 100-seed weight. High heritability and genetic progress in kernel color and length-to-width ratio indicate great selection potential. Reintroducing the diversity lost in cultivated maize inherent in Zea nicaraguensis has the potential to improve both its agronomic performance and quality. Future research should aim to identify genetic markers and examine the interaction between genetic and environmental influences to optimize maize varieties for specific environments and consumer preferences, ultimately contributing to global food security and agricultural sustainability.

Improving the network architecture of YOLOv7 to achieve real-time grading of canola based on kernel health

The occurrence of heated and immature canola kernels caused by excessive drying and frost damage is undesired by grain buyers due to lower oil yield and diminished market value. The current grading process is visually examining each kernel's endosperm color and counting the damaged seeds. As this process is time-consuming, laborious, and prone to errors, this study proposes an automated grading technique based on object detection, multi-object tracking, and counting. The detection task was achieved via an improved YOLOv7 network (YOLOv7_ours) that was modified to increase its performance in accurately identifying small objects by adding two convolutional block attention modules in the neck region and decrease its computational complexity (cost) and size by substituting convolutional layers with ghost layers in all the Efficient Layer Aggregation Networks modules, and in the Spatial Pyramid Pooling Cross Stage Partial module present in YOLOv7. The weights of the trained network were fed to the ByteTrack multiple object tracker to track the detections frame-by-frame in a video feed. The unique identities generated by the tracker for each detected object of interest were then used to count the number of defects using a line cross algorithm. The mean average precision (mAP@0.5) obtained after training the YOLOv7_ours model was 1.02% better and its cost and size were 32.1% and 37.1% lower than the baseline YOLOv7 model. In a test video, the overall model achieved a multi-object tracking accuracy and counting accuracy of 84.8% and 93.9%, respectively. This three-stage model can be readily deployed in an edge device for accurate and real-time grading of canola kernels by grain buyers.

Trait profile of maize varieties preferred by farmers and value chain actors in northern Ghana

Plant breeders’ knowledge of precise traits preferred by variety users would accelerate varietal turnover and widen adoption of newly developed maize varieties in Ghana. The objective of this research was to provide empirical evidence of trait preferences of farmers and other actors in the maize value chain in northern Ghana, based on which research strategies for maize improvement could be formulated. Participatory rural appraisal was conducted in 2016 to determine key traits preferred by maize value chain actors across the three regions in northern Ghana. A total of 279 maize value chain actors were interviewed. Different scoring and ranking techniques were used to assess the maize traits preferred by the different actors. Participatory variety selection trials were also conducted in the Tolon, West Gonja, Binduri, and Sissala East districts in northern Ghana from 2014 to 2016. The mother-baby trial approach was used to evaluate eight hybrids with 3000 farmers. Data on yield and agronomic performance of the hybrids and farmer’s selection criteria were collected. Data analyses were performed using GenStat Edition 16 and SPSS Edition 20 statistical packages. The participatory rural appraisal method identified farmers, input dealers, traders, and processors as the primary maize value chain actors in the study areas. Trait preferences of the different actors overlapped and revolved around grain quality including nutritional value, and stress tolerance and grain yield. Results of the participatory variety selection study revealed that across districts, farmers preferred high-yielding varieties with multiple cobs per plant, white grain endosperm color, and bigger and fully filled cobs. For the first time, our holistic assessment of the trait preferences of key actors of the maize value chain in northern Ghana revealed a comprehensive list of traits, which could be used by breeders to develop varieties that may be preferred by all value chain actors in northern Ghana.

Combining ability and heterotic grouping of turcicum‐resistant early‐maturing maize inbreds

AbstractMaize (Zea mays L.), an important source of calories and nutrients in sub‐Saharan Africa, is threatened by northern corn leaf blight (NCLB) caused by Exserohilum turcicum. This study examined combining ability and heterotic patterns of early‐maturing maize inbreds, gene action conditioning NCLB resistance, and performance of derived hybrids across environments and identified testers. Fifteen each of white and yellow inbreds were intercrossed using North Carolina Design II to obtain 75 hybrids per endosperm color. Hybrids plus six checks were inoculated with a virulent isolate of E. turcicum 4 wk after planting in six inoculated and three non‐inoculated environments in Nigeria in 2018 and 2019. Inbreds were assigned to heterotic groups using general combining ability (GCA) of multiple traits method. Specific combining ability (SCA), GCA, and genotype × environment (G × E) interactions were significant for grain yield (GYLD), disease severity, and other traits. Northern corn leaf blight caused 46% GYLD reduction. The effects of GCA were preponderant over SCA for GYLD and NCLB severity across environments, indicating that hybridization and recurrent selection would enhance genetic gains and hybrid performance. White and yellow inbreds were placed in two and three heterotic groups, respectively. High‐yielding NCLB‐resistant testers identified could be used to classify other inbreds yet to be field‐tested into heterotic groups. Genotypes TZEI 32 × TZEI 5 and TZEI 124 × TZEI 134 were identified as single‐cross testers. Genotypes TZEI 32 × TZEI 5 and TZEI 5 × TZEI 75 (white) and TZEI 124 × TZEI 134 and TZEI 124 × TZEI 11 (yellow) were identified for on‐farm testing and possible commercialization.

Genetic diversity and inter-trait relationship of tropical extra-early maturing quality protein maize inbred lines under low soil nitrogen stress.

Information on the genetic diversity, population structure, and trait associations of germplasm resources is crucial for predicting hybrid performance. The objective of this study was to dissect the genetic diversity and population structure of extra-early yellow and orange quality protein maize (QPM) inbred lines and identify secondary traits for indirect selection for enhanced grain yield under low-soil nitrogen (LN). One hundred and ten inbred lines were assessed under LN (30 kg ha -1) and assayed for tryptophan content. The lines were genotyped using 2500 single nucleotide polymorphism (SNP) markers. Majority (85.4%) of the inbred lines exhibited wide pairwise genetic distances between 0.4801 and 0.600. Genetic distances were wider between yellow and orange endosperm lines and predicted high heterosis in crosses between parents of different endosperm colors. The unweighted pair group method with arithmetic mean (UPGMA) and the admixture model-based population structure method both grouped the lines into five clusters. The clustering was based on endosperm color, pedigree, and selection history but not on LN tolerance or tryptophan content. Genotype by trait biplot analysis revealed association of grain yield with plant height and ear height. TZEEQI 394 and TZEEIORQ 73A had high expressivity for these traits. Indirect selection for high grain yield among the inbred lines could be achieved using plant and ear heights as selection criteria. The wide genetic variability observed in this study suggested that the inbred lines could be important sources of beneficial alleles for LN breeding programs in SSA.

Detection of Non-Additive Gene Action within Elite Maize Populations Evaluated in Contrasting Environments under Rainforest Ecology in Nigeria

Proper understanding of the mode of gene action in open-pollinated varieties (OPVs) maize parents helps breeder in the choice of appropriate breeding method to improve its genetic value. The objectives of the present study were to determine gene action controlling grain yield and other agronomic traits of late maturing elite OPVs and classify the varieties into heterotic groups. Ninety-one hybrids generated from 14 elite OPV parents using diallel mating design were evaluated with their parents plus three commercial checks under marginal rainfall, drought, and optimal environments in Nigeria from 2017 to 2018. The experiment was laid out in a 9 × 12 alpha lattice with three replications in each environment. Results showed that there were significant mean squares for grain yield and most agronomic traits. Significant general combining ability (GCA) and specific combining ability (SCA) mean squares for some of the traits indicated that additive and non-additive genetic gene actions were important in the inheritance of yield and those traits among this set of genotypes. However, non-additive genetic effects were more important than additive for grain yield and other agronomic traits in all research environments. Only TZL Comp-3 C3 DT had significant and positive GCA effects (0.336*) while three hybrids had significant and positive SCA for grain yield across research environments. Because of the preponderance of non-additive gene action over additive gene action, distinct heterotic groups could not be identified but four tester groups were identified by HSGCA (Heterotic grouping based on Specific and General Combining Ability) and three groups by HGCAMT (Heterotic grouping based on the GCA of Multiple Traits). Results of grouping were not related to the endosperm colour but grouping based on HGCAMT was related to the pedigree of the varieties. In conclusion, this study has demonstrated preponderance of non-additive gene action over the additive gene action for all measured traits. The presence of the non-additive gene action present in the studied materials can enhance identification of outstanding varietal hybrids and population testers that can serve as base genetic materials for future maize improvement through reciprocal recurrent selection program in SSA.

Genetic Diversity, Population Structure and Inter-Trait Relationships of Combined Heat and Drought Tolerant Early-Maturing Maize Inbred Lines from West and Central Africa

Adequate knowledge and understanding of the genetic diversity and inter-trait relationships among elite maize inbred lines are crucial for determining breeding strategies and predicting hybrid performance. The objectives of this study were to investigate the genetic diversity of 162 early maturing white and yellow tropical maize inbred lines, and to determine the population structure, heterotic groups and inter-trait relationships among the lines. Using 9684 DArT single nucleotide polymorphism (SNP) markers, a gene diversity (GD) of 0.30 was recorded for the inbred lines with polymorphic information content (PIC) ranging from 0.08 to 0.38. The genetic relatedness among the inbred lines evaluated revealed six different groups based on the history of selection, colour of endosperm and pedigree. The genotype-by-trait (GT) biplot analysis identified inbred 1 (TZEI 935) as outstanding in terms of combined heat and drought (HD) tolerance with the base index analysis identifying 15 superior inbreds in the HD environment. A wide range of genetic variability was observed among the inbred lines, indicating that they are an invaluable resource for breeding for HD tolerance in maize breeding programmes, especially in West and Central Africa.

Natural variation for carotenoids in fresh kernels is controlled by uncommon variants in sweet corn.

Sweet corn (Zea mays L.) is highly consumed in the United States, but does not make major contributions to the daily intake of carotenoids (provitamin A carotenoids, lutein and zeaxanthin) that would help in the prevention of health complications. A genome-wide association study of seven kernel carotenoids and twelve derivative traits was conducted in a sweet corn inbred line association panel ranging from light to dark yellow in endosperm color to elucidate the genetic basis of carotenoid levels in fresh kernels. In agreement with earlier studies of maize kernels at maturity, we detected an association of β-carotene hydroxylase (crtRB1) with β-carotene concentration and lycopene epsilon cyclase (lcyE) with the ratio of flux between the α- and β-carotene branches in the carotenoid biosynthetic pathway. Additionally, we found that 5% or less of the evaluated inbred lines possessing the shrunken2 (sh2) endosperm mutation had the most favorable lycE allele or crtRB1 haplotype for elevating β-branch carotenoids (β-carotene and zeaxanthin) or β-carotene, respectively. Genomic prediction models with genome-wide markers obtained moderately high predictive abilities for the carotenoid traits, especially lutein, and outperformed models with less markers that targeted candidate genes implicated in the synthesis, retention, and/or genetic control of kernel carotenoids. Taken together, our results constitute an important step toward increasing carotenoids in fresh sweet corn kernels.

Selecting for Coupling Phase Recombination between Potyvirus Resitance and White Endosperm Colour in Maize Preferred by Farmers in Sub-Saharan Africa (SSA)


 
 
 Maize lethal necrosis (MLN) disease caused by a combined infection of Maize chlorotic mottle virus (MCMV) and any cereal infecting potyvirus is a threat to food security in Sub-Saharan Africa (SSA). Resistance to potyvirus has been extensively studied and Mdm1 gene for potyvirus resistance on chromosome 6 of maize is linked to Y1 gene for maize endosperm colour. This study is aimed at se- lecting for coupling-phase recombination of potyvirus resistance and white endosperm colour. White susceptible maize lines CML333 and CML277 were crossed with a yellow resistant line, Pa405, to produce F1 and F2 progenies. Progenies were screened using molecular markers to recover 22 white endosperm recombinants. 22 selections were advanced to F3 recombinant families, and 10 were as- sayed for their responses to Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV). Four families segregated for SCMV resistance, selection of homozygous recombinants within these families will provide lines appropriate for improving lines with resistance to SCMV and MLN resistance in SSA.
 KEY WORDS: MAIZE LETHAL NECROSIS (MLN), WHITE MAIZE, POTYVIRUS RESISTANCE, GENETIC RECOMBINATION, SUB-SAHARAN AFRICA.
 
 

Endosperm color inheritance pattern of black Toraja rice

This study aims to obtain information about the endosperm color inheritance pattern of Toraja black rice. This research was conducted by the experimental farm, Hasanuddin University Faculty of Agriculture, from August 2017 to February 2018. This study was designed using a Randomized Block Design. The color of the seed as a treatment consists of full black (the outer and inner parts of rice), medium black (the outer part and a small portion of inner part of rice), and thin black (only the outer part of rice), with 8 replications so there were 24 experimental units. The seedling were planted in a bucket, one seedling for each bucket. The inheritance pattern of full black and thin black genotypes follows the Mendel inheritance pattern with a ratio of genotype 1 : 2 : 1. Percentage of full black endosperm color has a high heritability, while percentage of medium black and the percentage of thin black have moderate heritability.

Genetic diversity and population structure of early-maturing tropical maize inbred lines using SNP markers.

Information on genetic diversity and population structure are very important in any breeding programme for the improvement of traits of interest and the development of outstanding products for commercialization. In the present study, we assessed the genetic diversity of 94 early-maturing white and yellow tropical maize inbred lines using single nucleotide polymorphism (SNP) markers. The larger number of SNP markers used in this study allowed a clearer inference of the population structure of the 94 inbred lines. Cluster analysis resolved the inbred lines into different clusters based on their pedigree, selection history and endosperm colour. However, three heterotic groups were revealed by population structure analysis, but additional field evaluation could be more informative to confirm the heterotic groups identified. Nevertheless, wide genetic variability existed among the inbred lines making them unique with the potential to contribute new beneficial alleles to maize breeding programmes in the tropics, especially in the West and Central Africa (WCA) sub-region.

Selecting for Coupling-Phase Recombination Between Potyvirus Resistance and White Endosperm Colour in Maize Preferred by Farmers in Sub-Saharan Africa (SSA)

Maize lethal necrosis (MLN) disease caused by a combined infection of Maize chlorotic mottle virus (MCMV) and any cereal infecting potyvirus is a threat to food security in Sub-Saharan Africa (SSA). Resistance to potyvirus has been extensively studied and Mdm1 gene for potyvirus resistance on chromosome 6 of maize is linked to Y1 gene for maize endosperm colour. This study is aimed at selecting for coupling-phase recombination of potyvirus resistance and white endosperm colour. White susceptible maize lines CML333 and CML277 were crossed with a yellow resistant line, Pa405, to produce F1 and F2 progenies. Progenies were screened using molecular markers to recover 22 white endosperm recombinants. 22 selections were advanced to F3 recombinant families, and 10 were assayed for their responses to Maize dwarf mosaic virus (MDMV) and Sugarcane mosaic virus (SCMV). Four families segregated for SCMV resistance, selection of homozygous recombinants within these families will provide lines appropriate for improving lines with resistance to SCMV and MLN resistance in SSA.

A Connection between Lysine and Serotonin Metabolism in Rice Endosperm.

Cereal endosperms produce a vast array of metabolites, including the essential amino acid lysine (Lys). Enhanced accumulation of Lys has been achieved via metabolic engineering in cereals, but the potential connection between metabolic engineering and Lys fortification is unclear. In mature seeds of engineered High Free Lysine (HFL) rice (Oryza sativa), the endosperm takes on a characteristic dark-brown appearance. In this study, we use an integrated metabolomic and transcriptomic approach combined with functional validation to elucidate the key metabolites responsible for the dark-brown phenotype. Importantly, we found that serotonin biosynthesis was elevated dramatically and closely linked with dark-brown endosperm color in HFL rice. A functional connection between serotonin and endosperm color was confirmed via overexpression of TDC3, a key enzyme of serotonin biosynthesis. Furthermore, we show that both the jasmonate signaling pathway and TDC expression were strongly induced in the late stage of endosperm development of HFL rice, coinciding with serotonin accumulation and dark-brown pigmentation. We propose a model for the metabolic connection between Lys and serotonin metabolism in which elevated 2-aminoadipate from Lys catabolism may play a key role in the connection between the jasmonate signaling pathway, serotonin accumulation, and the brown phenotype in rice endosperm. Our data provide a deeper understanding of amino acid metabolism in rice. In addition, the finding that both Lys and serotonin accumulate in HFL rice grains should promote efforts to create a nutritionally favorable crop.

Free and esterified carotenoids in pigmented wheat, tritordeum and barley grains

Carotenoids are important phytonutrients responsible for the yellow endosperm color in cereal grains. Five carotenoids, namely lutein, zeaxanthin, antheraxanthin, α- and β-carotene, were quantified by HPLC-DAD-MS in fourteen genotypes of wheat, barley and tritordeum harvested in Czechia in 2014 and 2015. The highest carotenoid contents were found in yellow-grained tritordeum HT 439 (12.16μg/gDW), followed by blue-grained wheat V1-131-15 (7.46μg/gDW), and yellow-grained wheat TA 4024 (7.04μg/gDW). Comparing carotenoid contents, blue varieties had lower whereas purple ones had the same or higher levels than conventional bread wheat. Lutein was the main carotenoid found in wheat and tritordeum while zeaxanthin dominated in barley. The majority of cereals contained considerable levels of esterified forms (up to 61%) of which lutein esters prevailed. It was assessed that cereal genotype determines the proportion of free and esterified forms. High temperatures and drought during the growing season promoted carotenoid biosynthesis.

Stability of PAC (Psy-2A-CrtI) gene and agronomic traits in the F2:3 of IR36/PAC transgenic plants

This study was carried out to evaluate the expression of yellow endosperm color in the progeny of Psy-2A-CrtI (β-carotene gene, PAC) transgenic plants crossed with IR36. The selected 25 lines of F2 progeny exhibited stable expression of yellow endosperm color and high agronomic characteristics. IR36 and PAC transgenic plant of the grain length, width and ratio showed the same tendency of normal distribution. For progeny selection, colorimeters were as employed to distinguish differing visible colors. Correlation analysis was conducted to investigate the relationship between b* value and the expression of specific genes. b* value was associated with the relative expression of the PAC-Rev and MAR product by real-time PCR and t-test revealed significant difference. Based on this study, correlation between colorimetric values and real-time PCR was effective to detect gene expression. Yellow endosperm progenies represent a new genetic pool that might be useful to increase the genetic diversity of yellow endosperm rice.

Allele Mining of Exotic Maize Germplasm to Enhance Macular Carotenoids

ABSTRACTLutein and zeaxanthin are commonly referred to as the macular carotenoids, as they are localized to ocular tissues and their loss is associated with age‐related macular degeneration. Thirty‐four high‐carotenoid (HiC) lines exhibiting uniquely high concentrations of carotenoids resulted from allele mining of the Orange Flint race using traditional breeding techniques and visual selection for deep orange endosperm color. Total carotenoid concentrations of the HiC lines ranged from 50 to 101 μg g−1 dry weight (DW) with lutein and zeaxanthin concentrations as high as 66 and 65 μg g−1 DW, respectively, levels higher than reported in previous germplasm surveys. The HiC lines fall into three classes based on the accumulation of the major carotenoid: “high‐lutein,” “high‐zeaxanthin,” and “balanced.” Significant year effects were observed for carotenoid concentrations but not for profiles. During kernel development the pattern of carotenoid accumulation in the HiC lines did not appear to be different than in yellow corn belt dent lines. Collectively, the HiC lines represented only one y1 haplotype, 10 unique haplotypes of lcyE, and two unique haplotypes at crtRB1 Interestingly, previously identified diagnostic polymorphisms within lcyE did not appear to be useful in distinguishing between high‐lutein and high‐zeaxanthin HiC lines, and high β‐carotene levels were achieved despite the presence of a suboptimal crtRB1 allele. The HiC lines illustrate the utility of mining allelic variation from exotic sources coupled with the power of simple visual selection and the potential limitations of diagnostic polymorphisms.

The Kernels Endosperm Colour of a Longitudinal Section of Malting Barley and the Similarity amongst Varieties Part II. Colour Changes after Germination and Heating

The previous of our research showed that the endosperm colour of 13 varieties depends of differences in similarity of hordeins. The endosperm colour is not specific for varieties of high similarities of hordeins. Do changes in microstructure of endosperm as a result of 24 hours germinating and heating increase the differences of colour amongst varieties which are more similar in hordeins electrophoregrams. The endosperm colour of 13 varieties was measured using DIA System LUCIA G. It was proved that germinating and heating significant differences in colour of endosperm of some varieties with highly similar hordeins. It suggests the possibility of evaluating the variety uniformity of malting barley batch, as well as predicting the malting quality of grains using evaluation of endosperm colour after one day germinating and heating of grains.

The Kernels Endosperm Colour of a Longitudinal Section of Malting Barley and the Similarity amongst Varieties Part I. The Kernel Endosperm Colour of the Longitudinal Section Before Malting

Microstructure of malting barley kernels is one of the most significance factor of malt quality and is determined using simple evaluation of vitreous or mealy areas. The object of investigation was to verify the hypothesis, that the colour of endosperm of malting barley kernels depends of variety. The investigated materials were grains of 13 varieties of malting barley. The similarity of varieties was estimated by the electrophoresis of hordeins. The colour was measured using DIA system LUCIA G. It was found, that only the varieties for which the hordein image differed most (Maresi, Sezam, Granal) also differed in terms of the endosperm colour. The differences were statistically significant at p = 0.05. In majority of investigated varieties the endosperm colour was not specific variety feature, however, they are distinguished by hordein electrophoresis.