Inter-varietal sterility and fertility restoration in Oryza sativa Linn.

This study explored the underlining reproductive factors that cause sterility in rice, using hybrids obtained from crosses among landrace selections and improved varieties. The study was carried out between 2016 and 2018. Nine landrace cultivars and two improved varieties were involved in the hybridization experiment. Among the 17 putative hybrids that were obtained, only 5 were confirmed as true hybrids. Meiotic chromosome studies and pollen studies in the F1, and Mendelian segregation studies for fertility in the F2 were carried out. Some F2 lines were monitored to F3 to ascertain the level of fixation of gene combinations for fertility. The results obtained from the chromosomal studies showed that phenomena such as laggards, precocious movements, formation of multivalents, and unequal segregation to the poles are associated with pollen sterility in all - 5 hybrids, at the F1 and F2 generations. The indehiscence of anthers contributed to infertility due to pollen shortage than the fertility of the pollens themselves. Even though in males, there is a preponderance of male sterility, female sterility is also a phenomenon that is possibly contributing to inter-varietal sterility. The segregational pattern of 13:3 was observed for fertility in the F2 which suggests the inhibition of fertility by a gene in the dominant state. There was the restoration of fertility in many of the lines advanced to the F3 to up to 93 % fertility. It was, therefore, concluded from the study that landraces of rice still hold the key for the rice crop improvement and should therefore be conserved.

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Meiotic chromosome behavior of Haworthia limifolia

International Journal of Bioassays ◽

10.21746/ijbio.2016.03.009 ◽

2016 ◽

Vol 5 (03) ◽

pp. 4902

Author(s):

Afrin Nazli ◽

Kamini Kumar*

Keyword(s):

Genetic Recombination ◽

Meiotic Chromosome ◽

Pollen Sterility ◽

Meiotic Abnormalities ◽

Chromosome Behavior ◽

The Family ◽

Medicinal Properties ◽

Fruit Formation ◽

Meiosis I ◽

Chromosomal Behaviour

Haworthia limifolia is a xerophytic plant belonging to the family Liliaceae and is indigenous to Africa. It is use extensively for its medicinal properties like antibacterial, antifungal properties and used for the treatment of sores, superficial burns, as a blood purifier and to promote pregnancy in women and cattles. In present investigation chromosomal behaviour of H. limifolia in meiosis was studied. In diplotene stage chiasmata was observed showing the possibilities of genetic recombination. Chromosome clumps were observed in diakinesis indicating sticky nature of chromosomes. Meiotic abnormalities like stickiness, precocious movement, formation of bridges and laggards were also reported in both meiosis I and II. A fairly high percentage of pollen sterility that is 73.41% was recorded resulting in failure of fruit formation. This plant could be designated as facultative apomict (Swanson, 1957) as the only means of reproduction found was asexual or vegetative.

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Genetic Diversity of Landraces and Improved Varieties of Rice (Oryza sativa L.) in Taiwan

Rice ◽

10.1186/s12284-020-00445-w ◽

2020 ◽

Vol 13 (1) ◽

Author(s):

Ai-ling Hour ◽

Wei-hsun Hsieh ◽

Su-huang Chang ◽

Yong-pei Wu ◽

Han-shiuan Chin ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Indigenous Peoples ◽

Oryza Sativa L ◽

Crop Improvement ◽

Genetic Erosion ◽

Germplasm Conservation ◽

Gene Pools ◽

Improved Varieties ◽

Breeding Goals

Abstract Background Rice, the most important crop in Asia, has been cultivated in Taiwan for more than 5000 years. The landraces preserved by indigenous peoples and brought by immigrants from China hundreds of years ago exhibit large variation in morphology, implying that they comprise rich genetic resources. Breeding goals according to the preferences of farmers, consumers and government policies also alter gene pools and genetic diversity of improved varieties. To unveil how genetic diversity is affected by natural, farmers’, and breeders’ selections is crucial for germplasm conservation and crop improvement. Results A diversity panel of 148 rice accessions, including 47 cultivars and 59 landraces from Taiwan and 42 accessions from other countries, were genotyped by using 75 molecular markers that revealed an average of 12.7 alleles per locus with mean polymorphism information content of 0.72. These accessions could be grouped into five subpopulations corresponding to wild rice, japonica landraces, indica landraces, indica cultivars, and japonica cultivars. The genetic diversity within subpopulations was: wild rices > landraces > cultivars; and indica rice > japonica rice. Despite having less variation among cultivars, japonica landraces had greater genetic variation than indica landraces because the majority of Taiwanese japonica landraces preserved by indigenous peoples were classified as tropical japonica. Two major clusters of indica landraces were formed by phylogenetic analysis, in accordance with immigration from two origins. Genetic erosion had occurred in later japonica varieties due to a narrow selection of germplasm being incorporated into breeding programs for premium grain quality. Genetic differentiation between early and late cultivars was significant in japonica (FST = 0.3751) but not in indica (FST = 0.0045), indicating effects of different breeding goals on modern germplasm. Indigenous landraces with unique intermediate and admixed genetic backgrounds were untapped, representing valuable resources for rice breeding. Conclusions The genetic diversity of improved rice varieties has been substantially shaped by breeding goals, leading to differentiation between indica and japonica cultivars. Taiwanese landraces with different origins possess various and unique genetic backgrounds. Taiwanese rice germplasm provides diverse genetic variation for association mapping to unveil useful genes and is a precious genetic reservoir for rice improvement.

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Study of the possibilities of using sunflower lines with different colours of seeds to create poultry feed

Helia ◽

10.1515/helia-2021-0016 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Katerina Vedmedeva ◽

Tatiana Machova

Keyword(s):

Pollen Fertility ◽

Animal Feed ◽

Fertility Restoration ◽

Emerging Market ◽

Pollen Sterility ◽

Wild Birds ◽

Hybrid Breeding ◽

Poultry Feed ◽

Human Consumption ◽

Seed Colour

Abstract Sunflower is used for the production of oil, confectionery and animal feed. Birds are very fond of sunflowers and can be pests of sunflower crops, and are consumers of seeds. Sunflower poultry feed is an emerging market that determines the direction of breeding. Its development is based on the determination of bird preferences and the available variety of sunflower lines. This is what our research is devoted to. Experimental feeding of chickens with a mixture of sunflower seeds of different colours was carried out. Chickens have been found to prefer contrasting striped seeds with white and dark stripes more than others. The white colour of the seeds was eaten less than others. Studies of the genetics of sunflower colour allow us to distinguish two groups of lines by seed colour. The first has white seeds with the EwEwPP genotype, suitable for use in human confectionery and more protected from being eaten by wild birds in the fields. The second is striped seeds with the EstrEstrPP genotype, which can be fed whole seeds to birds. Donors of seed colour traits and other traits important for hybrid breeding were selected from the evaluated collection of sunflower lines. InK1039 line is a donor of small striped seeds and pollen fertility restoration. InK1587 line is a sterility fixer and donor of striped and early maturing seeds. To create hybrids with white seeds for human consumption and thus more resistant to ingestion by wild birds, white seed donors were isolated with KG9 to restore pollen fertility and I2K2218 in a pollen sterility fixer.

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Combining two semidwarfing genes d60 and sd1 for reduced height in ‘Minihikari’, a new rice germplasm in the ‘Koshihikari’ genetic background

Genetics Research ◽

10.1017/s0016672312000456 ◽

2012 ◽

Vol 94 (5) ◽

pp. 235-244 ◽

Cited By ~ 6

Author(s):

MOTONORI TOMITA

Keyword(s):

Recessive Gene ◽

Segregation Ratio ◽

Pollen Sterility ◽

Recurrent Parent ◽

Lethal Gene ◽

Mendelian Segregation ◽

Dwarf Gene ◽

Reduced Height ◽

Rice Yields ◽

Semidwarf Gene

SummaryDwarfing in rice has dramatically improved and stabilized rice yields worldwide, often controlled by a single dwarf gene, sd1. A novel semidwarf gene d60 complements the gametic lethal gene gal, such that the F1 between ‘Hokuriku 100’ (genotype d60d60GalGal, Gal: mutant non-lethal allele) and ‘Koshihikari’ (D60D60galgal, D60: tall allele) would show 25% sterility due to deterioration of gametes bearing both gal and d60. The F2 would segregate as one semidwarf (1 d60d60GalGal) : two tall and 25% sterile (2 D60d60Galgal) : six tall (2 D60d60GalGal : 1 D60D60GalGal : 2 D60D60Galgal : 1 D60D60galgal), skewed from a Mendelian segregation ratio of one semidwarf : three tall for a single recessive gene. To pyramid d60 and sd1, into the Japanese super-variety ‘Koshihikari’, the F1 (D60d60Galgal) of ‘Koshihikari’ × ‘Hokuriku 100’ was first backcrossed with ‘Koshihikari’, and the BCF1 segregated into a ratio of one tall and 25% sterile (D60d60Galgal) : two tall (1 D60D60Galgal : 1 D60D60galgal). Tall, 25% sterile BC1F1 plants (D60d60Galgal) were then selected for pollen sterility and backcrossed with ‘Koshihikari’ as the recurrent parent. It is unnecessary to grow out and select a semidwarf from the BCnF2 if a pollen parent with ∼70% pollen fertility is chosen from the BCnF1 to backcross with the recurrent parent. Semidwarfing genes d60 and sd1 were successfully pyramided into the ‘Koshihikari’ genome by crossing isogenic lines ‘Koshihikari d60’ and ‘Koshihikari sd1’, to produce ‘Minihikari’, a new parental source of both d60 and sd1. ‘Minihikari’ displayed super-short stature due to the combination of sd1 and d60, which are genetically and functionally independent.

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Efficient mapping of a female sterile gene in wheat (Triticum aestivum L.)

Genetics Research ◽

10.1017/s0016672309990218 ◽

2009 ◽

Vol 91 (5) ◽

pp. 337-343 ◽

Cited By ~ 40

Author(s):

BINGDE DOU ◽

BEIWEI HOU ◽

HAIMING XU ◽

XIANGYANG LOU ◽

XIAOFEI CHI ◽

...

Keyword(s):

Fertility Restoration ◽

Major Gene ◽

Triticum Aestivum L ◽

Wheat Breeding ◽

Female Sterility ◽

Genome Maps ◽

Fundamental Information ◽

Substantial Progress ◽

Trait Locus ◽

Elite Cultivar

SummaryStudies on inheritance of fertility are of great importance in wheat breeding. Although substantial progress has been achieved in molecular characterization of male sterility and fertility restoration recently, little effort has been devoted to female sterility. To identify the gene(s) controlling female sterility in wheat efficiently, an investigation was conducted for the seed setting ratio using a set of F2 populations derived from the cross between a female sterile line XND126 and an elite cultivar Gaocheng 8901. Bulked segregation analysis (BSA) method and recessive class approach were adopted to screen for SSR markers potentially linked to female fertility gene loci in 2005. Out of 1080 SSRs in wheat genome, eight markers on chromosome 2D showed a clear difference between two disparate bulks and small recombination frequency values, suggesting a strong linkage signal to the sterility gene. Based on the candidate linked markers, partial linkage maps were constructed with Mapmaker 3.0 (EXP) instead of whole genome maps, and quantitative trait locus (QTL) mapping was implemented with software QTLNetwork 2.0. A major gene locus designated as taf1, was located on chromosome 2DS. The above result was confirmed by the analysis for 2007 data, and taf1 was identified on the same chromosome 2DS with a confidence interval of 2·4 cM, which could explain 44·99% of phenotypic variation. These results provided fundamental information for fine mapping studies and laid the groundwork for wheat fertility genetic studies.

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Rewiring Meiosis for Crop Improvement

Frontiers in Plant Science ◽

10.3389/fpls.2021.708948 ◽

2021 ◽

Vol 12 ◽

Author(s):

Pallas Kuo ◽

Olivier Da Ines ◽

Christophe Lambing

Keyword(s):

Plant Breeding ◽

Chromosome Segregation ◽

Meiotic Recombination ◽

Meiotic Chromosome ◽

Crop Improvement ◽

Plant Performance ◽

Dna Double Strand Breaks ◽

Chromosome Engineering ◽

Division Process ◽

New Varieties

Meiosis is a specialized cell division that contributes to halve the genome content and reshuffle allelic combinations between generations in sexually reproducing eukaryotes. During meiosis, a large number of programmed DNA double-strand breaks (DSBs) are formed throughout the genome. Repair of meiotic DSBs facilitates the pairing of homologs and forms crossovers which are the reciprocal exchange of genetic information between chromosomes. Meiotic recombination also influences centromere organization and is essential for proper chromosome segregation. Accordingly, meiotic recombination drives genome evolution and is a powerful tool for breeders to create new varieties important to food security. Modifying meiotic recombination has the potential to accelerate plant breeding but it can also have detrimental effects on plant performance by breaking beneficial genetic linkages. Therefore, it is essential to gain a better understanding of these processes in order to develop novel strategies to facilitate plant breeding. Recent progress in targeted recombination technologies, chromosome engineering, and an increasing knowledge in the control of meiotic chromosome segregation has significantly increased our ability to manipulate meiosis. In this review, we summarize the latest findings and technologies on meiosis in plants. We also highlight recent attempts and future directions to manipulate crossover events and control the meiotic division process in a breeding perspective.

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Quantitative methods in microscopy to assess pollen viability in different plant taxa

Plant Reproduction ◽

10.1007/s00497-020-00398-6 ◽

2020 ◽

Vol 33 (3-4) ◽

pp. 205-219

Author(s):

Lorenzo Ascari ◽

Cristina Novara ◽

Virginia Dusio ◽

Ludovica Oddi ◽

Consolata Siniscalco

Keyword(s):

Statistical Power ◽

Quantitative Methods ◽

Pollen Viability ◽

Crop Improvement ◽

Pollen Grains ◽

Pollen Sterility ◽

Pollen Grain ◽

Automated Image Analysis ◽

Future Research ◽

Sterile Pollen

AbstractHigh-quality pollen is a prerequisite for plant reproductive success. Pollen viability and sterility can be routinely assessed using common stains and manual microscope examination, but with low overall statistical power. Current automated methods are primarily directed towards the analysis of pollen sterility, and high throughput solutions for both pollen viability and sterility evaluation are needed that will be consistent with emerging biotechnological strategies for crop improvement. Our goal is to refine established labelling procedures for pollen, based on the combination of fluorescein (FDA) and propidium iodide (PI), and to develop automated solutions for accurately assessing pollen grain images and classifying them for quality. We used open-source software programs (CellProfiler, CellProfiler Analyst, Fiji and R) for analysis of images collected from 10 pollen taxa labelled using FDA/PI. After correcting for image background noise, pollen grain images were examined for quality employing thresholding and segmentation. Supervised and unsupervised classification of per-object features was employed for the identification of viable, dead and sterile pollen. The combination of FDA and PI dyes was able to differentiate between viable, dead and sterile pollen in all the analysed taxa. Automated image analysis and classification significantly increased the statistical power of the pollen viability assay, identifying more than 75,000 pollen grains with high accuracy (R2 = 0.99) when compared to classical manual counting. Overall, we provide a comprehensive set of methodologies as baseline for the automated assessment of pollen viability using fluorescence microscopy, which can be combined with manual and mechanized imaging systems in fundamental and applied research on plant biology. We also supply the complete set of pollen images (the FDA/PI pollen dataset) to the scientific community for future research.

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Understanding Farmers’ Trait Preferences for Dual-Purpose Crops to Improve Mixed Crop–Livestock Systems in Zimbabwe

Sustainability ◽

10.3390/su13105678 ◽

2021 ◽

Vol 13 (10) ◽

pp. 5678

Author(s):

Mequanint B. Melesse ◽

Amos Nyangira Tirra ◽

Chris O. Ojiewo ◽

Michael Hauser

Keyword(s):

Crop Improvement ◽

Sub Saharan Africa ◽

Livestock Farming ◽

Dual Purpose ◽

Improved Varieties ◽

Trade Offs ◽

Mixed Crop ◽

Improvement Programs ◽

Trait Preferences ◽

Livestock Systems

Competition over land between food and fodder production, along with recurrent droughts and increasing population, has put mixed crop–livestock farming systems in the drylands of sub-Saharan Africa under pressure. Dual-purpose crops hold huge potential to ease this pressure and simultaneously improve food and fodder availability in these systems. We investigated farmers’ preferences for dual-purpose maize, sorghum, and groundnut traits, and analyzed linkages of stated trait preferences with production of dual-purpose crops and adoption of improved varieties involving 645 households from two districts in Zimbabwe. The three target crops cover more than 75% of households’ cropping lands. Highly preferred stated traits of dual-purpose crops include yield, disease resistance, and drought tolerance. Highly appreciated feed attributes encompass stover yield and digestibility. The adoption of improved varieties is high for maize but low for sorghum and groundnut. Trait preferences are correlated with the production of dual-purpose crops and the adoption of improved varieties of the crops. However, the strengths of these correlations differ for maize, sorghum, and groundnuts. We discuss these linkages and suggest why crop improvement programs should reconcile trade-offs between grain and feed attributes to support mixed crop–livestock systems in Zimbabwe successfully.

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NON-MENDELIAN FEMALE STERILITY IN DROSOPHILA MELANOGASTER: PRINCIPAL CHARACTERISTICS OF CHROMOSOMES FROM INDUCER AND REACTIVE ORIGIN AFTER CHROMOSOMAL CONTAMINATION

Genetics ◽

10.1093/genetics/91.3.455 ◽

1979 ◽

Vol 91 (3) ◽

pp. 455-471

Author(s):

Georges Picard

Keyword(s):

Drosophila Melanogaster ◽

Genetic Recombination ◽

Female Sterility ◽

Genetic Element ◽

Mendelian Segregation ◽

Principal Characteristics ◽

Classical Genetic ◽

Factor I ◽

I Factor

ABSTRACT Strains of Drosophila melanogaster can be divided into two main classes, inducer and reactive, in relation to non-Mendelian female sterility. The genetic element responsible for the inducer condition (I factor) is chromosomal and may be linked to any inducer-strain chromosome. Each chromosome carrying the I factor (i + chromosome) can produce females showing more-or-less reduced fertility when it is introduced by paternal gametes into a reactive oocyte. As long as i+ chromosomes are transmitted through heterozygous males with reactive originating chromosomes (r chromosomes), I factor strictly follows Mendelian segregation. In contrast, in heterozygous i+/r females, a varying proportion of r chromosomes may acquire I factor independently of classical genetic recombination, by a process called chromosomal contamination. This paper reports investigation of the characteristics of the three kinds of chromosomes produced by females in which contamination occurs. It appears that the contaminated reactive chromosomes have irreversibly acquired I factor and behave like i + chromosomes, while the i + chromosomes used as contaminating elements and the reactive originating chromosomes that have not been contaminated have not undergone any change.

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PAPER ADAPTED FROM PRESENTATION AT INTERNATIONAL WORKSHOP ON INCREASING WHEAT YIELD POTENTIAL, CIMMYT, OBREGON, MEXICO, 20–24 MARCH 2006 U-impact pathway for diagnosis and impact assessment of crop improvement

The Journal of Agricultural Science ◽

10.1017/s0021859607007046 ◽

2007 ◽

Vol 145 (3) ◽

pp. 195-206 ◽

Cited By ~ 6

Author(s):

J. DIXON ◽

J. HELLIN ◽

O. ERENSTEIN ◽

P. KOSINA

Keyword(s):

Agricultural Research ◽

Crop Improvement ◽

Yield Potential ◽

Value Chains ◽

Wheat Crop ◽

Farm Household ◽

Public And Private ◽

Improved Varieties ◽

Impact Pathway ◽

Household System

Agricultural research has contributed enormously to poverty reduction and increased food security worldwide. Wheat crop improvement is a good example of this contribution. Public investments in wheat research from the Green Revolution onwards led to significant productivity increases: following the widespread adoption of semi-dwarf varieties, annual yield growth rates peaked at 2·75% p.a. in the 1980s. Since then, public and private investments in crop (including wheat) research have been modest despite the potential of such research to contribute substantially to the first Millennium Development Goal (MDG) of halving hunger and poverty by 2015. Drawing on a wide spectrum of recent literature, the present paper broadens the usual frame of reference for diagnosing the adoption of improved technology and measuring impact. The adoption of improved varieties and management practices is influenced on the supply side by the nature and performance of the input delivery pathway from research to the farm (input value chains), and on the demand side by the characteristics of the farm household system and the marketing or value-adding chains from the farm to the consumer (output value chains). These three elements (input value chains, farm household system characteristics, and output value chains) can be viewed as a U-impact pathway. This pathway determines the rate and extent of adoption of improved varieties and practices, the magnitude of direct and indirect impacts, and the potential for feedback loops leading to improved functioning of the input and output value chains. The U-impact pathway provides a framework to identify an expanded set of beneficiaries from crop improvement which extend beyond the common focus on producers and final consumers; conventional surplus analysis can then be used to estimate the wider benefits to crop improvement. Additional metrics may be needed to estimate impact related to non-economic benefits, such as poverty, health and social capital. The implication of this fuller accounting of impacts is that the benefits accruing to agricultural research may be greater, and more widely distributed across the economy, than previously recognized by research managers and policy-makers. This strengthens the case for maintained or increased public and private sector investment in crop improvement.

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