In flowering plants, the term "apomixis" is commonly used in a restricted sense to mean agamospermy, i.e. clonal reproduction through seeds.
Thus, Apiomixis can be defined as the development of embryo with or without embryosac formation but without fertilization.
A game changer in plant breeding
,powerful breeding tool ,genetics ,asexual reproduction ,apomixis technology ,food ,agriculture research ,agriculture ,apomixis
Apomixis in flowering plants is defined as the asexual formation of a seed from the maternal tissues of the ovule, avoiding the processes of meiosis and fertilization, leading to embryo development.
A game changer in plant breeding
,powerful breeding tool ,genetics ,asexual reproduction ,apomixis technology ,food ,agriculture research ,agriculture ,apomixis
Apomixis in flowering plants is defined as the asexual formation of a seed from the maternal tissues of the ovule, avoiding the processes of meiosis and fertilization, leading to embryo development.
Presentation on the relevance of self-incompatibility, methods to overcome self-incompatibility, advantages and disadvantages, utilization in crop improvement
The modes of reproduction in crop plants may be broadly grouped into two categories: asexual and sexual.
Sexual reproduction involves the fusion of male and female gametes, whereas in asexual reproduction new plants may develop from vegetative parts of the plant (vegetative reproduction) or may arise from embryos that develop without fertilization (apomixis).
Plant breeding methods of vegetatively propagated crops Roksana Aftab Ruhi
Vegetatively propagated crops are bred by intentionally crossing of closely or distantly related individual to produce new crop varieties or lines with desirable traits. Breeding of vegetative crops have successfully improved quality, yield, tolerance of crops to environmental pressure. Breeding helps in producing crops that are resistant to viruses, fungi and bacteria and helps in longer storage period for the harvested crop.
Self-incompatibility refers to the inability of a plant with functional pollen to set seeds when self pollinated. It is the failure of pollen from a flower to fertilize the same flower or other flowers of the same plant.
This presentation includes, Single-locus self-incompatibility- {Gametophytic self-incompatibility (GSI) and Sporophytic self-incompatibility (SSI)},2-locus gametophytic self-incompatibility, Heteromorphic self-incompatibility,Cryptic self-incompatibility (CSI) and Late-acting self-incompatibility (LSI).
Food is synthesized in the green parts of a plant. The non-green parts are depended on the photosynthetic cells for nourishment. The main function of photosynthesis is to provide energy and carbon skeleton to all living cells in different regions of organs of plant body. The food in the form of sucrose is transported by the vascular tissue phloem. The transport of photosynthetic organic substance from leaf to any organ at relatively long distance is called translocation. Such translocation of organic substances occurs through a vascular tissue called phloem. The translocation of organic substances through phloem tissue is called phloem transport.
Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg. Due to the embryos resulting from the same egg, the embryos are identical to one another, but are genetically diverse from the parents.
Presentation on the relevance of self-incompatibility, methods to overcome self-incompatibility, advantages and disadvantages, utilization in crop improvement
The modes of reproduction in crop plants may be broadly grouped into two categories: asexual and sexual.
Sexual reproduction involves the fusion of male and female gametes, whereas in asexual reproduction new plants may develop from vegetative parts of the plant (vegetative reproduction) or may arise from embryos that develop without fertilization (apomixis).
Plant breeding methods of vegetatively propagated crops Roksana Aftab Ruhi
Vegetatively propagated crops are bred by intentionally crossing of closely or distantly related individual to produce new crop varieties or lines with desirable traits. Breeding of vegetative crops have successfully improved quality, yield, tolerance of crops to environmental pressure. Breeding helps in producing crops that are resistant to viruses, fungi and bacteria and helps in longer storage period for the harvested crop.
Self-incompatibility refers to the inability of a plant with functional pollen to set seeds when self pollinated. It is the failure of pollen from a flower to fertilize the same flower or other flowers of the same plant.
This presentation includes, Single-locus self-incompatibility- {Gametophytic self-incompatibility (GSI) and Sporophytic self-incompatibility (SSI)},2-locus gametophytic self-incompatibility, Heteromorphic self-incompatibility,Cryptic self-incompatibility (CSI) and Late-acting self-incompatibility (LSI).
Food is synthesized in the green parts of a plant. The non-green parts are depended on the photosynthetic cells for nourishment. The main function of photosynthesis is to provide energy and carbon skeleton to all living cells in different regions of organs of plant body. The food in the form of sucrose is transported by the vascular tissue phloem. The transport of photosynthetic organic substance from leaf to any organ at relatively long distance is called translocation. Such translocation of organic substances occurs through a vascular tissue called phloem. The translocation of organic substances through phloem tissue is called phloem transport.
Polyembryony is the phenomenon of two or more embryos developing from a single fertilized egg. Due to the embryos resulting from the same egg, the embryos are identical to one another, but are genetically diverse from the parents.
This slide serves as the completing part of BIO 101. It covers topics such as Basic reproduction, Genetics and heredity, ecology, evolution, animals and plants; lower and higher.
A review on Perennial fruits Seed production potential enhancement by using a...AI Publications
Globalization of agriculture is increasingly calling for improved efficiency and competitiveness of the existing production systems. Plants reproduce in different methods. Sexual reproduction of fruit trees is a rarely used method in horticulture. Mainly applied in research stations to conserve the richness of the gene pool and develop new varieties. On the production side, this method cannot satisfy the requirements for production quality and quantity. In other case plant can be asexually reproduced either by using part of two or more plants in a union or parts of the same plant which in the case of grafts age and in the rooting. All asexual propagation techniques belong one of the two categories. Seeds formed by apomixis have maternal genotype because their embryo is derived from that have not undergone of meiosis and fertilization that define sexual embryo development. Absence of meiotic process and paternal contribution to the embryo genotype do mean that apomixis offers a clonally propagating method of plants through seeds. As in most fruit tree species, walnut tree is a heterozygous plant, therefore the most certain way to get uniform plantations, with higher quality cultivars, is vegetative propagation. Vegetative propagation in walnut tree by grafting is still a difficult method that involves higher expenses. The most methods include Root Cuttings, Softwood cuttings, Hardwood cuttings, vegetative propagation by bud grafting or budding, Vegetative Propagation by grafting. Fruit formation by apomixy theoretical and practical significance; the embryo, being homozygous, is transmitting the similar characteristics of plant. (NICULINA, 2011). One of the most important prerequisites for genetic manipulation of plants in vitro is the ability to grow somatic cells in sterile plant growth medium and to regenerate viable plants from these cultures. Somatic embryogenesis, therefore, is a more efficient pathway for studies involving production of genetically transformed plants.(Kamle et al., 2011).
Slide 1: Title Slide
Extrachromosomal Inheritance
Slide 2: Introduction to Extrachromosomal Inheritance
Definition: Extrachromosomal inheritance refers to the transmission of genetic material that is not found within the nucleus.
Key Components: Involves genes located in mitochondria, chloroplasts, and plasmids.
Slide 3: Mitochondrial Inheritance
Mitochondria: Organelles responsible for energy production.
Mitochondrial DNA (mtDNA): Circular DNA molecule found in mitochondria.
Inheritance Pattern: Maternally inherited, meaning it is passed from mothers to all their offspring.
Diseases: Examples include Leber’s hereditary optic neuropathy (LHON) and mitochondrial myopathy.
Slide 4: Chloroplast Inheritance
Chloroplasts: Organelles responsible for photosynthesis in plants.
Chloroplast DNA (cpDNA): Circular DNA molecule found in chloroplasts.
Inheritance Pattern: Often maternally inherited in most plants, but can vary in some species.
Examples: Variegation in plants, where leaf color patterns are determined by chloroplast DNA.
Slide 5: Plasmid Inheritance
Plasmids: Small, circular DNA molecules found in bacteria and some eukaryotes.
Features: Can carry antibiotic resistance genes and can be transferred between cells through processes like conjugation.
Significance: Important in biotechnology for gene cloning and genetic engineering.
Slide 6: Mechanisms of Extrachromosomal Inheritance
Non-Mendelian Patterns: Do not follow Mendel’s laws of inheritance.
Cytoplasmic Segregation: During cell division, organelles like mitochondria and chloroplasts are randomly distributed to daughter cells.
Heteroplasmy: Presence of more than one type of organellar genome within a cell, leading to variation in expression.
Slide 7: Examples of Extrachromosomal Inheritance
Four O’clock Plant (Mirabilis jalapa): Shows variegated leaves due to different cpDNA in leaf cells.
Petite Mutants in Yeast: Result from mutations in mitochondrial DNA affecting respiration.
Slide 8: Importance of Extrachromosomal Inheritance
Evolution: Provides insight into the evolution of eukaryotic cells.
Medicine: Understanding mitochondrial inheritance helps in diagnosing and treating mitochondrial diseases.
Agriculture: Chloroplast inheritance can be used in plant breeding and genetic modification.
Slide 9: Recent Research and Advances
Gene Editing: Techniques like CRISPR-Cas9 are being used to edit mitochondrial and chloroplast DNA.
Therapies: Development of mitochondrial replacement therapy (MRT) for preventing mitochondrial diseases.
Slide 10: Conclusion
Summary: Extrachromosomal inheritance involves the transmission of genetic material outside the nucleus and plays a crucial role in genetics, medicine, and biotechnology.
Future Directions: Continued research and technological advancements hold promise for new treatments and applications.
Slide 11: Questions and Discussion
Invite Audience: Open the floor for any questions or further discussion on the topic.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Cancer cell metabolism: special Reference to Lactate Pathway
Apomixis.ppt
1. APOMIXIS
In botany, apomixis was defined by Hans Winkler as replacement of the
normal sexual reproduction by asexual reproduction, without fertilization.
Its etymology is Greek for "away from" + "mixing". This definition notably
does not mention meiosis.
In flowering plants, the term "apomixis" is commonly used in a restricted
sense to mean agamospermy, i.e. clonal reproduction through seeds.
Thus, Apiomixis can be defined as the development of embryo with or
without embryosac formation but without fertilization.
2. Apomixis (asexual seed formation) is the result of a plant gaining the ability to bypass the
most fundamental aspects of sexual reproduction: meiosis and fertilization.
Without the need for male fertilization, the resulting seed germinates a plant that develops
as a maternal clone.
The ability to generate maternal clones and therefore rapidly fix desirable genotypes in
crop species could accelerate agricultural breeding strategies.
The potential of apomixis as a next-generation breeding technology has contributed to
increasing interest in the mechanisms controlling apomixis.
Research is currently focused on two fronts. One aims to identify and characterize genes
causing apomixis in apomictic species that have been developed as model species. The
other aims to engineer or switch the sexual seed formation pathway in non-apomictic
species, to one that mimics apomixis.
3. TYPES OF APOMIXIS
Embryo develops from
cells of gametophytic
or sporophytic origin.
Embryo may or may
not form.
Asexual process occurs
in the reproductive
parts of plant.
APOMIXI
S
Agamospermy
Gamitophytic
Apomixis
Sporophytic Apomixis
Or
Adventitive Embryony
Vegetative
Apomixis
1.Bulbils
2. Vegetative
Buds
4. VEGETATIVE APOMIXIS
The flowers in the inflorescence are
replaced by bulbils or by vegetative
buds. e .g. Alium, Dioscoria, Agave.
Caribbean Agave producing plantlets (bulbils) on
the old flower stem.
5. AGAMOSPERMY
Agamospermy is formation of seeds or embryo without fertilization.
Agamospermy, asexual reproduction through seeds, occurs in flowering plants through many
different mechanisms and occurs mainly in two forms:
In gametophytic apomixis, the embryo arises from an unfertilized egg cell (i.e. by
parthenogenesis) or any other cells (i.e. by apogamy) in a gametophyte that was produced
from a cell that did not complete meiosis.
In Gametophytic Apomixis, embryo formation is accompanied with embryosac formation.
It may be recurrent ( embryosac is formed without meiosis) or non- recurrent ( embryosac is
formed after meiosis).
In adventitious embryony (sporophytic apomixis), an embryo is formed directly (not from a
gametophyte) from nucellus or integument tissue (i.e. sporophytic tissue).
This may results in polyembryony. e. g. Citrus and mango.
7. GAMITOPHYTICAPOMIXIS
GAMETOPHYTIC APOMIXIS IN FLOWERING PLANTS DEVELOPS IN SEVERAL
DIFFERENT WAYS.
A MEGAGAMETOPHYTE DEVELOPS WITH AN EGG CELL WITHIN IT THAT
DEVELOPS INTO AN EMBRYO THROUGH PARTHENOGENESIS.
THE CENTRAL CELL OF THE MEGAGAMETOPHYTE MAY REQUIRE
FERTILIZATION TO FORM THE ENDOSPERM, PSEUDOGAMOUS
GAMETOPHYTIC APOMIXIS, OR IN AUTONOMOUS GAMETOPHYTIC
APOMIXIS FERTILIZATION IS NOT REQUIRED.
GAMITOPHYTIC APOMIXES PASSES THROUGH TWO STAGES, THESE ARE:
Embryosac Formation
1. Diplospory
2. Apospory
Embryo Formation
1. Parthenogenesis
2. Apogamety
8. EMBRYOSAC FORMATION
DIPLOSPORY
In diplospory (also called
generative apospory), the
megagametophyte (embryosac)
arises from a cell of the
archesporium.
APOSPORY
In apospory (also called
somatic apospory), the
megagametophyte arises
from some other nucellus
cell.
10. CLASSIFICATION OF APOMIXIS BY MAHESHWARI
Maheshwari used the following simple classification of types of apomixis in flowering plants:
Nonrecurrent apomixis: In this type "the megaspore mother cell undergoes the usual meiotic divisions and a haploid
embryo sac [megagametophyte] is formed. The new embryo may then arise either from the egg (haploid parthenogenesis)
or from some other cell of the gametophyte (haploid apogamy)." The haploid plants have half as many chromosomes as
the mother plant, and "the process is not repeated from one generation to another" (which is why it is called
nonrecurrent). See also parthenogenesis and apogamy below.
Recurrent apomixis, is now more often called gametophytic apomixis: In this type, the megagametophyte has the same
number of chromosomes as the mother plant because meiosis was not completed. It generally arises either from an
archesporial cell or from some other part of the nucellus.
Adventive embryony, also called sporophytic apomixis, sporophytic budding, or nucellar embryony: Here there may be
a megagametophyte in the ovule, but the embryos do not arise from the cells of the gametophyte; they arise from cells of
nucellus or the integument. Adventive embryony is important in several species of Citrus, in Garcinia, Euphorbia dulcis,
Mangifera indica etc.
Vegetative apomixis: In this type "the flowers are replaced by bulbils or other vegetative propagules which frequently
germinate while still on the plant". Vegetative apomixis is important in Allium, Fragaria, Agave, and some grasses,
among others.