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transcript
Pollen cryopreservation-an aid for
plant breeding
Eighth International Training Course on In Vitro and Cryopreservation Techniques for
Conservation of Plant Genetic Resources, ICAR-NBPGR, New Delhi, November 5 - 19 2019
Gowthami R, Neelam Sharma & Vartika Srivastava
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01 Pollen grains represent male gametophytes
Transmit nuclear genetic material
Abundantly produced
Provide phylogenetic evidence in plant systematics
Pollen grains may look like simple structures, but each pollen grain is an independent unit that underwent a precise developmental program
Tiny grains with greater important in plant lifecycle
POLLEN
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
1. Exine: The outer thick layer made up of sporopollenin (resistant to physical and biological decomposition) and provides protection
2. Intine: The intine is pecto-cellulose in nature, associated pollen tube formation
3. Vegetative cell: Contains abundant food reserve. Provides the medium for the movement of male gametes inside the pollen tube
4. Generative cell: the generative cell cytoplasm is highly reduced but it contains the usual cell organelles. It divides mitotically to produce two functional male gamete
STRUCTURE OF MATURE POLLEN GRAIN
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Pollen – microscopic wonders of plant kingdom
Exine has the rare capacity to sustain heat upto 3,000 OC, could be located even in the Palaeozoic rocks of some 500 Ma old without being destroyed, where all other organic materials remain carbonized and distorted
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN: BEAUTIFUL COLORS, FASCINATING FORMS
Pollen colour chart created by a beekeeping association in the UK
Pollen grains resembles seed in many respects
Pollen Seed Pollen develops in the anther Seeds develop in the ovary/fruit
Pollen is covered by exine, which contains sporopollenin (highly resistant to chemical degradation)
Seed (embryo) is protected by endosperm and hard integuments resistant to fungal attack
Two phases of growth • Development of the microspore up to the end of sporoderm formation • First haploid mitosis , subsequent development of male gametophyte
Two phases of growth • Development of the embryo up to heart-shaped stage • Storage of reserves in the embryo or in Separate endosperm tissue
Two cell types produced during development: •. Vegetative cell has limited function, then degenerates •. Generative cell gives rise to two male gametes
Zygote divides and gives rise to two cell types: •Suspensor has limited function, then degenerates •Terminal cell gives rise to embryo
Different degrees of dehydration before dispersal: orthodox (Desiccation resistant) and recalcitrant (desiccation Sensitive)
Rarely remains viable for few days Seeds may live for years
IS POLLEN AND SEED BEHAVES SAME?
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Franchi et al., 2011
POLLEN AND SEED DEVELOPMENT IN ANGIOSPERMS
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Why so many pollen grains?
200 2000 20000 200000
Vulpia myuros
Rostraria cristata
Lamarckia aurea
Brachypodium distachyon
Bromus lanceolatus
Bromus hordeaceus
Lindernia ciliata
Limnophila sessiliflora
Murdannia nudiflora
Stipa capensis
Holcus lanatus
Hordeum leporinum
Phalaris minor
Cyanotis cristata
Enydra fluctuans
Trisetaria panicea
Briza maxima
Hydrocotyle sibthropioides
Holcus setiglumis
Aegilops geniculata
Hyparrhenia hirta
Avena barbata
Cynodon dactylon
Vulpia geniculata
Aegilops triuncialis
Elymus repens
Sorghum halepense
Eichhornia crassipes
Festuca arundinacea
Lolium rigidum
Arrhenatherum album
Ludwigia octovalvis subsp. Sessiliflora
Ipomoea aquatica
Nymphaeapubescens
Nymphaea rubra
No. of pollen grains/flower
Pollen production is species-specific
Autogamous (self-fertilizing ) <
Entomophilous (insect-pollinated) <
Anemophilous (wind-dispersed)
Draba reptans produces an average of only four pollen grains per ovule, while wind-pollinated species (e.g. Betula pendula) produce up to 2 million pollen grains per ovule
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
C. Subba Reddi & N. S. Reddi (1986)
Family P/O ratio Family P/O ratio Family P/O ratio Asclepiadaceae 11 Oxalidaceae 1632 Rhamnaceae 6570 Onagraceae 34 Fumariaceae 1731 Betulaceae 6734 Pyrolaceae 82 Lamiaceae 1808 Poaceae 8131 Alismataceae 175 Asteraceae 1939 Apiaceae 10363 Solanaceae 184 Rubiaceae 1991 Plantaginaceae 13157 Malvaceae 226 Juncaceae 2747 Boraginaceae 18015 Caryophyllaceae 266 Araceae 2750 Chenopodiaceae 18069 Geraniaceae 328 Fabaceae 3312 Rosaceae 23788 Polemoniaceae 441 Polygonaceae 3589 Ulmaceae 28367 Lentibulariaceae 450 Adoxaceae 3902 Balsaminaceae 80033 Saxifragaceae 634 Tiliaceae 4350 Aceraceae 94078 Campanulaceae 647 Trilliaceae 4831 Euphorbiaceae 122190 Ericaceae 665 Brassicaceae 5166 Hippocastanaceae 451543
Primulaceae 690 Liliaceae 5314 Fagaceae 636594 Scrophulariaceae 709 Ranunculaceae 6226 Corylaceae 2119717
What happens to the remaining pollen
Pollen as phytopathological amplifier Pollen as feed for animals Human consumption
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Why to store pollen
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
To serve plant breeders to attempt hybridization between plants cultivated/grown in different geographic regions, or showing non-synchronous flowering.
To provide a constant supply of short-lived (recalcitrant) pollen and for those crops that have recalcitrant seeds and exhibit poor response to tissue culture methods
To facilitates the supplementary pollinations in orchard crops
To ensures the availability of male gametes for hybridization program and eliminate the need to grow male lines continuously in breeding programs
To facilitate continuous source of pollen for studying pollen biology
To ensure the availability of pollen throughout the year
To conserve species where no other conservation methods are available (wild, rare and endangered)
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
TYPES OF POLLEN- STORAGE PERCPECTIVE
Mature pollen is of two types
BICELLULAR
TRICELLULAR
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
BICELLULAR AND TRICELLULAR POLLEN
Firon et al., 2012
Water status and pollen development Phase 1
Phase 3 & 4 Phase 2
Phase 5
Microsporogenesis Pollen maturation and Dehydration
Presentation and Dispersal
Pollen stigma interaction and
rehydration
Bicellular pollen Tricellular pollen
Desiccation-resistant, orthodox, or partially-dehydrated
Desiccation-sensitive, hydrated, partially-hydrated, or recalcitrant
70% of the species release pollen in a bicellular stage
About 30% of species release pollen in a tricellular stage
Pollen shed at a lower moisture content, survives desiccation (upto 10%)
Pollen shed at a high moisture content and survives only limited desiccation
All phylogenetically primitive taxa are bi- nucleate
Originated independently at many times during angiosperm evolution
Dispersed in a sexually immature, somewhat dehydrated, metabolically quiescent state
Dispersed in a sexually mature, well-hydrated, metabolically active state
Pollen less differentiated, long lived, often dormant at dispersal
Pollen terminally differentiated and dispersed in a nutrient poor conditions
Pollen longevity under natural conditions is long
Pollen longevity under natural conditions is short
Tolerant to desiccation & freezing Sensitive to desiccation and freezing
BICELLULAR AND TRICELLULAR POLLEN
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Bicellular Tricellular Both
Monocots Musaceae Zingiberaceae Amaryllidaceae Palmae Pandanaceae Dioscoreaceae
Poaceae Euphorbiaceae Convolvulaceae Rutaceae
Dicots Solanaceae Cucurbitacea Moraceae Annonaceae Piperaceae Malvaceae Vitaceae
Amaranthaceae Asteraceae Cruciferae Chenopodiaceae
BICELLULAR AND TRICELLULAR POLLEN
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Brewbaker (1967)
BICELLULAR AND TRI CELLULAR POLLEN
Pollen grains store water in vacuoles and the pollen water content is generally higher than 60% during development
During presentation and dispersal of mature pollen, water-containing vacuoles are absent and the water content generally decreases below 40%
In Tri-nucleate recalcitrant pollen, water loss to a minimum of 20-25 % moisture content causes a complete loss of pollen viability. Hence Desiccation sensitive pollen should be dried till no freezable water exist but above the level where desiccation injury is apparent
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Bi-nucleate pollen, water loss to a minimum of <10 % moisture content causes a reduction in pollen viability. Hence Desiccation tolerant pollen should be be dried to a moisture level below which freezable water does not exist
Franchi et al., 2011, Pacini et al., 2011
POLLEN: EXPLANT FOR CRYOPRESERVATION
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Pollen grains are simple, haploid organisms and can be
easily collected and stored in viable condition for long
period
Pollen grains can be cultured on simple medium
Pollen germination and pollen tube growth are rapid, and provide results within a few hours
Maintenance of aseptic conditions in collection and storage is not mandatory
Larger number of alleles can be stored in small space
Handling and Retrieval is easy
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
In case of sticky pollen, they can be extracted using organic solvents such as cyclohexane or hexane for 2-3 min (to remove the sticky pollen coat substances)
POLLEN COLLECTION
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Pollen should be harvested during peak flowering period and soon after anthesis, usually in the morning hours (8 – 10 am) on a bright sunny day
Pollen should not be collected from infected or insect pest-damaged flowers
Pollen should not be collected on a rainy day or if it had rained overnight
Pollen should not be forced from anther and pollen should be free of anther debris
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN VIABILITY ASSESSMENT
Fertilizing ability
Staining
In vitro germination
In vivo pollen germination and pollen
tube growth
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1. Tetrazolium (TTC) test 2. Fluorochromatic Reaction (FCR) or
Fluorescein Diacetate Test (FDA) 3. Acetocarmine test 4. Potassium Iodide staining
1. Hanging Drop Culture (Cavity slide method)
2. Sitting Drop Culture 3. Suspension Culture 4. Surface culture
Pollen –pisitl interaction studies
Seed set and fruit set percentage
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN VIABILITY: TTC
2,3,5-Triphenyltetrazolium chloride Prepare TTC in sucrose solution of suitable concentration, to prevent bursting of pollen grains
TTC solution undergoes photo-oxidation, hence store in a brown bottle TTC test is based on the reduction of a colorless soluble tetrazolium salt to a reddish formazan, in the presence of dehydrogenases in the pollen cytoplasm
Place a drop of TTC solution on a microslide
Viable pollen grains turn red
due to accumulation of
formazan
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Suspend a small amount of pollen in the TTC drop
Gently place a coverglass on pollen drop
Distribute pollen uniformly in the drop Transfer the
preparation to a humidity chamber
(>95% RH) for 5-10min
Incubate for 5-10min. at room temperature
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN VIABILITY: FDA OR FCR
Place a drop of sucrose-FDA mixture solution on
a microslide
Suspend a small amount of pollen in
the FDA solution drop
Gently place a coverglass on pollen drop
Distribute pollen uniformly in the drop Transfer the preparation
to a humidity chamber (>95% RH) for 5-10min
Incubate for 5-10min. at room temperature
Pollen grains that fluoresce
brightly as viable
Stock solution of FDA is prepared in acetone (2 mg/ml). Add drops of stock solution of FDA to 2-5 ml of sucrose solution until the resulting mixture shows persistent turbidity
Observe under the fluorescence microscope
The mixture (FDA and Sucrose) should be used within ca. 30 min from preparation; otherwise most of the FDA would precipitate
The non-polar non-fluorescent FDA enters the pollen cytoplasm, Esterases of cytoplasm hydrolyze FDA and release fluorescein, which is polar and fluorescent. Viable grains and gives green or yellowish-green fluorescence
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN VIABILITY: POTASSIUM IODIDE
Place a drop of sucrose-FDA mixture solution on
a microslide
Suspend a small amount of pollen in the
TTC drop
Gently place a coverglass on pollen drop
Distribute pollen uniformly in the drop
Incubate for 5-10 min at room temp
The dark blue-black colored grains are viable pollens
1% Potassium Iodide (KI): Dissolve 1 gm of iodine and 2 gm of potassium iodide in 100 ml of distilled water
Viable
Non-Viable
Rice
Black gram
Iodine broke up in a watery arrangement of potassium iodide the tri-iodide-anion groups with starch, creating blueblack color
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN VIABILITY: ACETOCARMINE
Place a drop of sucrose-FDA mixture solution on a
microslide
Suspend a small amount of pollen in the TTC drop
Gently place a coverglass on pollen drop
Distribute pollen uniformly in the drop
Incubate in laboratory temperature for 5-10 min
Observe under the
microscope
The dark red or pinkish colored grains are counted as viable
The pollen nucleus is rich in chromatin material and viable pollen stains pink to deep red with aceto-carmine, while sterile (mostly shriveled) pollen does not take any stain and thus remains almost white and transparent
Acetocarmine (2%): Weigh 2 g of carmine powder, dissolve it in 95ml of 45% glacial acetic. Add distilled water to make a total of 100ml solution. Boil it for 5 min, cool and filtered and stored in a refrigerator
Commonly used pollen culture media Ingredients Brewbaker &
Kwack's Medium Roberts' Medium
Hodgkin & Lyon's Medium
Sucrose 10% 20% 20%
Boric acid 100 mg/1 10 mg/1 100 mg/1
Calcium nitrate 300 mg/1 - 400 mg/1
Calcium chloride - 362 mg/1 -
Magnesium sulfate 200 mg/1 - 200 mg/1
Potassium nitrate 100 mg/1 100 mg/1 100 mg/1
Tris - 60-130 mg/1 -
TAPS - - 4.86 g/l
POLLEN VIABILITY: In vitro germination
In vitro pollen germination is the most commonly used and reliable viability testing method
Place a drop of pollen germination medium
Suspend a small amount of pollen in the
TTC drop
Gently place a coverglass on pollen drop
Distribute pollen uniformly in the drop
Incubate for 5-10min. at room
temp.
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
01 03 04
02 Hanging Drop
Culture (Cavity slide method)
Sitting Drop Culture
Suspension Culture
Surface culture
Solid media slice
Petriplate with solid media
POLLEN VIABILITY: In vitro germination methods
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Total number of well stained pollens Pollen viability percentage = ----------------------------------------------------------- x 100 Total number of stained and unstained pollens
A minimum of three replications A minimum of 10 microscopic fields to be counted (500 grains) per replication
POLLEN VIABILITY SCORING
Staining methods
In vitro germination
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Scoring of pollen germination (Stanley and Linskens, 1974)
Viability Per cent germination
Excellent More than 80
Good 60-80
Moderate 40-60
Low 20-40
Poor Less than 20
Pollen germination (%) = No. of germinated pollen per field of view
˟ 100 Total number of pollen grains per field of view
DETERMINATION OF MOISTURE CONTENT
The moisture content of pollen is of critical importance for the maintenance of viability during long periods of storage
Moisture content should be reduced to ~10 % or more (bicellular) for storage
Regular monitoring of the sample should be done to ensure high viability and low moisture content. Excessive desiccation can lead to a loss in viability
DESICCATION OF POLLEN
AIR DESICCATION SILICA GEL DESICCATION
Charged silica contained in
airtight desiccators Room temperature
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
4o C
Few Hours
Your Text Here
-20o C to - 40o C
- 80o C
- 196o C
Several days
Several Months
Several Years (∞) Ce
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tivi
tie
s
Temp.
POLLEN STORAGE
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
All the metabolic activities arrested during long
term conservation
POLLEN CRYOBANK
POLLEN COLLECTION
AIR DESSICATION SILICA GEL DESSICATION
POLLEN VIABILITY AND MOISTURE CONTENT
PACK ALUMINUM FOIL POUCHES/ CRYOVIALS
STORAGE IN LIQUID NITROGEN
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
POLLEN CRYOPRESERVATION- APPLICATION
Recalcitrant seed spp, wild, rare and endangered
Germplasm conservation
Biochemical and physiological studies
Haploid production
Pollen mediated gene transfer
In vitro pollination and In vitro fertilization
Plants that flowers different times, different places
Germplasm exchange
POLLEN CRYOPRESERVATION: OKRA
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Fully opened flower
Undehisced anther
Dehiscing anther
Fully opened inflorescence
Partially opened
inflorescence
Fully dehisced anther
Different stages of inflorescence and anthers
Place flowers under a table
lamp for dehiscing
Extract pollen using cyclohexane using a millipore filter and
collect the disc containing pollen
Place disc containing
pollen into a cryovial
Store in liquid nitrogen
POLLEN CRYOPRESERVATION: ALLIUMS
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Botanical name Duration Percentage of germination Reference
Before
cryostorage
After
cryostorage
Allium sepa 1 year 45.13 46.90 Ganeshan (1986)
Carica papaya 5 yrs 65 52 Ganeshan (1986)
Abelmoschus esculentus 1 year 82.3 51.7 Reka chaudhury et al.,
2010 Brassica juncea 6 months 70 72 ()
Cucumis sativus 6 months 30 25
Crotalaria tetragona 1 year 88.5 68.32
Elaeis guineensis 8 years 60 54.0
Litchi chinensis (CHES-6) 4 years 69.9 72.2
Litchi chinensis (Chaina) 4 years 48.7 46.5
Litchi chinensis (Kasba) 4 years 58.7 60.0
Mangifera indica (Amrapali) 4 years 85.5 87.0
Mangifera indica
(Bombay Green)
4 years 55.0 56.8
Mangifera indica (Neelum) 4 years 75.0 70.6
Mangifera indica (Kishan Bhog) 4 years 82.5 80.0
Vitis vinifera L. 5 yrs 73 76 Ganeshan (1985)
Cryopreservation of pollen
POLLEN CRYOPRESERVATION- ICAR- NBPGR, NEW DELHI
Bitter Gourd (Momordica charantia), Cherry (Prunus nepalensis), Citrus (Citrus indica), Coconut (Cocos nucifera), Cowpea (Vigna unguiculata), Cucumber (Cucumis sativus X Hardwickii), Indian Mustard (Brassica juncea), Kokum (Garcinia indica), Litchi (Litchi chinensis), Long Melon (Cucumis melo var. utilissimus), Maize (Zea mays), Malabar Tamarind (Garcinia gummi gutta), Mango (Mangifera indica), Mangosteen (Garcinia mangostana), Mustard (Brassica sp.), Okra (Abelmoschus spp),
A total of 576 accs in the form of pollen grains
Onion (Allium spp.), Oil palm (Elaeis guineensis), Pumpkin (Cucurbita moschata), Radish (Raphanus sativus), Rapeseed (Brassica rapa var. brown sarson), Snapmelon (Cucumis melo var. momordica), Sweet gourd (Momordica cochinchinensis), Sesame (Sesamum indicum), Toria (Brassica rapa var. toria), Watermelon (Citrullus vulgaris), Wheat (Triticum durum), Wild vigna (Vigna trinervia var. bourneae), Yellow mustard Wild barley (Hordeum spontaneum) etc.
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
ICAR-NBPGR- SUCCESS STORIES
Prunus sp
NBPGR RS, SHIMA
Mango
Central Institute of Subtropical
Horticulture, Lucknow
and IARI- New Delhi
Okra
Wide hybridization
NBPGR
Allium sp
NBPGR
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Let us join hands to Protect and Conserve Plant Biodiversity for our
future generations
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
Eighth International Training Course on ‘In vitro and Cryopreservation Approaches for Conservation of Plant Genetic Resources’, ICAR-NBPGR, New Delhi. Nov 5-19, 2019
But what the poet doesn't see is the
xylem and the phloem and the
pollen and the thousands of
generations of breeding and the
billions of years before that
A poet sees a flower , as how beautiful the colors are.
All of that is visible to the scientists George M. Church