Unit 6: Reproductive Biology

SELF INCOMPATBILITY Unit -6 D Pollen grooms produced by the anthers reach the Strymas dr various houvess or the same species or de other diferent Species by vartus pollomatang ingents or winds. Similarly, the Stigma & the Gower also receive pollen graim from vanias Fource. All the pulen gram that reach the Ayna do not bertilize the egg and produce feedf. Only the right mating type of pullen gram germinate, enter the stylar path, hertilize the egg and produe the seeds. The roght bare of pollen gram which facilitater lertilization and leads to seed elevelopment & known as compatible howhere as the pollen grans which don't elvest bertilization are learn as incompatible and the phenomenon if known as Cexaal in compatibility.. The sexual imcompatibility is of towo types & there ane!- Interspecitiz Introspecibre or sells incompatibility. Interspeulit sexual imcompatibling The Sexaal in compatibility which is reen between the individuals or diferent fpecies is known as interspeche imcompatibility. Introspecie imonpahib hitz Sexual incompatibility or selv incong The sexual imcompatibility which is seen between individuals of fame fpeccer Sell in Ampatibility. if known ar omtraiectil on Sell mcompatibility (Cl) & the inabdity stt a beatile hermaphrodite plant to produce reeds when pollinated by sells pollen grains (sells pollimation). Thus in 51, Sells pollimation of avoided and croce pillmabon or outbreed outbreeding process is guaranteed, even it the plant Produces bunchonal male and female gameter. The term Cells incompatibility was bortt Crined by Stout in 1917. Sells incompatibility species don't produce seed on sells pollinaton but lead to norval reed on cross pollination. Here the pollen grain reach the Shymes of the lame Plant or another plant arth came genotype. In Cl also the process of pollen fermimation, pollen tube grouth, syngamy or embryogenesis is terminated at come stayer & thus there it bantat bailure of reed Production. Types or 51 (sells incompatibling)→ It is coulegrared into two types such as: @Homamorphit sl & ③ Heteromorphic St. Homomorphie el In homomorphre Cl, all individuals dro species Produce only morphology one type of loverd ahich are similar The plank dont exhibit differencer in style and stomer or other floral beaturer. The 5t chocring the followimy heatures!- 1) The pollen grains donst germinate on the stigma do the The short style is known of Thrum tyre Which is represented by 'S' and is dominant. The lony style is known as pin morph and 4 represented as F... The 's' is dumirant over the allele . The Lony Style plants are homozygour's chile & the short sole plants are heterozygous 'Sc'. Akcordimy to S-allele hypothesis, dictyly if controlled by a single gene Complex cuith two allelaj Ses (diallalic) when a chort Style plant it is crared with long Ctyle plent is then. f produces equal number TE Progeny dr short style and long style typer. S (Short Style plant) X long style plant. Short style plent Lony Style prosyeny. Here in heteromorphic Cyetem, the incompatibling is determined by sporophyte genotyre. Here Here, the pollen from Sporoplyte is is compatible on lony style morph. Cpim morphoics) but & incompatible on short Styled morph Dictyly @It relsers to 3 types of style ie the anthers and styles have three diverent position in blowers. and these are!- Short Shyle medilim Style & lony style. Long style. Medium shyle. Short style. It is been im Lythraceae. It controlled by I gener M and south two alleler each. 'S'it epistatic over'm' ie when 'S'il present with 'M' at that timme the character as m' is suppressed by 's'. The long style morphs are homozygou recessive for bette the genes (mmss) The mal style morphs are homozygous recessive for I gene & heterozygous or homozyyour for allele m. The short style morphs ave heterozygous hor alleler '' gene and homozyyow or heterozygoutor bur alleles of m yever. Morphogene Getholynes Lory style morphs -are- mmss mod style morphs -are- mmes or Mimiss short style morphs-are- mm Ss or Mmfs or Momes. Diverence between GS1 KSSI System 551 is known as Sporopytre 51 & it controlled by arther. It fa-celled, dificult to geranimate, short lived. Having hagh respiration rate. The stryone is diry. 97 s duploud. where as Gfl is framatophytre si and if controlled by gamets or pollen gram. Εχ Βναρίται τας In GSI the pollen gramm are two-celled, pallen tube germinale normally or cavily.. The pollen tube Penetrates but hail to reach the base of Chole. It of Short loved. Having low respiration bafe. The Shyna it das weduwet. features Tyrg Incompatibility 551 GSI Aillen Cyklogy Intro germination Vitality Respirativan rate shyma 3 Celled Dilvicult Short loved High Dry Relative reactions on the stigma Celled Cary Short lived. Louw wet In the style METHODS TO OVERCOME SELF INCOMPATIBILITY Sells incompatiblity (51) in plante which is in which introduced by nature has enfilled oilt breeding and production ar good ollesprings with wiele adoptability and vigours. But that meetural si has stood or a banser in the Crop productam improvement or plant breeding programmes. un Sells compatibility or tertilization & can helps production of homozyyour alleles which & requited for plant Improvement programmes but st prevent this. So. it & necellary to break 51 in plants. or overcome the fl Some methods which have been discovered recently to overcome the si are!- Mixed pollination→ 11 gta a technique cabere incompatible and compatible pollen grains are dusted on the stigma of the towers mixed cvith each other But the disted Compatible pollen grains are imactivated bebure by isadişahın or are killed by treating them with lome Chemicals like methand. iss) The treatment & dime in fuch a way that their wall Proteims are not alrected. in Due to the these compatible pollons coun not alfrect herbilization as they are mactivated but are capable of germination. These Compatible pollent or the recognition pollens ave known as mentor pollens v) The wall proteins from these manter pallens get released on the chyma of the pathy and help the incompatible palen to gerenciate on the shyma. vity The wall proteans from these mentor pollens VII) The mentor pollen provede pollen factor or pifactor. The pullen hactors interacts with s-bactor brom the shyma. It outer renders the stigma accessible to the incompatible pollens. wil Sometimes, the pollentuber of incompatible pollens att alter the yormmation are inhibited in the stylar canal. In Crim a condition, the mentor provide a pollen growth Promoting substance (PGS) which help the pullen tubes to grow in the style of wall es im other bromit tellus. ovules ovary and ix Mixed pollimation technique is done im plants where the incompatible pollen yrams are unable to germmater on the shyma. Ex. Lily, Cormor, Petuma hydrida, Populur eh. @Bud Pullination In some plants, the incompatibity factor for the pollen is produced by the style, at the time or lower matunty or opening as the Houwer. So, here in the cove the pollsmatron of made at the bud stage when the incompatibabijby I'm compatibility factor has not been fynthesized. Thus, the pillen tube grows normally i'm the style and borcun bertilize the egg. Ex. Petunia axillaris. Stub-pollination→ Ouhen the stylar length of the bemale parent is laryer Han the maximum length of the pollen hibe of the male parent, at that time times the incompatibility occurs on the surhace as the shyma. fo on this care to overcome incompatibility stub Pollimation or stump Pollimation is done. is) Here the oncompatibility of remove by removing the sky ma and also upper part of the style. An agar-sucrole medim is applied to the cut furbace of the style. Thus, the cut Gribave of the Style pronde a agar agar sucrose fushave bort bor the pollen to tick on the curtare and can germinate. 2) The compatible pollons are put artificially on this ager- Sucrose Carfare. These pullen then gemminare and can Vertilize and be able to form seed. the Thus, incompatible factore are not produced dueto removal of the sitngima. Ex. Ipomoea trichocarpa, Nicethana tobacum, N-ostico ch. Intra-ovarian pollimaten: 1) This technique was developed by kanto chal. (1962) The intra-darman Allimation is done in plants, above the i'm compatibility bacter les in the Shyma or the Ctylay-regaon... In this process pollen Suspension is prepared with distilled water. 1) Tuwa punctiores are made in the wall it the ovary. The pollen Suspencion is introduced into the ovary through one puncture by hypodermit syringe. viy The other punchire releases the air present in the ovarian cavity. ni, Both the punctures are then sealed by petroleum Jelly. uni, Pollen grains directly germinate inside the ovary and bromy about fertilization. Ex. Papaveraceae. ⑤ In vitro pollination → 5) In the method, all stigmatre, stylear and ovarian hirves are removed. is) Then the pollen grams are directly durledren on the vuler. i) The ovules are then cultered on a nutrient medium. (v) It promotes the germination of pollen yrann. This germinated pollen gram then succesrtrully bentelize the eyg Ex. Remo Petunia axillaru Modivization as Staymatre Surface 5) Thus method is applied to specces where the Shymake Surbave acts as the barrier to pollen germinahon. 11) Some chemeals like hexane, Triton X-100 (a detergent), Concanavalient eh are appleed to the Strymabe Surbare to maditry it. 11). There chemicals are bind to the surface e stigma and mask the pellicle of the styma which is the banser for Pollen gesnimatron. 1) The pollen graim thus is able to germinate and berilece the egg producing seed. Parasexual Hybridization E. It was first dircareged by E-C. Cocking in 1969. 22. It is a technique of busan or csolated protoplaits to produce hybrids. is, It & also known as somatic busion. iv) In this technique the cell walls or the pollen gram are degraded by a mixture os enzyme cellulare and pechinare. Thus the it produces protoplast. of microspore or K The protoplast buscem occurs in 3 steps!- pollengraim. @rolation of protoplast First frall the walle and good protoplast of cfolated. ⑥ fuccon of protoplast The busion OF protoplast is done in polyethylene glyad (PEG). The Protoplast bure Completely and a helerokaryon & bormed. Culture or hybrid protoplast to regenerate the whole plant. The heterokaryon & then. colated & grow on the culture medium. at controlled Condition. Durmy the culture, the heleronuclei bure to borm diploid hybrind cell. vi) The deplaced lybood cell then divide and redivide and borm Callus. 1) The Callus then giver site to plantlets. The parasexnal hybridization & a method which overcomes all types of baries. In Vitro Fertilization (IVF) Fertilization imwlver the buson of male and bemale gameter. In natural condition the busorn takes plave imside the eyg cell of the embrys sac. Agarm the embrage fac if present imside the ovule. One male nuclei bure with the egg nuclei Vormimy zygote where as one male nude bure with the seandary nucleur. & & known as double bortilization. So t a lenthy & lengthy process. Agarn some plans are also havimy I'm compatibility. That of why, to overcome the incompatibility developed recently IVF has been Hestory→ IVF im plants as younger to IVF in animals. D.D. Cass (1973) was the lit to isolate the male gamete or barley CHordeum vulgare). Similarly Ity and Zhu (1985) war the Iit to polate living eng and central cell in tobacco plant. the After Yolation of sperm and eyg, works were done for IVA. Kranz and his group reported the Ist fuccerstoal IVF. They are able to made the electro busorn of the sperm and egy cell of marze and become successful to produce mutro zygote. Such zygote were then cultured to form mulkcellular struture (cullus). Later, they became Successful to produce textile plants. From there zygote by IVF. Steps ou IVF in plants 3 basic The luf technique in plants involve micro techniques & these are! @grolation and felection of male and benale. gametes Furano pairs of gametes. Single zgjate culture or Culture of the artificially forme zygole. gaolation and selectram of male and renere gametes Ar male gamete Two types as pollens are found im angiosperms Such as bicellular and tricellular. In bicellular pillong grain, it consists dr one Vegelahve call and one generative cell. But in tricellular Pollen grenn of consists or two sperms and one vegetative Cell. In care ar bizellular pillen graim, the Sperm is Jolated by inducing the pr bizellular pollen graim bor imntro culture. But in care ar tricellular pallen gram, the Sperm is directly isotated from pallen graim cuith out going for writro Culture. The sperm is clolated by osmote Chocks which of Coupled with plt shock. These sperm cells are then separated form brom pellen Contaminants. There after the vrability of the sperms are evaluated by FCR Next step is the recognization or the sperm se chich sperm perthlore the eyg cell and which sperm bertilice the central cells. It has been found that in maize the Sperm which fertilize the egy contaim B-chromosome. These sperar are then stored im proper medium so that it can be used im IVF Isolation dr Fyg cell The egg Cells are present in the embryo sac. Agaim the embryo fac of bound with im the ovale. The egg it clilated by enzymatic digestion dr ovule.x then by manual diffection of the embyo fac ⑤ Fusanos pans & gameter The sperm bure cuith the egg anklicinally to born zygote in the following method!- By electriz Gurion ic By cakaum induved busion k By PEG induced buscon (Polyethylene glycol) Electrobusom or electric busion The crolated egg and sperms cells which I held im marocapillaries were transferred to the burion droplets by using Computer Controlled dispensor. Fuscon was induced by giving one or a few short pulses of direct current. The buren was completed in lell than one second. karyogamy occurred in less than one hour. Fimally zygote is formed. By calcium induved busin In maize the busion of male and bemale gameter takes place in the medicim Contarinmy 5mm ea Colraum. Its Success if about 80% Fusion takes place in very short time hormony zygote. zei By PEG induced buran The busion of male and bemale gametes also takes. place by inducing it with. PEG. Sonyle zygole Culture or culture or the artitisually formed zygote The burim zygode is the cultured in culture medra, The zygote divide and rediride and lastly goves nue to bertile plantı. Significance de In vitro fertilization 1. It overcomes all incompatibilkty banter. 2. It helps to recognize gameter. 3. It helps bor hybrid lormation. 4. It is urebul in crop improvement programme. 5. The cholated sperm, eyg, central cell and bortficially formed. zyyok are mudved im IVF procedures. 6.It help to elevelop genetically transformed plants. 7-It is used to study transgenic yameter. CYBRIDS (Cytoplasmic Hyprids) → Cyborals are a type of Somatic hybrids of plants or cellu cuhich contain the nucleus of one species but the cytoplasm ds both the parental special A Cybrid may be a fanyle Cell, or a Complete grawimy plant called Cybond plant. The process of protoplast busion of known as "cybridization!! Cybrids Contaim only one parental nuclear genome and the Cytoplasmit genome as other parent or it may contain only one parental nuclear genome & the cytoplasmic yenome of bom the parents. Sanbrcance de Cybrids & Cybridization 1. Here the two parental genomes that can not reproduce Sexually are recombined. 2. It overcome various sexual incompatibility barniert. 3. It can be used to steady cytoplasmic genes and their actrutiner im plant breeding expt. 4. It of wed to tranfer male Sterntity through mohchondral Jenome. 5. It is ured to transfer antibiotic resistance character. 6. It is used to trangrer herbicide resistane. 7-9t is used in mitochondral research. 8. Cybands can be used to hidy Come human ducave. Producton && cybrids 1. Here It & exactly fimilar to fomatter hybridicahum. 2. Besredes have one nuclew of one parent of imachivated belove the busan. 3. The machvahion of nucleuw can be done by Chemical. treatments, t-ray or gamma istadiaten to one or the parental protoplants. 4.. These pretsplant cuithout nuclew of fused with the ther protoplout to form cybrid cells. 5. The cybreds cells are identitied 6. There selected cells are thon cultured im Bf & ms media under controlled Condition. 7. The cybird then dunde & lurm calls. 8. The callus is then indived through hormone treatment in the medita & lastly plantlets are regenerated. Cybards in plant improvement 1.If har been used in restoration of male sterility. 2. Streptomycin resistance has been transberred brom Nicotiana terlacum to three other sp-of tobacco. Dimerence beth Cybrids & Hybridi. In hlytind a fumate hybred there is busion of both the mucleus and the cytoplasm. Thus ploudy level in somake hybend is more than the individual pasent cells. A But in a cybrid, there is busion of the cytoplasm & the cell but there I no nuclear furion, Here one Ar the parent cell nucleus has either been removed or imactivated. The ploidy level of the cybied depends on which mucleus of inactivated or removed.