Sexual Incompatibility.

Sexual incompatibility is the major issue in organism both the human and plants.It is caused by many machanism occuring in plants.

1. SEXUAL …………………. .... INCOMPATiBILITY S.I

2. Definition interspecific intraspecific Pollen grain is fail to bring out fertilization in the ovule of the same plant Occurs between individual of different species … Same species

3. dichogamy basis of s.i Maturation of male and female at different time . E.g. Saxifraga aizoides anther dehisce before stigma attain receptivity E.g. Aristolochia stigma loss receptivity by the time of anther dehisce

4. herkogamy basis of s.i . Structure of male and female sex organ itself forms a barrier to self pollination E.g. Caryophyllaceae flower have stigma projecting beyond the stamens

5. physiology & biochemistry basis of s.i 1. Recognition reaction Pollen contact  stigma  REC reaction . 2. Rejection reaction Occur  stigma . Preventing entry of pollen tube  stigma

6. genetic & molecular basis of s.i East & Mangelsdorf 1925 Single gene with several alleles Avoiding

7. Crosses When the cross between S1S2 (pollen) x S1S2 (egg) = 0 % When the cross between S1S3 (pollen) x S1S2 (egg) = 50% When the cross between S3S4 (pollen) x S1S2 (egg) = 100%

8. Incompatible pollen tube growth is stops in stylar region due to synthesis of sRNA with in the style Which is enter in pollen tube and degrade the rRNA because it is responsiple for elongation of pollen tube E.g . Armeria maritime

9. S-locus Which is 3 loci. SCR (S-locus Cysteine Rich Protein) SRK (S-Receptor Kinase) SLG (S-Locus Glycoprotein) S1 & S2 pollen produces the SCR1 & SCR2 react with pistil Stigma activates the kinase enzyme , that makes stigma function for pollen tube germination Another protein MLPK of Serine –Threonine kinasae is attached to the plasmamembrane then inhibit the pollen

10. Other mechanisms of s.i 1. Heteromorphic S.I ; 2 or more morphologically distinct matting types within a species. Distinguised without the breeding test S.I is controlled by one gene with two alleles. E.g Primula S.I is controlled by two gene with four alleles. E.g Lathyrum

11. Heterostyly Two or more lengths of the style and stamen filaments E.g. Primula vulgaris

12. 2.homomorphic Within species , morphologically indistinguishable . Want a breeding test. Gametophytic S.I genotype of male gametophyte itself. E.g. Liliaceae . Reject reaction in style. Sporophytic S.I Genotype of the sporophytic tissue of the plant, where the pollen is derived. E.g . Asteraceae . Reject reaction in stigma.

13. 3 . Late acting S.I ; S.incompatible pollen reaches the ovule buy fail to set fruit . It’s called Ovarian S.I. occur 2 ways. A. Pre zygotic L.S.I Embryo sac deteriorates before the entry of pollen tube. E.g. Narcissus triandrus B. Post zygotic L.S.I The zygote is not able to develop. E.g. Spathodea campanulata

14. significance of s.i S elfing of plant produce , less surveying value. S.I is way to prevent. S.I favour to cross –pollination so new varieties and desired qualities are developed Interspecific S.I , emerges new races and species through open hybridization & mutation Etc…..,

15. methods to overcome s.i Bud pollination Pollination is done in early stage of bud , in Intraspecific S.I E.g. Petunia axillaris , at bud stage the stigma lacks the exudates. So the stigma is pollinated by pollen in bud stage. Its proved. Stub pollination The S.I reaction is occur in the Stigma or the style. So remove that. Its proved. E.g. Ipomoea trichocarpa Intra –Ovarian pollination S.I occur in both regions so the pollen is directly enter into the ovule . Its done by following steps ; ovary sterilization , two punctures are made , one for introduce the pollen by hypodermic syringe , another for aeration. After intro both punctures are closed with petroleum jelly. E.g. Argemome Mexicana

16. Heat treatment Provide upto 50 degree Celsius to style , it is used to reduce the S.I E.g. Lilium longifolium , above mentioned temperature for 6 mints. slightly increase the temperature is leads to injurious to pistil. Modification of stigmatic surface The pollen surface proteins and stima surface pellicle is essential for identify compatible or incompatible . Pre-treatment of triton-X 100 & some organic solvents like hexane modifies the pellicle and favours the fertilization.

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