Self incompatibility ppt

self incompatibilty is a method which induce cross pollination and used in hybrid seed production in breeding.

1. Assignment on S elf-incompatibility Course code:-PBG-503 Course title:-principle of plant breeding Credit hour:-3(2+1) -:Submitted to:- -:submitted by:- Dr B.D Padhan Mr Manas ku . Patel (Dept of plant breeding ) 01Fsc/2014 (Fruit sc and horticultural tech .)

2. Self incompatibility self incompatibility refers to the inability of plant to set seed with functional pollen after self polllination . Koelreuter -1 st reported S.I in Verbascum phoeniceum plants(18 th century) Self incompatibility reported in about 70 family of angiosperm including several crop spp. It is importnant for outbreeding mechanism(cross pollintaion ) for normal fruit set. It maintained high degree of heterozygosity and can take place any stage between pollination and fertilization.

3. Causes of S.I Self incompatible pollen grain may fail to germinate on the stigmatic surface.   Some may germinate but fails to penetrate the stigmatic surface.   Some pollen grains may produce pollen tube, which enters through stigmatic surface, but its growth will be too slow. By the time the pollen tube enters the ovule the flower will drop. Some time fertilziation is effected but embryo degenerates early.

4. Classification of self incompatibility According to Lewis (1954) the self incompatibility is classified as follow Self incompatibility   Heteromorphic system Homomorphic system       Distyl Tristylty Gametophytic S.I Sporophytic S.I  

5. Other classification of S.I S.R no Basis of classification Types of S.I Brief description 1 Gene involved monoallelic S.I controlled by single gene Diallelic S.I controlled by two gene polyallelic S.I controlled by several genes 2 Site of expression Stigmatic S.I gene express in the stigma Stylar S.I gene express in the style ovarian S.I gene express in the ovary 3 Polle n cytology Binucleate The pollen grains have 2 nuclei trinucleate The pollen grains have 3 nuclei

6. Heteromorphic S.I In this case there will be difference in the morphology of the flowers. For example in  Primula sp there are two types of distyly flowers namely PIN and THRUM. (Pin flower) (Thrum flower)

7. Results of 4 types of crosses in primula Mating progeny Phenotype genotype genotype phenotype Pin x Pin s sx ss incompatibility - Pin x Thrum SS xSs 1:1( pin:Thrum ) 1 pin and 1 Thrum Thrum x Pin Ss x ss 1:1( pin:Thrum ) 1 pin and 1 Thrum Thrum x Thrum Ss x Ss incompatibilty -

8. TRISTYLY is known in some plants like Lythrum salicaria . In this case the style of the flower may be short, long or medium length Homomorphic S.I Sporophitic S.I gametophitic S.I (S.I is governed by genotype of (S.I is governed by the genetic pollen producing plant). constitute of gamets )

9. MECHANISM OF SELF INCOMPATIBILITY There are 2 type of events considered to constitute basic of S.I a)stimulation of unlike genotype b)inhibit of like genotype 2 hypothesis proposed for explaining this S.I mechanism(by bateman ) a)complementary hypothesis b)oppositional hypothesis

10. Complimentary hypothesis Proposed by bateman in 1952 . S.I due to absence of stimulation by the pistil on pollen growth in the like genotype(S1S2xS1S2) Means S.I is due to absence of substance in the pistil or pollen which are essential for pollen tube penetration.

11. Oppositional hypothesis It states that interaction between like alleles(S1S2xS1S2) leads to production of inhibitor which inhibit the growth of pollen tube in the pistil. Interaction between like alleles, a substance is produced in pollen and pistil which property to interfere with normal metabolism of pollen grain and tube(inhibit enzyme or auxin , block pollen tube membrane, inhibit enzyme necessary for penetration.)

12. Overcome of S.I Bud pollination :-pollination of immature buds with mature pollen. Delay pollination :- pollination of aged pistls several days after maturity with normal incompatible pollen. Late season pollination :- self pollination at end of flowering season also lead to seed set.

13. Irradiation :- irradiation of style with X-ray immediately before selfing reulst in break down of S.I . High temp .:- treatment of high temp ranging from 30-60 degree leads to break down of S.I. Mutilation of style :- S.I could be broken by mutilating the stigma with steel wire brush during pollination . Invitro -fertilization :- placing the pollen grains in direct contact with ovules result in break down of S.I.

14. Utilization in plant breeding Production of hybrids :-(cabbage and brussel sprout hybrid seed production) H ybrid seed production without emasculation and without resorting of CMS and GMS. Practiced in japan.

15. Combining of desirable genes S.I system permits combining of desirable genes in a single genotype from two or more different sources through natural cross pollination which is not possible in self-compatible spp.

16. limitation very difficult to produce homozygous inbreed lines in a S.I spp. S.I is affected by environment factor i.e Temperature and humidity and photo period. Sometimes, bees visit only one parental line in the seed production plot resulting in sib matting.

17. DIFFERENCE SELF INCOMPATIBILITY No seed set in self pollination but possible in cross pollination S.I can utilized during hybrid seed production S.I is less used because most of crop has no S.I MALE STERILITY Un-functional pollen failure to set seed both in self and cross pollination. M.S can utilized during hybridization programme of breeding . M.S can used more.