Molecular basis of self- incompatibility
Molecular basis of self-incompatibility
What is self-incompatibility?Pollen produced reaches the stigma of a flower of the same plantThe process of pollen germination is halted(Buchanan, et al., 2005)
Source :-http://www.akitarescueoftulsa.com/parts-of-a-carnation-flower-diagram/
S locusSelf-incompatibility -controlled by a single genetic locus with multiple alleles, S locus. (Buchanan, et al., 2005)
S-RNase gene Pollen S-gene SLG (S-Locus Glycoprotein) gene SRK (S-Receptor Kinase) gene SCR (S-locus Cysteine-Rich protein) gene
Gametophytic self-incompatibility (GSI)
Sporophytic self-incompatibility (SSI)
(Buchanan, et al., 2005)
S-RNase–mediated degradation of pollen tube RNA
SLF (S-Locus F-box) gene
Pollen S-Locus-specific F-Box Protein 3 S-RNase-Binding-Regulating Domains
(SBRD) FD1,FD2,FD3 FD2- Binds with RNase FD1, FD3 - Determine S-allele-specificity of
SLF Weaken the strong interaction between FD2 of
SLF protein & S- RNase
S-Rnase gene
Pistil-polymorphic glycoprotein Ribonuclease catalytic activity Allele-specific cytotoxin
(Hua, et al., 2008)
S-RNase–mediated degradation of pollen tube RNA
(Takayama, et al., 2005)
S-protein–mediated signaling cascade
• S gene in S-locus - Female determinant • S-proteins - Small, Secreted proteins
• Ca2+ influx to pollen tube shank • Loss of the apical gradient of Ca2+
• Inorganic pyrophosphatase • Inhibitor - calcium-dependent protein kinase
(CDPK)
(Takayama, et al., 2005).
S-protein–mediated signaling cascade in pollen (Takayama, et al., 2005)
Receptor-kinase–mediated signaling in stigmaSCR (S-locus Cysteine-Rich) – In Pollen Small, Basic, Cysteine-rich protein
S-locus Receptor Kinase (SRK) S-Locus Glycoprotein (SLG) – In Pistil
ARC1 (Armadillo-Repeat-Containing 1) Activated by Interacting with the cytoplasmic domain of SRK
Stigmatic proteins - Ubiquitination & Proteasomal degradation
Inhibition of pollen germination & pollen tube elongation
Thioredoxin H-Like proteins (THL1 & THL2) Interact with transmembrane domain of SRK protein
Inhibits auto phosphorylation activity of SRK
(Takayama, et al., 2005).
Receptor-kinase–mediated signaling in stigma(Takayama, et al.,2005).
Inbreeding depressionLower the population’s ability to survive and reproduce Genetic variations - low Revolution process - low Recessive alleles - expressed
Prevented by Self-Incompatibility (Igic, et al., 2008)
Reference:-Buchanan, B. B. Gruissem, W. Jones, L.R. 2005. Biochemistry & molecular biology of plants, 6th edition. Courier Companies, Inc., U.S.A, pp. 1018-1022.
Igic, B. Lande, R. Kohn, J.R. 2008, Loss of Self‐Incompatibility and Its Evolutionary Consequences, “International Journal of Plant Sciences”, 169: 93-104.
Hua, H. Z. Fields, A. Kao, H. T. 2008, Biochemical Models For S-RNase-Based Self-
Incompatibility, “ Molecular Plant”, 1: 575-585.
Takayama, T. Isogai, A. 2005, Self-Incompatibility in Plants, “Annual Review of Plant
Biology”, 56: 467-489.
http://www.nature.com/nature/journal/v367/n6463/abs/367563a0.html(05.11.2015).
http://www.plantcell.org/content/14/suppl_1/S227/F2.expansion.html (05.11.2015).
http://www.akitarescueoftulsa.com/parts-of-a-carnation-flower-diagram/ (05.11.2015).
Thank you