Mg 2+ uptake QTLs
description
Transcript of Mg 2+ uptake QTLs
Mg2+ uptake QTLs
Hannah Itell and Eric Sawyer
Biological roles for Mg2+
● chlorophyll
● common cofactor (RNA pol, kinases, ATPases, …)
● most Mg2+ is not free in cytoplasm (ATP/nucleotide-chelated or in organelles) < 2 mM
chlorophyll a
Biological roles for Mg2+
● vacuole: 3-13 mM Mg2+
● highest [Mg2+]: thylakoid lumen (30-50 mM), but importers unknown!
● Mg2+ uptake hindered by acidic soils
● Mg2+ deficiency can lead to Al3+ toxicity; transporter competition
chlorophyll a
Signs of Mg2+ deficiency● chlorophyll breakdown
● impaired sugar mobilization
● reduced growth, particularly roots
Mg2+ biochemistryA. Cation channelsB. MGTC. MHXD. Slow activating vacuolar
channels (SVs)E. MGT5F. MGT10 and FACCs (G)
Bose et al. (2011)
1. Mg2+ channels (plasma membrane)● Hyperpolarization-activated● Depolarization-activated● Voltage-independent● Cyclic nucleotide-activated● Non-selective ion channels
● AtCNGC10 (A. thaliana): mediates Mg2+ mobilization through the plant
2. Mg2+ Carrier Proteins (MGTs)
● Magnesium (Mg2+) Transport Family
● AtMGT1, 5, 7a, 9, 10
● Vary in affinity and sensitivity to Al3+
Plasma Membrane Mitochondria Chloroplast
AtCNGC10 AtMGT family
Candidate gene BLAST results
C639,822,476 bp
QTL: 7,628,656 +/- 1 Mbp
IGB
No hits :(
C841,758,685 bp
QTL: 40,141,039 +/- 1 Mbp
IGBCation/Calcium Exchanger @ 39,717,422
Cation/H+ Exchanger @ 39,945,936
Cation/H+ Exchanger @ 39,950,514
Cation/H+ Antiporter @ 40,277,578
C546,902,585 bp
QTL: 44,023,210 +/- 1 Mbp
IGB
Heavy metal transport/detoxification domain-containing protein @ 43,792,027
Calmodulin-like protein @ 43,857,726
Metallothionein-like protein @ 43,295,039 Golgi-assoc. cation binding protein
Calcium transporting ATPase @ 43,882,735 Similar to AT1G07810 cation transporter
Heavy metal transport/detoxification superfamily protein @ 44,678,689
C748,366,697 bp
QTL: 35,691,416 +/- 1 Mbp
QTL: 39,973,848 +/- 1 Mbp
IGBV-type proton ATPase subunit d2 @ 35,255,037
Caleosin-related family protein @ 35,570,359
Heavy metal transport/detoxification superfamily protein @ 36,474,786
Cation transport regulator-like protein @ 36,606,567
Major facilitator superfamily protein @ 35,825,037 small solute transporter
V-type proton ATPase 16 kDa proteolipid subunit c1/c3/c5 @ 39,793,003
Heavy metal transport/detoxification superfamily protein @ 40,122,906
Cation proton exchanger @ 39,509,003
Vacuolar cation/proton exchanger @ 39,433,988 & 39,437,869
C453,719,093 bp
QTL: 40,219,218 +/- 1 Mbp
IGB
Magnesium Transporter (Predicted) @ 39,807,316
Mitochondrial Carrier Protein @ 40,692,677
Conclusions● No candidate gene BLAST hits within 1 Mbp of QTL
● CNGC10 and MGT family hit every QTL +/- 10 Mbp
● IGB search within 1 Mbp of QTLs foundo vacuolar pumps/transporters
o heavy metal transporters (Al3+-Mg2+ antagonism?)
o Ca2+, Mg2+, and general cation transporters and binding proteins
ReferencesBose, J. et al. 2010. Role of magnesium in alleviation of aluminium toxicity in
plants. Journal of Experimental Botany 62: 2251-2264.
Hermans, C. et al. 2010. Systems analysis of the responses to long-term magnesium deficiency and restoration in Arabidopsis thaliana. New Phytologist 187: 132-144.
Perez, V. et al. 2008. Homeostatic control of slow vacuolar channels by luminal cations and evaluation of the channel-mediated tonoplast Ca2+ fluxes in situ. Journal of Experimental Botany 59: 3845-3855.