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The role of VA mycorrhiza in the heavy metal tolerance of Agrostis capillaris L.
17'3
Agriculture, Ecosystems and Environment, 29 (1989) Elsevier Science Publishers B.V., Amsterdam Printed in Czechoslovakla
THE ROLE
OF VA
M Y C O R R H I Z A IN
173-177
THE HEAVY METAL TOLERANCE OF
AGROSTIS CAPILLARIS L. Griffioen, W~A.J. and Ernst, W.H.O. Dep. of Ecology and Ecotoxicology, Biol. Laboratory Free University, P.O.Box 7161, 1007 MC Amsterdam, The Netherlands Abstract The effects of sol1 contamination with heavy metals on the occurrence of VA mycorrhizal fungi and the role these fungi may play in the heavy metal tolerance of Agrostls capillaris were investigated. Plants of two populations, one non-tolerant and one tolerant to a copper and manganese, were placed on a ~oil naturally contaminated with copper and manganese
with
or
without
inoculum.
Growth
of
the two
populations differed but inoculation had no effect on the total biomass production. The shoot-to-root ratios for dry weight and the copper and manganese concentrations differed after inoculation, of the two metals, only the uptake of copper of the tolerant populatlon increased significantly. Introduction VA mycorrhlzal fungi may increase the
uptake of macro-
and micro-nutrients if the availability for the plant is limited (Abbott ~nd Robson, 1984). What is, however, their function if the nutrients are available in excess? Can these fungi play a role in the tolerance mechanism of the plants as suggested by Dueck et al. (1985)? Material and methods The influence of VA mycorrhiza on the uptake of copper and manganese by roots and shoots of Agrostis capillarie L. is investigated. Plants from a heavy metal tolerant population (copper mine, Imsbach FRG) are compared with those of a non-tolerant population (Wadden Island Schiermonnikoog, The
Neetherland), making four combinations: toleran~ and nontolerant plants with their natural VA mycorrhiza or without, growing on the soll of the heavy metal tolerant population. Plants of approximately the same height were collected on the above mentioned sites. Roots were cut off and the shoots were placed on nutrient solution to form new roots, free of mycorrhizal infection. After two weeks the plants were placed in steam-sterillzed soil with or without the addition of fresh root pieces and soil, as Inoculum. Harvest of the plants took place after three months of growth. At that time, dry weight and mineral contents of both shoots and roots were measured as also root infection. Before staining of the roots with ~hlorazol Black E (Brundrett et al., 1984}/ roots were fixed in FAA (Phillips and Hayman, 1970). Mineral analysis was carried out on an atom absorption spectrophotometer after wet-destruction with HNO~. Results an~ discussion There are differences between the two plant populations, independent of the mycorrhizal status. The blomass production and the uptake of copper and manganese are higher for the plants of the tolerant population (Fig. 1), while the shoot-to-root ratio is lower (Fig. 2). The inoculation of the tolerant and non-tolerant plants with VA mycorrhiza has no effect on the total biomass production. However, the shoot-to-root ratio of both plant populations decreases as a result of inoculation (Fig. 2). In addition, also the shoot-to-root ratios of copper and manganese are affected by inoculation (Fig.3}. For both plant populations increase and
these of
the copper
the non-tolerant population increase
significant more than these of the total
uptake
of
the
and manganese ratios
metals
has
tolerant population.
The
not changed, except the
copper uptake of the tolerant plant population been significantly increased (Fig. 4).
which has
175
A l t h o u g h t h e t o t a l u p t a k e o f c o p p e r and m a n g a n e s e i s n o t i n c r e a s e d a f t e r i n o c u l a t i o n ( e x c e p t t h e coppe~ u p t a k e of the tolerant population) the distribution of these lements between shoots and roots has considerably altered. This is a result of a decrease of the metal concentrations in the roots of the non-tolerant plants and an increase of the concentrations in the shoots of the tolerant plants. The difference between the two populations maybe due to a dilution effect of the soil in case of inoculation of the non-tolerant
plants.
This
effect
was seen in the way the
roots grew through the pot: without the addition of inoculum the
roots
were
short
inoculum there was more
with many short side-roots and with root
biomass
production
but only
growing in the Inoculum zone. On account of the higher copper and manganese shoot-toroot ratios of the the
possible
manganese
role
tolerant of
tolerance
of
VA A.
population mycorrhIza capillaris
after inoculation, in
the
cannot
copper and be
due to
retention of these metals on or in the internal hyphae. .&o
0.8"
i
Ow(o) 0.6
]
Cu endUn (~
.fLo • t.6
0.4,
.I.O 0.~) q
.o.5
0.0
0.O NT T Figure la.
Fig..l. Dry plants or a alter throe malngalnes¢
Cu
Mn Fioure lb.
weiaht production (s) and copper alnd in~nlt;~nc,c contcnl (b) of whole non-tolerant (biT) -nd - toloralnt ('J') phmt i)opulalion or Aarostis caplUari$ months of 8rowth. Valluc, arc mca.s of t~:,l pt-',n[s -nd di© of copper and content alter In-trunsrormallion. Vcrtic~d bar is the MSDo.o$.
176
• ;LO
shoot-lo-root t r.atiofor Ow !31 1,o "1
t
•
O.S
0.0
N •
•1.0 .1.6
r,n
II * T
*NT Figure 2.
Fill. 2. Shoot-to-root ratio for dry welsh| of I non-toleTant (NT) and a tolerant (T) plant population of A&rostix capiilarix. Means of five plants Idler In-transformation1, + sign stands for added inoculum, . sign stands for no added inoculum. Vertical bar is the MSDo.05.
shoot-to-root ratio for Mn 1,O'
0.5"
shoot-to-root ratio for Cu
• 1.0 "0,5
O.0
0,0
-0.5
-0,5
-1,0
-I.0
•I ,5
-1.5
,2,0
• -2.0
,2,5
• -2.5
,3,0
-3.0 ÷ NT
÷ T Figure 3a.
'-"-'-" + NT "
*
T
Figure 3b.
F i g . 3 . Shoot-to-root r a t i o f o r copper (a) and manganese (b) c o n c e n t r a t i o n o f a non-
tolerant (HT) and a tolerant (T) plant population of A&rozrix capillarl~'. Means of five plants after In-transformation, + sign stands for added iaoculum. - sign stands for no added inoculum. Vertical bar is the MSDo.os.
177
2.S. Cu content (pmol)
2.0.
1.5. 1.0. 0.5,
0.0 NT
T
Fig. 4. Copper content of whole plants of a non-tolerant (NT) and a tolerant (T) plant population of A&rostis capiifaris. Means of five plants after In-transformation, + sign stands for added i n o c u l u m . - sign stands for no added i.oculum. Vertical bar is the MSD0.05. References ABBOTT, L . K . , ROGSON, A.D. : The e f f e c t o f m y c o r r h i z a e on plant growth. In: PONELL, C.L., BAGYARAJ, D.J. (ed.) : VA Mycorrhiza, p. 113-130, CRC Press, Inc., Boca Raton, 1984. BRUNDDRETT, M.C., PICHE, Y., PETERSON, R.L. : A new method for observing the morphology of vesicular-arbuscular mycorrhizae. Canandian Journal of Botany 62: 2128-2234, 1984. DUECK, T.A., VISSER, R., ERNST, W.H.O., SCHAT, H.:Vesiculararbuscular mycorrhizae decrease zinc toxicity to grasses growing in zinc polluted soil. Soil Biology and Biochemistry 18: 331-333, 1986. PHILLIPS, J.M., HAYMAN, D.S. : Improved procedure for clearing of roots and staining of parasitic and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Transactions of the British Mycological Society 55: 158-161, 1970.
Grtffioen, W.A.J. and E r n s t , W.H.O., 1989: The r o l e o f VA mycorrhiza in the heavy metal tolerance of Aarost~$ L. A g r ~ c . E c o s y s t e m s E n v i r o n . , 29: 1 7 3 - 1 7 7 .
Agriculture, Ecosystems and Environment, 29 (1989) Elsevier Science Publishers B.V., Amsterdam Printed in Czechoslovakla
THE ROLE
OF VA
M Y C O R R H I Z A IN
173-177
THE HEAVY METAL TOLERANCE OF
AGROSTIS CAPILLARIS L. Griffioen, W~A.J. and Ernst, W.H.O. Dep. of Ecology and Ecotoxicology, Biol. Laboratory Free University, P.O.Box 7161, 1007 MC Amsterdam, The Netherlands Abstract The effects of sol1 contamination with heavy metals on the occurrence of VA mycorrhizal fungi and the role these fungi may play in the heavy metal tolerance of Agrostls capillaris were investigated. Plants of two populations, one non-tolerant and one tolerant to a copper and manganese, were placed on a ~oil naturally contaminated with copper and manganese
with
or
without
inoculum.
Growth
of
the two
populations differed but inoculation had no effect on the total biomass production. The shoot-to-root ratios for dry weight and the copper and manganese concentrations differed after inoculation, of the two metals, only the uptake of copper of the tolerant populatlon increased significantly. Introduction VA mycorrhlzal fungi may increase the
uptake of macro-
and micro-nutrients if the availability for the plant is limited (Abbott ~nd Robson, 1984). What is, however, their function if the nutrients are available in excess? Can these fungi play a role in the tolerance mechanism of the plants as suggested by Dueck et al. (1985)? Material and methods The influence of VA mycorrhiza on the uptake of copper and manganese by roots and shoots of Agrostis capillarie L. is investigated. Plants from a heavy metal tolerant population (copper mine, Imsbach FRG) are compared with those of a non-tolerant population (Wadden Island Schiermonnikoog, The
Neetherland), making four combinations: toleran~ and nontolerant plants with their natural VA mycorrhiza or without, growing on the soll of the heavy metal tolerant population. Plants of approximately the same height were collected on the above mentioned sites. Roots were cut off and the shoots were placed on nutrient solution to form new roots, free of mycorrhizal infection. After two weeks the plants were placed in steam-sterillzed soil with or without the addition of fresh root pieces and soil, as Inoculum. Harvest of the plants took place after three months of growth. At that time, dry weight and mineral contents of both shoots and roots were measured as also root infection. Before staining of the roots with ~hlorazol Black E (Brundrett et al., 1984}/ roots were fixed in FAA (Phillips and Hayman, 1970). Mineral analysis was carried out on an atom absorption spectrophotometer after wet-destruction with HNO~. Results an~ discussion There are differences between the two plant populations, independent of the mycorrhizal status. The blomass production and the uptake of copper and manganese are higher for the plants of the tolerant population (Fig. 1), while the shoot-to-root ratio is lower (Fig. 2). The inoculation of the tolerant and non-tolerant plants with VA mycorrhiza has no effect on the total biomass production. However, the shoot-to-root ratio of both plant populations decreases as a result of inoculation (Fig. 2). In addition, also the shoot-to-root ratios of copper and manganese are affected by inoculation (Fig.3}. For both plant populations increase and
these of
the copper
the non-tolerant population increase
significant more than these of the total
uptake
of
the
and manganese ratios
metals
has
tolerant population.
The
not changed, except the
copper uptake of the tolerant plant population been significantly increased (Fig. 4).
which has
175
A l t h o u g h t h e t o t a l u p t a k e o f c o p p e r and m a n g a n e s e i s n o t i n c r e a s e d a f t e r i n o c u l a t i o n ( e x c e p t t h e coppe~ u p t a k e of the tolerant population) the distribution of these lements between shoots and roots has considerably altered. This is a result of a decrease of the metal concentrations in the roots of the non-tolerant plants and an increase of the concentrations in the shoots of the tolerant plants. The difference between the two populations maybe due to a dilution effect of the soil in case of inoculation of the non-tolerant
plants.
This
effect
was seen in the way the
roots grew through the pot: without the addition of inoculum the
roots
were
short
inoculum there was more
with many short side-roots and with root
biomass
production
but only
growing in the Inoculum zone. On account of the higher copper and manganese shoot-toroot ratios of the the
possible
manganese
role
tolerant of
tolerance
of
VA A.
population mycorrhIza capillaris
after inoculation, in
the
cannot
copper and be
due to
retention of these metals on or in the internal hyphae. .&o
0.8"
i
Ow(o) 0.6
]
Cu endUn (~
.fLo • t.6
0.4,
.I.O 0.~) q
.o.5
0.0
0.O NT T Figure la.
Fig..l. Dry plants or a alter throe malngalnes¢
Cu
Mn Fioure lb.
weiaht production (s) and copper alnd in~nlt;~nc,c contcnl (b) of whole non-tolerant (biT) -nd - toloralnt ('J') phmt i)opulalion or Aarostis caplUari$ months of 8rowth. Valluc, arc mca.s of t~:,l pt-',n[s -nd di© of copper and content alter In-trunsrormallion. Vcrtic~d bar is the MSDo.o$.
176
• ;LO
shoot-lo-root t r.atiofor Ow !31 1,o "1
t
•
O.S
0.0
N •
•1.0 .1.6
r,n
II * T
*NT Figure 2.
Fill. 2. Shoot-to-root ratio for dry welsh| of I non-toleTant (NT) and a tolerant (T) plant population of A&rostix capiilarix. Means of five plants Idler In-transformation1, + sign stands for added inoculum, . sign stands for no added inoculum. Vertical bar is the MSDo.05.
shoot-to-root ratio for Mn 1,O'
0.5"
shoot-to-root ratio for Cu
• 1.0 "0,5
O.0
0,0
-0.5
-0,5
-1,0
-I.0
•I ,5
-1.5
,2,0
• -2.0
,2,5
• -2.5
,3,0
-3.0 ÷ NT
÷ T Figure 3a.
'-"-'-" + NT "
*
T
Figure 3b.
F i g . 3 . Shoot-to-root r a t i o f o r copper (a) and manganese (b) c o n c e n t r a t i o n o f a non-
tolerant (HT) and a tolerant (T) plant population of A&rozrix capillarl~'. Means of five plants after In-transformation, + sign stands for added iaoculum. - sign stands for no added inoculum. Vertical bar is the MSDo.os.
177
2.S. Cu content (pmol)
2.0.
1.5. 1.0. 0.5,
0.0 NT
T
Fig. 4. Copper content of whole plants of a non-tolerant (NT) and a tolerant (T) plant population of A&rostis capiifaris. Means of five plants after In-transformation, + sign stands for added i n o c u l u m . - sign stands for no added i.oculum. Vertical bar is the MSD0.05. References ABBOTT, L . K . , ROGSON, A.D. : The e f f e c t o f m y c o r r h i z a e on plant growth. In: PONELL, C.L., BAGYARAJ, D.J. (ed.) : VA Mycorrhiza, p. 113-130, CRC Press, Inc., Boca Raton, 1984. BRUNDDRETT, M.C., PICHE, Y., PETERSON, R.L. : A new method for observing the morphology of vesicular-arbuscular mycorrhizae. Canandian Journal of Botany 62: 2128-2234, 1984. DUECK, T.A., VISSER, R., ERNST, W.H.O., SCHAT, H.:Vesiculararbuscular mycorrhizae decrease zinc toxicity to grasses growing in zinc polluted soil. Soil Biology and Biochemistry 18: 331-333, 1986. PHILLIPS, J.M., HAYMAN, D.S. : Improved procedure for clearing of roots and staining of parasitic and vesicular-arbuscular mycorrhizal fungi for rapid assessment of infection. Transactions of the British Mycological Society 55: 158-161, 1970.
Grtffioen, W.A.J. and E r n s t , W.H.O., 1989: The r o l e o f VA mycorrhiza in the heavy metal tolerance of Aarost~$ L. A g r ~ c . E c o s y s t e m s E n v i r o n . , 29: 1 7 3 - 1 7 7 .