1. No category

Ions pattern of desert succulents from the
Succulent Karoo, South Africa
- Can we link ecophysiology and phylogeny?
Maik Veste
Can we link ions pattern and phylogeny ?
The Succulent Karoo
From the investigations we can conclude that in the
Aizoaceae a correlation between the evolution of plant
functional types and ecophysiology within the same family
obviously exits. Species of the genus Brownanthus
(Aizoaceae, subfamily Mesembryanthemoideae) are typical
stem succulents with 12 species in the Succulent Karoo and
southern Namib. In the Richtersveld B. pseudoschlichtianus,
B. aerenosus, B. pubescens and B. marlothii growing on
sandy, loessial and highly saline soils at the coast,
respectively. A survey of ion characteristics of the four
species (Fig. 5) growing on diferent soil types showed a
high accumulation of Na and Cl, which is typical also for
halophytic species in the Aizoaceae [3] and other plant
families. However, the lowest Na and Cl content can be
found in B. marlothii growing on saline soils at the coast
and B. pubescens. Both are sister species (Fig. 6) [5].
Surprisingly, the highest accumulation of ions were
observed in B. aerenosus growing on sand dunes (Fig. 4,5).
The storage of water in the leaves is positive correlated
with the salt accumulation.
The Succulent Karoo, a winter rainfall desert in north-western
South Africa, is a hotspot of biodiversity with a large number of
succulent species. The major succulent families are the
Aizoaceae
(Fig.1,2),
Apocynaceae,
Aspodelaceae
and
Crassulaceae. These succulents have developed various
integrated and co-adapted morphological and ecophysiological
features that maximise their chances of surviving the
detrimental conditions in arid habitats. Crassulaceen Acid
Metabolisms (CAM) is a common feature in various southern
African succulent plant families. Especially in the Aizoaceae the
evolution of photosynthetic pathways can be linked to their
phylogeny [2]
Brownanthus marlothii (B.marl), coast
B. pubescens (B.pub.), Annisvlakte
B. pseudoschlichtianus (B. ps.)
B. pseudoschlichtianus (B. ps.)
Fig.1 Mesembryanthemum barkleyii a bi-annual Aizoaceae in the Richtersveld. Plant height is
more than 2 m,fresh weight 120 kg and water storage 110 kg.
Halophytes
B. aerenosus (B. aren.)
sand dunes
From a comprehensive screening programme it can be shown
that the species of the Aizoceae shows the highest sodium
Fig. 4: Brownanthus marlothii (B.marl). B. pubescens (B.pub.), B. pseudoschlichtianus (B. ps.), B.
chloride accumulations (Fig. 3) [1,3]. The ions accumulation is
aerenosus (B. aren.)
closely related to the development of leaf and stem succulence.
The most interesting feature is that succulents with high salt Conclusions
accumulation expend less energy and hence carbon to envelope In summary, like other succulents from the Aizoaceae,
one unit water than succulents with low salt content (e.g. in Brownanthus develops a genetic fxed ion pattern, which
Aizoaceae, subfamily Mesembryanthemoideae) [1,4].
can be related to their phylogeny [5].
B r o w n a n th u s ( R ic h te r s v e ld )
A
A iz o a c e a e
7000
a n io n s ( m m o l k g - 1 T G )
5000
3000
c a t io n s ( m m o l k g - 1 T G )
B
5000
3000
Fig. 2: Opophytum aquosum (Aizoaceae), annual
mesemb with the highest salt accumulation in the
Richtersveld.
1000
w a te r c o n te n t (k g k g -1 T G )
Phyllobolus digitatus
B. arenosus
1000
.
7000
16
A
3000
1000
.
c a t io n s ( m m o l k g - 1 T G )
5000
C
12
8
Fig. 3: Ions growing in Numees, Richtersveld.
4
0
1
2
3
4
5
6
7
8
9
10 11 12
C l
N a
w a te r
K
1 Opophytum aquosum, 2 Mesembryanthemum
barkle pattern and water content in
succulentsyii, 3 Mesembryanthemum pellitum,
4 Brownanthus pseudoschlichtianus, 5 Ruschia
spec., 6 Stoberia betzii, 7 Cheiridopsis robusta
8 Othonna opima, 9 Tylecodon paniculatus,
10 Ceraria namaquensis, 11 Aloe ramosissima,
12 Aloe personii.
5000
B
increasing NaCl
accumulation
B. pseudoschlitianus
3000
B. nucifer
1000
w a te r c o n te n t (k g k g -1 T G )
a n io n s ( m m o l k g - 1 T G )
N u m e e s , R ic h te r s v e ld ( R S A )
10
8
B. marlothii
B. pubescens
C
6
4
2
0
B . m a rl . B . p u b . B .p s
[ c o a s t] [A n n is v la k t e ]
B . p s . B . a re n .
[d u n e ] [d u n e ]
c h lo r id e
N a
s u lf a t e
K
w a te r
M g
Fig. 5: Ions pattern and water content in four
Brownanthus species, Richtersveld (see Fig.4).
Fig. 6: Strict consensus tree of combined molecular
analysis for Brownanthus.[5]
References
[1]
[2]
[3]
[4]
[5]
Von Willert DJ, Eller B, Werger MJA, Brinckmann, E, Ihlenfeldt, H-D, 1992. Life strategies of succulents in deserts with special reference to the Namib desert. Cambridge University Press, Cambridge. 340 pp.
Veste M, Thiede J, 2004. Diversity, fexibility and phylogeny of photosynthetic types in the succulent fora of southern Africa. In: Breckle S-W et al. (eds.), Ergebnisse weltweiter Forschung, Stuttgart, 361-370
Veste M, 2007. Der Salzhaushalt der Sukkulenten. Avonia 25(2): 43-50.
Waisel Y, 2000. Halosucculence: an old enigma with a new interpretation. In: Spatz H-C, Speck T (eds), Proceedings Plant Biomechanics Conference Freiburg, Thieme, Stuttgart, pp. 278-284.
Klak, C, Nowell TL, Hedderson TAJ, 2006. Phylogeny and revision of Brownanthus and its close allies Aspazoma and Dactylopsis (Aizoaceae) based on morphology and four DNA regions. Kew Bull.36: 353-400.