Agriculture Reference
In-Depth Information
2012
; Nikiforova et al.
2005
; Davidian and Kopriva
2010
). As a result, despite the
negative effect of nutrient depletion on photosynthesis (Fig.
8.6
) photosynthesis-
derived carbohydrates might accumulate in the leaves. Reduced sink strength due to
reduced growth or seed development leads to a reduction of the carbohydrate export
from the leaf further contributing to carbohydrate accumulation (Rao et al.
1990
;
Stitt
1991
). This lack of sink strength and carbohydrate accumulation eventually
leads to oxidative stress under high light conditions, as excess energy cannot be
fully dissipated as heat. Consequently, nutrient starvation leads to photo oxidation,
which further damages the remaining photosynthetic apparatus (Cakmak and
Marschner
1992
; Groot et al.
2003
) and induction of senescence (Rolland
et al.
2006
), resulting in feedback down-regulation of photosynthesis (Pieters
et al.
2001
). A similar effect is caused when phloem loading is impaired leading
Fig. 8.6 A comparison of major metabolic pathway gene expression using MapMan. Data for
senescence is from ATGE experiments. Ratio (senescent leaf/green leaf) is shown in log2 scale.
Green leaf: L6 (ATGE_14A-C) and L8 (ATGE_15A-C). Senescent leaf: ATGE experiment
senescent leaf (ATGE_25A-C; Buchanan-Wollaston et al.
2005
). Data for sulfate, nitrate and
phosphate deficiencies are from the same references as Fig.
8.5
. Fold changes relative to the
nutrient sufficient control are shown in log2 scale.
Red
and
Blue squares
indicate genes induced or
repressed, respectively. First, different nutrient depletions show common response patterns, even
with the senesce data, especially for light reactions, Calvin cycle, and photorespiration. Further,
the strength of response to nutrient starvations affect plant metabolism in the order nitrogen,
phosphate, and sulfate
