Title: Influence of arsenic and phosphate on the growth and metabolism of cultivated plants.
Abstract: In growing cereal and legume seedlings arsenate is more toxic for root growth than shoot growth. Arsenate treatment affects the activity of antioxidant scavenging enzymes, level of oxidative stress markers, sugar and starch contents as well as carbohydrate metabolizing enzyme activities causing adverse effects on growth and metabolism of seedlings of cereals and legumes. In wheat and rice arsenate treatment decreases total and soluble N2 contents, nitrate and nitrite contents and activities of nitrate and nitrite reductase that lead to limitation of NO3 uptake by root. The activities of ammonium assimilating enzymes, i.e. glutamine synthetase and glutamate synthase, are decreased whereas deaminating activity of glutamate dehydrogenase is increased leading to an accumulation of toxic NH3. Arsenic treatment results in an alteration of shape of chloroplast and disorganizes the membrane structure in bean plants. All such alterations inhibited growth and development of test seedlings. On arsenate exposure, levels of various Krebs cycle intermediates and also activities of different respiratory enzymes are decreased causing changes in growth pattern in rice and wheat seedlings. In presence of arsenate, the glutathione level and the activities of the synthesizing enzymes that are required for normal growth and metabolism of rice seedlings are suppressed. The production of phytochelatins on arsenate exposure enhanced the detoxifying mechanism against arsenate in the test seedlings. Arsenate forms complex with the thiol group of phytochelatin and gets sequestered in the plant vacuole enabling researchers to design a process of detoxification of arsenic. This knowledge is helpful to produce plant cultivars that are more resistant to arsenic or that have reduced arsenic uptake. Combined application of phosphate with arsenate can ameliorate the damaging effects caused by arsenate treatment alone in cereal and legume seedlings. Hence, the use of phosphate-enriched fertilizers in arsenic-contaminated soil may help normal growth of cultivated plants.
Publication Year: 2015
Publication Date: 2015-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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