Review. Drought influence on nitrogen metabolism fixed during Bradyrhizobium-soybean symbiosis

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J. A. Freixas

Abstract

Soybean (Glycine max L. Merr.) establishes
symbiosis with N2-fixing bacteria of the Rhizobia group, such
as Bradyrhizobium sp. Specific molecules secreted by
Bradyrhizobium, named nodulation factors, play a pivotal role
in the development of root nodule. Inside nodules, rhizobia
are differentiated into bacteroids, which reduce atmospheric
nitrogen into ammonia. The major part of ammonia is assimilated
into glutamine, which participates indirectly in nodule ureide
synthesis. Among the leguminous family, soybean is one of
the most sensitive to drought stress, which leads to a
significant decrease in the biological nitrogen fixation (BNF).
Drought-sensitive soybean genotypes accumulate ureides
during drought stress; however, drought-tolerant genotypes
have lower shoot ureide concentrations, which seem to
alleviate drought stress on BNF. Researches based on new
tools to increase BNF have been a priority during the last
decade. Manganese fertilization under moderate drought
conditions increases the catabolism of ureides and N2 fixation
in soybean. The enzyme 1-aminocyclopropane-1-carboxylate
(ACC) deaminase in Rhizobium cleaves ACC, the immediate
precursor of ethylene in plants, decreasing the inhibitory effect
of ethylene on nodulation. Induction of nodulation genes in
Bradyrhizobium has positive effects on soybean growth under
moderate drought stress. The aim of this review is focused to
enclose new molecular targets that allow improving BFN in
soybean under drought stress conditions.

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How to Cite
Freixas, J. A. (2012). Review. Drought influence on nitrogen metabolism fixed during Bradyrhizobium-soybean symbiosis. Cultivos Tropicales, 31(2), 66–73. Retrieved from https://ediciones.inca.edu.cu/index.php/ediciones/article/view/101
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Original Article