TITLE:
Nitrogen Nutrition, Its Regulation and Biotechnological Approaches to Improve Crop Productivity
AUTHORS:
Mettu Madhavi Reddy, Kandasamy Ulaganathan
KEYWORDS:
Nitrogen, Nitrogen Use Efficiency, Genomics, Genetic Engineering, RNA-Seq, Nitrome, microRNA
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.6 No.18,
November
11,
2015
ABSTRACT: Nitrogen is the most important macronutrient needed for plant growth and development. The
availability of nitrogen in the soil fluctuates greatly in both time and space. Crop plants, except leguminous
plants, depend on supply of nitrogen as fertilizers. Large quantities of nitrogen fertilizers
are applied to crop plants, but only 33% of it is utilized by the plant. Plants have developed efficient
mechanisms to sense the varying levels of nitrogen forms and uptake them. They also have
well developed mechanisms to assimilate the incoming nitrogen immediately or translocate to
different parts of the plant wherever it is needed. Maintenance of nitrogen homeostasis is essential
to avoid toxicity. Apart from translocation and assimilation, plants have developed different
mechanisms, nitrogen efflux; vacuolar nitrogen storage and downward transport of nitrogen from
aerial parts to roots, for maintaining nitrogen homeostasis. In crop plants the “grain yield per unit
of available nitrogen in the soil” is referred as the nitrogen use efficiency (NUE) for which remobilization
of nitrogen, mediated by various transporters plays a crucial role. All these processes are
tightly regulated by proteins and microRNA in response to both external and internal nitrogen levels,
carbon status of the plant and hormones. As most crop plants are non-leguminous and depend
on soil nitrogen, more production could be achieved if crop plants can be made to utilize the
available nitrogen efficiently. The recent explosion of research information and the mechanisms
behind nitrogen sensing, signaling, transport and utilization enables biotechnological interventions
for better nitrogen nutrition of crop plants. This review discusses such possibilities in the
context of recent understanding of nitrogen nutrition and the genomic revolution sweeping the
crop science.