Physico-Chemical and Epigenetic Aspects towards Revealing Aroma Biology in Oryza Sativa L

Authors: Anita Kumari1, J Kumar, Anil Kumar and Gaur AK*

Volume 3, Issue 1

Abstract

Aroma is a complex attribute governed all the way through a complicated network of regulatory mechanisms of metabolic pathways at various levels. Abiotic factors of an environment like temperature, photoperiod and humidity seem to be more prominent signals as they influence chemical, biochemical and molecular responses. Molecular events are also important to understand the role of various proteins and nucleic acids in this complex regulation of aroma character visa vis role of structural genes/ promoters which are found either inducible or constitutive with respect to a specific macro/ micro environment. On the one side many molecules including different esters derived from lipids and or other secondary metabolites specially 2-Acetyl-1-Pyrroline (2-AP) had been reported as a major compound responsible for aroma based on organoleptic sensory evaluation test involving Human subjects providing them wide popular common food preparations. Many plants mainly Pandanus amaryllifolius Roxb had also reported for appreciable amount of 2-AP. Oryza sativa L. had been widely accepted for the presence of 2-AP including basmati, non-basmati varieties and other scented landraces. The biogenesis of this molecule is complex. However, precursor and product relationship has been established differently. One such relationship for 2-AP had been established from plant stress related imino acid (proline) through its one of the derivative 2-hydroxy-1- pyrolline. Although such molecules had been shown derived from carbon and nitrogen metabolism. Deletion in the betaine aldehyde dehydrogenase 2 (BADH2) gene leads in the accumulation of Δ1 -pyrroline which reacts non-enzymatically with methylglyoxal in order to form 2-AP. Due to non-functionality of this gene which regulates the synthesis of γ-amino butyric acid (GABA), plant species synthesizing 2-AP suffers for the yield losses and susceptibility to biotic and abiotic stresses. Since, BADH2gene is under regulation differing from BADH1 gene those are coupled with 2-AP synthesis, however, BADH2 gene had been proven as a gene of metabolic diversion with reference to Oryza species. Thus, present review focus on 2-AP in relation with stress and aroma biology which in turn will help to understand the productivity and aesthetic value of rice which is a major staple food of majority of global human population

Keywords: 2-Acetyl-1-Pyrroline (2-AP); Aroma Compounds; Betaine Aldehyde Dehydrogenase 1(BADH 1); Betaine Aldehyde Dehydrogenase 2 (BADH2); Γ-Amino Butyric Acid (Γ-GABA); Scented Landraces

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