Volatile Organic Compound Based Markers for the Aroma Trait of Rice Grain

Abstract

A study was conducted to determine the volatile organic compounds (VOCs) associated with rice grain aroma in 37 commonly grown lines within Uganda, as well as elites. The aim of the study was to identify potential volatile biochemical markers, if any, for the rice grain aroma trait. Certified rice seeds were obtained from the Uganda National Crops Resources Research Institute germplasm collection. The seeds were sown into experimental plots, under field conditions and the mature paddy harvested. Polished rice grains were heated to 80 oC and the liberated VOCs subjected to untargeted metabolite analysis using gas chromatography-time-of-flight mass spectrometry. In total, nine functional groups were present; hydrocarbons, alcohols, ketones, aldehydes, N-containing compounds, S-containing compounds, esters, oxygen heterocycles and carboxylic acids. More specifically, 148 VOCs were identified across the 37 rice lines, of which 48 (32.4%) including 2-acetyl-1-pyrroline (2-AP) appeared to elucidate the difference between non-aromatic and aromatic rice. Furthermore, 41 (27.7%) VOCs were found to be significantly correlated with 2-AP abundance, the principle rice aroma compound. Amongst the 41 VOCs, only ten compounds were found to contribute highly towards variation in 2-AP abundance, indicative of their possible modulation roles in regard to rice aroma. Within the ten influential volatiles, three aroma active compounds; toluene, 1-hexanol, 2-ethyl and heptane, 2,2,4,6,6-pentamethyl- were established as the most reliable biochemical surrogates to the rice aroma trait. Thus, the aforementioned compounds may be used in rice breeding programme for enhancing development of the grain aroma trait.

Soybean Cyst Nematodes Influence Aboveground Plant Volatile Signals Prior to Symptom Development

“…VOCs are often derived from alanine, valine, leucine, isoleucine, and methionine (Knudsen et al, 2006 ). We only identified one amino acid derivative in soybean, O-Decyl Hydroxylamine (CPV34), an N-containing compound, which has not been well studied, but has been shown to be expressed in certain rice grains (Ocan et al, 2020 ).…”

Breeding for Rice Aroma and Drought Tolerance: A Review

“…Thus, 2AP has been considered the key compound influencing aroma in rice [5]. Ocan et al [33] recently found 41 VOCs to be significantly correlated with 2AP in 37 lines that are commonly grown in Uganda.…”

“…These methods include sensory evaluation, electronic nose, near-infrared spectroscopy and gas chromatography methods [5]. Aroma strength can be analysed using gas chromatography, which is used to assess the amount of 2AP content in rice leaves and grains [18,33]. Aroma can be smelt after soaking rice grains in KOH solution [33,36,47].…”

“…Aroma strength can be analysed using gas chromatography, which is used to assess the amount of 2AP content in rice leaves and grains [18,33]. Aroma can be smelt after soaking rice grains in KOH solution [33,36,47]. However, KOH inhalation may damage nasal passages if too many samples are evaluated [36].…”

Volatilome evolution during storage and in vitro starch digestibility of high-power ultrasonication pretreated wholegrain Oryza sativa L.

“…In addition to the relation with flavoring properties and VOCs-based markers for the rice aroma traits, the emerging role of volatile compounds and their precursors of plant foods, such as health benefits and reliable indicators of quality modifications and cellular biochemical reactions, has been recently highlighted (Ayseli & Ayseli, 2016;Ocan et al, 2020;Xia et al, 2020b;Xia et al, 2022). In this work, the volatile fingerprinting was monitored to clarify the ultrasonic effects on the quality-related chemical reactions, particularly the possible synergistic and/or antagonistic effects induced by combined physical fields via identifying the most quality relevant VOCs metabolites as influenced by hpu irradiation pretreatments during storage process.…”