NEUTRAL VOLATILE COMPOUNDS IN FCV TOBACCO CULTIVARS AND BREEDING LINES

Abstract

Smoking quality of flue-cured Virginia (FCV) tobacco can be assessed by the relative abundance of the volatiles that vary with genotype and stalk position. Hence, gas chromatograph-mass spectrometry (GCMS) analysis of neutral volatile compounds (NVCs) was undertaken in FCV tobacco ruling varieties and promising advanced breeding lines undergoing advanced varietal trials and pre-release bulk assessment in northern light soils (NLS) and traditional black soils (TBS) at CTRI Research Station, Jeelugumilli and CTRI Farm, Katheru, respectively. One hundred and thirty compounds were identified and their relative content in the neutral volatile fraction (NV) was calculated. The compounds were segregated into four groups viz., nor-carotenoids, nor-isoprenoids, northunberganoids and neophytadiene which accounted for 79 to 92% of the NV fraction in different samples. The remaining 8 to 21% of the NV fraction was composed of products of phenylalanine metabolism and Maillard reactions. Samples from TBS, had lower percentage of nor-isoprenoids and nor-carotenoids in the NV fraction than the samples from NLS and a similar trend was observed in the case of neophytadiene. However, the trend was reverse in the case of nor-thunberganoids. The qualitative and quantitative differences between the samples from NLS and TBS could be attributed to the genetic makeup of the samples and crop husbandry. Considering the proportion of the 25 most important compounds in the NV fraction, volatile profiles of different samples were prepared to help Plant Breeders in evaluating breeding material. Two somaclones, TOBIOS 6 and TOBIOS 7 and the advanced breeding lines, NLST 3 and NLST 5 had higher relative content of NVCs compared to the cultivar, Kanchan in NLS, thus exhibiting their potential for more flavour. In TBS, the inter-specific cross derivative TBST 2 had a volatile profile superior to the ruling variety, Siri. Higher relative content of neophytadiene, geranyl acetone, isomers of megastigmatrienone, 3-hydroxy solavetivone, benzyl alcohol, phenylethyl alcohol was recorded in the T-position in the samples from NLS when compared to L-position samples.