Development of a single kernel analysis method for detection of 2-acetyl-1-pyrroline in aromatic rice germplasm

Because of the high demand for aromatic rice cultivars that command a premium, it is important to have efficient methods for determining 2-acetyl-1-pyrroline (2-AP), the aromatic compound found in rice, that can be used in breeding efforts and to detect aromatic/non-aromatic blended rice in the marketplace. Solid-phase microextraction (SPME) in conjunction with GC/MS was used to distinguish non-aromatic rice ( Oryza sativa , L.) kernels from aromatic rice kernels. In this method, single kernels along with 10 μl of 0.1 ng μl −1 2,4,6-Trimethylpyridine were placed in sealed vials and heated to 80 °C for 18 min. During the heating stage volatile compounds, which include 2-AP, were adsorbed onto a SPME fiber. Volatiles were desorbed from the fiber and separated using gas chromatography. 2-AP was quantitated by mass spectrometry using the 111, 83 and 68 m/z ions. The method detected 2-AP in milled rice and brown rice; however, its detection in paddy rice was less successful. In a mixture of aromatic and non-aromatic rice, the aromatic rice kernels were differentiated from the non-aromatic rice kernels using the described method. Therefore, this method can be used to identify segregating from non-segregating progeny during early generations in an aromatic rice breeding program when quantities of seed are very limited and can determine if aromatic rice has been adulterated with non-aromatic rice either through inadvertent mixtures, outcrosses or prepared blends.