Genetic relationship and source species identification of 58 Qi-Nan germplasms of Aquilaria species in China that easily form agarwood

Abstract

Recently, Qi-Nan germplasm, the germplasm of Aquilaria species that easily forms agarwood, has been widely cultivated in Guangdong and Hainan Provinces in China. Since the morphological characteristics of Qi-Nan germplasm are similar to those of Aquilaria species and germplasm is bred by grafting, it is difficult to determine the source species of this germplasm by traditional taxonomic characteristics. In this study, we performed a DNA barcoding analysis of 58 major Qi-Nan germplasms as well as Aquilaria sinensis, A. yunnanensis, A. crassna, A. malaccensis and A. hirta with 5 primers (nuclear gene internal transcribed spacer 2 (ITS2) and the chloroplast genes matK, trnH-psbA, rbcL and trnL-trnF). This field survey in the Qi-Nan germplasm plantations in Guangdong and Hainan Provinces aimed to accurately identify the source species of Qi-Nan germplasm. According to the results, ITS2 and matK showed the most variability and the highest divergence at all genetic distances. This ITS2+matK combination, screened for with TaxonDNA analysis, showed the highest success rate in species identification of the Qi-Nan germplasm. Clustering in the phylogenetic trees constructed with Bayesian inference and maximum likelihood indicated that the Qi-Nan germplasm was most closely related to A. sinensis and more distantly related to A. yunnanensis, A. crassna, A. malaccensis and A. hirta. Therefore, this study determined that the source species of the Qi-Nan germplasm is A. sinensis.

Anatomical, chemical and endophytic fungal diversity of a Qi-Nan clone of Aquilaria sinensis (Lour.) Spreng with different induction times

“…In comparison to trees from ordinary seed seedlings following artificial induction, Qi-Nan clones are a high-quality cultivar that is reproduced through the process of grafting onto ordinary seed seedlings of A. sinensis and can more easily yield higher grade agarwood ( Wang et al., 2020 ; Yu et al., 2021 ). According to recent study, the species of the Qi-Nan clone is A. sinensis ( Kang et al., 2022 ); nevertheless, when exposed to wounding stress, the Qi-Nan germplasm elicited distinct biological responses than ordinary A. sinensis ( Lv et al., 2022 ).…”

Physiological and Endophytic Fungi Changes in Grafting Seedlings of Qi-Nan Clones (Aquilaria sinensis)

“…Spreng, has been selected from the wild population and used as a scion for grafting cultivation. These excellent clones, namely "Qi-Nan", have the characteristics of more easily induced agarwood and high-quality agarwood [6][7][8][9]. For ordinary A. sinensis, it is almost impossible to obtain agarwood with more than 10% of the alcohol soluble extractive content only with the drilling method over one year, but this special agarwood germplasm of A. sinensis can have more than 40% of the alcohol soluble extractive content with the same inducing method [6].…”