Assessment of suitable region of Asparagus cochinchinensis (Lour.) Merr. under different climatic conditions in China by the MaxEnt model and HPLC analysis.

Abstract

Asparagus cochinchinensis is a member of the Asparagaceae family whose medicinal part is the dried root tuber. The distribution of A. cochinchinensis and its secondary metabolites are closely associated with environmental factors, such as climate and soil properties. By establishing and optimizing a maximum entropy model, we analyzed and predicted the distribution pattern and migration direction of suitable habitats for A. cochinchinensis and determined the main environmental factors affecting the accumulation of secondary metabolites. Under current climatic conditions, the area of suitable habitats for A. cochinchinensis (208.38 × 104 km2) accounts for 21.71% of the land area of China, and the areas of lowly, moderately, and highly suitable areas were 64.15 × 104 km2, 113.66 × 104 km2, and 30.57 × 104 km2, respectively. Under future climate scenarios, the total area of suitable habitats hardly changes. The area of highly suitable habitats significantly decreases under the SSP1-RCP2.6 scenario (to 83.22% of the current value) and the SSP3-RCP7 scenario (to 48.94% of the current value), but eventually increases to 112.86% of the current value under the SSP5-RCP8.5 scenario, which indicates that A. cochinchinensis might adapt better to a high-carbon-emissions scenario. Under different climate scenarios, low-impact areas mainly occur in southern China and will correspond 92.07% of the current suitable area. Highly suitable habitats primarily occur in the southeastern Sichuan Basin, northern Guangxi, eastern Guizhou, and western Hunan. HPLC analysis showed that the content of protodioscin (0.373%) and protogracillin (0.044%) in S2 was the highest. The total saponins contents of S1 and S2 were the highest, which were 35.6586 and 33.1262 mg/g, respectively. The total polysaccharide content of S9 was the highest (16.9467%). The total contents of saponins and polysaccharides in A. cochinchinensis were significantly, but oppositely, correlated with temperature, precipitation, and other factors. This study has identified environmental factors affecting the growth and quality of A. cochinchinensis, which has guiding significance for resource conservation and site selection for large-scale cultivation.