Responses of Sphagneticola trilobata , Sphagneticola calendulacea and Their Hybrid to Drought Stress

is an invasive plant in South China. A hybrid between . and (a native related species) has also been found in South China. The drought resistance of . , . and their hybrid was studied in this paper. Under drought stress, the leaves of . synthesized more abscisic acid (ABA) than those of the other species to reduce stomatal opening and water loss. The activities of antioxidant enzymes were the highest in . and the lowest in . The leaves of suffered the most serious damage, and their maximum photochemical efficiency was the lowest. RNA-sequencing ware used to analyze the expression levels of genes in ABA, antioxidant enzyme, sugar and proline synthesis and photosynthesis pathways. Further real-time PCR detection verified the RNA-sequence results, and the results were in accordance with the physiological data. The results showed that . was the most drought tolerant, and the drought tolerance of the hybrid did not show heterosis but was higher than . Therefore, compared with and the hybrid, the population number and distribution of may be less in arid areas.