Physiological Response and Principal Component Analysis of Morchella sextelata Mycelia under NaCl Stress

Morchella sextelata was used as experimental material to explore the effects of NaCl stress on mycelia growth and physiological indexes. The mycelial growth index, mycelial morphology, biomass, mycelial membrane permeability, osmotic regulatory substance content and antioxidant enzymes of M. sextelata were measured under different concentrations of NaCl (0, 100, 200, 300, 400 and 500 mmol/L). The effects of different levels of NaCl stress on mycelial growth and resistance physiology of M. sextelata were analyzed. Correlation analysis and principal component analysis were used to screen the key physiological indexes during the mycelial growth of M. sextelata under different NaCl concentrations. The results indicated that as the concentration of NaCl in the medium increased, the mycelial growth rate, mycelial biomass, mycelial diameter and intercellular polysaccharide (IPS) content of M. sextelata showed a downward trend, while the osmotic pressure (OP) and electrical conductivity (EC) showed an upward trend. The soluble protein content, malondialdehyde (MDA) content, proline (Pro) content, superoxide dismutase (SOD) activity, peroxidase (POD) activity and catalase (CAT) activity all increased first and then decreased with the increasing of NaCl concentration. At 200 mmol/L NaCl concentration, the malondialdehyde (MDA) content, peroxidase (POD) activity and catalase (CAT) activity peaked, proline content and SOD activity peaked at 300 mmol/L salt concentration, while soluble protein content peaked at 400 mmol/L NaCl concentration. Through principal component analysis, the accumulative contribution rate of the first three principal components was 96.611%. Among them, when NaCl concentration was 0~100 mmol/L, the indicative physiological indexes were growth rate, mycelial diameter, dry weight, fresh weight and IPS content. When NaCl concentration was 100~200 mmol/L, the indicative physiological indexes were MDA content, soluble protein content, SOD activity, POD activity and CAT activity. When NaCl concentration was 200~400 mmol/L, the indicative physiological indexes were Pro content, soluble protein content and SOD activity.