The vacuolar proton pump ATPase (V-H⁺-ATPase), which is a multi-subunit membrane protein complex, plays a major role in the activation of ion and nutrient transport and has been suggested to be involved in several physiological processes, such as cell expansion and salt tolerance. In this study, three genes encoding V-H⁺-ATPase subunits B (ScVHA-B, GenBank: JF826506), C (ScVHA-C, GenBank: JF826507) and H (ScVHA-H, GenBank: JF826508) were isolated from the halophyte Suaeda corniculata. The transcript levels of ScVHA-B, ScVHA-C and ScVHA-H were increased by salt, drought and saline-alkali treatments. V-H⁺-ATPase activity was also examined under salt, drought and saline-alkali stresses. The results showed that V-H⁺-ATPase activity was correlated with salt, drought and saline-alkali stress. Furthermore, V-H⁺-ATPase subunits B, C and H (ScVHA-B, ScVHA-C and ScVHA-H) from S. corniculata were introduced separately into the alfalfa genome. The transgenic alfalfa was verified by Southern and Northern blot analysis. During salt and saline-alkali stresses, transgenic linevacuolar proton pump, salt tolerance, saline-alkali tolerance, alfalfa
s carrying the B, C and H subunits had higher germination rates than the wild type (WT). More free proline, higher superoxide dismutase (SOD) activity and lower malondialdehyde (MDA) levels were detected in the transgenic plants under salt and saline-alkali treatments. Moreover, the ScVHA-B transgenic lines showed greater tolerance to salt and saline-alkali stresses than the WT. These results suggest that overexpression of ScVHA-B, ScVHA-C and ScVHA-H improves tolerance to salt and saline-alkali stresses in transgenic alfalfa.

In northern China, the soil-born diseases of wheat have been getting more and more serious under a new farming system that returns maize straw to the field. In order to investigate the allelopathy of the decomposed maize straw products on three soil-born diseases of wheat, culture dish and pot experiments were conducted and the compounds in the products were identified by gas chromatography-mass spectrometry (GC-MS). Culture dish experiments showed that the mycelial growth, sclerotia formation amount and total weight of Rhizoctonia cerealis were promoted at concentrations of 0.03, 0.06 and 0.12 g mL–1 and inhibited at concentration of 0.48 g mL–1 of the decomposed products. No significant effects were found of the product concentrations on average weight of the sclerotia. Mycelial growth of Gaeumannomyces graminis was promoted at almost all concentrations except the highest one. Mycelial growth and spore germination of Bipolaris sorokiniana were significantly inhibited by all concentrations of the decomposed products, with enhanced inhibition effects along with the increased concentrations. The length, number and dry weight of roots together with the root superoxide dismutase activity were promoted by the lowest concentration (0.03 g mL–1), with a synthetic effect index of 0.012, and inhibited by other concentrations. The ion leakage of roots was increased and the root peroxidase activity of roots was lowered by all the treatments. Pot experiments revealed that occurrence of the sharp eyespot was reduced by 0.03 and 0.06 g mL–1 of decomposed products after irrigation. However, the incidence rates and disease indexes were significantly increased by 0.12, 0.24 and 0.48 g mL–1 of decomposed products. The results indicated that incidence rates and disease indexes of the take-all were significantly promoted after being irrigated with the decomposed products, while occurrences of the common rot didn’t change, significantly. GC-MS results showed that the compounds of the decomposed products included organic acids, esters, hydrocarbons, amides and aldehydes, with the proportions 25.26, 24.01, 17.22, 14.39 and 7.73%, respectively. Further analysis investigated that the allelochemicals identified in straw decomposed products contained p-hydroxybenzoic acid (9.21%), dibutyl phthalate (6.94%), 3-phenyl-2-acrylic (5.06%), 4-hydroxy-3,5-dimethoxybenzoic acid (2.26%), hexanoic acid (1.73%), 8-octadecenoic acid (1.06%), 3-(4-hydroxy-3-methoxy-phenyl)-2-propenoic acid (1.04%), 4-hydroxy-3-methoxy-benzoic acid (0.94%) and salicylic acid (0.94%).