Genetic diversity of diazotrophs and total bacteria in the phyllosphere ofPyrus serotina,Prunus armeniaca,Prunus avium, andVitis vinifera

The phyllosphere, which supports a large number of microorganisms, represents the interface between the aboveground parts of plants and air. In this study, four nifH clone libraries were constructed from the phyllosphere of Pyrus serotina (L), Vitis vinifera (P), Prunus armeniaca (X), and Prunus avium (Y). Clones related to Skermanella (L, 12.1%; X, 15.6%; Y, 62.5%; P 70.8%), Bradyrhizobium (X, 2.1%; P, 15.1%; L, 63.7%), Erwinia (X, 68.8%), Pseudomonas (L, 3.3%; P, 7.6%), and Chroococcidiopsis (P, 0.9%; L, 4.4%, X; 5.2%, Y; 19.6%) were present at high percentages, highlighting their critical role in contributing nitrogen to the phyllosphere ecosystem. The 16S rDNA sequence analysis suggested that phyllosphere-associated bacteria were affiliated with a wide range of taxa, encompassing members from Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria, Actinobacteria, Bacteroidetes, Firmicutes, Cyanobacteria, Tenericutes, and Deinococcus–Thermus. Additionally, the abundance of the nifH gene and 16S rDNA was assessed with quantitative PCR. The number of copies of nifH and 16S rDNA ranged from 1.14 × 103to 1.49 × 104and from 3.72 × 106to 7.02 × 107copies/g fresh leaf sample, respectively. In conclusion, our work sheds light on the microbial communities of the phyllosphere that are important for plant growth. Moreover, we observed a unique composition of nitrogen-fixing bacteria in each phyllosphere sample, suggesting the existence of specific interactions between these functional microorganism and plants, which may provide information or be a reference for the development of bacterial fertilizers.

Evaluation of susceptibility of pear and plum cultivars to winter frost

ABSTRACT The damage to pear and plum buds was investigated in Mashhad, after a period of unusually warm weather for a few days in March 2013 followed by a sudden drop in temperature to -12°C. Frost damages of vegetative and reproductive buds and spur-part below the buds of pear and plum cultivars were investigated based on visual observations. The following pear (Pyrus communis L.) cultivars were investigated: William’s, Bell de june, Ida, Spadona, Koshia, Domkaj, Dare Gazi, Mohamad Ali, Boheme, Shekari, Ghodumi and one Asian pear (Pyrus serotina Rehd.). Japanese plum (P. salicina L.) included ’Shiro’, ’Shams’, ’Computi’ and European plum (Prunus domestica L.) included ’Stanley’, ‘Early Santa Rosa’, ’Late Santa Rosa’, ’Shablon’ and ’Black Diamond’. Electrical conductivity (EC) and proline content were measured in reproductive buds. It was discovered that visual damages were different between cultivars, as the vegetative pear bud of ‘Ghodumi’ suffered the most damage and all parts of ‘Late Santa Rosa’ were the most susceptible in plum cultivars. On the other hand, ‘Computi’ had the most resistant reproductive bud and no damage was observed in the other parts. The EC and proline content of ‘Dare Gazi’ were the highest despite the fact that high proline content did not show high resistance, which was related to the phenological stage of ‘Dare Gazi’.

Constituents of Twig Bark of Pear Cultivars (Pyrus species)

Organic solvent extracts from fresh twig bark of Japanese pear cultivars ( Pyrus serotina) Shinko and Nijisseiki, and European pear cultivar ( P. communis) Le Lectier were obtained by maceration with n-hexane and EtOAc, and analyzed in GC-EIMS experiments. In these two Japanese cultivars, the lupeol, betulin, epifriedelinol, friedelin and arbutin contents of Nijisseiki were higher than those of Shinko. In the case of the lupane-type triterpenes, lupeol and betulin, the lupeol content of Japanese pears Shinko and Nijisseiki was higher than that of European pear Le Lectier. The betulin content of Le Lectier was higher than those of Shinko and Nijisseiki. Friedelane-type triterpenes, epifriedelinol and friedelin, were not detected in twig bark of Le Lectier. Quantitative and qualitative differences in the constituents of these three pear cultivars were observed.

Physiological Responses of Kuerle Fragrant Pear Fruit to Different Atmospheres in Storage

Kuerle fragrant pear (Pyrus serotina Reld) were stored in different controlled atmospheres (4-6 % O2 plus 2-4 % CO2) and air control at -1~0 °C to determine the effects of different O2 and CO2 atmospheres on physiology, quality and decay during storage. The results indicated that CA-I inhibited polyphenol oxidase (PPO) activity, reduced total phenol content, prevented peel browning and decreased fruit decay in comparison with CA-II and air control at -1~0 °C, and more effectively reduced ethanol production in the flesh and maintained peel green color and extended storage life of Kuerle fragrant pear by comparison with CA- II treatment and air control at -1~0 °C treatment.