It was the aim of this study to identify the newly isolated fungal pathogen of A. angustifolia seeds and screen for rhizosphere streptomycetes which, upon germination on ground, can affect the growth of this pathogen. Furthermore, we present a list of exudate compounds produced by the fungus-inhibiting bacteria
in single culture, and alterations due to the co-culture with the fungal pathogen. Results and discussion The pathogenic fungus on A. angustifolia seedlings: effects and identification After 50 days of germination, about 30% of Araucaria seedlings were infected by a fungus that promoted INK1197 price the death of the cotyledons and interrupted the connection between the seedling and the buy SAHA HDAC megagametophyte (Figure 1A, B). Of these, about 50% died, and the surviving ones showed delay in plant development. After 150 days, 52.3% of surviving plants with retarded development were dead. The cause for delayed development or seedling death might be attributed to the early interruption in the carbon and nutrients transfer from the megagametophyte to the embryonic tissues. Electron microscopy analyses showed the presence of high amounts
of starch grains in the Selleck Bleomycin megagametophyte of infected seedlings (Figure 1C, D), compared with the non-infected tissue (Figure 1E, F). Figure 1 Neofusicoccum parvum infection of A. angustifolia seedlings (Bar = 1 cm in A, B, F). A, Seedling; B, Megagametophyte and cotyledons infected with the fungus; C, Scanning electron microscopy of infected megagametophyte tissue that surrounds the cotyledon; D, Starch grains covered by hyphae; E-F, Non infected tissues. All images were taken from plants/tissues after 50 days of germination. ct – haustorial cotyledon, se – seed, mg – megagametophyte, st – starch grain. The natural infection of the A. angustifolia seeds by the fungus might have happened during cone maturation and before seed dispersion. The fungus infected specifically the megagametophyte tissue and promoted necrosis of Buspirone HCl the seed-enclosed region, and the cotyledons, after their emergence. The first visible symptoms were the decay of the cotyledons and seed browning. In this species,
the cotyledons act as a haustorial organ by transferring the reserves from the megagametophyte to the embryonic axis [16], supporting the seedling growth until about 70 to 120 days [17, 18]. The early cotyledon interruption leading to seedling death or delayed plant development, significantly reduced the chances for seedling establishment. ITS sequencing of the fungal isolate with the primer pairs ITS1 and ITS4 ([19], accession number ITS [JN811822]) yielded the highest homologies (100%) with Neofusicoccum parvum/N. ribis and Botryosphaeria parva, all members of the Botryosphaeriaceae. This is due to the fact that Neofusicoccum parvum is the anamorph of Botryosphaeria parva[20]. N. parvum and N. ribis were originally considered to be part of the Botryosphaeria dothidea complex [21].
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