A Transcriptomic Approach Provides Insights on the Mycorrhizal Symbiosis of the Mediterranean Orchid Limodorum abortivum in Nature

The study of orchid mycorrhizal interactions is particularly complex because of the peculiar life cycle of these plants and their diverse trophic strategies. Here, transcriptomics has been applied to investigate gene expression in the mycorrhizal roots of Limodorum abortivum, a terrestrial mixotrophic orchid that associates with ectomycorrhizal fungi in the genus Russula. Our results provide new insights into the mechanisms underlying plant–fungus interactions in adult orchids in nature and in particular into the plant responses to the mycorrhizal symbiont(s) in the roots of mixotrophic orchids. Our results indicate that amino acids may represent the main nitrogen source in mycorrhizal roots of L. abortivum, as already suggested for orchid protocorms and other orchid species. The upregulation, in mycorrhizal L. abortivum roots, of some symbiotic molecular marker genes identified in mycorrhizal roots from other orchids as well as in arbuscular mycorrhiza, may mirror a common core of plant genes involved in endomycorrhizal symbioses. Further efforts will be required to understand whether the specificities of orchid mycorrhiza depend on fine-tuned regulation of these common components, or whether specific additional genes are involved.

Seleksi Isolat Orchid mycorrhiza pada Bibit Anggrek Phalaenopsis amabilis pada Media Cocopeat dan Arang Sekam Saat Aklimatisasi

Orchid mycorrhiza merupakan suatu bentuk asosiasi mutualistik antara akar tanaman anggrek dengan fungi tertentu yang berfungsi sebagai biofertilizer (pupuk hayati). Fungi ini akan menginfeksi anggrek melalui akar yang ditandai dengan adanya struktur hifa yang berbentuk lilitan padat pada korteks yang disebut dengan peleton. Penelitian ini bertujuan untuk (1) menentukan apakah empat isolat Orchid mycorrhiza yang diuji mampu menginfeksi dan bersimbiosis dengan akar anggrek P. amabilis, (2) menentukan media tanam yang terbaik untuk aklimatisasi tanaman anggrek P. amabilis, (3) mengetahui apakah respon tanaman anggrek terhadap pemberian Orchid mycorrhiza dipengaruhi oleh media tanam yang digunakan, dan (4) menentukan media tanam yang terbaik untuk empat jenis isolat Orchid mycorhhiza. Penelitian ini dilaksanakan di Laboratorium Perkebunan, Fakultas Pertanian, Universitas Lampung dan Rumah Kaca Fakultas Pertanian Universitas Lampung, menggunakan Rancangan Acak Kelompok (RAK) dengan perlakuan yang disusun secara faktorial (5x2). Faktor pertamaadalah jenis isolat Orchid mycorrhiza (M) yaitu kontrol tanpa Orchid mycorrhiza(m0), isolat Orchid mycorrhiza M1 (m1), isolat Orchid mycorrhiza M9 (m2), isolat Orchid mycorrhiza M12 (m3), dan isolat Orchid mycorrhiza M14 (m4). Faktor kedua yaitu media tanam (T) yang terdiri dari dua level yaitu cocopeat (t1) dan arang sekam (t2). Setiap perlakuan diulang 4 kali dan masing-masing ulangan terdiri dari 2 bibit anggrek.Bibit anggrek dikelompokkan menjadi 4 berdasarkan jumlah daun.Data yang diperoleh diujihomogenitas ragamnya dengan uji Bartlett dan aditivitasnya dengan uji Tukey.Data dianalisis dengan analisis ragam dan dilanjutkan dengan uji BNT pada taraf 5%. Hasil penelitian menunjukkan bahwa semua isolat yang diuji M1, M9, M12, dan M14 merupakan Orchid mycorrhiza karena mampu menginfeksi dan bersimbiosis dengan akar anggrek P. amabilis dan membentuk peleton di dalam sel korteks akar.Media tanam cocopeat dan arang sekam menghasilkan respon yang sama terhadap pertumbuhan tanaman anggrek P. amabilis saat aklimatisasi.Respon tanaman anggrek terhadap pemberian Orchid mycorrhiza tidak dipengaruhi oleh media tanam yang digunakan.Media tanam cocopeat dan arang sekam menghasilkan respon yang sama terhadap keempat jenis isolat Orchid mycorrhiza.

Perkembangan Penelitian Mikoriza di Papua**

The mycorrhizas are ‘balanced’ mutualistic associations in which the fungus and plant exchange commodities required for their growth and survival. The are many type of mycorrhizal namely endomycorrhiza, ectomycorrhiza, Orchid-mycorrhiza, ericoid mycorrhiza, and ectendo mycorrhiza. Most research is in endo and ectomycorrhiza, due to their role in Papua. Research in mycorrhiza has also been done recently. The research started in 2005 with ectomycorrhiza studies conducted by Suharno & Sufaati. Study on endomycorrhiza were begin in 2006 and orchid mycorrhiza in 2007. Exploration study of endomycorrhiza in corn plant at Koya Barat showed that there were 7 species of VAM namely Glomus sp1., Glomus sp2., Glomus sp3., Gigaspora sp., Acaulospora., Scutellospora sp1., and Scutellospora sp2. Similar research have also been done on other agriculture comodity, and the weed as well. Study on the endomycorrhiza associated with matoa (Pometia pinnata) found 13 species. Furtheremore, preliminary research on ectomycorrhiza showed that at least four species have been found at Mount Cycloops Nature Reserve, Jayapura. In Papua, there were 18 strain isolate of Scleroderma have been collected and 4 species were already identified. For orchid-mycorrhiza there were only 17 species has been found so far. Among them there species were identified: Rhizoctonia sp., Tulasnella sp., dan Ceratorhiza sp. The potency of mycorrhiza in Papua is high and need to be explored. Some isolate were already tested to variety of the growth of plant. The result showed that the isolate affected significantly. More exploration, compatibility test, and the role of mycorrhiza will be continued to study. The goals of all the study here was to find a good quality of isolate that can be used as a propagule to produce biofertilizer.Key words: endomycorrhiza, ectomycorrhiza, orchid-mycorrhiza, biofertilizer, Papua.

Two new genera, Mycophoris gen. nov., (Orchidaceae) and Synaptomitus gen. nov. (Basidiomycota) based on a fossil seed with developing embryo and associated fungus in Dominican amber

Aside from a variety of arthropod remains, Dominican amber also contains an assortment of leaves, flowers, and seeds. An orchid seed with a developing embryo in Dominican amber is described as Mycophoris elongatus gen. et sp. nov. Cells of the developing embryo were infected with a fungus that is described as Synaptomitus orchiphilus gen. et sp. nov. The fungus represents a Basidiomycota that was probably serving as an orchid mycorrhiza (OM), based on its morphology and the formation of pelotons inside infected embryo cells. The single piece of amber containing the fossil was obtained from a mine in the Dominican Republic and is at least 15–20 Ma.

Trophic relationships in orchid mycorrhiza – diversity and implications for conservation

Orchid species are perennial, and though demo- graphic data suggest that the family includes r- as well as K-strategists (Whigham & Willems 2003), most species are potentially long-lived. Individual plants may be kept in living plant collections or in nature reserves for practically unlimited periods of time. There are several reports on natural populations suspected of little or no seedling recruitment, “senile populations” (Tamm 1991, Rasmussen 1995), espe- cially among rare orchids under critical surveyance. Such populations may function as a seed source to neighbouring areas but are likely to eventually disap- pear from the site.