The Effects of Single and dual inoculations of Arbuscular mycorrhizal Fungi (AMF) on plant growth, and the EST and MDH Isozyme profiles of maize roots (Zea mays L.) grown on limited growth media

SANCAYANINGSIH S., Retno Peni, Promotor Prof.Dr.Ir. Joedoro Soedarsono

2005 | Disertasi | S3 MIPA (Biologi)

Efektivitas fungi mikoriza arbuskula (FMA) pada pertumbuhan tanaman jagung dipengaruhi berbagai faktor termasuk kehadiran species FMA lain. Beberapa penelitian mengenai tanggapan pertumbuhan telah banyak dilaporkan, sedangkan kajian tentang pengaruh interaksi dua species FMA terhadap tanaman inang belum banyak dilakukan. Oleh karenanya penelitian ini dirancang untuk mengungkapkan efektivitas inokulasi FMA tunggal dengan inokulasi ganda terhadap pertumbuhan tanaman. Penelitian ini juga diharapkan dapat memberikan informasi baru tentang peran fungsional FMA pada tanaman jagung. Empat species FMA terpilih dalam penelitian ini adalah : Glomus manihotis INDO-1 (Gm), Glomus etunicatum FL 126 (Ge), Gigaspora rosea FL 105 (Gr), dan isolat FMA lokal Glomus sp. (Gl) yang ditumbuhan pada inang jagung manis. Dilakukan dua pendekatan percobaan pot, yaitu: percobaan dengan inokulum yang terkonsentrasi pada rhizosphere (CIPE), dan percobaan dengan inokulum yang tersebar secara acak (RDIPE). Di masing-masing percobaan dilaksanakan 11 perlakuan termasuk 2 buah kontrol (Cs dan Co), 4 perlakuan inokulum tunggal (Ge, Gm, Gr, dan Gl) dan 5 perlakuan inokulum ganda (GmGe, GmGr, GmGl. GmCo, dan GeGr). Delapan kali pengamatan terhadap berat kering sebagai parameter pertumbuhan, dan ekstraksi protein untuk analisis profil isozim dicuplik dari 6 ulangan dengan selang waktu 2 minggu. Pola distribusi pita isozym malat dehydrogenase (MDH) dan esterase (EST) akar diamati dengan pengecatan substrat setelah pemisahan isozim dengan cara elektroforesis gel 7.5% (PAGE) non denaturasi. Aktivitas isozym diukur menggunakan “scanner” yang dikalibrasi menggunakan enzym standard. Pada percobaan RDIPE, pengaruh perlakuan inokulasi tunggal lebih efektif dibandingkan pengaruh pada inokulasi ganda, namun perlakuan ganda GeGr dan GmCo pada percobaan CIPE, lebih efektif dibandingkan perlakuan tunggalnya. Koefisien korelasi antara berat kering dengan kolonisasi internal menunjukkan bahwa perlakuan tunggal berkorelasi positif dan lebih tinggi dari pada perlakuan ganda tanpa melihat peletakan inokulum. Efektivitas FMA meningkatkan berat kering pada kedua percobaan peletakan inokulum sesuai dengan efektivitasnya terhadap penyerapan hara. Pada perlakuan ganda yang mempunyai efektivitas terendah berhubungan dengan rendahnya kemampuan menyerap P. Hasil penelitian juga merekomendasikan penggunaan inokulum yang diletakkan secara tersebar sebagai alternatif peletakan inokulum terpusat Pada percobaan CIPE, penyerapan P pada perlakuan tunggal lebih baik dari pada perlakuan ganda, dan efektivitas penyerapan N perlakuan tunggal sangat berbeda bergantung pada species FMA, sementara penyerapan P berbeda antar genera. Nisbah N/P pucuk tanaman dengan perlakuan tunggal cenderung menurun dari kontrol sedangkan perlakuan ganda lebih meningkat. Kandungan beberapa mineral (K, Ca, Fe, Zn, Cu, and Mn) yang lebih tinggi dijumpai pada akar tanaman bermikoriza, kecuali mineral Mg. Mikoriza paling efektif mempunyai kandungan mineral makro dan mikro yang tinggi di dalam akar. Kecenderungan adanya kandungan K dan Mn yang lebih tinggi dan kandungan Zn serta Cu yang lebih rendah dijumpai pada perlakuan inokulasi tunggal dibandingkan inokulasi ganda. Terdapat 8 isozym EST baru dan 7 isozym MDH yang terinduksi pada pembentukan mikoriza. Dua isozym MDH yang selalu dijumpai pada semua perlakuan adalah isozym pada Rf 0,54-0,56 dan 0,58-0,60. Isozym MDH Rf 0,64-0,66 dan 0,67- 0,70 sering ditemukan pada pengamatan terakhir. Tiga isozym EST pada Rf 0,70-0,72, 0,76-0,77, dan 0,83-0,85 dijumpai pada baik perlakuan tunggal maupun ganda. Aktivitas isozim Rf 0,76-0,77 yang tinggi pada perlakuan tunggal di percobaan CIPE sejalan dengan kenaikan berat kering tanaman. Dengan demikian, hadirnya Isozym Spesifik Mikoriza (ISM) dengan berbagai nilai Rf dan aktivitas menunjukkan adanya metabolisme yang kompleks terjadi pada akar tanaman bermikoriza. Apakah isozym tanaman ataukah isozym fungi dalam sel akar yang terinduksi masih perlu penelitian lebih lanjut.

The effectivity of an Arbuscular Mycorrhizal Fungi (AMF) on plant performances is affected by many factors, including the presence of other AMF species. Many studies have been reported on growth responses to single AMF inoculation, but few studies have observed the effects of two interacting AMF species in host plants. Therefore, the objective of this research was to reveal the effectivity of single and dual AMF inoculation on host plant growth. This study was also expected to give new information on the functional role of mycorrhiza in maize. The four AMF species selected for this study were Glomus manihotis INDO-1 (Gm), Glomus etunicatum FL 126 (Ge), Gigaspora rosea FL 105 (Gr), and a local AMF isolate Glomus sp.(Gl), which were grown, either singly or in combination, on maize. To test inoculum placement, two pot experiments were conducted: the centralized inoculum placement experiment (CIPE), and the randomly distributed inoculum placement experiment (RDIPE). In each experiment, eleven treatments were applied: two controls (Co and Cs), four single treatments (Gm, Ge, Gr, and Gl), and five dual treatments (GmGe, GmGr, GmGl, GmCo, and GeGr). Eight observations on shoot biomass as growth parameter, and protein extracts of roots for isozyme profile analysis were taken at two-week intervals from six replicates. The isozyme pattern of malate dehydrogenases (MDH) and esterases (EST) of protein extract from root samples were visualized using substrate staining following 7.5% non-denaturing PAGE separation. A scanner calibrated using an enzyme standard was used to measure isozyme activity. In the RDIPE, all single treatments were more effective than dual inoculation treatments, whereas in the CIPE, however, combination of GeGr and GmCo was more effective than its single treatments. Colonization coefficients relating plant dry weight and internal colonization in single treatments were positive and higher than those in dual treatments regardless of inoculum placement. Effectivity of AMF species in increasing plant dry weight in both inoculum placement experiments was mostly in line with nutrient uptake effectivity. The least effective dual treatment in the CIPE related to the lower effectivity of P uptake. This study also recommended using RDIPE as an alternative for the CIPE as commonly applied. In the CIPE, P uptake in single treatments was significantly better than dual treatments, and nitrogen uptake effectivity in single treatments was different among AMF species, while P uptake was different between genera. N/P ratio of plant shoot in single treatments was decrease while in dual treatments were increase. Higher content of minerals (K, Ca, Fe, Zn, Cu, and Mn) in roots was detected in mycorrhizal plants, with the exception of magnesium. The most effective mycorrhiza in this study were found to have a significantly high content of macro and micro minerals in roots. A general trend of higher K and Mn content, and lower Zn and Cu content was found in plant roots treated with a single AMF species compared to those treated with a combination of two AMF species. The presence of eight new EST isozymes and seven new MDH isozymes were induced by mycorrhization. In the CIPE, two MDH isozymes found in all treatments were at Rf 0.54-0.56 and 0.58-0.60 having high range of activity (6-1000 μU and 29- 743 μU). MDH isozymes at 0.64-0.66 and 0.67-0.70 were mostly found in the later observation times. Three EST isozymes at Rf 0.70-0.72, 0.76-0.77, and 0.83-0.85 were found most frequently in both single and dual AMF treatments. High activity of EST at Rf 0.76-0.77 (22-90 μU) complemented with Rf 0.83-0.85 in single treatments of the CIPE followed its increase in shoot dry weight at the late plant growth. The presence of these Mycorrhizal Specific Isozymes (MSI) with various Rf values and activities indicates that complex metabolisms occurred within mycorrhizal roots. Whether AMF inoculation induced plant isozymes or intra radical fungal isozymes needs to be resolved.

Kata Kunci : Fungi Mikoriza Arbuskula,Pertumbuhan Jagung,