Identifikasi Mekanisme Target-site Resistance Herbisida Glifosat pada Eleusine indica (L.) Gaertn. dari Kebun Kelapa Sawit Jonggol, Jawa Barat
Abstract
Resistensi glifosat dapat terjadi melalui mekanisme target-site resistance (TSR) dengan adanya mutasi pada gen target herbisida yaitu 5-enolpiruvil-sikimat-3-fosfat sintase (EPSPS). Penelitian ini bertujuan mengidentifikasi mekanisme TSR yang berkaitan dengan TIPS mutation pada spesies Eleusine indica yang telah dilaporkan resisten di kebun kelapa sawit asal Jonggol, Bogor, Jawa Barat. Analisis bio-assay dilakukan menggunakan Rancangan Kelompok Lengkap Teracak (RKLT) faktor tunggal yaitu dosis herbisida dengan 8 taraf dosis dan 3 ulangan. Banyaknya satuan percobaan adalah 24 satuan percobaan setiap blok. Percobaan dimulai dengan pengambilan biji E. indica resisten pada Blok II dan Blok V. Biji gulma E. indica ditanam pada pot dengan cara disebar. Gulma yang telah tumbuh dipelihara dengan melakukan penyiangan, penyiraman, dan seleksi pertumbuhan agar seragam. Aplikasi glifosat dilakukan saat gulma berdaun 4 menggunakan delapan taraf dosis yaitu 0, 1/8x, 1/4x, 1/2x, x, 2x, 4x, 8x dengan x adalah dosis rekomendasi, sehingga dosis herbisida glifosat adalah 0, 121,5, 243, 486, 972, 1944, 3888, dan 7776 g ha-1. Volume semprot yang digunakan adalah 400 L ha-1. Persentase kerusakan gulma diperoleh dari biomasa tanaman kemudian analisis regresi dilakukan untuk memperoleh LD50 dan nisbah resistensi. Biotipe E. indica asal Kebun Jonggol Blok V memiliki LD50 sebesar 1737 g ha-1 dengan status resistensi penurunan sensitivitas dan nisbah resistensi 2,343. Blok II masih berstatus sensitif dengan nisbah resistensi 1,588 dan nilai LD50 sebesar 1177,30 g ha-1. Identifikasi TSR dilakukan dengan isolasi dan amplifikasi gen penyandi EPSPS dari DNA genom E. indica asal kebun kelapa sawit Jonggol sebagai biotipe resisten dan asal pinggir jalan kampus IPB Dramaga sebagai biotipe sensitif. Hasil runutan basa nukleotida disejajarkan menggunakan algoritma MUSCLE dan visualisasi hasil penjajaran menggunakan Geneious Prime. Hasil pensejajaran basa nukleotida menunjukkan tidak adanya titik mutasi penyebab resistensi glifosat pada rentang basa 979 sampai dengan 1280 gen penyandi EPSPS. Nilai LD50 yang tinggi pada pada Blok V mengindikasikan adanya potensi resistensi akibat perbedaan basa nukleotida pada titik lain dari gen EPSPS maupun mekanisme non-target-site resistance (NTSR). Target-site resistance (TSR) to glyphosate is caused by mutation in targeted gene namely 5-enolpyruvyl-shikimate-3-phosphate synthase (EPSPS). This research was aimed to identify TSR mechanism assosiated with TIPS mutation in Eleusine indica biotypes from Oil Palm Plantation in Jonggol which was reported resistant recently. Bio-assay analysis was conducted using a single-factor Randomized Completely Block Design (RCBD), namely herbicide dose with 8 dose levels and 3 replications. The number of experimental units was 24 experimental units per block. The experiment began with the collection of resistant E. indica seeds in Block II and Block V. E. indica seeds were planted in pots by spreading. Weeds that had grown were maintained by weeding, watering, and selecting for uniform growth. Glyphosate application was carried out when the weeds were 4-leafed using eight dose levels, namely 0, 1/8x, 1/4x, 1/2x, x, 2x, 4x, 8x with x being the recommended dose, so that the herbicide dose of glyphosate was 0, 121.5, 243, 486, 972, 1944, 3888, and 7776 g ha-1. The spray volume used was 400 L ha-1. Percentage of weed damage was obtained from plant biomass then regression analysis was conducted to obtain LD50 and resistance ratio. E. indica biotype from Block V Jonggol Plantation had an LD50 of 1737 g ha-1 with a resistance status of decreased sensitivity and a resistance ratio of 2.343. Block II was still sensitive with a resistance ratio of 1.588 and an LD50 value of 1177.30 g ha-1. TSR identification was conducted by amplifying partial fragment of gene coding EPSPS from the genomic DNA of E. indica isolated from Jonggol oil palm plantation as the resistant biotype and from IPB Dramaga roadside as the sensitive biotype. Amplified fragments were sequenced and further aligned using the MUSCLE algorithm and visualized using Geneious Prime. The alignment analysis of fragment 979 to 1280 bp of gene coding ESPS from the resistant and sensitive biotypes showed the absence of mutation points causing glyphosate resistance. The high LD50 value in Block V indicates resistance potential due to other mechanisms, such as point mutation at the other part of EPSPS coding gene or non-target-site resistance (NTSR) mechanisms.
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- MT - Agriculture [3778]