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<p>Genetic Variation of Keprok SoE Mandarin (Citrus reticulata Blanco) Resulted from Gamma Iradiation Based on ISSR Markers. SoE mandarin is one of the best mandarin from Indonesia which has been chosen as one of mandarin for import substitution. The citrus quality could be improved through breeding program, one of this program was mutation breeding using gamma rays irradiation. The research was aimed to obtain information of SoE mandarin genetic variation derived from gamma rays irradiation using ISSR marker. The research was conducted at Breeding and Tissue Culture Laboratory of Indonesian Citrus and Subtropical Research Institute (ICISFRI) from May to September 2008. Five ISSR primers were used to amplify DNA samples. Matrix data was counted and dendrogram of samples was established using UPGMA and SAHN methods. The resulst showed that 3 of the primers indicated polymorphism. About 22 locus were amplified from 3 primers, 9 (40.9%) locus showed polymorphism. The genetic similarity of SoE mandarin derived from gamma rays irradiation were 73-100%.</p><p> </p><p><strong>Abstrak</strong></p><p>Jeruk keprok SoE merupakan salah satu jeruk keprok unggulan Indonesia untuk mensubstitusi jeruk impor. Kualitas jeruk dapat ditingkatkan melalui program pemuliaan, salah satunya adalah melalui pemuliaan mutasi dengan menggunakan sinar gamma. Tujuan penelitian ini adalah untuk mendapatkan informasi tentang variasi genetik jeruk keprok SoE hasil radiasi sinar gamma menggunakan penanda ISSR. Penelitian dilaksanakan di Laboratorium Pemuliaan dan Kultur Jaringan, Balai Penelitian Tanaman Jeruk dan Buah Subtropika (Balitjestro) pada bulan Mei-September 2008. Lima penanda ISSR digunakan untuk mengamplifikasi sampel DNA. Pengelompokan tanaman di dalam dendrogram dihitung menurut UPGMA menggunakan metode SAHN. Hasil penelitian menunjukkan bahwa tiga penanda mengindikasikan adanya polimorfisme. Dari 22 lokus yang terbentuk dari tiga penanda, sembilan lokus (40,9%) menunjukkan polimorfisme. Tingkat kesamaan genetik jeruk keprok SoE hasil radiasi sinar gamma berkisar antara 73-100%.</p>

When obtaining plantlets, embryo maturation and simultaneous germination are important steps in plant micropropagation via somatic embryogenesis. Several studies have shown that the use of carbohydrates as a carbon source plays a significant role in inducing somatic embryo development in certain plant species. This study aimed to establish a somatic embryo maturation protocol for Batu 55 Mandarin (C. reticulata Blanco.) by examining the effect of various types of sugar and concentrations. The results showed that the type and concentration of sugar added to the medium affect the somatic embryo maturation of Batu 55 Mandarin. Galactose and maltose enhance somatic embryo maturation more effectively than does sorbitol. The combination of galactose or maltose with sorbitol was able to improve somatic embryo maturation more effectively than galactose or maltose alone. The combination of galactose and sorbitol enhanced the maturation of somatic embryos more effectively than did change the concentrations of maltose or sorbitol. It can be concluded that sugar type and concentration had effects on citrus somatic embryo development. The combination of sorbitol (36.5 mM) with galactose 73 mM was able to augment citrus somatic embryo maturation more effectively than the other concentrations applied.

Until now, Huanglongbing-HLB disease caused by a simple bacterium (Ca. Liberibacter spp) and distributed by Asian citrus psyllid vector (Diaphorina citri) and clonal propagation (grafting), was a major challenge in the national citrus production even almost all citrus nation production center in Asia, Africa also at the USA. This disease attack at phloem vessels by callouses forming that covering plasmodesmata and could be crop failure. There have been no citrus varieties reported resistant to HLB attack. Plant ploidy increase derived from in vitro breeding through somatic hybridization and endosperm culture expected to increase the plant’s defense system. The aim of this study was to evaluate the tolerance of polyploidy plant to HLB attack. Tolerance of in vitro shoot of citrus regenerated from protoplast fusion (Citrus nobilis + C. unshiu) and culture of tangerine (C. nobilis) endosperm were screened by HLB pathogen suspense as selecting an agent and local lime as a negative control (HLB susceptible citrus). In vitro selection result that in vitro shoots derived from somatic hybridization shows resistance increase to HLB and characterize by recoverability after were selected.

This research aimed to identify accessions of jeruk keprok Garut plants (Citrus reticulata) grown from endosperm culture with stomata analysis, chloroplasts analysis, and chromosome analysis. This research was conducted at the Plant Breeding Laboratory of Indonesian Citrus and Subtropical Fruits Research Institute (ICSFRI), Malang. This research used seven accessions of jeruk keprok Garut (local mandarin citrus) from endosperm culture and mother plant of Garut mandarin. Data analysis was carried out with the Statistical Package for the Social Sciences (SPSS) application Application 22.0. The alignment analysis showed that all one accession (GT 224) out of seven accessions of Garut mandarin grown from the endosperm cultures is consistent with the mother plant according to chromosome number observation, stomata number observation, and chloroplast number observation.