AKDENİZ ÜNİVERSİTESİ ZİRAAT FAKÜLTESİ DERGİSİ, 2005, 18(3), 397-404 EFFECT OF EXPLANT AND GENOTYPE ON CALLUS CULTURE AND REGENERATION IN ONION ( ALLIUM CEPA L.) Anil KHAR 1,3 Ram Dhan BHUTANI 1 Neelam YADAV 2 Vijay Kumar CHOWDHURY 2 1 Department of Vegetable Crops, 2 Department of Biotechnology and Molecular Biology CCS Haryana Agricultural University, Hisar, Haryana, INDIA 3 National Research Centre for Onion and Garlic, Rajgurunagar, Pune, INDIA Abstract The present investigation explores the possibility of developing in vitro system which could have wider application such as germplasm conservation micropropagation, production of virus/disease free materials. Plant regeneration system evolved in this study may help researchers to improve these crops. Onion is one of the most important vegetable crop grown throughout the world. Three genotypes of onion viz., B-780, N-2-4-1 and Hisar-2 along with three explants i.e., shoot tip, root tip and seeds were used to study the effect of genotype and explant on indirect organogenesis in onion. In vitro grown axenic seedlings were used as the explant source. It was observed that on an overall basis MS medium supplemented with 2,4-D 0.5mg/l was optimum for maximum callus formation in all the three explants studied. Among the genotypes tested, B-780 was found to be best genotype giving good response and in explants shoot tip was adjudged best on the basis of its callus formation ability. Keywords: Allium cepa, genotype, explant, callus culture, regeneration Soğanda (Allıum cepa L.) Eksplant Tipi ve Genotipin Kallus Kültürü ve Regenerasyon Üzerine Etkileri Özet Bu çalışmada germplazm muhafazası, çoğaltma, hastalık ve zararlılardan ari üretim için geliştirilen in vitro tekniklerinin soğanda kullanım olanakları araştırılmıştır. Araştırmada geliştirilen bitki regenerasyon sistemi, dünyada yetiştirilen en önemli ürünler arasında yer almakta olan bu türün geliştirilmesinde araştırıcılara yardımcı olacaktır. Çalışmada 3 soğan genotipi (B-780, N-2-4-1 and Hisar-2) ve sürgün ucu, kök ucu ve tohum olmak üzere 3 farklı eksplantın direkt ve indirekt organogenesis üzerine etkisi araştırılmıştır. In vitro eksplant kaynağı olarak axenic fideler kullanılmıştır. Her üç eksplantta da maksimum kallus oluşumu için MS ortamına 0.5 mg/l 2,4-D eklenmesi uygulaması en iyi sonucu vermiştir. Denenen gentotipler arasında B-780, kallus oluşumu açısından en iyi genotip ve sürgün ucu ise en uygun eksplant tipi olarak belirlenmiştir. Anahtar Kelimeler: Allium cepa, genotip, eksplant, kallus kültürü, regeneration 1. Introduction Onion (Allium cepa L.), a member of Alliaceae family, is one of the most important vegetable crop grown throughout the world for its medicinal and cuisine value. No Indian kitchen is complete without this vegetable crop. India ranks second to China in area (4.26 lakh ha.) and production (54.84 lakh tonnes) with an average productivity of 12.87 t/ha (Anonymous, 2002). Besides this, about 90% of vegetable export form India comprises mainly of onion. A lot of work on conventional methods of breeding and production has been done in India but the in vitro studies on Indian genotypes are in rudimentary stage. Except a few reports on garlic (Bhojwani, 1980; Koul et al., 1994) not much work has been done in this crop. Tissue culture provides an affordable alternative for propagation of elite and rare material, development of homozygous lines through anther/ovary/ovule culture and, thereby, jettisoning the breeding programme since onion is an outbreeder with a ‘two years per generation cycle’ crop. Moreover, an efficient and reproducible protocol is important for development of any transformation protocol. Keeping in view all the above facts, an experiment was conducted to study the effect of explant and genotype on callus culture and regeneration in onion. 2. Materials and Methods Three genotypes of onion viz., 397