Azhar et al., J. Anim. Plant Sci. 23(5):2013 1436 GOSSYPIUM GOSSYPIOIDES: A SOURCE OF RESISTANCE AGAINST COTTON LEAF CURL DISEASE AMONG D GENOME DIPLOID COTTON SPECIES M. T. Azhar, Z. I. Anjum * , and S. Mansoor Agricultural Biotechnology Division, National Institute for Biotechnology and Genetic Engineering (NIBGE), P O Box 577, Jhang Road, Faisalabad, Pakistan * Central Cotton Research Institute (CCRI), Multan, Pakistan Corresponding Author e-mail: tehseenazhar@gmail.com ABSTRACT The diploid cotton species belonging to A, D and tetraploids with AD genome were screened for the presence/absence of components of cotton leaf curl complex. These cotton species are being maintained in a living herbarium for more than fourdecades under natural conditions. As expected, the two diploid species (Gossypium arboreum and G. herbaceum) of A genome, were found to be free of virus when screened by PCR and Φ29 DNA polymerase. The two cotton species of D genome (G. thurberii and G. aridum) showed the presence of begomovirus. The species belonging to AD genome were found to be susceptible to CLCuD due to the presence of both begomovirus and betasatellite. However, the interesting exception among D genome species was G. gossypioides. The results from present study suggest that G. gossypioides is a valuable resource for mapping of resistance by developing segregating populations and for developing synthetic tetraploids. Key words: Resistance, susceptibility, Cotton leaf curl disease, betasatellite. INTRODUCTION Cotton belongs to genus Gossypium, which is comprised of more than 50 species including wild as well as cultivated. Among them 45 are diploid and five are allotetraploid in nature (Fryxell, 1979). These wild species are divided into eight genomes from A through G and K. There are four cultivated species of cotton that include Gossypium hirsutum (cultivated species, allotetraploid, AD 1 ), G. barbadense (cultivated species, allotetraploid, AD 2 ), G. arboreum (cultivated, diploid, A 2 ) and G. herbaceum (cultivated, diploid, A 1 ) originated from South Mexico, South America (Peru), Indian sub- continent and South Africa, respectively. The two tetraploid cotton species that originated in the New World now contribute more than 90% of cotton produced in the world. The wild species of cotton are potential source of resistance to biotic (insects and diseases) and abiotic stresses like salinity, cold, drought, heat (Yik and Birchfield, 1984, Narayanan and Singh, 1994). Some of wild species namely, G. darwinii, G. stocksii, G. harkensii, G. aridum, are good donors for drought tolerance whereas G. thurberii has resistant genes for frost tolerance (Rooney et al., 1991). Due to their potential, these wild species (diploids and tetraploids) are being utilized in various hybridization programs (Mehetre et al., 2003, Mehetre et al., 2004). Cotton leaf curl disease (CLCuD) is the most important limiting factor for cotton production in Pakistan and bordering areas of India (Briddon and Markham, 2000). The disease is caused by monopartite begomoviruses that require a disease-specific DNA satellite named Cotton leaf curl Multan betasatellite (CLCuMB) (Briddon et al., 2001; Mansoor et al., 2003). The betasatellite is a symptom determinant and is essential for the induction of disease symptoms (Qazi et al., 2007) and DNA A encodes various genes required for replication (Hanley-Bowdoin et al., 1999) and coat protein that play important role in disease transmission (Azzam et al., 1994). The first epidemic of CLCuD started in early 1990s (known as “Multan strain”) was managed by the introduction of resistant varieties developed through conventional breeding. However, in 2001 symptoms of the disease started to appear on previously resistant varieties due to emergence of “Burewala strain” (Amrao et al., 2010). The breakdown of natural resistance in G. hirsutum introgressed from LRA5166 and CP15/2 has further enhanced interest and efforts to utilize resistance from diploid species through interspecific hybridization. G. arboreum is still grown commercially and has consistently shown resistance against both “Multan strain” and “Burewala strain” of CLCuD. Surveys on large number of plants of G. arboreum did not identify even a single plant showing symptoms of CLCuD (Briddon and Markham, 2000). One of the largest living herbarium of wild species of Gossypium is being maintained at Central Cotton Research Institute (CCRI), Multan, Pakistan. These wild species are being maintained since 1970s and are growing in an area with inoculum of CLCuD and other begomoviruses (Azhar et al., 2010). No information is available in the literature about the contribution diploid wild species for resistance to CLCuD. Efforts have been The Journal of Animal & Plant Sciences, 23(5): 2013, Page: 1436-1440 ISSN: 1018-7081