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Banana and plantains are one of the important fruit crops grown extensively in the tropical and subtropical regions of the world. The world production of banana is 145 million tons of which only a few million tons is exported, which means that most production is primarily for local consumption. The banana cultivars are derived from two diploid wild species, Musa acuminata (AA genome) and Musa balbisiana (BB genome). Majority of the edible banana cultivars are propagated vegetatively, and hence, the improvement of banana through conventional breeding methods is difficult. Attempts have been made to improve banana by inducing genetic variability by using both physical and chemical mutagens and exploiting the somaclonal variation a few varieties have been released for cultivation. Transgenic approach has also been used to incorporate the desirable traits into banana. Recent advances in genomics and the availability of genome sequence of both Musa acuminata and Musa balbisiana helps in the improvement of this fruit crop. Also the recent reports of genome editing through CRISPR-CAS9 will aid in speeding up the banana improvement programmes in the near future. This review summarizes the various advances made in inducing genetic diversity in banana.

The rapid loss of genetic diversity has become a major concern worldwide for the genetic improvement of crops for sustainable agriculture especially under the climate change. Moreover, events like rapid human population growth, industrialization, deforestation, and natural calamities, are some of the major factors in this loss. The conservation, distribution, and utilization of natural and induced genetic diversity have become essential by the establishment of gene/germplasm bank both at the national and international levels. In vitro conservation techniques such as cryopreservation and low temperature storage are being routinely used for genetic resources conservation of a wide range of crops including seed propagated and vegetatively propagated crops. Cold-storage is done at 4-5°C and has a major disadvantage of frequent subcultures of in vitro cultures; may run into a risk of contamination. This method is routinely used for seed storage by national and international gene banks, maintained by CGIAR institutes, e.g., International Rice Research Institute (IRRI). Cryopreservation of genetic material is done in liquid nitrogen at -196°C on the long-term basis without going through frequent subcultures. In vitro cultures are suitable for cryo-storage, that includes somatic embryos, cell suspension, callus, and should be able to regenerate plants maintaining their genetic fidelity. In date palm, in vitro conservation work done is very limited. Nowadays, the date palm tissue culture system is well established via somatic embryogenesis and organogenesis, which is of course genotypic dependent on frequency of plant regeneration rate. Most commonly somatic embryogenic cultures have been used for cryo-storage of date palm genetic material. INTRODUCTION Date palm (Phoenix dactylifera) is one of the most ancient cultivated plants since over 4000 years. The continuous selection for desirable traits by man has resulted in narrowing the genetic diversity, and has left hardly any scope for developing new cultivars with useful traits. Very few plant species have been so closely connected with the survival and well being of humans living in hot and arid environments. Also, the date palm tree has a great socio-economic importance and nutritional value in the Middle East and north Africa. In addition, date palm trees withstand adverse environmental changes such as drought, rains, flood, temperature fluctuations, and also help in preventing desertification. These drastic climatic changes could have adverse consequences by losing the genetic diversity. Date fruits are a very important source of human nutrition as well as an export item for date palm growing countries. Most importantly the plant contributes in the creation of a ‘microclimate’ within the fragile oasis ecosystem and allows development of agriculture in drought and saline conditions; multiple cropping system such as grapes, tomato and so on. The genetic diversity of date palm represents different local cultivars grown under varied climatic conditions. The most popular Sudanese date palm cultivars described as soft and dry types, showed detectable genetic variation in fruit morphology (Elshibi, 2009; Jain, 2011). Moreover no conventional methods e.g., seed storage were used to conserve genetic diversity due to high nature of heterozygosis for a mohan.jain@helsinki.fi Proc. 4 Int. Date Palm Conference Eds.: A. Zaid and G.A. Alhadrami Acta Hort. 882, ISHS 2010 786 developing date palm breeding programs. With the development of in vitro culture techniques organogenesis, somatic embryogenesis, embryo rescue-plant regeneration has already been accomplished, which is highly genotypic dependent; has made possible shortand long-term storage of in vitro cultures, large-scale multiplication of plants of elite genotypes (Jain, 2011). CONSERVATION OF GENETIC DIVERSITY Plant genetic diversity conservation has become an important issue among researchers worldwide for present and future agriculture. The rapid loss of genetic resources is mainly due to rapid industrialization, fire, deforestation, and environmental pollution. Moreover, lack of availability or non-existence of desirable genotypes hampers plant breeders for developing new cultivars. Seed source is commonly used to conserve plant genetic resources and stored at low temperature. It is quite cost effective, safer, and easy to handle. The second approach is in vitro conservation of in vitro cultures in cold storage and cryo-storage (Bekheet et al., 2001, 2005, 2007). The success of this approach is very much dependent on plant regeneration and the maintenance of genetic fidelity of the stored genotypes. Nowadays international germplasm exchange has become more cumbersome and sometimes it is rather difficult to obtain elite genotypes. Many countries do not share the germplasm because of patent and ownership problems, and have established national germplasm conservation or gene bank facilities. In India, the National Bureau of Plant Genetic Resources (NBGR) was established in Delhi to conserve local and imported genetic material for proper utilization in developing new cultivars. Countries like Costa Rica, South Korea, Thailand and others have established germplasm conservation facilities. Gene banks of CGIAR institutes worldwide are an important source of exchange of germplasm (Jain, 2011). In the European Union, there are several projects being carried out on germplasm identification, collection, conservation, and utilization of various crops, e.g., Allium spp., and have established websites of available genetic resources. CONSERVATION OF INDUCED GENETIC DIVERSITY The natural genetic diversity is gradually eroded and consequently loss of valuable genetic resources that hinders genetic improvement of crops including date palm. Moreover the rate of spontaneous mutations is extremely slow and makes the availability of wide genetic diversity harder for plant breeders. Therefore, induced mutations hasten the rate of genetic diversity in a short period and are readily available to plant breeders for developing new cultivars. Mutations are induced by physical (e.g., gamma radiation) and chemical mutagen (e.g., sodium azide) treatment in seed and vegetative propagated crops including the date palm (Jain, 2010a,b; Jain et al., 2010). The FAO/IAEA Mutant Variety Database (MVD) collects information on plant mutant varieties (cultivars) released officially or commercially worldwide (http://www.iaea.org). A mutant variety is a new plant variety that is bred through: 1. direct use of a mutant line that is developed through physical and chemical mutagenesis, or somaclonal variation; 2. indirect use of a mutant line/lines, which is/are used as a parental variety/varieties in cross breeding (cross between mutant lines or with a commercial cultivar/cultivars); 3. the use of a mutant gene allele (trait) Calrose 76 sd1 allele (semi-dwarf 1 trait) in rice; 4. use of wild species’ genes translocated into plant genomes through irradiation facilitated translocations, e.g., genes of wheat wild relative species. In the FAO/IAEA mutant variety database, date palm mutants are yet to be available. However, mutation work on date palm has produced putative mutants showing tolerance to Bayoud disease (Jain, 2007).

Under the Joint FAO/IAEA programme, radiation-induced mutations are used for genetic improvement of both seed and vegetatively propagated plants. The FAO/IAEA programme maintains a database of officially released mutant varieties worldwide (http://www-mvd.iaea.org/). Currently, over 2300 mutant varieties are registered in our database. Coordinated Research Projects (CRPs) and Technical Co-operation Projects (TCP) are two major activities at IAEA that serve Member States at the national, regional and interregional levels. This article highlights CRPs on banana, underutilized and neglected crops, and tropical and subtropical fruits. CRPs on banana and underutilized and neglected crops have already been concluded. TCPs in South East Asia (Thailand, and Malaysia), Africa (Algeria, Morocco, Tunisia, Ghana), and the Middle East (Yemen) are discussed. The main projects in South East Asia are on genetic improvement of ornamental plants, fruits and cereals. In Africa, projects are on cassava, date palm, salinity and drought. In the Middle East, funded projects are related to salinity, and drought. In this article, major achievements are highlighted through CRPs and TCPs on low cost tissue culture, banana, underutilised and neglected crops, tropical and subtropical fruits.

Stress responses are largely conserved in eukaryotic cells, but with plants having certain distinctive reactions to specific stresses, e.g. the induction of pathogenesis-related proteins. General responses to stress involve signaling stress detection via the redox system, checkpoints arresting the cell cycle and DNA repair processes stimulated in response to DNA damage. Specific responses to stress include the induction of protective metabolites, such as betaines, and protective proteins, for example, heat shock proteins. Chemical signals, e.g. reactive oxygen species, Ca2+ and plant hormones, acting through signal transduction cascades activate genomic re-programming. Genome plasticity in plants allows adaptation to environmental conditions and includes genomic or epigenetic changes (histone acetylation, methylation, chromatin remodeling etc.) and possibly directed mutation. In plants, recent research has indicated that intricate stress response mechanisms and `cross talk' between stress responses exist. Here, changes in the plant genome and in genomic expression in development and as a response to environmental stress are reviewed as background to a discussion of the basis of aberrant genomic expression in vitro. Markers are discussed which may be used to characterize the stress exposure of in vitro tissues.

Induction of mutations is an effective approach for enhancing natural genetic resources. FAO/IAEA Coordinated Research Projects (CRP) have been established on tropical and subtropical fruits as well as on banana, and the Technical Co-operation (TC) sub-Regional Project on date palm. The objectives are to improve these fruit crops by induced mutations. These programs have four major components: in vitro culture, radiation induction of mutations, mutation screening, and characterization of mutants with molecular markers. In most of the important fruit crops, tissue culture is well established for plant regeneration either via somatic embryogenesis or organogenesis. Since somatic embryo cultures often originate from a single cell, it is an ideal system for induction of mutations as it helps in preventing chimerism. The rate of somatic embryo germination is very poor, which has become a major hurdle for large-scale plant multiplication of desirable induced mutants. The major focus will be on the development of mutant lines of fruits with improved tolerance against abiotic and biotic stresses, seedlessness e.g. in guava and citrus.

Tissue culture generates a wide range of genetic variation in plant species which can be incorporated in plant breeding programmes. By in vitro selection, mutants with useful agronomic traits, e.g. salt or drought tolerance or disease resistance, can be isolated in a short duration. The successful use of somaclonal variation is very much dependent on its genetic stability in the subsequent generations for which molecular markers such as RAPDs, AFLPs, SSRs and others can be helpful. The potential of somaclonal variation has yet to be fully exploited by breeders, even though a few cultivars have been developed in crops such as Brassica juncea, rice and others.

Litchi chinensis Sonn. ranks (high) among the most important horticultural crops, belongs to the family Sapindaceae and widely grown in tropical and subtropical regions (Menzel 1985). The tree produces delicious top quality fruits that are in great demand for their wholesome taste, sweet aroma and attractive colour. They are mainly consumed as a fresh table fruit worldwide but in China, dried litchis, called litchi nuts with the taste of the raisin are quite popular. They are also preserved and canned in syrup or used as squash. In Florida, frozen fruits are consumed on a limited scale. China, India and Taiwan are the major producers of litchi whereas in the last 40 years substantial increase in production in South Africa, Australia, Thailand, Vietnam, USA and Israel has led litchis to become a significant commodity in the international trade, (Underhill et al. 1997). Major thrust of litchi research has been on prevention of physiological browning and retention of bright red colouration of litchi fruits in several countries. Exotic litchi fruits have received worldwide attention. Increase in popularity has necessitated litchi cultivation in a wide range of environmental conditions. In fact litchi is generally adapted to various soil types via alluvial sands, loams, heavy clay, organic soil and calcareous soil with 30% lime and rock files (Chapman 1984a). In China, the best litchi trees are prevalent in Gwanagdong province close to the rivers on alluvial sands with good drainage and access to the water table (Chapman 1984b). They are also grown in gravelly sandy loam to loam soils as well as in swampy areas. However, soil in Fijian province is very high in clay, poorly drained and acidic in reaction (Winks et al. 1983). In South Africa, trees are more vigorous in growth on acid soils rather than on neutral or alkaline soils (Marloth 1947). Under Indian conditions, litchi cultivation in Bihar state is common on calcareous soils containing more than 40% free calcium carbonate and trees flourish well in a moist subtropical climate and in deep loamy soil with high moisture content. However

Section A.- Totipotency and the cell cycle.- Micropropagation via organogenesis in slash pine.- Micropropagation of Coast Redwood (Sequoia Sempervirens).- Micropropagation of Pinus pinea L.- Micropropagation of Pinus armandii var. Amamiana.- Organogenesis and Cryopreservation of Juvenile Radiata Pine.- Genetic Fidelity Analyses of In Vitro Propagated Cork Oak (Quercus suber L.).- Protocol for Micropropagation of Quercus spp.- Micropropagation of Mediterranean cypress (Cupressus sempervirens L.).- In vitro Shoot Development of Taxus Wallichiana Zucc., a Valuable Medicinal Plant.- Micropropagation of Yew (Taxus Baccata L.).- Micropropagation of Larix Species via Organogenesis.- Propagation of Selected Pinus Genotypes Regardless of Age.- Root Induction of Pinus Sylvestris L. Hypocotyl Cuttings using Specific Ectomycorrhizal Fungi in Vitro.- Micropropagation of Betula Pendula Roth including Genetically modified Material.- Protocol for Doubled-Haploid Micropropagation in Quercus suber L. and Assisted Verification.- In vitro Propagation of Fraxinus Species.- Micropropagation of Black Locust (Robinia Pseudoacacia L.).- Albizia Odoratissima L.F. (Benth) Micropropagation.- Micropropagation of Salix caprea L.- Micropropagation of Cedrela fissilis Vell. (Meliaceae).- Micropropagation of Mature Trees of Ulmus Glabra, Ulmus Minor and Ulmus Laevis.- Section B.- Micrografting in Grapevine (Vitis spp.).- Micrografting Grapevine for Virus Indexing.- Apricot micropropagation.- In vitro conservation and Micropropagation of Breadfruit (Artocarpus Altilis, Moracea).- Micrografting of Pistachio (Pistacia vera L. cv. Siirt).- Protocol for Micropropagation of Castanea Sativa.- Micropropagation of Cashew (Anacardium occidentale L.).- In vitro Mutagenesis and Mutant Multiplication.- In vitro propagation of Nutmeg, Myristica Fragrans Houtt.- Micropropagation of Elite Neem Tree (Azadirachta Indica A. Juss.).- Micropropagation Protocol for Microspore Embryogenesis in Olea Europaea L.- Micropropagation of Prunus Domestica and Prunus Salicina using Mature Seeds.- Micropropagation of Juglans regia L.- Tissue culture propagation of Mongolian cherry (Prunus fruticosa L.) and Nanking cherry (Prunus Tomentosa L.).- Micropropagation of Fig Tree (Ficus carica sp).- High frequency shoot formation of yellow passion fruit (Passiflora edulis F. flavicarpa) via thin Cell Layer (TCL) Technology.- Micropropagation of Calabash tree Crescentia Cujete L.- Micropropagation of Papaya (Carica Papaya L.).- Section C.- Protocol for Micropropagation of Selected Vaccinium spp.- Protocol for Micropropagation of Vaccinium Vitis-Idaea L.- Micropropagation of Bamboo Species Through Axillary Shoot Proliferation.- In vitro Culture Of Tree Peony Through Axillary Budding.- Micropropagation of pineapple, Ananas comosus (L.) Merr.- Date Palm Phoenix dactylifera L. Micropropagation.- Light-Emitting Diodes as an Effective Lighting Source for In Vitro Banana Culture.- In vitro Mutagenesis in Banana (Musa spp.) using Gamma Irradiation.

Litchi (Litchi chinensisSonn.) is one of the precious and economically important fruit crops of the world. The species belongs to the family Sapindaceae, which comprises about 2000 species of tropical and subtropical trees, shrubs, and vines that have been classified into 140 genera (Chapman, 1984). Litchi has been shown to possess variable diploid chromosome numbers where 2n = 28, 30, 32. The variation in chromosome number is thought to be because the modem species had more than one wild progenitor. Litchi fruit contain high levels of ascorbic acid ranging from 40 to 80 mg/IOO g of flesh, making it an excellent source of vitamin C (Cavaletto, 1980). The edible portion of fruit is a thick juicy aril having high moisture content (77 to 83 %), low fat (less than 1 %) and high sugar (14 to 23° Brix) and phosphorus contents. The fruit is an excellent thirst quencher and serves as a tonic for brain, heart and liver. In addition to medicinal uses, litchi fruit and their starchy seeds are used in brewing sweets and fragrant wine.

Section A. 1. Gene transfer techniques and their relevance to woody plants S.C. Minocha, J.C. Wallace. 2. Selection of marker-free transgenics plants using the oncogenes (ipt, rol A, B, C) of Agrobacterium as selectable markers H. Ebinuma, et al. 3. Agrobacterium rhizogenes for rooting recalcitrant woody species H.M. Haggman, T.S. Aronen. 4. Genetic engineering of conifers for plantation forestry Pinus radiata transformation C. Walter, L.J. Grace. 5. Transformation of Picea species D.H. Clapham, et al. 6. Transgenic in Larix M.A. Lelu, G. Pilate. 7. Genetic transformation of Populus toward improving plant performance and drought tolerance T. Tzfira, et al. 8. Progress on genetic engineering in four tropical Acacia spp. M. Quoirin, et al. 9. Genetic engineering of rose (Rosa species) M.R. Davey, et al. 10. Transformation of Actinidia species (kiwifruit) E. Rugini, et al. 11. Genetic transformation in Citrus G.A. Moore, et al. 12. Olive (Olea europaea var. sativa) transformation E. Rugini. 13. Transformation of Malus F.A. Hammerschlag. 14. Genetic transformation of Hevea brasiliensis (rubber trees) and its applications towards crop improvement and production of recombinant proteins of commercial value P. Arokiaraj. 15. Production of Transgenic oil palm (Elaeis guinensis JACQ.). using biolistic techniques G. Kadir, A. Parveez. Section B. 16. Molecular characterization of the mycorrhizas of woody plants S. Hambleton, R.S. Currah. 17. Molecular epidemiology tree pathogens R.C. Hamelin. 18. Development of insect resistance in fruit and nut tree crops M. Escob, A.M. Dandekar. 19. Structural and biochemical aspects of cold hardiness in woody plants M. Wisniewski, R. Arora. 20. Herbicide tolerant forest trees D.J. Llewellyn. 21. Cloning of defense related genes against pathogens in forest trees G. Lakshmi Sita, et al. Section C. 22. Research Ethics for Molecular Silviculture P.B. Thompson, S.H. Strauss.

Section A. 1. Somatic Embryogenesis in White Spruce: Studies of Embryo Development and Cell Biology L. Kong, et al. 2. Proliferative Somatic Embryogenesis in Woody Species K. Raemakers, et al. 3. Somatic Embryo Germination and Desiccation Tolerance in Conifers E.I. Hay, P.J. Charest. 4. Performance of Conifer Stock Produced Through Somatic Embryogenesis S.C. Grossnickle. 5. Apoptosis During Early Somatic Embryogenesis in Picea spp L. Havel, D.J. Durzan. 6. Water Relation Parameters in Conifer Embryos: Methods and Results N. Dumont-Beboux, et al. 7. Image Analysis for Sorting Somatic Embryos Y. Ibaraki. 8. Somatic Embryogenesis in Woody Legumes R.N. Trigiano, et al. 9. Cold Storage and Cryopreservation of Camellia Embryogenic Cultures A.M. Vieitez, A. Ballester. 10. Cryopreservation of Embryogenic Cultures of Conifers and Its Application to Clonal Forestry D.R. Cyr. 11. Commercialization of Plant Somatic Embryogenesis B.C.S. Sutton, D.R. Polonenko. Section B. 12. Somatic Embryogenesis in Myrtaceous Plants J.M. Canhoto, et al. 13. Somatic Embryogenesis Induction in Bay Laurel (Laurus nobilis L.) J.M. Canhoto, et al. 14. Somatic Embryogenesis in Simarouba glauca Linn G.R. Rout, P. Das. 15. Somatic Embryogenesis in Magnolia spp. S.A. Merkle. 16. Somatic Embryogenesis and Evaluation of Variability in Somatic Seedlings of Quercus serata by RAPD Markers K. Ishii, et al. 17. Somatic Embryogenesis from Immature Fruit of Juglans cinerea P.M. Pijut. Section C. 18. Somatic Embrygonesis in Pinus patula Scheide et Deppe N.B. Jones, J. van Staden. 19. Somatic Embryogenesis in African Cycads (Encephalartos) A.K. Jager, J. van Staden. 20. Somatic Embryogenesis in Picea wilsonii Y. Yang, Z. Guo. 21. Somatic Embryogenesis in Jack Pine (Pinus banksiana Lamb) Y.S. Park, et al. 22. Somatic Embryogenesis in Hybrid Firs J. Jasik, et al. 23. Somatic Embryogenesis in Taxus S.R. Wann, et al.

The aim of this study was to isolate Phytopthora cactorum-resistant strawberry plants, regenerated from gamma-irradiated explants on a shoot regeneration medium. Three gamma doses (0, 5, 10, 15 krad) were used to irradiate strawberry axillary buds taken from in vitro-grown plants. After irradiation, axillary buds were cultured on a shoot regeneration medium containing 0.75 mg BA/liter and 0.4 mg IBA/liter. Shoot regeneration occurred mainly from axillary buds irradiated with 5 and 10 krad. The highest dose (15 krad) produced few shoots. The shoot regeneration rate was highest at the 50-krad dose. All the regenerated plants were transferred in the greenhouse. The crude extract of P. cactorum, isolated from the strawberry field, was prepared in sterile water; 1 ml of it was put directly in the center of the crown of each of 400 regenerated plants. After 2 weeks, leaves of most of the plants wilted. Only 20 plants survived the first round of selection; they grew slowly when compared with the control and also showed some tolerance to drought. Further investigations are in progress to reconfirm the resistance of selected putative disease-resistant strawberry plants.