An efficient, rapid and direct multiple shoot regeneration system amenable to Agrobacterium-mediated transformation from primary leaf with intact petiole of blackgram (Vigna mungo) is established for the first time. The effect of the explant type and its age, type and concentration of cytokinin and auxin either alone or in combination and genotype on multiple shoot regeneration efficiency and frequency was optimized. The primary leaf explants with petiole excised from 4-day-old seedlings directly developed multiple shoots (an average of 10 shoots/ explant) from the cut ends of the petiole in 95 % of the cultures on MSB (MS salts and B 5 vitamins) medium containing 1.0 μM 6-benzylaminopurine. Elongated (2-3 cm) shoots were rooted on MSB medium with 2.5 μM indole-butyric acid and resulted plantlets were hardened and established in soil, where they resumed growth and reached maturity with normal seed set. The regenerated plants were morphologically similar to seed-raised plants and required 8 weeks time from initiation of culture to establish them in soil. The regeneration competent cells present at the cut ends of petiole are fully exposed and are, thus, easily accessible to Agrobacterium, making this plant regeneration protocol amenable for the production of transgenic plants. The protocol was further successfully used to develop fertile transgenic plants of blackgram using Agrobacterium tumefaciens strain EHA 105 carrying a binary vector pCAMBIA2301 that contains a neomycin phosphotransferase gene (nptII) and a β-glucuronidase (GUS) gene (uidA) interrupted with an intron.The presence and integration of transgenes in putative T 0 plants were confirmed by polymerase chain reaction (PCR) and Southern blot hybridization, respectively. The transgenes were inherited in Mendelian fashion in T 1 progeny and a transformation frequency of 1.3 % was obtained. This protocol can be effectively used for transferring new traits in blackgram and other legumes for their quantitative and qualitative improvements.

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Plants serve as major sources for all essential minerals required by humans. Unfortunately, major staple food crops are deficient in some of the micronutrients. The population depending on staple food crops (cereals) or those inhabiting regions where soil mineral imbalances occur, often suffer from mineral malnutrition (Fe, Zn, I or Se deficiencies) which is damaging the health of 3 billion (half of the world's population) people especially in developing countries where a diversified diet is not affordable for the majority. The strategies aimed at reducing mineral deficiencies, i.e. supplementation and fortification of food, are also not accessible to the rural poor. An alternative approach is to increase minerals in the edible crops (biofortification) through mineral fertilization, use of mycorrhiza inoculants, and plant breeding and/or transgenic strategies. The first two approaches are costly and non-sustainable. Breeding for enhanced micronutrient concentration in edible portions of crop plants is particularly very difficult. Recent studies have shown that gene technology can complement breeding for developing crops with produce rich in micronutrients to curb malnutrition in a cost effective and sustainable manner. This chapter will provide an updated account of the different approaches used in obtaining biofortified crops to overcome mineral malnutrition.