Expression of a Neurospora crassa zinc transporter gene in transgenic Nicotiana tabacum enhances plant zinc accumulation without co‐transport of cadmium

Zinc (Zn) is an essential micronutrient required for growth and development of all organisms. Deficiency of Zn in humans is widespread, affecting 25% of world population and efforts are underway to develop crop plants with high levels of Zn in their edible parts. When strategies for enhancing Zn in crop plants are designed, it is essential to exclude cadmium (Cd), a toxic analogue of Zn. In the present work, a high affinity and high specificity zinc transporter gene (tzn1) from Neurospora crassa was cloned and introduced into Nicotiana tabacum with the objective of enhancing the potential of plants for zinc acquisition. When grown in hydroponic medium spiked with ⁶⁵Zn, transgenic plants showed enhanced accumulation of Zn (up to 11 times) compared to control plants, which was confirmed further by environmental scanning electron microscopy coupled with Energy Dispersive X‐ray analysis. More importantly, no significant difference in uptake of Cd²⁺, Fe²⁺, Ni²⁺, Cu²⁺, Mn²⁺ and Pb²⁺ between the transgenic and control plants was observed. The present studies have shown that Neurospora crassa tzn1 is a potential candidate gene for developing transgenic plants for improving Zn uptake, without co‐transport of Cd and may have implications in Zn phytofortification and phytoremediation.     

Ontogeny of Somatic Embryos of Vigna aconitifolia, Vigna mungo and Vigna radiata

Callus cultures were initiated from immature cotyledons of Vignaaconitifolia, V. mungo and V. radiata on MS medium supplementedwith NAA, picloram or 2, 4-D. On transfer to L-6 liquid mediumsupplemented with low concentrations of picloram, GA₃ and cytokinins,large number of somatic embryos differentiated from the callus.The cells destined to become somatic embryos divided to formspherical or filamentous proembryos. From the filamentous proembryo,the embryo proper developed either at single or multiple sites.Development of somatic embryos from multiple sites resultedin several embryos connected by a common suspensor at the radicleend. Continued divisions of the proembryos led to globular,heart shaped and dicotyledonary stages of somatic embryogenesis.The somatic embryos of V. mungo and V. aconitifolia differentiatedinto tiny plantlets at low frequency (1%) in liquid suspensioncultures supplemented with zeatin, picloram and GA₃. Vigna aconitifolia Jacq, Marechal, mothbean, Vigna mungo L. Hepper, urdbean, Vigna radiata L. Wilczk, mungbean, somatic embryo     

Callus Induction from Mesophyll and Hypocotyl Protoplasts of Mungbean (Vigna radiata (L))

Mesophyll and hypocotyl protoplasts were isolated from Vignaradiata using a combination of Cellulase Onozuka RIO (1%) andMacerozyme (0·2%). On a modified V-47 medium, 60% ofthe cultured protoplasts divided and developed into colonies.Protoclones differentiated roots on MS medium supplemented withdifferent auxins and cytokinins; however, shoot differentiationwas not obtained. Co-cultivation of protoplasts with wild andshooter mutants of Agrobacterium tumefaciens did not lead todifferentiation of plantlets. Lysopine and nopaline dehydrogenasewere not detected in any of the selected protoclones. Vigna radiata, Mungbean, Agrobacterium tumefaciens, co-cultivation, protoplasts     

Direct Somatic Embryogenesis, Plant Regeneration and Evaluation of Plants Obtained from Mesophyll Protoplasts of Brassica juncea)

Isolated mesophyll protoplasts of Brassica Juncea directly developedinto somatic embryos on medium supplemented with an auxin anda cytokinin. The somatic embryos germinated into plantlets whenmedium was supplemented with GA₂, and ABA. The plantlets weretransferred to the field and the second generation (P₂) wasevaluated for various agronomic characters. Some of the P₂ linesshowed variation in height and time required for flowering.Only two out of 53 lines were comparable to the control in grainyield Brassica Juncea, Indian mustard, direct embryogenesis, protoclonal variation, yield