Unlike zygotic embryogenesis, during somatic embryogenesis an induction phase is required where differentiated somatic cells acquire embryogenic potential. The transition of somatic cells to embryogenic phase is the first and crucial step in somatic embryogenesis. This process involves reprogramming of gene expression patterns as well as changes in the morphology, physiology and metabolism. These changes are dependent on the up and down regulation of certain genes which are essential for the transition. Although the mechanism is still unclear, the search for such genes led to the discovery of SERK gene. The objective of the present study is to determine the expression pattern of the HbSERK gene during the transition of somatic cells to the embryogenic state. In RT-PCR assay, no SERK transcripts could be detected in somatic callus before embryo induction. However, the SERK expression was restricted in embryogenic cells. Regarding the HbSERK expression in other tissues, no signal was found either in leaves or in nonembryogenic callus, but was observed in emerging shoot. Thus the present study demonstrated that in addition to the acquisition of embryogenic competence, SERK gene also plays a role in shoot organogenesis in Hevea.
Renewability and environmental friendliness impart natural rubber latex-based adhesives a greener outlook.The main objective of this study was to investigate the role of dry rubber content and the size of rubber particles in the latex on the adhesive properties of ammonia preserved natural rubber field latex as contact adhesives for bonding leather specimens. Both peel strength and shear strength of field latex adhesive were tested. It was found that adhesive strength of field latex was increased with dry rubber content (drc) and maximum strength obtained was for 45 per cent drc latex. The effect of particle size and proteins on the adhesive properties of natural rubber latex was confirmed by comparing the adhesive peel strength of centrifuged latex and its combinations with skim latex, field latex etc. Role of various compounding ingredients and tackifier resins on the peel strength of natural rubber latex at various ageing conditions was also studied.