Date palm (Phoenix dactylifera L.) is one of the most important fruit trees that contribute a major part to the economy of Middle East and North African countries. It is quintessentially called "tree of life" owing to its resilience to adverse climatic conditions, along with manifold nutritional-cum-medicinal attributes that comes from its fruits and other plant parts. Being a tree with such immense utility, it has gained substantial attention of tree breeders for its genetic advancement via in vitro biotechnological interventions. Herein, an extensive review of biotechnological research advances in date palm has been consolidated as one of the major research achievements during the past two decades. This article compares the different biotechnological techniques used in this species such as: tissue and organ culture, bioreactor-mediated large-scale propagation, cell suspension culture, embryogenic culture, protoplast culture, conservation (for short- and long-term) of germplasms, in vitro mutagenesis, in vitro selection against biotic and abiotic stresses, secondary metabolite production in vitro, and genetic transformation. This review provides an insight on crop improvement and breeding programs for improved yield and quality fruits; besides, it would undeniably facilitate the tissue culture-based research on date palm for accelerated propagation and enhanced production of quality planting materials, along with conservation and exchange of germplasms, and genetic engineering. In addition, the unexplored research methodologies and major bottlenecks identified in this review should be contemplated on in near future.

Light is one of the main limiting factors for phenolic compound biosynthesis in plants and shade levels play an important role in the cultivation of medicinal plants. Kaempferia parviflora a popular rhizomatous medicinal plant was investigated for secondary metabolite and plant biomass accumulation in response to shading and cultivar type. Two cultivars KPM (K.parviflora Malysia) and KPT (K.parviflora Thai) were analyzed for growth and secondary metabolite content under four shade levels (0%, 30%, 50%, and 70%). Photosynthetic capability, plant biomass and total flavonoid content were highest both cultivars under 30% shade after 9 months of growth cycle. 0% shade induced stress on plant growth and reduced photosynthetic capability and the flavonoid accumulation in both cultivars. 5,7dimethoxyflavone (DMF) was used as a chemical marker to quantify secondary metabolite content in K. parviflora cultivars. DMF was greatest in KPM grown under 30% shade. KPT had higher biomass than KPM under 30% but lower DMF content. In conclusion, K. parviflora is a semi shade loving plant suitable to grow under 30% shading for high yield and secondary metabolite production.

Highlights • Multiple shoot regeneration was found most successful on Murashige and Skoog (MS) media supplemented with 35.52 µM N6-benzyladenine. • High survivability was observed with an acclimatisation percentage of 100%. • Microrhizomes were successfully induced in MS media with an optimal concentration of 6% (w/v) sucrose.

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