Staminodes evolution and in vitro development innovation in date palm (Phoenix dactylifera L.).

The in vitro cultivation of date palm staminodes (vestigial stamens) at different stages of female floral ontogenesis confirms the persistence at an immature state of such organs at all the floral differentiation stages. This is evidenced even in fully mature female flowers. Our study revealed the advanced developmental patterns of these rudimentary structures, which bear diverse morphogenetic potentialities. In vitro cultivation of staminodes provides new opportunities for in vitro regeneration of date palm. Such developmental processes were found to be modulated by the stage of floral differentiation, which closely reflected the level of staminode maturity. Development was also impacted by the composition and concentration in plant growth regulators (NAA, BAP and 2,4-D) of the culture media. The large morphogenetic plasticity of the staminodes disposed them to evolutionary variations of the date palm reproduction system. The practical benefits (micropropagation) and the fundamental interests (evolutionary process) of our investigation are discussed.

The date palm (Phoenix dactylifera L.) micropropagation using completely mature female flowers.

This study describes an efficient and reproducible protocol for in vitro date palm propagation using mature female flowers. It focuses on the promising proliferation capacity exhibited by a number of female flower tissues taken at the final developmental stage. This capacity resided in the ability to preserve minuscule zones in a juvenile state located at the floral organ armpits (sepals and petals). The originality of this method lies in the possibility of propagation of very rare varieties, particularly the genotypes that exist in only one copy without the excision of the plant mother, the source of the tissue collected to be cultivated, which was not the case for all previous methods. The findings revealed that 2,4-D at 1mg/l, most of the varieties tested showed reactivity. The success of this technique was also noted to depend on the concurrent control of various factors pertaining mainly to the hormonal composition of the culture medium and the appropriate time of tissue transfer, which depends on the proliferation state as well as the culture period. This study describes the nature of the proliferation from the mature female flowers and their outcome, particularly those at the origin of embryogenic and budding strains and discusses the advantages of this novel multiplication method as compared to the currently available ones.

In vitro hermaphrodism induction in date palm female flower.

This study explores and reports on the gain brought to the morphogenetic aptitude of female date palm inflorescences through in vitro hermaphrodism induction. It investigates the main factors involved in the process of sex modification through hormonal induction, such as the floral developmental stage and hormone combination and concentration. It demonstrates that the vestigial stamens (staminodes) of female date palm flowers display a new and high capacity to proliferate under particular in vitro conditions, without blocking carpel's development, leading to morphologically typical hermaphrodite flowers. This de novo activation of repressed stamens was found to occur rapidly. The isolated pollen mother cells appear in the obtained anther's locules and undergo an ordinary microsporogenesis process. The data show that hermaphrodism induction depended heavily on both the growth regulators applied and the flower's developmental stage. They also confirm the early theory that suggests that dioecious plants come from a hermaphrodite ancestor. Such hermaphrodism control can provide new prospects and opportunities for the investigation of the in vitro self-fertilization process. It can also be useful in improving the understanding of the genetic mechanism involved in sex organ development in date palm.