Abstract
Traditionally date palm (Phoenix dactylifera L.) is propagated through offshoots but limited numbers bar their wide distribution. With the advent of tissue culture massive expansion of elite cultivars was made possible, but commercially in vitro plants were introduced only in the last two decades. Propagation of date palm through tissue culture generally results in true-to-type plants but some off-types with abnormal phenotypes also develop due to somaclonal variation caused by genetic and/or epigenetic changes during the tissue culture process. In tissue culture-derived date palm many off-type phenotypes are detected that include stunted or severely retarded growth, leaves with wide leaflets, variegated leaves, malformation of inflorescence, abnormal flowers, abnormal multiple carpels and low levels of fruit set. Off-types with genetic changes may be produced due to excessive plant multiplication cycles and growth regulators used to get a maximum number of plants from a single mother plant. Interestingly many of these off-types appear in the plants at maturity thus escaping the selection and screening at an early stage. It is therefore important that appropriate quality assurance tests are performed both at the molecular and morphological levels to ensure true-to-typeness. Since phenotypic identification of off-types is not reliable at early growth stages of tissue culture-derived plants, identification at the molecular level, isozyme and DNA, is inevitably the solution. The use of hormones as a remedy to abnormalities is also discussed.