Abstract
It is widely known that during the reproductive stage (flowering), plants do not root well. Most protocols of shoot regeneration in plants utilize juvenile tissue. Adding these two realities together encouraged us to study the role of florigen in shoot regeneration. Mature tobacco tissue that expresses the endogenous tobacco florigen mRNA regenerates poorly, while juvenile tissue that does not express the florigen regenerates shoots well. Inhibition of Nitric Oxide (NO) synthesis reduced shoot regeneration as well as promoted flowering and increased tobacco florigen level. In contrast, the addition of NO (by way of NO donor) to the tissue increased regeneration, delayed flowering, reduced tobacco florigen mRNA. Ectopic expression of florigen genes in tobacco or tomato decreased regeneration capacity significantly. Overexpression pear PcFT2 gene increased regeneration capacity. During regeneration, florigen mRNA was not changed. We conclude that florigen presence in mature tobacco leaves reduces roots and shoots regeneration and is the possible reason for the age-related decrease in regeneration capacity.
Highlights
It is widely known that during the reproductive stage, plants do not root well
Florigen and a rejuvenator are both homologs to the A. thaliana gene FLOWERING LOCUS T (AtFT1) gene, coordinating the repeated cycles of vegetative and reproductive growth in woody perennial like p oplar[24] (Populus spp.) or pear[21] by cycling expression year-round
While the phase change from vegetative to reproductive growth in a plant is accompanied by changing leaf shape[33], we found that inducing early flowering and reducing regeneration ability is not related to this shape change
Summary
It is widely known that during the reproductive stage (flowering), plants do not root well. We conclude that florigen presence in mature tobacco leaves reduces roots and shoots regeneration and is the possible reason for the age-related decrease in regeneration capacity. Zhang et al.[11] showed that miR156, a chronologically regulated microRNA, regulates shoot regeneration in leaf segments from tobacco plants by allowing the gradual changes in SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) mRNA levels[11]. The above effects indicate that the capacity to regenerate roots or shoots and maintain cell division activity in the cambium is associated with the plants’ maturity state. I it is a common practice in vegetative rooting of cuttings to use as juvenile tissue as possible.
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