Four-leaf clovers are rare in nature, about one to four in every 10 thousand clovers have more than the normal three leaves. Now scientists have found the gene mutation that explains the aberration.
Four-leaf clovers are reputed to bring good fortune: they represent luck, hope, faith, and love. They are also a business opportunity to those who have a secret formula (feeding a genetically-engineered ingredient to the plants to encourage the aberration) to produce as many as 10,000 four-leaf plants a day which are sold as "lucky charms".
The white clover Trifolium repens
In scientific nomenclature the genus in which clovers are classified is Trifolium, which means just that: three leaves. However, occasionally, clovers and other plants of the same family (Fabaceae) show more than the normal 3 leaves, sometimes four and in some extreme cases as many as 21.
Until now, scientists were unsure about the causes of the existence of four or more leaves in plant species of the Fabaceae family. Possible explanations could be environmental or genetic factors. Now an international team of researchers has discovered the gene responsible for the presence of more than three leaves in plants of the Fabaceae family which may also explain the existence of four-leaf clovers.
The researchers used the barrel clover (Medicago truncatula) as a model in their study. The result of the research was published May 24 in the journal Proceedings of the National Academy of Sciences (PNAS).
Spanish plant scientist Francisco Madueño, one of the co-authors of the paper explains to newspaper El Mundo (in Spanish):
The barrel clover Medicago truncatula
"The formation of new leaves occurs at the apex of the stem, from tiny bumps called primordia, formed by cells that are multiplying,"
“The formation of new primordia is due to the expression in certain areas of the original primordium of the transcription factor SGL1, which favours the proliferation of that group of cells leading to more leaflets.”
In simpler terms: the study found that a gene identified as PALM1, precisely controls the expression of SGL1. However, in cases when PALM1 is not working properly (a mutation), the factor SGL1 is expressed out of control, allowing the formation of a greater number of leaflets.