New research shows how the houseplant "mother of thousands" (Kalanchoe
diagremontiana) makes the tiny plantlets that drop from the edges of its
leaves.
Having lost the ability to make viable seeds, the plant has shifted
some of the processes that make seeds to the leaves, said Neelima Sinha,
professor of plant biology at UC Davis.

Many plants reproduce by throwing out long shoots or runners that can
grow into new plants. But mother of thousands goes further: the plantlets
are complete miniature plants that become disconnected from the mother
plant's circulatory system and drop off, allowing them to spread rapidly and
effectively. The houseplant has lost the ability to make viable seeds and
only reproduces through plantlets.

Helena Garc?s, a graduate student in Sinha's laboratory, Sinha and
colleagues looked at two genes, STM and LEC, in mother of thousands and
close relatives, some of which make seeds instead of plantlets. STM controls
shoot growth, while LEC is involved in making seeds.

Expression of STM in leaves was essential for making plantlets. In
most plants LEC is expressed in seeds, but mother of thousands' version of
the gene, LEC1, was expressed in leaves as well. When the researchers
transferred the LEC1 variant into other plants, they were unable to make
viable seeds.

Mother of thousands appears to have lost the ability to reproduce
sexually and make seeds, but transferred at least part of the embryo-making
process to the leaves to make plantlets, Sinha said. The findings could be
useful in manipulating plant reproduction, she said.

The other authors on the paper are: Connie Champagne and Soomin Park,
postdoctoral researchers at UC Davis; graduate student Brad Townsley; Rui
Malho, University of Lisbon, Portugal; Maria Pedroso, Monsanto Co., St.
Louis; and John Harada, professor of plant biology at UC Davis. The work was
supported by grants from the National Science Foundation and the Fundaç?o
para a Ci?ncia e Tecnologia, Portugal,and is published online by the journal
Proceedings of the National Academy of Sciences.

Additional information:
[www-plb.ucdavis.edu]