Hybrids and Polyploids Grow More in Daytime

Hybrid plants tend to grow faster, bear more flowers and fruit, or be more adaptable than their parents. The same holds true for polyploid plants, those that have two or more sets of chromosomes. Many important agricultural crops such as wheat, banana, cotton and canola, are polyploid in nature. Scientists at the University of Texas found that hybrids and polyploids grow bigger and better because many of their genes for photosynthesis and starch metabolism are more active during the day. Their work appears in the current issue of Nature.

"Before this discovery, no one really knew how hybridization and polyploidy led to increased vigor," says lead author Dr. Jeffrey Chen. "This is certainly not the only mechanism behind this phenomenon, but it is a big step forward." The research team discovered a direct connection between circadian clock regulators and growth vigor in both hybrids and polyploids. Repressors of circadian clock genes were found to be more active during the day in the hybrids and polyploids, leading to increases in their photosynthesis and starch accumulation.

With this knowledge, scientists can now develop genomic and biotechnological tools to find and make better hybrids and polyploids.

Read the full article at http://www.utexas.edu/news/2008/11/24/hybrid_vigor/ The paper published by Nature is available at http://dx.doi.org/10.1038/nature07523