Scientists have discovered how plants manage to live alongside each other in places that are dark and shady. Plants in the deep darkness of a thick forest, where natural supplies are not very great in amount, won’t attempt to top their neighbors in growth as those in moderate (中度的) shade do. In deep shade conditions, it would be a waste of energy and harmful to survival because green shoots would never be able to top their larger neighbors in growth.

So how do plants prevent such growth in deep shade conditions? The secret lies in the clocks inside them, say scientists from the John Innes Centre and the University of Bristol.

They have discovered that when plants notice deep shade, this changes the expression of genes in certain parts of the circadian clock (昼夜节律时钟) — the internal daily time r found in plants and other living things. These clock components perform an additional role in preventing plants from lengthening and over topping neighbors.

The work identifies a previously unknown role of the circadian clock in controlling plant development, and the findings may have possible effects on both natural plant populations and crops. Professor Antony Dodd of the John Innes Centre said, “The biological clock of plants plays a big part in their development and fitness. This work casts new light on a new role of the circadian clock in adapting plants to competition with other plants in their environments.” “It also gives us new insights into how plants adapt to very deep shade, where resources are very limited,” said Professor Kerry Franklin at the University of Bristol.

This work provides evidence for the stability of the circadian clock in stressful environments, and information that may be useful in developing new generations of crops in a challenging climate.

【小题1】What do plants normally do in moderate shade?

A．Struggle to preserve energy.	B．Compete for very limited resources.
C．Try to outgrow their neighbors.	D．Depend on each other to survive.

【小题2】How does the circadian clock affect plants?

A．By changing their gene expression.

B．By making them realize light change.

C．By helping them adapt to the darkness.

D．By controlling their growth in deep shade.

【小题3】According to Professor Antony Dodd, which statement is TRUE?

A．The circadian clock’s role in plant development remains unknown.

B．Plants’ living environments are very competitive.

C．The circadian clock affects plants’ adaptability to survival competition.

D．Plants can adapt to very deep shade where resources are very limited.

【小题4】Why does the author write the text?

A．To share a new discovery about plants.

B．To introduce the role of the circadian clock.

C．To compare plants living in certain conditions.

D．To explain plants’ secret of living in forests.