In the early edition of PNAS this week is Ecological modulation of plant defense via phytochrome control of jasmonate sensitivity.
This paper describes how plants balance the tradeoff between growth and defence. The same light sensor that detects other plants crowding in and gives the signal to switch on the synthesis of the plant growth hormone auxin reduces the plant's responsiveness to the hormone jasmonic acid, which orchestrates the synthesis of a whole array of defensive chemicals.
Coupling shade avoidance syndrome with the regulation of resource allocation to defense could provide a major selective advantage for plants growing in the wild, but might increase the vulnerability of densely planted crops to insects.
Hmm. I guess this is more relevant to next quarter but I thought it was an interesting paper. Here are a couple of past posts of more relevance to our current topics: