Protein Family Key To Helping Plants Adapt, Purdue Researchers Report

The proteins, AtCPLs, apparently play a crucial role in triggering a gene that controls plants' reactions to stressful conditions, said Purdue University researchers. They, along with collaborators at the University of Arizona, published their findings in two papers appearing in a recent issue of Proceedings of the National Academy of Sciences.

AtCPLs are enzymes of a protein family that in humans controls initiation of gene activation. The family is called the C-terminal domain phosphates family.

Specifically, this enzyme family controls RNA required to produce messenger RNA, the initial product of the gene expression process. RNA, a molecule closely related to DNA, serves as a blueprint that tells cells to manufacture specific proteins.

"This family of proteins, AtCPLs, is undefined in plants," said Mike Hasegawa, co-senior author of a study describing two of the proteins. "The members we examined have both overlapping and unique functions, and this is novel."

Hasegawa, co-senior author Ray Bressan, and their team uncovered the proteins' function by studying mutated Arabidopsis thaliana, a common research plant, to determine its response to the stress of growing in salty soil. The same mutations, called cpl1 and cpl3, also seem to alter response to cold and drought, and alter growth and flowering time.

"It's become the prevailing feeling that when a plant senses its environment and signals to provide defense, the process turns on and off a number of different signal pathways that ultimately control the expression of specific genes that are required for adaptation," said Hasegawa, a horticulture professor.

"This research identifies a new temporal component of gene regulation that occurs after the initiation of transcription of the gene and seems to regulate important stress response processes of plants."

Transcription is when RNA copies and transfers the gene's instructions to the cell onto a template of DNA.

Hasegawa, Bressan and their colleagues have mainly focused on plant adaptability to soil salinity. However, by working with a number of different mutations, they have identified genes that are relevant for plant adaptation to other environmental stresses such as cold and drought.

Now the scientists are investigating other proteins that may be involved in plant reaction to environmental stress. They hope to determine the overlapping and unique functions of AtCPL family members so they can use bioengineering to improve plant tolerance for adverse growing conditions.

The other researchers involved in the study in which Hasegawa and Bressan are principal investigators are: research biologist Hisashi Koiwa, Adam Barb, biomedical engineering senior research assistant Fang Li, Michael McCully, post doctoral fellow Irina Sokolchik, Zhizhong Gong, graduate research assistant Altanbadralt Sharkhuu and Yuzuki Manabe, and Shuji Yokoi all of the Purdue Department of Horticulture Center for Plant Environmental Stress Physiology. From the University of Arizona Department of Plant Sciences senior investigator Jianhau Zhu and researchers Liming Xiong, Jian-Kang Zhu, and Byeong-ha Lee. Muppala Reddy of Central Salt and Marine Chemicals Researcher Institute in India also participated in the study.

A National Science Foundation Plant Genome Award and a U.S. Department of Agriculture National Research Initiative Grant provided funding for this project.