Though composed of only a few bases, microRNAs often perform a critical function by switching the expression of certain genes off. Turning off gene expression is just as important a regulatory mechanism in plant development as switching genes on, Zhang noted.

This switching-off function of microRNA has been known for more than a decade.

Further work had shown that it is microRNAs that actually guide the argonaute to actually do the switching off, sort of how a software application controls a smart phone or computer, according to Zhang.

Work by Zhang’s team had demonstrated that if miR166/165 did not load into AGO10, or the AGO10 gene was missing, then the meristem part of the plant would be deformed, but why this was so remained a mystery.

Zhang and his team proposed that AGO10 functions as "a decoy for miR166/165" to prevent it being loaded into other AGO proteins, particularly AGO1, which “plays a potent but inhibitory role in correct development of the meristem area cells,” he said.

“In other words, if miR166/165 is loaded into AGO1, they would shut their target genes off,” Zhang said. “But if miR166/165 is loaded into AGO10 protein, they won’t switch-off target genes. Thus, AGO10 works in an opposite way compared to AGO1: It protects target genes and secures their expression.”

Other members of the team were:  Dr. Martin Dickman, director of the Institute for Plant Genomics and Biotechnology; Dr. Sing-Hoi Sze, associate professor of computer science with the Texas A&M University department of biochemistry and biophysics; Dr. Hongliang Zhu, post-doctorate; technicians Ronghui Wang and Xin Zhou; graduate student, Fuqu Hu and undergraduate students Lisa Wen Liou and Ashley Barefoot.

The work was jointly funded by a National Science Foundation grant and by Texas A&M University and AgriLife Research.