Auxin Drives Leaf Flattening

Leaves are fundamental light-capture organs of plants. The vast majority of higher plants utilize leaves as their solar panels to harvest solar energy. A common feature of leaves is their flat blades. Scientists from the Institue of Genetics and Developmental Biology in Beijing discovered that the classical phytohormone auxin enables leaf blade expansion and leaf flattening.

 

The flattening of leaves to form broad blade is an important adaptation that maximize photosynthesis. However, the molecular mechanism underlying this process remains unclear.

 

A new research led by JIAO Yuling from the Institute of Genetics and Developmental Biology, Chinese Academy of Sciences (CAS), showed that spatial auxin signaling defines the expression of two redundent genes WOX1 and PRS, which enables leaf blade expansion and flattening.

 

Following their previous report on the auxin regulation of leaf polarity pattening (Qi et al., 2014, PNAS 111:18769-18774), the researchers further found that auxin and auxin response factors (ARFs) have limited overlaps, which refines auxin signaling in the middle domain of leaf primordium.

 

Furthermore, they found that MP/ARF5, an ARF activator directly activates the expression of WOX1 and PRS, which promote the marginal meristem and enable leaf flattening. On the other hand, ARF repressors expressed in the abaxial (ventral) domain inhibit WOX1 and PRS expression.

 

“The new findings in this work explain how adaxial-abaxial (dosal-ventral) polarity patterns the mediolateral axis and subsequent lateral expansion of leaves”, said Dr. JIAO Yuling. He also mentioned that another recent research of the their group described auxin regulation of leaf development at the biomechanical level (Qi et al., 2017, Nature Plants 3:724-733).“Finding how leaf get flattened will be necessary to maintain and enhance yield in cultivated plants and crops” said JIAO.

 

This study entitled “Spatial auxin signaling controls leaf flattening in Arabidopsis” has been published online in Current Biology (DOI: 10.1016/j.cub.2017.08.042) on September 22^nd, with GUAN Chunmei as the first author.

 

This study was supported by the National Basic Research Program of China (973 Program), the National Natural Science Foundation of China, and the State Key Laboratory of Plant Genomics.

 

 

 

Dr. JIAO Yuling

Email: yljiao@genetics.ac.cn