Scientists have gained insights into the mechanisms plants use to uptake and transport essential nutrients. A key question remains: how do these nutrient transporters reach their necessary locations within plant cells?
For instance, plants require boron, which enters cells through specific molecules known as boric acid channels. However, the process by which the proteins that create these channels reach the plasma membrane is not well understood.
A research team led by Professor Junpei Takano at Osaka Metropolitan University’s Graduate School of Agriculture has identified a mutant strain of Arabidopsis thaliana where the boric acid channels fail to properly reach the plasma membrane. Their findings are detailed in the Journal of Experimental Botany.
The researchers found that this issue is caused by a deficiency in the KAONASHI3 (KNS3) protein. The name “kaonashi,” meaning “faceless” in Japanese, was given in 2008 by a team led by Associate Professor Sumie Ishiguro from Nagoya University, who is also a co-author of the current study.
Through a thorough investigation, the team discovered that KNS3, along with two related proteins known as KNSTH1 and KNSTH2, likely forms a complex that aids in transporting boric acid channels from the endoplasmic reticulum to the Golgi apparatus and ultimately to the plasma membrane.
Additionally, the study noted that the pollen of Arabidopsis thaliana typically exhibits a surface pattern resembling muskmelon skin. However, in mutant strains lacking the KNS3 gene, this pattern is absent, resulting in a “faceless” appearance. This change may be linked to the disrupted transport of another protein involved in the formation of pollen exine.
“Based on the mechanism of intracellular transport for membrane proteins outlined in this study, it appears that plants can regulate nutrient uptake and pollen structure by managing the transport of specific proteins through the KNS3-KNSTH1-KNSTH2 complex,” said Professor Takano. “Our findings could lead to methods for reducing fertilizer use while enhancing crop yields.”
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