Plant fertility - how hormones get around

09-Feb-2015 - Japan

Researchers at Tokyo Institute of Technology have identified a transporter protein at the heart of a number of plant processes associated with fertility and possibly aging.

Very low quantities of hormones instigate a number of the plant processes needed for survival, growth and proliferation - all significant factors affecting crop yield. However getting the right hormones to the right place is crucial. Recent studies have identified a number of hormone-transporting proteins that import and export hormones across the plasma membrane into and out of cell, helping to understand certain key processes. Now researchers at Tokyo Institute of Technology, Tohoku University and the RIKEN Center for Sustainable Resource Science have identified a protein that is core to a number of the processes that control fertility in the small mustard-like plant, Arabidopsis.

Hiroyuki Ohta and his team used gene network analysis to highlight genes that respond to jasmonic acid (JA) – a type of hormone associated with fertility, aging and defence responses for which so far no transporter protein has been identified. They noticed tight co-expression between the gene encoding GTR1/NPF2.10 protein and JA biosynthesis genes. Further studies showed that treatment with JA increased GTR1 expression in seedlings confirming the link. Hormone and stamen development was affected in plants with GTR1 associated mutations and their leaves seemed to turn brown and age in the presence of JA, suggesting GTR1 affects JA sensitivity.

Further studies suggested that GTR1 plays a key role in the transport of another hormone gibberellin (GA), because GA treatment fully complemented the defect of gtr1 in stamen development and fertility. While former research had established that JA and GA were both key to plant fertility and that there may be crosstalk between the two, the function of interplay had not been well established. Treating JA-deficient mutants with GA led to swollen fruit but no mature seeds. “These results indicated that JA signalling is required for stamen development and is independent of the stimulation of GA signalling, even though GA could partially compensate for a lack of JA function during floral development," state the researchers in their report.

The researchers conclude that GTR1/NPF2.10 is a multifunctional transporter for a bioactive form of JA, GA and glucosinolates – a class of organic compound derived from glucose and amino acid. The results also suggest that GTR1/NPF2.10 plays an important role in stamen development and fertility and may also be important for hormone transport in vegetative tissue.

Original publication

H. Saito, T. Oikawa, S. Hamamoto, Y. Ishimaru, M. Kanamori-Sato, Y. Sasaki-Sekimoto, T. Utsumi, J. Chen, Y. Kanno, S. Masuda, et al.; “The jasmonate-responsive GTR1 transporter is required for gibberellin-mediated stamen development in Arabidopsis”; Nature Communications.

https://www.bionity.com/en/news/151534/plant-fertility-how-hormones-get-around.html