New discoveries on pollen tube growth
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New discoveries on pollen tube growth in plants by ENS Lyon researchers 

Researchers discover a new insight on how the proper development of pollen tubes in flowering plants is ensured by an enzyme, the outcomes of the study is released in the open-access journal eLife on September 1, 2020.

An unforeseen function of KATANIN in moderating the mechanical properties of the papilla cell wall in Arabidopsis thaliana, and thereby avoiding disordered pollen tube development and enabling the tube to locate its right path to the underlying tissues of the female plants are revealed by this research. The outcomes suggest that KATANIN has most likely played a significant function in the success of blooming plants on earth much more extensively.

When gametes (male and female germ cells) fuse – the seeds are formed. Female gametes are located in the ovules, which are embedded in the pistil, and the male gametes are located in the pollen grain. Pollen grains require to meet the surface of the pistil, composed of a layer of elongated cells called papillae, for effective seed production to occur. The pollen grain is rehydrated while a pollen grain arrives on a papilla, and then it develops a tube to

move the male gametes towards the ovules.

Initially, exerting physical pressure on the cell surface, the pollen tubes grow within the papilla cell wall. Then they grow in the intercellular space of underlying cells, after crossing the papilla layer. Later, the pollen tube is lead to the ovules where it reaches the female gametes by compounds produced by the pistil. Yet it remains undiscovered how the tube orientates itself when it arises at the papilla surface from the pollen.

Lucie Riglet, the lead author, was a Ph.D. student, said that it is surprising that the pollen tube grows to the base of the papilla in the direction of the ovules, whatever the position of the flower and hence the pistil on the stem. They wanted to check out the mechanisms that enable this correct orientation of plant pollen tubes on the papilla cells.

By regulating the orientation of cortical microtubules, which subsequently intercede the deposition of cellulose microfibrils, a very important function is played by the mechanical forces in plant cell shape. To reveal that the enzyme KATANIN, which cuts microtubules, likewise acts upon cellulose microfibril orientation and also provides mechanical properties to the papilla cell wall that enable correct pollen tube alignment, Riglet and her coworkers incorporated imaging, genetic as well as chemical approaches.

Thierry Gaude, Group Leader at the Laboratory of Plant Reproduction and Development, ENS Lyon, and the senior author of the study, said that KATANIN has likely played a significant function in the success of flowering plants by promoting fertilization, by forcing the pollen tubes to take the best direction from their early places in the papilla. It is possible that KATANIN plays a role in regulating mechanical properties in other processes, as it is found in most organisms, including humans beings – however, this is a great topic that remains to be studied.


New discoveries on pollen tube growth in plants by ENS Lyon researchers 

Author: Sruthi S