CYP77A7 is required for proper polar growth in Arabidopsis

CASCALLARES, MILAGROS; SETZES, NICOLÁS; DISTEFANO, AYELEN M.; ZABALETA, EDUARDO; PAGNUSSAT, GABRIELA C.

Santa Fe

Congreso; XXXIII Argentinian meeting of Plant Physiology; 2021

Sociedad Argentina de Fisiología Vegetal

In plants, cytochromes P450 (CYPs) catalyze a variety of monooxygenation/hydroxylationreactions involved in the biosynthesis and degradation of a plethora of compoundsimplicated in diverse physiological responses, including growth and development. In thisstudy, we explore the function of CYP77A7, a cytochrome P450 that belongs to the CYP77family, with several members identified as putative fatty acid oxidases. A co-expressionanalysis determined that CYP77A7 co-expresses with genes related to synthesis andmodification of the cell wall, such as a pectinesterase and glycosyl hydrolases, all of themstrongly expressed in pollen and pistils. Although a previous study with a transposoninsertion mutant in this gene (une9) determined that the line had defects in femalegametogenesis and pollen germination, we concluded that those defects we probably dueto a mutation that, although probably tightly linked, was not in CYP77A7. We analyzed fivemutants alleles with insertions in CYP77A7. In all cases we obtained homozygousmutants. No evident defects were observed in homozygous plants. However, mutantpollen tubes exhibited abnormal growth patterns, showing bifurcations and tip swelling. Asthe expression pattern of CYP77A7 showed expression not only in pollen tubes but also inother structures characterized by polar growth such as trichomes and roots, we closelylooked at those organs in mutant lines. While trichomes did not show defects, root hairsshowed more than one tip and aberrant tip shapes. These results support a role forCYP77A7 in the organization of the cell wall during polar growth, whose bases arecurrently under study.