The Arabidopsis transcription factors AtPHL1 and AtHB23 act together promoting carbohydrate transport from pedicel-silique nodes to seeds

SPIES, FIORELLA PAOLA; RAINERI, JESICA; MIGUEL, VIRGINIA NATALÍ; CHAN, RAQUEL L.

PLANT SCIENCE

ELSEVIER IRELAND LTD

Año: 2022 vol. 315

0168-9452

Carbohydrates are produced in green tissues through photosynthesis and then transported to sink tissues. Carbonpartitioning is a strategic process, fine regulated, involving specific sucrose transporters in each connectingtissue. Here we report that a screening of an Arabidopsis transcription factor (TF) library using thehomeodomain-leucine zipper I member AtHB23 as bait, allowed identifying the TF AtPHL1 interacting with theformer. An independent Y2H assay, and in planta by BiFC, confirmed such interaction. AtHB23 and AtPHL1coexpressed in the pedicel-silique nodes and the funiculus. Mutant plants (phl1, and amiR23) showed a markedreduction of lipid content in seeds, although lipid composition did not change compared to the wild type. Whileprotein and carbohydrate contents were not significantly different between mutants and control mature seeds,we observed a reduced carbohydrate content in mutant plants young siliques (7 days after pollination). Moreover, using a CFDA probe, we revealed an impaired transport to the seeds, and the gene encoding the carbohydrate transporters SWEET10 and SWEET11, usually expressed in connecting tissues, was repressed in theamiR23 and phl1 mutant plants. Altogether, the results indicated that AtHB23 and AtPHL1 act together, promoting sucrose transport, and the lack of any of them provoked a reduction in seeds lipid content.