SEEDSTICK Controls Arabidopsis Fruit Size by Regulating Cytokinin Levels and FRUITFULL.

Maurizio Di Marzo, Humberto Herrera-Ubaldo, Elisabetta Caporali, Ondřej Novák, Miroslav Strnad, Vicente Balanzà, Ignacio Ezquer, Marta A Mendes, Stefan de Folter, Lucia Colombo

Cell reports 2020 Feb 25

filter terms:

Upon fertilization, the ovary increases in size and undergoes a complex developmental process to become a fruit. We show that cytokinins (CKs), which are required to determine ovary size before fertilization, have to be degraded to facilitate fruit growth. The expression of CKX7, which encodes a cytosolic CK-degrading enzyme, is directly positively regulated post-fertilization by the MADS-box transcription factor STK. Similar to stk, two ckx7 mutants possess shorter fruits than wild type. Quantification of CKs reveals that stk and ckx7 mutants have high CK levels, which negatively control cell expansion during fruit development, compromising fruit growth. Overexpression of CKX7 partially complements the stk fruit phenotype, confirming a role for CK degradation in fruit development. Finally, we show that STK is required for the expression of FUL, which is essential for valve elongation. Overall, we provide insights into the link between CKs and molecular pathways that control fruit growth. Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.

Citation

Maurizio Di Marzo, Humberto Herrera-Ubaldo, Elisabetta Caporali, Ondřej Novák, Miroslav Strnad, Vicente Balanzà, Ignacio Ezquer, Marta A Mendes, Stefan de Folter, Lucia Colombo. SEEDSTICK Controls Arabidopsis Fruit Size by Regulating Cytokinin Levels and FRUITFULL. Cell reports. 2020 Feb 25;30(8):2846-2857.e3