AUTHOR=Liu Bin , Santo Domingo Miguel , Mayobre Carlos , Martín-Hernández Ana Montserrat , Pujol Marta , Garcia-Mas Jordi 

TITLE=Knock-Out of CmNAC-NOR Affects Melon Climacteric Fruit Ripening

JOURNAL=Frontiers in Plant Science

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2022.878037

DOI=10.3389/fpls.2022.878037

ISSN=1664-462X

ABSTRACT=<p>Fruit ripening is an important process that affects fruit quality. A QTL in melon, <italic>ETHQV6.3,</italic> involved in climacteric ripening regulation, has been found to be encoded by <italic>CmNAC-NOR</italic>, a homologue of the tomato <italic>NOR</italic> gene. To further investigate <italic>CmNAC-NOR</italic> function, we obtained two CRISPR/Cas9-mediated mutants (<italic>nor-3</italic> and <italic>nor-1</italic>) in the climacteric Védrantais background. <italic>nor-3</italic>, containing a 3-bp deletion altering the NAC domain A, resulted in ~8 days delay in ripening without affecting fruit quality. In contrast, the 1-bp deletion in <italic>nor-1</italic> resulted in a fully disrupted NAC domain, which completely blocked climacteric ripening. The <italic>nor-1</italic> fruits did not produce ethylene, no abscission layer was formed and there was no external color change. Additionally, volatile components were dramatically altered, seeds were not well developed and flesh firmness was also altered. There was a delay in fruit ripening with the <italic>nor-1</italic> allele in heterozygosis of ~20 days. Our results provide new information regarding the function of <italic>CmNAC-NOR</italic> in melon fruit ripening, suggesting that it is a potential target for modulating shelf life in commercial climacteric melon varieties.</p>