Biology subjects

Martin-Hernandez, A. M.

Publications and source records attributed to Martin-Hernandez, A. M..

3 recordsLinked to original sources

bioRxiv2022

Mutations in CmVPS41 controlling resistance to Cucumber Mosaic Virus display specific subcellular localization

Resistance to Cucumber mosaic virus (CMV) in melon has been described in several exotic accessions. It is controlled by a recessive resistance gene, cmv1, which encodes a Vacuolar Protein Sorting 41 (CmVPS41). Cmv1 prevents systemic infection by restricting the virus to the bundle sheath cells, preventing viral phloem entry. CmVPS41 from different resistant accessions carried two causal mutations, either a G85E change, found in Pat-81 and Freemans Cucumber, or L348R found in PI161375, cultivar Songwhan Charmi (SC). The analysis of the subcellular localization of CmVPS41 in N. benthamiana has revealed differential structures in resistant and susceptible accessions. Susceptible accessions showed nuclear and membrane spots and many transvacuolar strands, whereas the resistant accessions showed many intravacuolar invaginations. These specific structures colocalize with late endosomes. Artificial CmVPS41 carrying individual mutations causing resistance in the genetic background of CmVPS41 from the susceptible variety Piel de Sapo (PS), revealed that the structure most correlated with resistance was the absence of transvacuolar strands. Co-expression of CmVPS41 with the viral MPs, the determinant of virulence, did not change these localizations; however, infiltration of CmVPS41 from either SC or PS accessions in CMV-infected N. benthamiana leaves showed a localization pattern closer to each other, with up to 30% cells showing some membrane spots in the CmVPS41SC and fewer transvacuolar strands (from a mean of 4 to 1-2) with CmVPS41PS. Our results suggest that the distribution of CmVPS41PS in late endosomes includes transvacuolar strands that facilitate CMV infection and that CmVPS41 is re-localized during viral infection.

cell biology↗

bioRxiv2022

Knock-out of CmNAC-NOR affects melon climacteric fruit ripening

Fruit ripening is an important process that affects fruit quality. In melon, ETHQV6.3, a QTL involved in climacteric ripening regulation, was previously found to be encoded by CmNAC-NOR, a homologue of the tomato NOR gene. To further investigate CmNAC-NOR function we have obtained two CRISPR/Cas9 mediated mutants (nor-3 and nor-1) in the climacteric Vedrantais background. nor-3, containing a 3-bp deletion altering the NAC domain A, resulted in ~8 days delay of ripening without affecting fruit quality. In contrast, nor-1 contained a 1-bp deletion resulting in a fully disrupted NAC domain, which completely blocked climacteric ripening. nor-1 fruits did not produce ethylene, abscission layer was not 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. nor-1 allele in heterozygosis showed ~20 days delay of fruit ripening. Our results provide new information regarding the function of CmNAC-NOR in melon fruit ripening, suggesting that it as a potential target to modulate shelf life in climacteric melon commercial varieties.

plant biology↗

bioRxiv2022

CRISPR/Cas9 gene editing uncovers the role of CTR1 and ROS1 in melon fruit ripening and epigenetic regulation

Melon (Cucumis melo L.) has emerged as an alternative model to study fruit ripening due to the coexistence of climacteric and non-climacteric varieties. The previous characterization of a major QTL ETHQV8.1 sufficient to trigger climacteric ripening in a non-climacteric background allowed the identification within the QTL interval of a negative regulator of ripening CmCTR1-like (MELO3C024518), and a putative DNA demethylase CmROS1 (MELO3C024516), the orthologue of DML2, a DNA demethylase regulating fruit ripening in tomato. To understand the role of these genes in climacteric ripening, we generated homozygous CRISPR knockout mutants of CmCTR1-like and CmROS1 in a climacteric genetic background. The climacteric behavior was altered in both loss-of-function mutants in two summer seasons with an advanced ethylene production profile compared to the climacteric wild type, suggesting a role of both genes in climacteric ripening in melon. Single cytosine methylome analyses of the CmROS1 knockout mutant revealed DNA methylation changes in the promoter regions of key ripening genes as ACS1, ETR1 and ACO1, and ripening associated-transcription factors as NAC-NOR, RIN and CNR, suggesting the importance of CmROS1-mediated DNA demethylation for triggering fruit ripening in melon.

plant biology↗