%0 Journal Article
%T GhATL68b Regulates Cotton Fiber Cell Development by Ubiquitinating the Enzyme Required for β-oxidation of Polyunsaturated Fatty Acids.
%A Li X
%A Huang G
%A Zhou Y
%A Wang K
%A Zhu Y
%J Plant Commun
%V 0
%N 0
%D 2024 Jun 13
%M 38877704
%F 8.625
%R 10.1016/j.xplc.2024.101003
%X E3 ligases are key enzymes required for protein degradation. Here we identified a C3H2C3 RING domain-containing E3 ubiquitin ligase gene named GhATL68b. It is preferentially and highly expressed in developing cotton fiber cells, and is more conserved in plants than in animals or in archaea. All four orthologs copies of this gene in various diploid cottons and eight in the allotetraploid G. hirsutum were found to originate from a single common ancestor that can be traced back to C. reinhardii at about 992 million years ago (MYA). Structural variations (SVs) occurred in the promoter regions of G. hirsutum, G. herbaceum, G. arboreum and G. raimondii correlated with significantly different methylation patterns. Homozygous CRISPR-Cas9 knock-out cotton lines produced significant poor fiber quality in terms of upper half mean length, elongation at break, uniformity and mature fiber weight. GhATL68b was shown to modulate the homeostasis of 2,4-dienoyl-CoA reductase (GhDECR), a rate-limiting enzyme for β-oxidation of polyunsaturated fatty acids (PUFAs) via the ubiquitin proteasome pathway through in vitro ubiquitination and cell-free protein degradation assays. Fiber cells harvested from these knockout mutants contained significantly lower levels of PUFAs important for glycerophospholipids production and also for plasma membrane fluidity regulations. Finally, the mutant fiber-growth defective phenotype can be fully compensated by adding linolenic acid (C18:3), the most abundant type of PUFA externally in ovule culture media. To our knowledge, this is the first experimentally characterized C3H2C3 type E3 ubiquitin ligase that is involved in regulating fiber cell elongation, and it may thus provide us with a new genetic target for improved cotton lint production.