Phenotypic diversity in leaf cuticular waxes in brassica carinata accessions

Authors: Tomasi, Pernell; Abdel-Haleem, Hussein

Submitted to: Plants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2023
Publication Date: 10/29/2023
Citation: Tomasi, P., Abdel-Haleem, H.A. 2023. Phenotypic diversity in leaf cuticular waxes in brassica carinata accessions. Plants. 12. Article 3716. https://doi.org/10.3390/plants12213716.
DOI: https://doi.org/10.3390/plants12213716

Interpretive Summary: Brassica carinata, Ethiopian mustard, has received considerable attention as a renewable biofuel crop for semi-arid zones. To expand carinata production areas into more arid regions, it is important to develop new drought resistant cultivars that can grow under water-limited conditions. Increasing accumulated leaf cuticular wax in plants is one of the strategies to reduce nonstomatal water loss and thus increase crop tolerance to drought. To extend the understanding of phenotypic variations in cuticular wax content and composition in Carinata, leaf waxes were extracted and quantified from 315 accessions. These accessions represent a diversity panel with a wide range in total leaf wax contents, wax classes and its components. High heritability values of these waxes suggested the high likelihood of selection for these waxes during early generations of B. carinata breeding programs. Positive correlations coefficients and effects of these waxes on leaf wax content accumulation suggest that modifying specific wax constituents could increase the wax loads, which in turn could enhance cuticle composition and properties. Identifying leaf waxes traits in the B. carinata will underpin future analysis of the wax biosynthetic pathways, help dissect its genetic regulatory elements, identify candidate genes controlling these traits, and enable the development of molecular markers for molecular breeding programs aimed at increasing drought tolerance of Carinata.

Technical Abstract: Brassica carinata has received considerable attention as a renewable biofuel crop for semi-arid zones due to its high oil content and polyunsaturated fatty acids contents. It is important to de-velop new drought resistant cultivars of B. carinata production to expand its areas into more arid regions. Accumulation of leaf cuticular wax on plant surfaces is one of the mechanisms to reduce nonstomatal water loss and thus increase drought resistance in plants. To explore the phenotypic variations in cuticular wax in B. carinata, leaf waxes were extracted and quantified from a diversity panel consists of 315 accessions. Results indicated that the accessions have wide range in total leaf wax content (289 - 1356 µg dm-2), wax classes and their components. The C29, C31 homologues of alkanes, C29 ketone homologue, C29 secondary alcohol and C30 aldehyde were the most abundant leaf waxes extracted from B. carinata accessions. High heritability values of these waxes pointed to the positive selection for high wax content during early generations of future B. carinata breeding programs. Positive correlation coefficients combined with the effects of these waxes on leaf wax content accumulation suggested that modifying specific wax content could lead to increase the total wax content and enhance cuticle composition. Identified leaf wax content and compositions in B. carinata will lead to future discovery of the wax biosynthetic pathways, dissect its genetic regulatory networks, identify candidate genes controlling production of these waxes, and thus develop and release new B. carinata drought tolerance cultivars.