Biotechnological Potential of the Stress Response and Plant Cell Death Regulators Proteins in the Biofuel Industry

Abstract

Production of biofuel from lignocellulosic biomass is relatively low due to the limited knowledge about natural cell wall loosening and cellulolytic processes in plants. Industrial separation of cellulose fiber mass from lignin, its saccharification and alcoholic fermentation is still cost-ineffective and environmentally unfriendly. Assuming that the green transformation is inevitable and that new sources of raw materials for biofuels are needed, we decided to study cell death—a natural process occurring in plants in the context of reducing the recalcitrance of lignocellulose for the production of second-generation bioethanol. “Members of the enzyme families responsible for lysigenous aerenchyma formation were identified during the root hypoxia stress in Arabidopsis thaliana cell death mutants. The cell death regulatory genes, LESION SIMULATING DISEASE 1 (LSD1), PHYTOALEXIN DEFICIENT 4 (PAD4) and ENHANCED DISEASE SUSCEPTIBILITY 1 (EDS1) conditionally regulate the cell wall when suppressed in transgenic aspen. During four years of growth in the field, the following effects were observed: lignin content was reduced, the cellulose fiber polymerization degree increased and the growth itself was unaffected. The wood of transgenic trees was more efficient as a substrate for saccharification, alcoholic fermentation and bioethanol production. The presented results may trigger the development of novel biotechnologies in the biofuel industry.

Genomic Identification and Expression Profiling of Lesion Simulating Disease Genes in Alfalfa (Medicago sativa) Elucidate Their Responsiveness to Seed Vigor

“…PCD is the ultimate end of the cell cycle, which occurs in all living multicellular organisms. Some of the best-described Arabidopsis proteins in the context of PCD regulation are LSD1 , EDS1 , and PAD4 [ 27 , 28 ]. LSD1 is a negative regulator of PCD, suppressing EDS1 and PAD4 activities since the double mutants eds1/lsd1 and pad4/lsd1 demonstrate a reverted lsd1 -specific phenotype in terms of ethylene and ROS accumulation and cell death [ 27 ].…”

METACASPASE8 (MC8) Is a Crucial Protein in the LSD1-Dependent Cell Death Pathway in Response to Ultraviolet Stress

“…This mutant exhibits a runaway cell death (RCD) phenotype which is manifested by the inability to restrict CD propagation if it has been initiated by an external stimulus [ 3 , 8 , 12 ]. It has been shown that RCD can be induced in the lsd1 mutant by the following stress factors: high light and photorespiration [ 13 , 14 ], root hypoxia [ 1 , 15 ], drought [ 16 , 17 ], cold [ 18 ], UV radiation [ 16 , 19 ] or biotic stresses [ 20 , 21 ]. However, the lsd1 RCD phenotype is dependent on growing conditions and was not observed when plants were grown in multivariable field conditions [ 16 , 22 ].…”