MALATE DECARBOXYLATION IN SPECIES BELONGING TO DIFFERENT C4 SUBTYPES INSIDE THE PANICOIDEAE CLADE.

CALACE, PAULA; DRINCOVICH, MARIA FABIANA; ANDREO, CARLOS S; GERRARD WHEELER, MARIEL C.

Congreso; XXXII Reunión Argentina / XVI Congreso Latinoamericano de FISIOLOGÍA VEGETAL; 2018

SOCIEDAD ARGENTINA DE FISIOLOGÍA VEGETAL.

As an adaptation to changing climatic conditions that caused high rates of photorespiration, plants have evolved the C4 pathway, which creates a CO2 pumpthat concentrates it around the RuBisCO. In most C4 species, this is achieved through compartmentalizing the initial and definitive CO2 assimilation processesinto two discrete cell types, namely mesophyll (M) and bundle sheath (BS) cells. As part of this mechanism a compound of four carbon atoms is transported from Mto BS cells. Setaria italica (foxtail millet) and Panicum virgatum (switchgrass) are two members of the Panicoideae clade used for feed and biofuel production.Despite their evolutionary closeness, they have been classified into different C4 subtypes as they posseses a NADP or NAD-dependent malic enzyme as major malate decarboxylase within chloroplastsor mitochondria of BS cells, respectively. In this study we characterize the kinetic and structural properties that distinguish each decarboxylase enzyme operating in both grasses.Furthemore, we carried out a comparative analysis in order to identify the isoforms involved in the C4 cycle and to characterize the differences between the photosynthetic and the non-photosyntheticversions.These results werecompared with thoseofotherspecies previously studied by our group.