Lignin biosynthesis in sugarcane is affected by low temperature

•Sugarcane is an abundant and promising source of plant biomass for biofuel production.•As a tropical crop, sugarcane is sensitive to low temperatures.•Low temperature affects lignin deposition and composition in sugarcane.

Sugarcane is an abundant and promising source of plant biomass for biofuel production. The use of biomass for conversion to ethanol is limited by the recalcitrance of lignocellulosic material mainly due to the presence of lignin. This study characterised some aspects of lignification in the stem of two sugarcane genotypes grown under low (CT) and warmer (HT – reference) temperatures. Stems were separated in young and mature culms and the culms were separated in cortex (rind) and medulla (pith). Plants of the genotype IACSP04-627, which has more lignin in the stem, grew better (fresh weight of the stem) than IACSP04-065 under HT. Cold negatively affected plant growth but apparently IACSP04-065 was more sensitive than the other genotype. Lignin content was significantly increased in the young rind of IACSP04-627 plants at CT, what could not be directly correlated with the expression profile of genes of the monolignols biosynthesis. Lignin content in mature rind was reduced in IACSP04-065 plants exposed to CT, what could be correlated with the low expression level of the genes ShCAD2, ShCOMT1 and ShCCoAOMT1. The high expression of ShF5H occurred preferentially in mature pith of both sugarcane genotypes, what is possibly related with the early formation of the secondary cell wall induced by low temperature. In conclusion, lignin deposition in sugarcane under low temperature seems to be differentially regulated in rind and pith tissues and it is genotype-dependent.