TY - JOUR
T1 - Cell- and development-specific degradation controls the levels of mixed-linkage glucan in sorghum leaves
AU - Kim, Sang Jin
AU - Zemelis-Durfee, Starla
AU - Mckinley, Brian
AU - Sokoloski, Rylee
AU - Aufdemberge, William
AU - Mullet, John
AU - Brandizzi, Federica
N1 - Publisher Copyright:
© 2023 The Authors. The Plant Journal published by Society for Experimental Biology and John Wiley & Sons Ltd.
PY - 2023/10
Y1 - 2023/10
N2 - Mixed-linkage glucan (MLG) is a component of the cell wall (CW) of grasses and is composed of glucose monomers linked by β-1,3 and β-1,4 bonds. MLG is believed to have several biological functions, such as the mobilizable storage of carbohydrates and structural support of the CW. The extracellular levels of MLG are largely controlled by rates of synthesis mediated by cellulose synthase-like (CSL) enzymes, and turnover by lichenases. Economically important crops like sorghum accumulate MLG to variable levels during development. While in sorghum, like other grasses, there is one major MLG synthase (CSLF6), the identity of lichenases is yet unknown. To fill this gap, we identified three sorghum lichenases (SbLCH1-3) and characterized them in leaves in relation to the expression of SbCSLF6, and the abundance of MLG and starch. We established that SbLCH1-3 are secreted to the apoplast, consistent with a role of degrading MLG extracellularly. Furthermore, while SbCSLF6 expression was associated with cell development, the SbLCH genes exhibited distinct development-, cell-type-specific and diel-regulated expression. Therefore, our study identifies three functional sorghum MLG lichenases and highlights that MLG accumulation in sorghum leaves is likely controlled by the activity of lichenases that tune MLG levels, possibly to suit distinct cell and developmental needs in planta. These findings have important implications for improving the growth, yield, and composition of sorghum as a feedstock.
AB - Mixed-linkage glucan (MLG) is a component of the cell wall (CW) of grasses and is composed of glucose monomers linked by β-1,3 and β-1,4 bonds. MLG is believed to have several biological functions, such as the mobilizable storage of carbohydrates and structural support of the CW. The extracellular levels of MLG are largely controlled by rates of synthesis mediated by cellulose synthase-like (CSL) enzymes, and turnover by lichenases. Economically important crops like sorghum accumulate MLG to variable levels during development. While in sorghum, like other grasses, there is one major MLG synthase (CSLF6), the identity of lichenases is yet unknown. To fill this gap, we identified three sorghum lichenases (SbLCH1-3) and characterized them in leaves in relation to the expression of SbCSLF6, and the abundance of MLG and starch. We established that SbLCH1-3 are secreted to the apoplast, consistent with a role of degrading MLG extracellularly. Furthermore, while SbCSLF6 expression was associated with cell development, the SbLCH genes exhibited distinct development-, cell-type-specific and diel-regulated expression. Therefore, our study identifies three functional sorghum MLG lichenases and highlights that MLG accumulation in sorghum leaves is likely controlled by the activity of lichenases that tune MLG levels, possibly to suit distinct cell and developmental needs in planta. These findings have important implications for improving the growth, yield, and composition of sorghum as a feedstock.
KW - Sorghum bicolor
KW - cellulose synthase-like F6
KW - in situ hybridization
KW - lichenase
KW - mixed-linkage glucan
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U2 - 10.1111/tpj.16376
DO - 10.1111/tpj.16376
M3 - Article
C2 - 37395650
AN - SCOPUS:85165690127
SN - 0960-7412
VL - 116
SP - 360
EP - 374
JO - Plant Journal
JF - Plant Journal
IS - 2
ER -