Influence of plant residue chemistry on soil CO₂-C production: A study with Arabidopsis thaliana cell wall mutants of KNAT7, MYB75 and CCR1

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• 作者：Shamim Gul^a ; ^b ; Joann K. Whalen^a ; ^{joann.whalen@mcgill.ca} ; Brian E. Ellis^c ; Arif F. Mustafa^d
• 关键词：Arabidopsis thaliana ; Carbon mineralization ; Cell wall mutant ; Lignin ; C ; N ratio ; Acid unhydrolyzable fraction
• 刊名：Pedobiologia
• 出版年：2012
• 出版时间：10 November, 2012
• 年：2012
• 卷：55
• 期：6
• 页码：349-356
• 全文大小：545 K

文摘

Alteration of plant lignin concentration is expected to affect the C mineralization of crop residues. Mutations of single genes involved in biosynthesis of secondary cell walls such as KNOTTED ARABIDOPSIS THALIANA 7 (KNAT7), PRODUCTION OF ANTHOCYANIN PIGMENT 1 (PAP1) also known as MYB75, and cinnamoyl CoA reductase 1 (CCR1) coding genes could change lignin concentration in specific plant tissues. This study assessed the CO₂-C production of soil amended with stem and root tissues of down-regulated (k/o) and over expression (o/x) KNAT7 and MYB75 and the CCR1 k/o mutant lines of A. thaliana. KNAT7 k/o and MYB75 k/o were grown in two different environmental conditions (two cohorts) in the greenhouse. Oven dried, finely ground (<0.5 mm) stem and root residues underwent biochemical analysis, then were mixed separately with sandy loam or clay loam soil to assess CO₂-C production under controlled laboratory conditions for 63 days. Compared to wild ecotypes, C:N ratio and acid unhydrolyzable fraction (AUF) concentration tended to be higher in stem residues of KNAT7 k/o and MYB75 k/o mutant lines. The C:N ratio was lower in stem and roots of CCR1 k/o line, and the AUF concentration was lower in CCR1 k/o stem residues than in the wild ecotypes. Hemicelluloses were lower in stem residues of KNAT7 k/o and MYB75 k/o (first cohort) than their wild ecotypes. Cumulative CO₂-C production was lower in soil amended with stem residues of KNAT7 k/o (first cohort) and MYB75 k/o (first and second cohorts). CCR1 k/o stem tissues caused higher CO₂-C production from soil. After 63 days incubation, the acid/aldehyde ratio (Ad/Al) of vanillin (V) and syringyl (S) lignin monomers of soil was higher for stem amended CCR1 k/o and lower for stem amended MYB75 k/o soils as compared to their wild ecotypes. Generally root residues caused lower CO₂-C production from soil than stem residues. There was no difference in CO₂-C production for root residues between mutant lines and their wild ecotypes. In conclusion, KNAT7 k/o, MYB75 k/o and CCR1 k/o mutations resulted in altered C:N ratio and resistant compounds (i.e., AUF) especially in stems, and these alterations in residue chemistry influenced CO₂-C production and also lignin degradation in soil.