Laccase-13 Regulates Seed Setting Rate by Affecting Hydrogen Peroxide Dynamics and Mitochondrial Integrity in Rice

Abstract

Seed setting rate is one of the most important components of rice grain yield. To date, only several genes regulating setting rate have been identified in plant. In this study, we showed that laccase-13 (OsLAC13), a member of laccase family genes which are known for their roles in modulating phenylpropanoid pathway and secondary lignification in cell wall, exerts a regulatory function in rice seed setting rate. OsLAC13 expressed in anthers and promotes hydrogen peroxide production both in vitro and in the filaments and anther connectives. Knock-out of OsLAC13 showed significantly increased seed setting rate, while overexpression of this gene exhibited induced mitochondrial damage and suppressed sugar transportation in anthers, which in turn affected seed setting rate. OsLAC13 also induced H2O2 production and mitochondrial damage in the root tip cells which caused the lethal phenotype. We also showed that high abundant of OsmiR397, the suppressor of OsLAC13 mRNA, increased the seed setting rate of rice plants, and restrains H2O2 accumulation in roots during oxidative stress. Our results suggested a novel regulatory role of OsLAC13 gene in regulating seed setting rate by affecting H2O2 dynamics and mitochondrial integrity in rice.

The Altered Expression of microRNA408 Influences the Arabidopsis Response to Iron Deficiency

“…Our results matched the concomitant increase in ferroxidase activity and ROS generation in mutant 408-KO under Fe scarcity conditions compared to the WT (Figures 6B, 7A). The results shown herein also agree with the proposed role of LMCOs functioning as ascorbate oxidases and, subsequently, with increasing H 2 O 2 levels by competing with ascorbate peroxidases for reduced ascorbate (Yu et al., 2017). Hence according to the levels of the miR408 target LMCOs (Figures 3, 7A), H 2 O 2 levels increased in mutant 408-KO and decreased in the 35S:408-14 line compared to the WT.…”

“…H 2 O 2 scavenging in the culture medium significantly decreases the amount of extracellular lignin formed in Norway spruce, and the inhibition of superoxide (normalO2−) synthesis, or its dismutation to H 2 O 2 by superoxide dismutases reduces lignin content (Kärkönen et al., 2002; Karlsson et al., 2005). Rice OsLAC3 has been shown to induce H 2 O 2 accumulation, which affects the seed setting rate and mitochondria integrity in vascular tissues and root tips (Yu et al., 2017). Given the striking similarity between OsLAC3 and L-ascorbate oxidases, a role in oxidizing ascorbate, which drives to restrain H 2 O 2 removal, has been proposed to explain the observed phenotypes.…”

Differential co-expression networks of long non-coding RNAs and mRNAs in Cleistogenes songorica under water stress and during recovery

“…Laccases (LACs) belong to a large group of enzymes termed blue copper proteins, which include ascorbic acid oxidase and plastocyanin. A previous study has shown that OsLAC13 can produce H 2 O 2 and is regulated by miRNA397 [69]. In this study, seven miRNA397a/b target genes were identified as being from the LAC family, including 2 laccase-13, 2 laccase-3, 2 laccase-10 and 1 laccase-4.…”

Major Domestication-Related Phenotypes inIndicaRice Are Due to Loss of miRNA-Mediated Laccase Silencing

“…On the other hand, AtLAC15 was involved in two different phenotypes, seed coat coloration and root elongation, both linked to lignin (Liang et al, 2006). OsLAC13 regulated the seed setting rate in rice by suppressing the transport of sugars to the anthers and promoting H 2 O 2 production through unknown mechanisms (Yu et al, 2017). However, heterologous expression of OsLAC10 in Arabidopsis plants increased lignification around vasculature and increased Cu stress tolerance (Liu et al, 2017).…”