期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2022
卷号：119
期号：1
DOI：10.1073/pnas.2101846119
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Significance
In recent years, phenotypic plasticity has received attention for improving plant adaptability to variable environments. For more than half a century, it has been known that rice and cereal plants develop different types of lateral roots (LRs), unlike the dicot model plant
Arabidopsis. Despite the importance of plastic LR development under variable water conditions, the molecular mechanisms regulating LR types are unknown. Here, we report the regulatory mechanism of LR primordium size in rice, an important determinant of LR type. We identified two
WUSCHEL-related homeobox (WOX) transcription factors that opposingly regulate LR primordium size. Our findings form the basis for improving root phenotypic plasticity for sustainable crop production under variable environments.
The development of a plastic root system is essential for stable crop production under variable environments. Rice plants have two types of lateral roots (LRs): S-type (short and thin) and L-type (long, thick, and capable of further branching). LR types are determined at the primordium stage, with a larger primordium size in L-types than S-types. Despite the importance of LR types for rice adaptability to variable water conditions, molecular mechanisms underlying the primordium size control of LRs are unknown. Here, we show that two
WUSCHEL-related homeobox (
WOX) genes have opposing roles in controlling LR primordium (LRP) size in rice. Root tip excision on seminal roots induced L-type LR formation with wider primordia formed from an early developmental stage.
QHB/OsWOX5 was isolated as a causative gene of a mutant that is defective in S-type LR formation but produces more L-type LRs than wild-type (WT) plants following root tip excision. A transcriptome analysis revealed that
OsWOX10 is highly up-regulated in L-type LRPs.
OsWOX10 overexpression in LRPs increased the LR diameter in an expression-dependent manner. Conversely, the mutation in
OsWOX10 decreased the L-type LR diameter under mild drought conditions. The
qhb mutants had higher
OsWOX10 expression than WT after root tip excision. A yeast one-hybrid assay revealed that the transcriptional repressive activity of QHB was lost in
qhb mutants. An electrophoresis mobility shift assay revealed that
OsWOX10 is a potential target of QHB. These data suggest that QHB represses LR diameter increase, repressing
OsWOX10. Our findings could help improve root system plasticity under variable environments.
