A Large Transposon Insertion in the stiff1 Promoter Increases Stalk Strength in Maize

Abstract

Stalk lodging, which is generally determined by stalk strength, results in considerable yield loss and has become a primary threat to maize (Zea mays) yield under high-density planting. However, the molecular genetic basis of maize stalk strength remains unclear, and improvement methods remain inefficient. Here, we combined map-based cloning and association mapping and identified the gene stiff1 underlying a major quantitative trait locus for stalk strength in maize. A 27.2-kb transposable element insertion was present in the promoter of the stiff1 gene, which encodes an F-box domain protein. This transposable element insertion repressed the transcription of stiff1, leading to the increased cellulose and lignin contents in the cell wall and consequently greater stalk strength. Furthermore, a precisely edited allele of stiff1 generated through the CRISPR/Cas9 system resulted in plants with a stronger stalk than the unedited control. Nucleotide diversity analysis revealed that the promoter of stiff1 was under strong selection in the maize stiff-stalk group. Our cloning of stiff1 reveals a case in which a transposable element played an important role in maize improvement. The identification of stiff1 and our edited stiff1 allele pave the way for efficient improvement of maize stalk strength.

Large-scale genome-wide association study reveals that drought-induced lodging in grain sorghum is associated with plant height and traits linked to carbon remobilisation

“…Similar results have been previously observed in maize, with reduced lignin content in the stem resulting in increased stalk lodging (Sun et al 2018). More recently, Zhang et al (2020) reported that downregulation of a maize gene, stiff1, resulted in thicker stalk cell walls with increased cellulose and lignin, which improved stalk strength and reduced lodging.…”

Contribution of phenylpropanoid metabolism to plant development and plant–environment interactions

“…The most apparent function of lignin is providing mechanical strength and rigidity to the cell wall and facilitating the formation of xylem vessels to transport water and nutrients over a long distance (Zhao, 2016; Figure 2). In maize ( Zea mays ), an increase in the content of cellulose and lignin gives rise to greater stalk strength and resistance to stalk lodging, which threatens the yield of maize under high‐density planting (Zhang et al, 2020f). However, the ectopic lignification and lignin biosynthesis caused by the mutation of UGT72B1 , which is responsible for the glycosylation of monolignols, were found to lead to growth repression (Lin et al, 2016).…”

Stalk architecture, cell wall composition, and QTL underlying high stalk flexibility for improved lodging resistance in maize

“…Lodging due to stalk fracture can seriously interfere with the mechanical harvesting process of corn, and hence negatively impact yield [1]. Although many previous studies have used stalk stiffness as an indicator for resistance to lodging in crop plants, flexibility may be an indispensable trait in some cases [18,19]. Generally, the stalk breaks when wind pressure exceeds the load that a plant can withstand.…”