A mechanistic view on lodging resistance in rye and wheat: a multiscale comparative study

Area of Science:

• Plant Breeding and Genetics
• Agricultural Science
• Plant Anatomy and Physiology

Background:

• Lodging, or stem collapse, is a major challenge in cereal cultivation, impacting yield and quality.
• Developing lodging-resistant crop varieties is a key objective for breeding programs worldwide.
• The rye mutant 'Stabilstroh' exhibits remarkable lodging resistance, tall stature, and high biomass.

Purpose of the Study:

• To characterize the structural and biochemical properties contributing to the superior lodging resistance of the rye mutant 'Stabilstroh'.
• To identify key traits for improving lodging resistance in tall cereal crops.
• To validate findings in wheat, comparing resistant and susceptible genotypes.

Main Methods:

• Nuclear Magnetic Resonance (NMR) imaging to visualize stem vascular bundle architecture.
• Histology and electron microscopy to examine stem tissue composition and cell wall structure.
• Biochemical analyses (Fourier-transform infrared spectroscopy, ICP-OES) for lignin, xylan, zinc, and silicon content.
• Mathematical modeling to simulate mechanical stress distribution in stems.
• Comparative evaluation of lodging-resistant (wheat 'Babax') and lodging-prone (wheat 'Pastor') genotypes.

Main Results:

• Lodging-resistant rye stems showed increased vascular bundle numbers and greater obliquity.
• Enhanced stem fortification observed, with higher sclerenchyma proportion, thickened cell walls, and epidermal invaginations.
• Elevated levels of lignin, xylan, zinc, and silicon correlated with superior culm stability.
• Mathematical model demonstrated improved mechanical force distribution in stable stems.
• Findings were consistent in wheat, supporting the heritability of these traits.

Conclusions:

• The exceptional lodging resistance of 'Stabilstroh' is attributed to a combination of anatomical, structural, and biochemical features.
• Increased vascularity, enhanced sclerenchyma, and elevated lignin, xylan, zinc, and silicon contribute to superior culm mechanical stability.
• These identified traits offer valuable targets for breeding programs aiming to improve lodging resistance in tall cereal varieties.