Wheat Escapes Low Light Stress by Altering Pollination Types

Area of Science:

• Plant Science
• Agronomy
• Stress Physiology

Background:

• Low light stress negatively impacts crop fertility and grain yield.
• Wheat's strong self-pollination (autogamy) limits its ability to compensate for yield loss through cross-pollination (outcrossing).
• Mechanisms enabling wheat to switch to outcrossing under stress remain poorly understood.

Purpose of the Study:

• To investigate how low light stress influences wheat's reproductive strategy.
• To elucidate the morphological, physiological, and molecular changes that facilitate outcrossing after low light stress.
• To identify key genes and pathways involved in stress-induced alterations in pollination.

Main Methods:

• Imposed low light stress at critical developmental stages (microspore and booting stages).
• Combined morphological, physiological, and transcriptomic analyses.
• Quantified floret opening, pollen viability, and phytohormone levels.
• Analyzed gene expression patterns, focusing on transcription factors and cell wall-related genes.

Main Results:

• Low light stress induced pollen abortion and increased lemma and glume opening angles (11.6-78.5%).
• Outcrossing compensated for 2.1-18.0% of grain number loss.
• Elevated jasmonic acid (JA) and methyl jasmonate (MeJA) levels were observed.
• Decreased lignin and cellulose content and enriched cell wall-related gene ontology terms were identified.
• 88-710 differentially expressed transcription factors were found, some linked to cell wall modification and floret opening.

Conclusions:

• Wheat can alter its pollination strategy from autogamy to outcrossing under low light stress.
• Phytohormones and cell wall modifications play crucial roles in facilitating floret opening and enabling outcrossing.
• This adaptive mechanism enhances seed set survival under adverse conditions.