Structural variation and spatial polysaccharide profiling of intervessel pit membranes in grapevine

Area of Science:

• Plant biology
• Plant cell wall structure
• Plant physiology

Background:

• Intervessel pit membranes (PMs) are crucial cell wall components in plant xylem.
• Their structure and polysaccharide composition influence water transport and disease susceptibility.

Purpose of the Study:

• To analyze the structure and polysaccharide composition of intervessel PMs in grapevine.
• To understand the spatial distribution of pectic and hemicellulosic polysaccharides within PMs.

Main Methods:

• Utilized immunogold-scanning electron microscopy on grapevine xylem.
• Simultaneously analyzed intervessel PM structure and polysaccharide localization at high resolution.

Main Results:

• Observed significant structural variation in intervessel PMs, with ~90% intact and ~10% degraded.
• Identified distinct spatial distributions for weakly methyl-esterified homogalacturonans (WMe-HGs), heavily methyl-esterified homogalacturonans (HMe-HGs), xylans, and fucosylated xyloglucans (F-XyGs).
• Elucidated the process of cell wall material removal during PM degradation.

Conclusions:

• Grapevine intervessel PMs show diverse structures and contain specific pectic and hemicellulosic polysaccharides.
• This detailed polysaccharide profiling is vital for understanding PMs' roles in water transport and vascular disease resistance.