Newly discovered protease inhibitors help in potato cultivation without inhibition

When humans domesticate plants, they preserve certain seeds according to desirable traits to be planted
for the next growing season.
On this path of domestication, susceptibility to disease suddenly emerged, but wild plant varieties were resistant to these pathogens
.
Today, most cultivated potato varieties are susceptible to soft rot and black-legged disease, but work as hard as their wild ancestors to fight pathogens
.
The specific resistance genes are currently unknown, and Pectobacterium is a major threat to
global potato production and food security.

To help subdue this threat, Janak Joshi and his colleagues from Colorado State University recently conducted a study investigating wild potatoes (nightshade chacoense)
from South America.

In a previous study, they revealed that wild potatoes produce molecules called metabolites that reduce disease toxicity
by interrupting the bacteria's communication system and preventing the bacteria's ability to degrade plant cell walls.
In the authors' latest study, they compared the protein profiles of wild and domestic potatoes and found that a second group of molecules — protease inhibitors — also protects against bacterial malignancies
.

This exciting discovery led the researchers to clone the DNA of several protease inhibitor genes and purify the proteins
they encode.
In testing the effects of these proteins on bacteria, Joshi and colleagues found that these proteins cause bacteria to change shape, strangely clump together, inhibit their ability to degrade plant cells, and even hinder their mobility
.

In their study, the authors aim to breed the next generation of potato varieties that are resistant to pathogens persistently and independently, reducing rotting waste and chemical sprays
.
Corresponding author Adam Heuberger commented: "Our findings are the second resistance mechanism we have observed in this plant, which supports the idea that wild plant species have evolved multiple resistance factors, or their own 'pyramid' traits, that can be translated into our food and ornamental plant industries
.
" ”

A set of defense traits is thought to be persistent because it worsens the bacteria's ability to
overcome this resistance.
"They may have evolved to dodge one molecule and be hit in the head
by another," Heuberger said.

The protease inhibitors identified in this study could benefit potato breeding programs in the long term and may have more immediate effects
as purified proteins used to protect field plants.