Proteolysis and Characterization of Peptidases in Forage Plants

Abstract

Plant peptidases are involved in protein degradation in the rumen of grazing animals, but little is known about the variation in their activity under anaerobic conditions at 39°C. We investigated the activity of endogenous peptidases in 342 accessions of grass and legume forages and the molecular weight and class of peptidases in a subsample of them. Proteolytic activity was measured by in vitro incubation of tissue over a gelatin substrate. Molecular weight and class of peptidases were assessed by zymograms. A wide range in proteolytic activity index (PAI) was detected (mean PAI = 0.35, ranged from 0.00 to 1.30). More than 88% of the observed variance was due to differences in genus, species, and cultivar. Most of the species had one main peptidase, and their molecular weights ranged from 54 to 130 kDa. In the six species tested, proteases present corresponded to the serine class. The wide variation in proteolysis observed and the predominant occurrence of one peptidase of the same enzyme class support the idea that a reduction of protease activity in forages can be achieved by genetic improvement.

The effect of cultivar on the changes in protein quality during wilting and ensiling of red clover (Trifolium pratense L.)

“…According to McKersie (1985), the rate and endpoint of proteolysis in silage is largely dependent on the rate of pH decline and the proteolytic activity in the leaves of the ensiled forage legumes. Furthermore, the proteolytic activity of forage crops is not only species-dependent; cultivars within species also affect the proteolytic activity (Tremblay et al 2001;Pichard et al 2006). However, differences in the extent of proteolysis among the tested red clover cultivars were absent in the present study ( Table 5).…”

Can alternative forages substantially reduce N leaching? findings from a review and associated modelling

“…For instance, it is believed that plant-induced proteolysis contributes considerably to degradation and release of N in the rumen (Kingston-Smith et al 2003). Plant-induced proteolysis is a stress response of 'living' plant tissue whereby peptidases are initiated within cell vacuoles upon entry to the rumen (Kingston-Smith et al 2005;Pichard et al 2006). There is considerable variation in proteolytic activity among and within forages (Pichard et al 2006) and identification of plants with reduced proteolytic activity may offer an opportunity to improve rumen N utilisation (Kingston-Smith et al 2002).…”

“…Plant-induced proteolysis is a stress response of 'living' plant tissue whereby peptidases are initiated within cell vacuoles upon entry to the rumen (Kingston-Smith et al 2005;Pichard et al 2006). There is considerable variation in proteolytic activity among and within forages (Pichard et al 2006) and identification of plants with reduced proteolytic activity may offer an opportunity to improve rumen N utilisation (Kingston-Smith et al 2002). Species with a high proteolysis activity index (PAI) such as phalaris, oats and lucerne may be expected to more rapidly degrade in the rumen than species with a low PAI such as brome, Italian ryegrass, lotus and red clover (Pichard et al 2006).…”

“…There is considerable variation in proteolytic activity among and within forages (Pichard et al 2006) and identification of plants with reduced proteolytic activity may offer an opportunity to improve rumen N utilisation (Kingston-Smith et al 2002). Species with a high proteolysis activity index (PAI) such as phalaris, oats and lucerne may be expected to more rapidly degrade in the rumen than species with a low PAI such as brome, Italian ryegrass, lotus and red clover (Pichard et al 2006). However, this area of research requires further exploration at the animal level to validate the impact of these hypotheses on N metabolism and N excretion in the ruminant.…”

Reducing Water‐Soluble Phosphorus in Soil through Flue Gas Desulfurization Gypsum Application: Year of Application Effects at Multiple Sites in Wisconsin

“…Studies conducting correlations to identify soil properties likely to show gypsum benefits have been rare. The majority of studies examining P runoff have used high-P soils in the southern United States (Endale et al, 2014;Watts and Torbert, 2016), were conducted in a laboratory setting (Stout et al, 2003;Yu et al, 2003;Ige et al, 2007), or used mined rather than FGD gypsum (Chen et al, 2005;Favaretto et al, 2006). This study used an unincorporated, surface application of FGD gypsum in active production fields on soils common to northern Wisconsin.…”