RING-Type E3 Ubiqitin Ligase Barley Genes (HvYrg1-2) Control Characteristics of Both Vegetative Organs and Seeds as Yield Components.

Zoltán Zombori,János Pauk,László Sass,András Cseri,Dénes Dudits,Gábor Horváth V,Róbert Mihály,Bettina Nagy

doi:10.3390/plants9121693

Abstract

Previously, studies on RING-type E3 ubiquitin ligases in cereals were preferentially focused on GW2 genes primarily controlling seed parameters in rice and wheat. Here we report cloning two HvYrg genes from barley that share significant homology with rice GW2 gene. In antisense genotypes efficiency of gene silencing varied between genes and transgenic lines: ASHvYrg1: 30–50% and ASHvYrg2: 20–27%. Reduced activity of both genes altered shoot system with increasing number of side shoots. Changes in leaf width, weight, or plant weight and height reached significant levels in some transgenic lines. Lowering expression of the two barley HvYrg genes caused opposite responses in spike development. Plants with ASHvYrg1 gene construct showed earlier heading time and prolonged grain-filling period, while plants from ASHvYrg2 genotype flowered in delay. Digital imaging of root development revealed that down-regulation of HvYrg1 gene variant stimulated root growth, while ASHvYrg2 plants developed reduced root system. Comparison of seed parameters indicated an increase in thousand grain weight accompanied with longer and wider seed morphology. In summary we conclude that in contrast to inhibition of GW2 genes in rice and wheat plants, down-regulation of the barely HvYrg genes caused substantial changes in vegetative organs in addition to alteration of seed parameters.

Highlights

Insuring the yield potential and stability of small-grain cereals, such as wheat (Triticum species), rice (Oryza sativa L.), and barley (Hordeum vulgare L.) is a priority for global food security
These experimental results were not supported by other studies showing negative effects on expression of TaGW2-A1, a wheat homolog on thousand grain weight (TGW) [9,10,11]
Despite a variable degree of gene silencing, the presented data support the conclusion that RING-type E3 ubiquitin ligases encoded by HvYrg1 and HvYrg2 are involved in regulation of both vegetative and generative organ size and developmental processes as timing heading or seed maturation in barley

Summary

Introduction

Insuring the yield potential and stability of small-grain cereals, such as wheat (Triticum species), rice (Oryza sativa L.), and barley (Hordeum vulgare L.) is a priority for global food security. Functional divergence of GW2 encoded pathways in cereals was highlighted by down-regulation of wheat TaGW2 transcript-levels, which led to reduction in endosperm cell number associated with reduction in final grain weight and size [8] These experimental results were not supported by other studies showing negative effects on expression of TaGW2-A1, a wheat homolog on thousand grain weight (TGW) [9,10,11]. Despite a variable degree of gene silencing, the presented data support the conclusion that RING-type E3 ubiquitin ligases encoded by HvYrg and HvYrg are involved in regulation of both vegetative and generative organ size and developmental processes as timing heading or seed maturation in barley

Results and Discussion

Representative

Materials and Methods