ATP-citrate lyase B (ACLB) negatively affects cell death and resistance to Verticillium wilt

Mapping QTLs for blight resistance and morpho-phenological traits in inter-species hybrid families of chestnut (Castanea spp.)

Chestnut blight (caused by Cryphonectria parasitica), together with Phytophthora root rot (caused by Phytophthora cinnamomi), has nearly extirpated American chestnut (Castanea dentata) from its native range. In contrast to the susceptibility of American chestnut, many Chinese chestnut (C. mollissima) genotypes are resistant to blight. In this research, we performed a series of genome-wide association studies for blight resistance originating from three unrelated Chinese chestnut trees (Mahogany, Nanking and M16) and a Quantitative Trait Locus (QTL) study on a Mahogany-derived inter-species F2 family. We evaluated trees for resistance to blight after artificial inoculation with two fungal strains and scored nine morpho-phenological traits that are the hallmarks of species differentiation between American and Chinese chestnuts. Results support a moderately complex genetic architecture for blight resistance, as 31 QTLs were found on 12 chromosomes across all studies. Additionally, although most morpho-phenological trait QTLs overlap or are adjacent to blight resistance QTLs, they tend to aggregate in a few genomic regions. Finally, comparison between QTL intervals for blight resistance and those previously published for Phytophthora root rot resistance, revealed five common disease resistance regions on chromosomes 1, 5, and 11. Our results suggest that it will be difficult, but still possible to eliminate Chinese chestnut alleles for the morpho-phenological traits while achieving relatively high blight resistance in a backcross hybrid tree. We see potential for a breeding scheme that utilizes marker-assisted selection early for relatively large effect QTLs followed by genome selection in later generations for smaller effect genomic regions.

Shoot transcriptome revealed widespread differential expression and potential molecular mechanisms of chickpea (Cicer arietinum L.) against Fusarium wilt

Introduction

The yield of chickpea is severely hampered by infection wilt caused by several races of Fusarium oxysporum f. sp. ciceris (Foc).

Methods

To understand the underlying molecular mechanisms of resistance against Foc4 Fusarium wilt, RNA sequencing-based shoot transcriptome data of two contrasting chickpea genotypes, namely KWR 108 (resistant) and GL 13001 (susceptible), were generated and analyzed.

Results and Discussion

The shoot transcriptome data showed 1,103 and 1,221 significant DEGs in chickpea genotypes KWR 108 and GL 13001, respectively. Among these, 495 and 608 genes were significantly down and up-regulated in genotypes KWR 108, and 427 and 794 genes were significantly down and up-regulated in genotype GL 13001. The gene ontology (GO) analysis of significant DEGs was performed and the GO of the top 50 DEGs in two contrasting chickpea genotypes showed the highest cellular components as membrane and nucleus, and molecular functions including nucleotide binding, metal ion binding, transferase, kinase, and oxidoreductase activity involved in biological processes such as phosphorylation, oxidation-reduction, cell redox homeostasis process, and DNA repair. Compared to the susceptible genotype which showed significant up-regulation of genes involved in processes like DNA repair, the significantly up-regulated DEGs of the resistant genotypes were involved in processes like energy metabolism and environmental adaptation, particularly host-pathogen interaction. This indicates an efficient utilization of environmental adaptation pathways, energy homeostasis, and stable DNA molecules as the strategy to cope with Fusarium wilt infection in chickpea. The findings of the study will be useful in targeting the genes in designing gene-based markers for association mapping with the traits of interest in chickpea under Fusarium wilt which could be efficiently utilized in marker-assisted breeding of chickpea, particularly against Foc4 Fusarium wilt.

General Regulatory Factor7 regulates innate immune signalling to enhance Verticillium wilt resistance in cotton

Sessile growing plants are always vulnerable to microbial pathogen attacks throughout their lives. To fend off pathogen invasion, plants have evolved a sophisticated innate immune system that consists of cell surface receptors and intracellular receptors. Somatic embryogenesis receptor kinases (SERKs) belong to a small group of leucine-rich repeat receptor-like kinases (LRR-RLKs) that function as co-receptors regulating diverse physiological processes. GENRAL REGULATORY FACTOR (GRF) proteins play an important role in physiological signalling transduction. However, the function of GRF proteins in plant innate immune signalling remains elusive. Here, we identified a GRF gene, GauGRF7, that is expressed both constitutively and in response to fungal pathogen infection. Intriguingly, silencing of GRF7 compromised plant innate immunity, resulting in susceptibility to Verticillium dahliae infection. Both transgenic GauGRF7 cotton and transgenic GauGRF7 Arabidopsis lines enhanced the innate immune response to V. dahliae infection, leading to high expression of two helper NLRs (hNLR) genes (ADR1 and NRG1) and pathogenesis-related genes, and increased ROS production and salicylic acid level. Moreover, GauGRF7 interacted with GhSERK1, which positively regulated GRF7-mediated innate immune response in cotton and Arabidopsis. Our findings revealed the molecular mechanism of the GRF protein in plant immune signaling and offer potential opportunities for improving plant resistance to V. dahliae infection.

Metabolic regulation of the plant epigenome

Chromatin modifications shape the epigenome and are essential for gene expression reprogramming during plant development and adaptation to the changing environment. Chromatin modification enzymes require primary metabolic intermediates such as S-adenosyl-methionine, acetyl-CoA, alpha-ketoglutarate, and NAD⁺ as substrates or cofactors. The availability of the metabolites depends on cellular nutrients, energy and reduction/oxidation (redox) states, and affects the activity of chromatin regulators and the epigenomic landscape. The changes in the plant epigenome and the activity of epigenetic regulators in turn control cellular metabolism through transcriptional and post-translational regulation of metabolic enzymes. The interplay between metabolism and the epigenome constitutes a basis for metabolic control of plant growth and response to environmental changes. This review summarizes recent advances regarding the metabolic control of plant chromatin regulators and epigenomes, which are involved in plant adaption to environmental stresses.