Abstract Diseases of Theobroma cacao L. (Malvaceae) disrupt cocoa bean supply and economically impact growers. Vascular streak dieback (VSD), caused by Ceratobasidium theobromae, is a new encounter disease of cacao currently contained to southeast Asia and Melanesia. Resistance to VSD has been tested with large progeny trials in Sulawesi, Indonesia, and in Papua New Guinea with the identification of informative quantitative trait loci (QTLs). Using a VSD susceptible progeny tree (clone 26), derived from a resistant and susceptible parental cross, we assembled the genome to chromosome‐level and discriminated alleles inherited from either resistant or susceptible parents. The parentally phased genomes were annotated for all predicted genes and then specifically for resistance genes of the nucleotide‐binding site leucine‐rich repeat class (NLR). On investigation, we determined the presence of NLR clusters and other potential disease response gene candidates in proximity to informative QTLs. We identified structural variants within NLRs inherited from parentals. We present the first diploid, fully scaffolded, and parentally phased genome resource for T. cacao L. and provide insights into the genetics underlying resistance and susceptibility to VSD.

The utility of CRISPR in plants has remained limited by the dual difficulties of delivering the molecular machinery to target cells and the use of somatic cell techniques that require tissue culture-based de novo organogenesis. We developed 5-10 nm isodiametric polyplex nanoassemblies, comprising poly [2-(dimethylamino)ethylmethacrylate] PDMAEMA (PD) polycationic linear homopolymers and CRISPR/Cas9 ribonucleoproteins (RNPs), that enable endocytosis-driven RNP uptake into pollen grains. Pollen from wheat plants (genotype Gladius+Sr50), homozygous for monogenic Sr50 -mediated resistance to stem rust ( Puccinia graminis f. sp. tritici -Pgt), were incubated with RNP/PD nanoassemblies targeting the dominant, Sr50 rust resistance gene. The treated pollen grains were then used to fertilize Gladius+Sr50 florets and the resulting M1 plants were tested for loss of Sr50 function via rust resistance screens. The identification of fully susceptible M1 seedlings indicated that the Sr50 RNPs acted on both alleles, indicating they were transferred via the treated pollen to the zygote. The ability to readily deliver CRISPR RNPs to reproductive cells via biodegradable, polymeric nanocomplexes has significant implications for the efficiency of gene editing in plants.

The suspensor is a short-lived tissue critical for proper embryonic development in many higher plants. While the tissue was initially thought to simply suspend the embryo in the endosperm, it has been found through decades of research that it serves multiple important purposes. The suspensor has been found to be vital for proper embryo patterning and numerous studies have been undertaken into the complex transcriptional cross-talk between the suspensor and the embryo proper. Indeed, many suspensor mutants also display abnormalities in the embryo. The suspensor's role as a nutrient conduit has been shown using ultrastructural and histochemical techniques. Biochemical approaches have found that the suspensor is a centre of early embryonic hormone production in several species. The suspensor has also been frequently used as a model for programmed cell death as it shows signs of termination almost immediately upon developing. This review covers the essential functions of the suspensor throughout its short existence from multiple disciplines including structural, genetic and biochemical perspectives.