Data on inheritance of race 2 anthracnose resistance in watermelon (Citrullus spp.) biparental mapping populations.

Anthracnose of watermelon is caused by a fungal pathogen Colletotrichum orbiculare. We generated F2 individuals from three different populations: Population 1 (PI 189225 x 'New Hampshire Midget'), Population 2 ('Perola' x PI 189225), and Population 3 ('Verona' x PI 189225). The biparental F2 populations, parents and F1 individuals were inoculated with an isolate of race 2 anthracnose isolated from watermelon. Leaf lesions were visually rated seven days post inoculation on a scale of 0% (no lesion) to 100% (dead true leaf). Here we present the datasets obtained after the disease inoculation. The distribution of data obtained was visualized using histograms and goodness-of-fit was tested using Chi-Square. These datasets provide information on the mode of inheritance of race 2 anthracnose resistance in watermelon.

Genome of 'Charleston Gray', the principal American watermelon cultivar, and genetic characterization of 1,365 accessions in the U.S. National Plant Germplasm System watermelon collection.

Years of selection for desirable fruit quality traits in dessert watermelon (Citrullus lanatus) has resulted in a narrow genetic base in modern cultivars. Development of novel genomic and genetic resources offers great potential to expand genetic diversity and improve important traits in watermelon. Here, we report a high-quality genome sequence of watermelon cultivar 'Charleston Gray', a principal American dessert watermelon, to complement the existing reference genome from '97103', an East Asian cultivar. Comparative analyses between genomes of 'Charleston Gray' and '97103' revealed genomic variants that may underlie phenotypic differences between the two cultivars. We then genotyped 1365 watermelon plant introduction (PI) lines maintained at the U.S. National Plant Germplasm System using genotyping-by-sequencing (GBS). These PI lines were collected throughout the world and belong to three Citrullus species, C. lanatus, C. mucosospermus and C. amarus. Approximately 25 000 high-quality single nucleotide polymorphisms (SNPs) were derived from the GBS data using the 'Charleston Gray' genome as the reference. Population genomic analyses using these SNPs discovered a close relationship between C. lanatus and C. mucosospermus and identified four major groups in these two species correlated to their geographic locations. Citrullus amarus was found to have a distinct genetic makeup compared to C. lanatus and C. mucosospermus. The SNPs also enabled identification of genomic regions associated with important fruit quality and disease resistance traits through genome-wide association studies. The high-quality 'Charleston Gray' genome and the genotyping data of this large collection of watermelon accessions provide valuable resources for facilitating watermelon research, breeding and improvement.

Mannitol in Plants, Fungi, and Plant-Fungal Interactions.

Although the presence of mannitol in organisms as diverse as plants and fungi clearly suggests that this compound has important roles, our understanding of fungal mannitol metabolism and its interaction with mannitol metabolism in plants is far from complete. Despite recent inroads into understanding the importance of mannitol and its metabolic roles in salt, osmotic, and oxidative stress tolerance in plants and fungi, our current understanding of exactly how mannitol protects against reactive oxygen is also still incomplete. In this opinion, we propose a new model of the interface between mannitol metabolism in plants and fungi and how it impacts plant-pathogen interactions.