Genome-Wide Association Mapping of Virulence Genes in Wheat Karnal Bunt Fungus Tilletia indica Using Double Digest Restriction-Site Associated DNA-Genotyping by Sequencing Approach.

Tilletia indica is a quarantine fungal pathogen that poses a serious biosecurity threat to wheat-exporting countries. Acquiring genetic data for the pathogenicity characters of T. indica is still a challenge for wheat breeders and geneticists. In the current study, double digest restriction-site associated-DNA genotyping by sequencing was carried out for 39 T. indica isolates collected from different locations in India. The generated libraries upon sequencing were with 3,346,759 raw reads on average, and 151 x 2 nucleotides read length. The obtained bases per read ranged from 87 Mb in Ti 25 to 1,708 Mb in Ti 39, with 505 Mb on average per read. Trait association mapping was performed using 41,473 SNPs, infection phenotyping data, population structure, and Kinship matrix, to find single nucleotide polymorphisms (SNPs) linked to virulence genes. Population structure analysis divided the T. indica population in India into three subpopulations with genetic mixing in each subpopulation. However, the division was not in accordance with the degree of virulence. Trait association mapping revealed the presence of 13 SNPs associated with virulence. Using sequences analysis tools, one gene (g4132) near a significant SNP was predicted to be an effector, and its relative expression was assessed and found upregulated upon infection.

First Report of Pea Enation Mosaic Virus Affecting Lentil (Lens culinaris) in Syria.

Symptoms suggestive of virus infection in lentil (Lens culinaris Medik.) fields in Dara'a in southern Syria have been observed, in epidemic proportions, almost annually since 1994. A similar epidemic was observed on many lentil genotypes at the ICARDA farm, near Aleppo, as well as in other locations in northern Syria during 1998. Symptoms included growth reduction and rolling of leaves, accompanied by mottling with tip wilting or necrosis. Field symptoms were reproduced on lentil cv. Syrian Local upon mechanical inoculation of plants with inoculum from symptomatic field plants. Transmission tests showed that the disease agent can be transmitted from lentil to lentil, pea (Pisum sativum L.), and faba bean (Vicia faba L.) plants by the pea aphid (Acyrthosiphon pisum Harris) in a persistent manner. More than 500 symptomatic lentil plants were collected and tested for the presence of 14 different viruses by the tissue-blot immunoassay (TBIA) (2). Around 80% of the samples reacted only with antiserum to pea enation mosaic virus (PEMV), a Dutch isolate (E1540) provided by L. Bos, Wageningen, The Netherlands (1). Surveys conducted during the 1997/1998 growing season showed that PEMV was widely distributed in the major lentil-growing areas of Syria: some lentil fields had more than 50% virus incidence. This is the first record of PEMV naturally infecting lentil in Syria. References: (1) K. Mahmood and D. Peters. Neth. J. Plant Pathol. 79:138, 1973. (2) K. M. Makkouk and A. Comeau. Eur. J. Plant Pathol. 100:71, 1994.