Use of isozyme markers to select for resistance to Ascochyta blight in lentil

Non-Peer ReviewedThe possible linkages of isozyme loci with genes for resistance to Ascochyta blight, caused by Ascochyta fabae f. sp. lentis Gossen et al., was investigated in lentil (Lens culinaris Medikus). The F2 seeds of five crosses, their parents and five lentil lines (DuPuy, Laird, PI 339283, PI 374118 and PR 86-360) were space planted with a susceptible check, Spanish Brown lentil. Disease inoculation was performed by spreading Ascochyta infected lentil debris and providing mist irrigation to enhance disease development. Gel electrophoresis was· used to resolve eight isozyme loci using leaf tissue of F2 plants in three gel and electrode buffer systems. Resistance to Ascochyta is due to a dominant gene (Rai1) in ILL 5588 lentil, and a recessive gene (ral2) in Indianhead lentil. Significant contingency chi-squared values occurred between the Ral 1 gene and the isozyme locus Aat-p (29 eM) and between the ral2 gene and the isozyme locus Pgd-p (28 eM). These markers are useless in selecting for resistance to Ascochyta due to the large map distance from the genes for resistance. Thus, markers more closely linked with these genes are required. More powerful molecular markers, such as RAPD, can be used in this endeavour. Two RAPD markers, tightly linked with Ral1 and ral2 genes, respectively, will greatly facilitate "pyramiding" of these two genes into one lentil line and thus, produce a stable genetic resistance to Ascochyta

Ascochyta resistance in lentil (Lens culinaris Medikus)

Non-Peer ReviewedThe genetic basis of resistance to Ascochyta blight was determined for 20 lentil genotypes and six F2 populations. Plants were space planted in rows in the field with adjacent spreader rows of the susceptible check Spanish Brown. Plants were inoculated by spreading infested crop debris and mist irrigation was used to create epiphytotic conditions. The disease reaction was measured by rating leaf symptoms on a 1-9 scale and by plating random samples of seed from each F2 plant on PDA agar to estimate percent seed-borne infection. Lines PI 339283, PI 374118, ILL 5588 and PR 86-360 had high resistance levels with less than 7.5% seed-borne infection. Laird, Eston, CDC-Richlea and other lines were susceptible with seed-borne infection as high as 57%. Indianhead lentil was moderately resistant. Analysis of F2 data from the six segregating populations suggests that ILL 5588 has one dominant gene and Indianhead has one recessive gene for resistance to Ascochyta blight of lentil

RAPD markers for Ascochyta resistance in lentil

Non-Peer ReviewedGenetic linkage of RAPDmarkers with genes for resistance to Ascochyta blight was studied in two crosses of lentil. DNA was extracted from F, plants of both crosses (ILL 5588 x Eston and Indianhead x Eston). Screening for Ascochyta was performed on F,-derived F, lines in a disease nursery with a susceptible check. Bulked segregant analysis was used to identify polymorphic RAPD bands in four bulks for 60 primers. Two polymorphic RAPD bands ( one each in primer #333 and 362 in the resistant bulk) were detected in ILL 5588 x Eston population, indicating linkage with the dominant gene, RuZI for Ascochyta resistance. Another polymorphic RAPD band (#338 in the susceptible bulk) was detected in Indianhead x Eston population, indicating linkage with the recessive gene, ra12. These marker linkages must be confirmed by studying individual plants so that they can be useful in the selection program for Ascochyta resistance in lentil

Linkage of RAPD markers and Ascochyta resistance in lentil

Non-Peer Reviewe

Application of biotechnology in breeding lentil for resistance to biotic and abiotic stress

Lentil is a self-pollinating diploid (2n = 14 chromosomes) annual cool season legume crop that is produced throughout the world and is highly valued as a high protein food. Several abiotic stresses are important to lentil yields world wide and include drought, heat, salt susceptibility and iron deficiency. The biotic stresses are numerous and include: susceptibility to Ascochyta blight, caused by Ascochyta lentis; Anthracnose, caused by Colletotrichum truncatum; Fusarium wilt, caused by Fusarium oxysporum; Sclerotinia white mold, caused by Sclerotinia sclerotiorum; rust, caused by Uromyces fabae; and numerous aphid transmitted viruses. Lentil is also highly susceptible to several species of Orabanche prevalent in the Mediterranean region, for which there does not appear to be much resistance in the germplasm. Plant breeders and geneticists have addressed these stresses by identifying resistant/tolerant germplasm, determining the genetics involved and the genetic map positions of the resistant genes. To this end progress has been made in mapping the lentil genome and several genetic maps are available that eventually will lead to the development of a consensus map for lentil. Marker density has been limited in the published genetic maps and there is a distinct lack of co-dominant markers that would facilitate comparisons of the available genetic maps and efficient identification of markers closely linked to genes of interest. Molecular breeding of lentil for disease resistance genes using marker assisted selection, particularly for resistance to Ascochyta blight and Anthracnose, is underway in Australia and Canada and promising results have been obtained. Comparative genomics and synteny analyses with closely related legumes promises to further advance the knowledge of the lentil genome and provide lentil breeders with additional genes and selectable markers for use in marker assisted selection. Genomic tools such as macro and micro arrays, reverse genetics and genetic transformation are emerging technologies that may eventually be available for use in lentil crop improvement