Rhizobial survival and nodulation of chickpea as influenced by fungicide seed treatment.

The survival of Rhizobium ciceri on chickpea (Cicer arietinum cv. Myles) seed, treated separately with 1 of 4 commercial fungicides, i.e., Apron, Arrest 75W, Crown, or Captan, was examined under laboratory conditions using standard serial dilution and plate count techniques. The resulting effects of fungicide-Rhizobium interactions on nodulation, N2 fixation, and plant growth were assessed in a controlled environment. Fungicide treatment decreased the number of viable rhizobia on the seed. In general, the toxicity of the fungicides in terms of rhizobial viability increased in the following order: Control = Crown < Arrest = Apron < Captan. Although Crown had no effect on rhizobial viability assessed under laboratory conditions, it significantly reduced nodulation, percent N derived from the atmosphere (%Ndfa), and shoot dry matter. Seed treated with Arrest and Captan decreased nodule dry weight and %Ndfa, but only Arrest reduced dry matter yield. Apron had no effect on any of the parameters measured at the early pod-filling stage and was compatible with the chickpea inoculum used in this study.

Genetics of isozymes in grasspea.

We studied the inheritance and linkage of ACO-1, ACO-2, AAT-1, AAT-2, EST-3, EST-6, FDH, LAP-1, PGD-2, SKDH, and TPI-1 in four F2 populations of grasspea (Lathyrus sativus L.) using horizontal starch-gel electrophoresis. Mendelian inheritance was observed for all of the isozymes studied. All isozymes showed codominant gene expression except for EST-3, which was expressed in a dominant fashion due to the presence of a null allele. Monomeric quaternary structure was observed for ACO-1, ACO-2, EST-6, LAP-1, and SKDH. Dimeric quaternary structure was observed for AAT-1, AAT-2, FDH, PGD-2, and TPI-1. The isozyme loci Aat-2 and Skdh were linked with a map distance of 28 cM.

Cytological identification of some trisomics of Russian wildrye (Psathyrostachys juncea).

Russian wildrye, Psathyrostachys juncea (Fisch.) Nevski (2n = 2x = 14; NsNs), is an important forage grass and a potential source of germplasm for cereal crop improvement. Because of genetic heterogeneity as a result of its self-incompatibility, it is difficult to identify trisomics of this diploid species based on morphological characters alone. Putative trisomies (2n = 2x + 1 = 15), derived from open pollination of a triploid plant by pollen grains of diploid plants, were characterized by Giemsa C-banding. Based on both karyotypic criteria and C-banding patterns, four of the seven possible primary trisomics, a double-deletion trisomic, and two tertiary trisomics were identified.

Genetic relationships in the genus Cicer L. as revealed by polyacrylamide gel electrophoresis of seed storage proteins.

Total seed storage protein of the cultivated chickpea, C. arietinum L., and eight other wild annual Cicer species (all 2n = 16) was separated and compared by sodium dodecyl sulphate polyacrylamide gel electrophoresis. The seed-protein profile was a conservative and species-specific trait. Relative interspecific similarities of protein patterns were estimated using Jaccard's similarity index, and a cluster analysis was performed. The resultant dendrogram generally agreed with the limited data already available on interspecific relationships in Cicer based on morphological characteristics, crossability, genome pairing in hybrids, karyotypes and isozyme analysis. The difference between the profiles of C. judaicum and C. pinnatifidum supported the idea that they are indeed two separate species. The closest relative of C. arietinum was C. reticulatum, followed by C. echinospermum and other species, while C. cuneatum was the farthest relative. In general, C. cuneatum was also genetically the farthest removed from any other species. The suggestion that C. reticulatum is the wild progenitor of the cultivated chickpea was therefore further supported.

Isozyme polymorphism and phylogenetic interpretations in the genus Cicer L.

Allozyme variation among 50 accessions representing the cultivated chickpea (Cicer arietinum L.) and eight wild annual Cicer species was scored and used to assess genetic diversity and phylogeny. Sixteen enzyme systems revealed 22 putative and scorable loci of which 21 showed polymorphism. Variation was prevalent between species (Dst = 0.510) but not within species (Hs = 0.050). No variation for isozyme loci was detected in the cultivated chickpea accessions. Cicer reticulatum had the highest proportion of polymorphic loci (0.59) while the loci Adh-2 and Lap were the most polymorphic over all the species accessions. The phylogeny of annual Cicer species, as determined by allozyme data, generally corroborated those based on other characters in previous studies. Cicer arietinum, C. reticulatum and C. echinospermum formed one cluster, while C. pinnatifidum, C. bijugum and C. judaicum formed another cluster. Cicer chorassanicum was grouped with C. yamashitae, whereas C. cuneatum formed an independent group and showed the largest genetic distance from C. arietinum.

Genetic control and linkage relations of additional isozyme markers in chick-pea.

Allozyme polymorphisms of nine enzymes - aspartate aminotransferase (AAT), diaphorase (DIA), esterase (EST), formate dehydrogenase (FDH), ß-galactosidase (GAL), ß-glucosidase (GLU), malate dehydrogenase (MDH), malic enzyme (ME), and peroxidase (PRX) - were described in chick-pea (Cicer L.). Thirteen isozyme loci, Aat-c, Dia-4, Est-2, Est-4, Est-10, Fdh, Gal-2, Gal-3, Gal-4, Glu-3, Mdh-2, Me-2, and Prx-2, were genetically defined. Alleles of each of these isozyme loci expressed codominantly in heterozygotes and exhibited a codominant, single-locus segregation ratio in F2. The loci Est-2, Mdh-2, and Me-1 were expressed only in flower. Linkage relations were determined for these 13 and several previously defined isozyme loci. The following new genetic linkages were identified: Pgm-p (locus for plastid phosphoglucomutase) - Est-10; Ald-p1 (one of the duplicate loci for plastid aldolase) - Glu-3 - Gal-2 - Est-2,3; Gal-3 - Aco-m (locus for mitochondrial aconitase) - Prx-2,3; Gpi-c (locus for cytosolic glucosephosphate isomerase) - Fdh; and Est-4 - Me-1. This study provides further confirmation on the existence of several conserved linkage groups among Cicer, Pisum, and Lens.