Genetic divergence analysis among barley genotypes using inter-retrotransposon amplified polymorphism markers (IRAP)

The genetic diversity among 14 barley accessions was evaluated using seven designed primers based on long terminal repeat (LTR) retrotransposons derived from the barley genome. LTR primers amplified 96 bands of > 100- 1500 bp, of which 84 were polymorphic. The number of polymorphic fragments ranged from 5 (LTR, LTR1 and LTR6150) to 18 (Sukkula) with an average of 9.33. The highest marker index (MI) was observed with the primer Nikita (3.93) and the lowest with the primer LTR2 (1.05), with an average MI of 2.28 per primer. The insertion patterns of retrotransposones have interesting implications for genome organization in Hordeum. The Shannon diversity index with markers obtained on the accessions level was 0.45. Barely accessions are clustered according to their pedigree and caryopsis character (hulled or naked caryopsis). This study demonstrates the efficiency of IRAP markers as a genetic tool for selection of suitable accessions for breeding programs.

Cytogenetic relationships of certain artificial and natural species of Avena

1. The desirability of employing the genetic variation present in diploid and tetraploid wild species for the improvement of the cultivated hexaploid species stimulated an investigation into the synthesis of various amphiploid forms in Avena.2. Five amphiploids at the hexaploid level have been produced, but the present investigation is limited to the amphiploids developed from the cross A. barbata (2n = 28)×.A. strigosa subsp. hirtula (2n= 14), their hybrids with the natural hexaploid species and with other amphiploid types.3. These amphiploids, like their parents, possessed black paleae, with hairs and a fairly strong geniculate awn on both the lower and upper grains. The bases of both the lower and upper grains possessed the articulation surfaces characteristic of A. fatua. Their hybrids with A. fatua were similar in spikelet morphology, but the A. sterilis type of spikelet was dominant in both the amphiploid 6x × A. sterilis and amphiploid 6x × A. byzantina. Partial dominance of the cultivated type base over the shedding type was evident in crosses with A. sativa and A. nuda but the naked caryopsis and multiflorous spikelet were recessive in the latter cross. In crosses between the A. barbata/A. hirtula 6x amphiploid and the A. abyssinica/A. strigosa 6x amphiploid (Cc 4387) the hybrid exhibited a reversal of dominance relationships, with the cultivated base type of Cc4387 being completely recessive to the shedding base.