Genome relationships in the perennial Triticeae based on diploid hybrids and beyond

Abstract

Diploid intergeneric hybrids were synthesized among diploid species of the genera Agropyron Gaertn. (P genome), Pseudoroegneria (Nevski) A. Löve (S genome), Thinopyrum A. Löve (J‐E genome), Psathyro‐stachys Nevski (N genome), Hordeum L. (H genome), and Secale L. (R genome). Chromosome pairing patterns in these diploid hybrids permit the estimation of genomic similarity among the various genomes. Measurements of genome similarity based on chromosome pairing in diploid hybrids are generally in agreement with those based on other measurements. It is consistent that Jb and Je (= E) are the most closely‐related genomes, with the genetic similarity ranging from 0.50 to 0.68, based on various studies. Next to the Jb‐Je genome are S and P genomes. The N, H, and R genomes are remotely related to the J‐S‐P cluster. These relationships are also reflected in hybrids of higher ploidy levels when genes controlling chromosome pairing are kept in check. Since genome designation is traditionally based on chromosome pairing data and the ability of two genomes to pair without interfering factors is a reliable measurement of genome similarity, diploid pairing data should be used for genome symbol determination. It is logical to set a diploid c value of 0.50 for designating the basis genome symbol; i.e., when the diploid hybrids have a mean c > 0.50, the two genomes in the hybrid should be given the same basic symbol. Copyright © 1992, Wiley Blackwell. All rights reserved