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Title: INHERITANCE AND ALLELISM FOR RESISTANCE TO RUSSIAN WHEAT APHID IN AN IRANIAN SPRING WHEAT (REVISE TITLE, JOURNAL, ADD ACC. DATE)

Author
item EHDAIE, B - UNIV CALIFORNIA,RIVERSIDE
item Baker, Cheryl

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/14/1999
Publication Date: N/A
Citation: N/A

Interpretive Summary: The Russian wheat aphid (RWA) has become an important pest of wheat in the USA. Developing adapted wheat cultivars with genetic resistance is an effective strategy to protect the wheat crop from RWA. In order to use selected resistant lines effectively, it is important for wheat breeders to know how desired traits are genetically controlled. In addition, it is important to know if a resistant line carries resistance genes that are ne and different from those in other resistant lines. Use of different genes creates a broader genetic base with more genetic diversity. Genetic studies were conducted to determine the mode of inheritance of gene(s) conferring resistance in a new Iranian landrace wheat line, G 5864. The allelic relationships of genes in this line with genes in other resistant lines, PI 137739 (Dn1), PI 262660 (Dn2), PI 372129 (Dn4), PI 294994 (Dn5), and PI 243781 (Dn6), was also studied. Resistance in G 5864 seemed to be controlled by two independent dominant genes with additive action. It appears that the resistance genes present in G 5864 are most probably different from those carried by the other resistant lines examined because, 1) no susceptible segregants were observed in the crosses with the other resistant lines, 2) there was segregation for different levels of resistance in these crosses, and 3) G 6864 shows a higher level of resistance than the other resistant lines.

Technical Abstract: Russian wheat aphid (RWA), Diuraphis noxia (Mordvilko), has become an important pest of wheat (Triticum aestivum L.) in the United States. Developing genetic resistance in adapted wheat cultivars is an effective strategy to protect the wheat crop from RWA. Genetic studies were conducted to determine the mode of inheritance of gene(s) conferring resistance in a new Iranian landrace wheat line, G 5864. The allelic relationships of this line with other resistant lines, PI 137739 (Dn1), PI 262660 (Dn2), PI 372129 (Dn4), PI 294994 (Dn5), and PI 243781 (Dn6), was also studied. For the inheritance study, G 5864 was crossed with susceptible wheat cultivar 'Yecora Rojo' and line PR 2375, and seedlings of F1, reciprocal F1, F2, BC1F1, and BC2F1 generations were screened for RWA reaction. Three phenotypic segregation ratios, 9 resistant:3 rolled leaves:3 stunted plants:1 susceptible, 9 resistant:6 intermediate:1 susceptible, and 9 resistant:7 susceptible, were tested and compared for goodness of fit. The 9:3:3:1 ratio was superior because it covered the actual range of symptoms observed in the F2 progeny and also satisfied the statistical tests performed. Resistance in G 5864 seemed to be controlled by two dominant independent genes with additive action. Segregation patterns observed in G 5864 x resistant-derived F2 populations developed for test of allelism were not clear. Susceptible plants were not observed in these F2 populations. However, the higher manifestation of resistance observed in G 5864 indicated that the genes for resistance in G 5864 were most probably different from those carried by the other resistant lines examined.