Genetic analysis of late blight (<italic>Phytophthora infestans</italic> (mont.) de Bary) resistance in tomato.

Diallel analysis provides basic genetic information that is critically important to identify parents involved in hybridization breeding programs. This study was initiated to estimate combining ability effects and determine the type of gene action involved in inheritance of late blight resistance. Five tomato lines and 10F1 progenies produced by crossing of parents in a 5 &#215; 5&#160;half-diallel fashion were assessed for late blight resistance in field conditions. The combining ability ratio was greater than unity for all traits considered in this stud. At the same time, the degree of dominance was less than unity for all the traits, indicating a greater importance of additive gene effects for the inheritance of late blight resistance. The parents ’Eshete’ and ’Roma VF’ were general combiners, exhibiting significantadverse general combining ability effects for all studied traits. Specific combining ability effects of ’Roma VF &#215; Eshete’ and ’Melkashola &#215; Eshete’ were significantly negative for disease incidence, with all the lines exhibiting significant negative general combining ability effects for the trait, indicating transgressive segregants that are late blight resistant could be produced from crossing of these parental lines. These results, accordingly, indicated that the parents could be utilized in the crossing programme to develop late blight resistant transgressive segregant varieties. [ABSTRACT FROM AUTHOR]