The interrelation between plus-hybrid effect on grain yield and genetic distance of studied hybrids

Abstract

The combined effect of cytoplasmic male sterility and xenia is referred to as the Plus-Hybrid effect. A mixture of hybrids, in which one is a sterile female component and the other is a fertile pollinator, was sown. The objective of the present study was to determine whether the increase of a hybrid genetic distance would result in the increased gain from Plus-hybrid effects on grain yield. Two ZP hybrids (ZP 1 and ZP 2), i.e. their sterile and fertile counterparts, as well as, five hybrid pollinators (ZP 1, ZP 2, ZP 3, ZP 4 and ZP 5) were selected for the studies. The three-replicate trail was set up according to the randomized split-plot design at Zemun Polje in 2009. SSR markers were used to determine the genetic distance between hybrids. Ten out of total 12 applied primers gave results. Coefficients of similarity were estimated according to Dice and Jaccard. The greatest (0.37), i.e. smallest genetic distance (0.08), according to Dice, was obtained between hybrids ZP 1 and ZP 5, i.e. ZP 1 and ZP 4, respectively. Values of genetic distance according to Jaccard were between 0.14 (ZP 1 and ZP 4) and 0.54 (ZP 1 i ZP 5 ). By using the cluster analysis, four hybrids (ZP 1, ZP 4, ZP 3 and ZP 2) were grouped into one sub-cluster that was loosely linked to ZP 5. The Plus-hybrid effect on grain yield of the hybrid ZP 1 was negative. The greatest gain was detected in the ZP 2st ' ZP 1 combination, between two hybrids that were genetically very similar and belonged to the same sub-cluster, and then in ZP 2st x ZP 3 and ZP 2st x ZP 4 combinations, between hybrids that also belonged to the same sub-cluster. It can be concluded that the Plus-hybrid effect, after all, depends not on the hybrid genetic distance but on the hybrid genotype.

Kombinovani uticaj citoplazmatske muške sterilnosti i ksenija na svojstva hibrida kukuruza naziva se Plus-hibrid efekat. Seje se mešavina dva hibrida, od kojih je jedan sterilna majka, a drugi fertilni polinator. Cilj istraživanja je bio da se utvrdi da li se sa povećanjem genetičke distance hibrida povećava dobit od Plus-hibrid efekta na prinos zrna. Za ispitivanje su odabrana dva ZP hibrida (ZP 1 i ZP 2), tj. njihove sterilne i fertilne verzije, kao i pet hibrida oprašivača (ZP 1, ZP 2, ZP 3, ZP 4 i ZP 5). Za utvrđivanje genetičke distance između hibrida korišćeni su SSR markeri. Izračunati su i koeficijenti genetičke distance po Dice-u i Jaccard-u. Najveća genetička distanca po Dice-u dobijena je između hibrida ZP 1 i ZP 5 (0.37), a najmanja između ZP 1 i ZP 4 (0.08). Vrednosti genetičke distance po Jaccard-u su u opsegu od 0.54 (ZP 1 i ZP 5) do 0.14 (ZP 1 i ZP 4). Klaster analiza je grupisala četiri hibrida ZP 1, ZP 4, ZP 3 i ZP 2 u jedan subklaster za koji je labavo vezan ZP 5. Oba hibrida su u kombinaciji sa ZP 5, koji im je genetički najudaljeniji, dali najlošije rezultate. Može se zaključiti da Plus-hibrid efekat, ipak, zavisi od genotipa hibrida, a ne njihove genetičke distance.