Danijela Ristic

Development of High Tryptophan Maize Near Isogenic Lines Adapted to Temperate Regions through Marker Assisted Selection - Impediments and Benefits

Breeding program aimed at converting standard maize inbred lines to their quality protein maize (QPM) counterparts for growing in temperate climate is being conducted at Maize Research Institute (MRI). The objective of the research presented herein was to develop QPM versions of two commercial ZP inbreds through marker assisted selection (MAS) with opaque2 specific molecular markers, while maintaining their good agronomic performances and combining abilities. Donor line was a tropical QPM line CML 144. After two backcross and three selfing generations, six near isogenic lines (NILs) with 93% recovery of the recurrent parent genome were created from one cross. Average increments of 30% in tryptophan content and 36% in quality index were obtained, as well as kernels with less than 25% opaque endosperm. Grain yield was increased by 11–31% and combining abilities of the improved lines were on a par with the original line. Correlations between biochemical and agronomic parameters revealed that selection for plant height, ear length and kernel row number together with tryptophan content could be recommended for development of QPM with this material. However, several impediments emerged during selection. Major drawbacks in NIL development were small number of opaque2 recessive homozygotes (4.5% and 7.6% in BC2F2 of two crosses) and poor seed set throughout selection, which led to the loss of one cross. Moreover, in the other cross many plants in different generations had to be omitted from further selection due to the insufficient number of kernels. This phenomenon could be explained by incompatibility between pollen and style, possibly due to the exotic donor germplasm. Overall, it could be expected that the use of NILs, which are adapted to temperate climate and have high percentage of domestic germplasm, would outbalance the noted impediments and increase MAS efficiency in different breeding programs.

Analysis of intra-population variability of bald cypress (Taxodium distichum L. Rich.) in seed stand near Backa Palanka using RAPD markers

The analysis of Bald cypress genetic variability at the level of test trees was performed using RAPD (Random Amlified Polymorphic DNA) markers. RAPD analysis was performed on 20 test trees with 13 primers. A total of ten primers gave a clear picture while three primers amplified weakly. 60 is a total number of detected bands obtained by RAPD analysis with 10 selected primers, and the average number of bands is 6. Based on presence/absence of RAPD fragments among all 20 Bald cypress test trees were calculated similarity coefficients by Dice and they range from 0.73 to 1. Based on similarity coefficients was performed the cluster analysis and results were presented as a dendrogram. All 20 test trees were grouped into two sub-clusters. Test trees 1, 4 and 11 were grouped in the first sub-cluster while other test trees were grouped in the second sub-cluster. By analysis of relations within every sub-cluster and sub-sub-cluster the existence of genetic distances between observed test trees can be noticed. The greatest similarity is between test trees 2, 12, 15 and 18. The results of genetic similarity and distance between observed test trees indicate the overwhelming presence of genetic diversity. [Projekat Ministarstva nauke Republike Srbije, br. TR 31070: The developments of technological procedures in forestry in order to attain an optimal forest cover percentage]

Individual and combined (Plus-hybrid) effect of cytoplasmic male sterility and xenia on maize grain yield

Plus-hybrid effect refers to a combined effect of cytoplasmic male sterility (CMS) and xenia in maize (Zea mays L.) It could be used in commercial production by growing a mixture of 80% CMS hybrid and 20% of another fertile hybrid. The aim of this research was to examine individual and combined CMS and xenia effects on two hybrids widely grown in Serbia. Sterile and fertile versions of ZP 1 and ZP 2 hybrids (three-way; Iodent × Lancaster dents) were used as females, while ZP 1, ZP 2, ZP 3, ZP 4, and ZP 5 (three-way or single cross; Iodent (BSSS) × Lancaster dents) were used as pollinators. All of them belong to medium maturity group. The trial was set up at one location in Serbia (Zemun Polje) in 2009, 2010, and 2011. Molecular analysis of the five genotypes was done using simple sequence repeat (SSR) primers. Plus-hybrid effect on grain yield ranged from -6.2% to 6.2%; on thousand kernel weight from -1.7% to 5.2%; on number of kernels per area from -1.0% to 8.0%. The poor response could be due to a use of three-way instead of single cross hybrids in S type of sterility. Modified Rogers’ distance between hybrids was in the range 0.211 to 0.378 and was not relevant for the effect, which depended mostly on the sterile hybrid genotype and the fertile hybrid pollinator ability. This approach should be more suitable for female hybrids with slightly poorer performance, already being produced on a sterile base.