Variability for the in vitro culture response in tomato recombinant inbred lines

Abstract

The aim of this work was to estimate genetic variability for in vitro culture response of recombinant inbred lines (RILs) of the genus Lycopersicon. The callus percentage (C), the regeneration percentage (R) and the productivity rate (PR) were evaluated 45 d after culture initiation in a set of 16 elite tomato RILs and their parents. The narrow sense heritability (h 2 ) values were 0.38 ± 0.04 for C, 0.46 ± 0.04 for R, and 0.28 ± 0.03 for R, while the genetic correlation (r g ) values were -0.96 ± 0.07 between C and R, 0.81 ± 0.14 between PR and R, and -0.79 ± 0.16 between PR and C. Three AFLP markers associated to the in vitro traits were identified.Additional key words: amplified fragment length polymorphism (AFLP), callus production, Lycopersicon esculentum, Lycopersicon pimpinellifolium, plant breeding, shoot formation. ⎯⎯⎯⎯Intra and interspecific variability for callus proliferation and shoot regeneration has been widely reported in the genus Lycopersicon (Tal et al. 1977, Pratta et al. 1997. Dedifferentiation of leaf explants into a callus, either followed or not by shoot formation, was dependent on genotype, culture medium and physiological stage of the donor plants. Although genetic control of in vitro culture traits was investigated in various crops (Kuroda et al. 1998, Nestares et al. 1998, Ogburia 2003) there is not enough information about the inheritance of callus production and shoot formation in the cultivated tomato (Lycopersicon esculentum Mill.) (Frankerberger et al. 1981, Pratta et al. 2003. Reports on molecular markers associated to the tomato in vitro culture responses are even scarcer. Koornneef et al. (1993) mapped a high regeneration QTL to chromosome III in an interspecific tomato cross by RFLP analysis. Torelli et al. (1996) detected by the differential display technique, some specific mRNA transcripts expressed during the earlier incubation period of tomato explants that were associated to the shoot formation capacity, while Takashina et al. (1998) found at least two RAPD and one isoenzymatic markers linked to the high regeneration capacity of the wild L. chilense.The objective of this research was to evaluate both the in vitro callus production and shoot formation, and to detect cosegregating AFLP markers in a set of elite tomato genotypes. Our ultimate goal was to contribute to the knowledge of the inheritance of in vitro culture response of the tomato.Seeds of 16 elite tomato recombinant inbred lines (RILs) and their parents (Lycopersicon esculentum (L.) Mill. cv. Caimanta and L. pimpinellifolium Mill. LA722, included as testers) were sown in seedling trays under greenhouse conditions at the field station "José F. Villarino" (Facultad de Ciencias Agrarias UNR, Zavalla, Argentina, 33°S and 61°W). RILs were the F 7 filial generation (more than 99 % homozygotes) from the interspecific cross Caimanta × LA722. They were developed through a breeding program to obtain long shelf life and high mass tomato genotypes through divergent and antagonic selection. In vitro culture was performed acc...

Genetic analysis of the in vitro culture response in tomato

“…Cultivar 'Caimanta' of L. esculentum as the high regeneration capacity genotype (regeneration percentage = 87.93 ± 3.88) and accession LA722 of L. pimpinellifolium as the low regeneration capacity genotype (regeneration percentage = 34.44 ± 15.17) were selected based on previous results (Pratta et al 2006). Crosses were made to obtain F 1 (Caimanta · LA722) and both backcrosses (BC I = F 1 · LA722, and BC II = Caimanta · F 1 ).…”

“…Pratta et al (2006) evaluated the in vitro behavior of 16 recombinant lines derived from a crossing between the same progenitors used in this work. These authors found a narrow sense heritability value important for callus percentage as well as for regeneration percentage, which can be explained by the expected changes in the genetic variance composition (that is, an increase in the additive component) throughout successive cycles of self-fertilization.…”

“…Approaches from Quantitative Genetics allow to segregate the genetic and environmental factors affecting the in vitro response, so that the analysis of some aspects of gene transmission and regulation becomes possible (Frankenberger et al 1981;Koornneef et al 1987;Pratta et al 2006;Pratta et al 2003). In addition, plant breeding strategies aiming to increase organogenic ability can be planned on the principles of genetic variability and enviromental influences.…”

Phenotypic and molecular characterization of selected tomato recombinant inbred lines derived from the cross Solanum lycopersicum × S. pimpinellifolium

“…The selective amplification samples were prepared using 5 μL of this dilution and the same components mentioned earlier. Three primer +3 combinations reported by Pratta et al (2006) were used: A combination: 5 -GACTGCGTACCAATTCAGA-3 / 5 -GAT GAGTCCTGAGTAACTA-3 ; B combination: 5 -GACTGC GTACCAATTCAGC-3 / 5 -GATGAGTCCTGAGTAACAT-3 ; N combination: 5 -GACTGCGTACCAATTCATC-3 / 5 -GATGAGTCCTGAGTAACAT-3 .…”