Inheritance and genetic linkage analysis of a firm‐ripening tomato mutant

Abstract

The tomato cv. ÔSanta ClaraÕ is widely cultivated among tomato producers in most of the South-east of Brazil. Recently, some plants of this cultivar were identified with morphological alterations in both vegetative and reproductive organs. These plants showed firm (firme) ripe fruits, slow and delayed ripening. They also had yellow leaves associated with precocious senescence and flowers with pale stigmas. The objective of this work was to determine the genetic model of inheritance for this mutation and to evaluate its effects on shelf life and loss of firmness in mature fruits, as well as analyse the occurrence of genetic relationships between this putative mutant and other pleiotropic mutants. Mutated plants were crossed with the non-mutant cv. ÔSanta ClaraÕ and some previously described pleiotropic mutants. Seeds of F 1 and F 2 generations and backcrosses were obtained for the segregation analysis. Morphological characteristics modified by this mutation are governed by a recessive gene with pleiotropic effects. In addition, the test of allelism showed a lack of genetic complementation between the ÔfirmeÕ mutant and lutescent-2 mapped on chromosome 10. Fruits of the ÔfirmeÕ mutant had a slower rate of softening compared with the cv. ÔSanta ClaraÕ and its hybrids. The fruit shelf life of the mutant ÔfirmeÕ was significantly superior to the other genotypes. No maternal effect was detected in either qualitative or quantitative characteristics. Based on the data, the mutation ÔfirmeÕ in the cv. ÔSanta ClaraÕ is located in the region containing the l-2 locus, which promoted alterations in ripening and post-harvest physiology of fruits. The mutation ÔfirmeÕ may represent a new allele of the gene lutescent-2 or a gene linked to physiological events of fruit ripening.

A Reevaluation of the Key Factors That Influence Tomato Fruit Softening and Integrity

“…However, DFD fruits show remarkably small changes in their firmness when compared with the well studied experimental AC and indeed, as far as we are aware, with all previously reported tomato cultivars. While some tomato mutants show delayed softening for up to several weeks (Mutschler, 1984;Schuelter et al, 2002), DFD fruits typically remain firm for at least 6 months after reaching the RR stage, exhibiting negligible tissue collapse (Figs. 1, C and D and 3A).…”

Transgressive segregation for fruit quality traits in a cross between exotic and mutant genotypes ofLycopersicon

“…ratio) and fruit shelf life (in days) were determined in a sample between 9 and 10 fruit per plant. To evaluate fruit shelf life, these fruit were 11 11 stored at 25°C until the first symptoms of deterioration and softening appeared (Schuelter et al 2002). Fruit firmness and colour were determined in a sample between 2 and 3 fruit per plant.…”

Molecular markers detect stable genomic regions underlying tomato fruit shelf life and weight

“…The total number of harvested fruits was 3114 in CI (approximately 20 per plant) and 2958 in CII (approximately 15 per plant). Fruits at the breaker stage were evaluated for fruit weight (FW, in grams) and fruit shelf life (SL) in days from harvest to the beginning of fruit softening (Schuelter et al 2002) …”

“…Fruit shelf life (SL) is a ripening associated trait important for determining the tomato fresh marketability (Schuelter et al 2002). Though genetic engineering and spontaneous ripening mutants have been used to modify metabolic pathways involved in prolonging SL, such approaches were not commercially well-accepted by consumers (Bartoszewski et al 2003).…”