Seed vigor and germination at different temperatures of near-isogenic lines for the ripening inhibitor (rin) gene

Abstract

Tomato seed germination and stand establishment may be reduced under adverse (extreme) temperatures. Seed performance at different environmental conditions depends on its physiological quality as well as genetic background. Ethylene-responsive genes are associated with a number of physiological and adaptive traits in plants. The wild type ripening inhibitor (Rin) allele is a MADS-box gene necessary for complete tomato fruit ripening. A recessive mutation controls extended fruit shelf life by slowing the ripening process and interfering with the ethylene synthesis. However, little is known about the pleiotropic effects of the Rin gene on seed germination under extreme temperatures. The study aimed to test the physiological quality and seed germination under extreme (low and high) temperatures of two near-isogenic tomato lines for the ripening inhibitor gene. Seeds of two near-isogenic tomato lines for the gene rin were employed in the present study. Seeds from the line ‘TX 625-20’ (rin/rin) and ‘TX 625-97’ (Rin/Rin) were germinated at 6, 12, 20/30 and 35°C. Accelerated ageing, cold, and seedling emergence tests were performed. At alternated temperatures (20/30°C), seed germination of ‘TX 625-97’ (Rin/Rin) and ‘TX 625-20’ (rin/rin) were equivalent, i.e., 100 and 95%, respectively. However, under low (6 and 12°C) and high (35°C) temperatures, the germination frequency was lower in the two lines when compared to the standard alternate (20/30°C) conditions. Seed germination of the line ‘TX 625-97’ (Rin/Rin) was higher than ‘TX 625-20’ (rin/rin) in all temperatures. The results of seed vigor from the accelerated ageing, as well as in cold and seedling emergence tests, also showed a superiority of the near-isogenic line ‘TX 625-97’ (Rin/Rin), indicating that the dominant wild type (Rin) allele might provide better tolerance to adverse conditions when compared with the recessive mutant (rin) allele.