Carotenoid and fruit development effects on germination and vigor of tomato (Lycopersicon esculentum Mill.) seeds

The tomato crop is an important source of carotenoids such as β-carotene and lycopene. These carotenoids play important roles in human health and nutrition. Consequently, humans benefit from the development of tomatoes with enhanced carotenoid content. High pigment genes, such as dark green (dg) and high pigment (hp) that result in higher levels of carotenoids are available. The effects of these genes on plant development are not well understood. In addition, their effects in other traits such as seed longevity and total antioxidant capacity (TAC) have not been evaluated. This study evaluated the effect of fruit development on seed quality of tomato varieties with different concentrations of carotenoids. Gibberellin and norflurazon (an inhibitor of carotenoid synthesis) effects on speed of germination of varieties with different concentrations of carotenoids were also evaluated. Fruits and seeds of these varieties were assayed for TAC using the Photo-induced Chemiluminescense (PCL) and the Total Equivalent Antioxidant Capacity (TEAC) methods. Results indicated that the effect of fruit development on seed germination depends on the genotype and that the low speed of germination characteristic of the high lycopene line is independent of the gradual accumulation of lycopene. Seeds of the high pigment line treated with norflurazon plus gibberellin germinated faster than the control indicating that abscisic acid (ABA) is involved in the low speed of germination of high lycopene genotypes. Fruits of the dg line had significantly greater antioxidant capacity than fruits of the recurrent parent. However, seeds of the recurrent parent had higher antioxidant capacity than seeds of the high pigment line as assayed by both PCL and TEAC methods, suggesting that antioxidants in the fruit may compete with antioxidants in the seed. In conclusion, genotypes carrying the dg gene result in a high content of lycopene and antioxidant capacity and have delayed seed germination possibly caused by higher levels of ABA. Based on these results, fruits with high lycopene content may be desirable for human health perspective but result in lower quality planting material. The application of ABA inhibitors can minimize the effect of high pigment genes on the speed of seed germination.