Molecular dynamics of pre-germinative metabolism in primed eggplant (Solanum melongena L.) seeds

Abstract

Seed priming, a pre-sowing technique that enhances the antioxidant/DNA repair activities during the pre-germinative metabolism, still retains empirical features. We explore for the first time the molecular dynamics of pre-germinative metabolism in primed eggplant (Solanum melongena L.) seeds in order to identify hallmarks (expression patterns of antioxidant/DNA repair genes combined with free radical profiles) useful to discriminate between high- and low- quality lots. The hydropriming protocol hereby developed anticipated (or even rescued) germination, when applied to lots with variable quality. ROS (reactive oxygen species) raised during hydropriming and dropped after dry-back. Upregulation of antioxidant/DNA repair genes was observed during hydropriming and the subsequent imbibition. Upregulation of SmOGG1 (8-oxoguanine glycosylase/lyase) gene detected in primed seeds at 2 h of imbibition appeared as a promising hallmark. On the basis of these results, the investigation was restricted within the first 2 h of imbibition, to verify whether the molecular landscape was reproducible in different lots. A complex pattern of antioxidant/DNA repair gene expression emerged, reflecting the preponderance of seed lot-specific profiles. Only the low-quality eggplant seeds subjected to hydropriming showed enhanced ROS levels, both in the dry and imbibed state, and this might be a useful signature to discriminate among lots. The plasticity of eggplant pre-germinative metabolism stimulated by priming imposes a plethora of heterogeneous molecular responses that might delay the search for quality hallmarks. However, the information hereby gained could be translated to eggplant wild relatives to speed-up their use in breeding programs or other agronomical applications.

References

[1] Heydecker, W., Higgins, J. & Gulliver, R. L. Accelerated germination by osmotic seed treatment. Nature 246, 42-46 (1973).

[2] Bailly, C., Benamar, A., Corbineau, F. & Côme, D. Free radical scavenging as affected by accelerated ageing and subsequent priming in sunflower seeds. Physiol. Plant. 104, 646-652 (1998).

[3] Ventura, L. et al. Understanding the molecular pathways associated with seed vigor. Plant Physiol. Biochem. 60, 196-206 (2012).

[4] Paparella, S. et al. Seed priming: state of the art and new perspectives. Plant Cell Rep. 34, 1281-1293 (2015).

[5] Wojtyla, L., Lechowska, K., Kubala, S. & Garnczarska, M. Different modes of hydrogen peroxide action during seed germination. Front. Plant Sci. 7, 66 (2016).

[6] Farooq, M. et al. Effects, tolerance mechanisms and management of salt stress in grain legumes. Plant Physiol. Biochem. 118, 199-217 (2017).

[7] Macovei, A. et al. Systems biology and genome-wide approaches to unveil the molecular players involved in the pre-germinative metabolism: implications on seed technology traits. Plant Cell Rep. 36, 669-688 (2017).

[8] Gallardo, K. et al. Proteomic analysis of Arabidopsis seed germination and priming. Plant Physiol. 126, 835-848 (2001).

[9] Balestrazzi, A., Confalonieri, M., Macovei, A. & Carbonera, D. Seed imbibition in Medicago truncatula Gaertn.: expression profiles of DNA repair genes in relation to PEG-mediated stress. J. Plant Physiol. 168, 706-713 (2011).

[10] Bailly, C. Active oxygen species and antioxidants in seed biology. Seed Sci. Res. 14, 93-107 (2004).

[11] Kranner, I., Minibayeva, F. V., Beckett, R. P. & Seal, C. E. What is stress? Concepts, definitions and applications in seed science. New Phytol. 188, 655-673 (2010).

[12] Bray, C. M. & West, C. E. DNA repair mechanisms in plants: crucial sensors and effectors for the maintenance of genome integrity. New Phytol. 168, 511-528 (2005).

[13] Waterworth, W. M., Bray, C. M. & West, C. E. Seeds and the art of genome maintenance. Front. Plant Sci. 10, 706 (2019).

[14] Macovei, A., Balestrazzi, A., Confalonieri, M., Faè, M. & Carbonera, D. New insights on the barrel medic MtOGG1 and MtFPG functions in relation to oxidative stress response in planta and during seed imbibition. Plant Physiol. Biochem. 49, 1040-1050 (2011).

[15] Chen, H. et al. Overexpression of AtOGG1, a DNA glycosylase/AP lyase, enhances seed longevity and abiotic stress tolerance in Arabidopsis. J. Exp. Bot. 63, 4107-4121 (2012).

[16] Cordoba-Canero, D., Roldan-Arjona, T. & Ariza, R. R. Arabidopsis ZDP DNA 30-phosphatase and ARP endonuclease function in 8-oxoG repair initiated by FPG and OGG1 DNA glycosylases. Plant J. 79, 824-834 (2014).

[17] Lebedeva, N. A., Rechkunova, N. I. & Lavrik, O. I. AP-site cleavage activity of tyrosyl-DNA phosphodiesterase 1. FEBS Lett. 585, 683-686 (2011).

[18] Macovei, A., Balestrazzi, A., Confalonieri, M. & Carbonera, D. The Tdp1 (Tyrosyl-DNA phosphodiesterase) gene family in barrel medic (Medicago truncatula Gaertn.): bioinformatic investigation and expression profiles in response to copper- and PEG-mediated stress. Planta 232, 393-407 (2010).

[19] Pagano, A., Araújo, S., Macovei, A., Leonetti, P. & Balestrazzi, A. The seed repair response during germination: disclosing correlations between DNA repair, antioxidant response, and chromatin remodeling in Medicago truncatula. Front. Plant Sci. 8, 1972 (2017).

[20] Pagano, A. et al. Metabolic and gene expression hallmarks of seed germination uncovered by sodium butyrate in Medicago truncatula. Plant Cell Environ. 42, 259-269 (2019).

[21] Mennella, G. et al. Chemical and bioactive quality traits during fruit ripening in eggplant (S. melongena L.) and allied species. J. Agr. Food Chem. 60, 11821-1131 (2012).

[22] Gürbüz, N., Uluisik, S., Frary, A. & Doganlar, S. Health benefits and bioactive compounds of eggplant. Food Chem. 268, 602-610 (2018).

[23] Joshua, A. Seed germination of Solanum incanum: an example of germination problems of tropical vegetable crops. Acta Hortic. 83, 155-162 (1978).

[24] Ibrahim, M., Munira, M. K., Kabir, M. S., Islam, A. K. M. S. & Miah, M. M. U. Seed germination and graft compatibility of wild Solanum as rootstock of tomato. J. Biol. Sci. 1, 701-703 (2001).

[25] Demir, L., Ennis, S., Okyu, G. & Matthews, S. Vigour tests for predicting seedling emergence of aubergine (Solanum melongena L.) seed lots. Seed Sci. Technol. 33, 481-484 (2005).

[26] Adebola, P. O. & Afolayan, A. J. Germination responses of Solanum aculeastrum, a medicinal species of the Eastern Cape, South Africa. Seed Sci. Technol. 34, 735-740 (2006).

[27] Taab, A. & Andersson, L. Seasonal changes in seed dormancy of Solanum nigrum and Solanum physalifolium. Weed Res. 49, 90-97 (2009).

[28] Ranil, R. H. et al. Improving seed germination of the eggplant rootstock Solanum torvum by testing multiple factors using an orthogonal array design. Sci. Hortic. 193, 174-181 (2015).

[29] Miceli, A., Sabatino, L., Moncada, A., Vetrano, F. & D’Anna, F. Nursery and field evaluation of eggplant grafted onto unrooted cuttings of Solanum torvum Sw. Sci. Hortic. 178, 203-210 (2015).

[30] Zhang, Y., Liu, H., Shen, S. & Zhang, X. Improvement of eggplant seed germination and seedling emergence at low temperature by seed priming with incorporation SA into KNO₃ solution . Front. Agric. China 5, 534-537 (2011).

[31] Gomes, D. P. et al. Priming and drying on the physiological quality of eggplant seeds. Hortic. Bras. 30, 484-488 (2012).

[32] Gonzalez, L. M. R. Germination response of eggplant (Solanum melongena L.) seeds to different vinegar concentration as seed priming agents. Int. J. Sci. Res. Pub. 5, 1-4 (2015).

[33] Mahesh, H. M., Murali, M., Anup Chandra Pal, M., Melvin, P. & Sharada, M. S. Salycilic acid seed priming instigates defence mechanisms by inducing PR-proteins in Solanum melongena L. upon infection with Verticillum dahlie Kleb. Plant Physiol. Biochem. 117, 12-23 (2012).

[34] Neto, F. J. D. et al. Effects of plant growth regulators on eggplant seed germination and seedling growth. Aust. J. Crop Sci. 11, 1277-1282 (2017).

[35] Ali, M. et al. Priming of Solanum melongena L. seeds enhances germination, alters antioxidant enzymes, modulates ROS, and improves early seedling growth: indicating aqueous garlic extract as seed-priming bio-stimulant for eggplant production. Appl Sci. 9, 2203 (2019).

[36] Barchi, L. et al. A chromosome-anchored eggplant genome sequence reveals key events in Solanaceae evolution. Sci. Rep. 9, 11769 (2019).

[37] Ranal, M. A. & Garcia de Santana, D. How and why to measure the germination process? Braz. J. Bot. 29, 1-11 (2006).

[38] Bailly, C., El-Maarouf-Bouteau, H. & Corbineau, F. From intracellular signaling networks to cell death: the dual role of reactive oxygen species in seed physiology. C. R. Biol. 331, 806-814 (2008).

[39] Job, C., Rajjou, L., Lovigny, Y., Belghazi, M. & Job, D. Patterns of protein oxidation in Arabidopsis seeds and during germination. Plant Physiol. 138, 790-802 (2005).

[40] Kubala, S. et al. Enhanced expression of the proline synthesis gene P5CSA in relations to seed osmopriming improvement of Brassica napus germination under salinity stress. J. Plant Physiol. 183, 1-12 (2015).

[41] Chen, K. & Arora, R. Priming memory invokes seed stress-tolerance. Environ. Exp. Bot. 94, 33-45 (2013).

[42] Oracz, K. et al. The mechanisms involved in seed dormancy alleviation by hydrogen cyanide unravel the role of reactive oxygen species as key factors of cellular signaling during germination. Plant Physiol. 150, 494-505 (2009).

[43] Bailly, C., Benamar, A., Corbineau, F. & Come, D. Antioxidant systems in sunflower (Helianthus annuus L.) seeds as affected by priming. Seed Sci. Res. 10, 35-42 (2000).

[44] Rouhi, H. R. et al. Change in several antioxidant enzymes activity of Berseem clover (Trifolium alexandrinum L.) by priming. Int. J. AgriSci. 2, 273-243 (2012).

[45] Sharma, S. N. & Maheshwari, A. Expression patterns of DNA repair genes associated with priming small and large chickpea (Cicer arietinum) seeds. Seed Sci. Technol. 43, 250-261 (2015).

[46] Parreira, J. R., Balestrazzi, A., Fevereiro, P. & De Sousa Araujo, S. Maintaining genome integrity during seed development in Phaseolus vulgaris L.: evidence from a transcriptomic profiling study. Genes 9, E463 (2018).

[47] Macovei, A. et al. Prolonged cold storage affects pollen viability and germination along with hydrogen peroxide and nitric oxide content in Rosa hybrida. Not. Bot. Horti. Agrobo. 44, 6-10 (2016).

[48] Gantasala, N. P. et al. Selection and validation of reference genes for quantitative gene expression studies by real-time PCR in eggplant (Solanum melongena L.). BMC Res. Notes 6, 312 (2013).

[49] Barbierato, V. et al. A spiking strategy facilitates housekeeping selection for RT-qPCR analysis under different biotic stresses in eggplant. Protoplasma 254, 2215-2223 (2017).

[50] Pfaffl, M. W. A new mathematical model for relative quantification in real-time RT-PCR. Nucleic Acids Res. 29, e45 (2001).