Transcriptome analysis in osmo-primed tomato seeds with enhanced longevity by heat shock treatment

Abstract

Seed priming is widely used in commercial seeds and its main function is to accelerate and synchronize seed germination. Undesirably, primed seeds show reduced longevity and treatments like heat shock have been shown to improve longevity in primed seeds. Nonetheless, the effect of heat shock treatment on primed seeds at the mRNA level is not known. Thus, the aim of this work was to investigate the effect of heat shock treatment on the longevity of primed tomato (Solanum lycopersicum) seeds at the physiological and transcriptome levels. Tomato seeds were primed and dried (control). Alternatively, primed seeds were subjected to heat shock treatment (38 °C/32% relative humidity) before drying. Germination, vigor and longevity were evaluated. Transcriptome analysis was performed by RNA sequencing (RNA-seq) from biological samples collected immediately after priming and another samples collected from primed seeds followed by the heat shock treatments. The gene expression was validated by quantitative real time PCR (RT-qPCR). We showed that applying heat shock treatment after priming increased germination speed, enhanced seed longevity and preserved the vigor during storage of primed tomato seeds. Through transcriptome analysis, 368 differentially expressed genes were identified, from which 298 genes were up-regulated and 70 were down-regulated. We showed the increase of mRNA levels of HEAT SHOCK FACTOR-like and HEAT SHOCK PROTEIN-like chaperone genes, suggesting the involvement of the proteins coded by these transcripts in the enhancement of longevity in primed tomato seeds. The heat shock treatment after priming enhances and preserves the vigor of tomato primed seeds during storage. In addition, improves seed longevity through the increase in the expression of transcripts related to protection by response to stress.

Priming and Growth Inhibitor in the Production of High-Quality Pepper Seedlings

“…According to Brandão and Lopes (2019), this test can generate inaccurate results in small-sized seeds, as in the case of pepper seeds.The beneficial effect of seed conditioning may not persist over the seed storage period (Batista et al, 2020;Silva and Marcos -Filho, 2020). According to Marcos Filho (2015), the process has several advantages, as the physiological conditioning guarantees the absorption of water under controlled conditions, allowing the beginning of the germination process, activating phases I and II of germination, but not the phase of radicle protrusion.…”

Seed longevity and genome damage

“…An element of the germination vigour conferred by priming may also result from stresses incurred during the priming process. For example, tomato seed priming was improved by heat shock, which also led to elevated heat shock factor gene expression [ 140 ]. Priming alters ROS levels, with reduction in hydrogen peroxide accumulated in aged seeds, accompanied by increased catalase activity as seeds recover from the loss of catalase protein during ageing [ 135 , 137 , 141 ].…”

Genetic Aspects and Molecular Causes of Seed Longevity in Plants—A Review

“…This can be ameliorated by heat shock to primed seeds. The genetic determinants of this improvement in longevity were investigated using primed and dried tomato seeds [ 154 ]. RNA-seq and subsequent transcriptome analysis of the tomato seeds after priming and after heat shock treatment post-priming demonstrated that from a total of 368 differentially expressed genes, 298 genes were up-regulated and 70 were down-regulated.…”