Seed coat lignification level is crucial in Capsicum spp seed longevity

Abstract

Capsicum (pepper) is known for its poor seed germination, particularly seed longevity is usually much shorter than other Solanaceae. However, the molecular mechanisms involved are mostly unknown in these species. The present study examines the differences in seed longevity among Capsicum species and varietal types. Feral or less domesticated species, such as Capsicum chinense and particularly Capsicum frutescens, showed higher germination rates than the more domesticated Capsicum annuum after accelerated seed aging treatments. In addition, variability was detected in the expression of genes involved in the response to seed deterioration. The differences observed in ASPG1 expression led us to study the seed protein profile in dry and germinating seeds. Seed storage protein mobilization during germination was faster in seed aging-resistant genotypes. Similarly, the transcriptional change observed for the orthologous gene of the trans-species regulator AtHB25 prompted us to study the structure and molecular components of the seed coat in peppers. All the Capsicum pepper accessions analyzed presented very lignified testa and we observed a positive correlation between the amount of lignin and seed viability. Our results provide essential information to explain the poor germination observed in pepper seeds and provide an experimental framework for future improvements in this important character.

Aqueous extract of coconut shell biochar as a pre-germination treatment increases seed germination and early seedling growth in chiltepín pepper (Capsicum annuum var. glabriusculum)

“…The imbibition rates determined here were similar to those of Cano-Vázquez et al (2015) and Cano-González et al (2021). Imbibition percentages > 50% after the first 4 h of seed immersion in the CSBA solution (highest with CSBA0.25, CSBA0.50, and CSBA1.00; Figure 3) reflect the absence of morphological germination problems due to the presence of a too-thick testa, since high testa lignification can prevent or reduce imbibition and gaseous exchange between the embryo and the environment (Bissoli et al, 2022). During this process, which follows the Lucas-Washburn law, there is a gradual swelling from water penetration into the seed tissues caused by gradients and capillary pressure (Louf et al, 2018).…”

“…Seeds of the genus Capsicum usually have low or poor germination rates (Bissoli et al, 2022) due to their high dormancy rates (Beltrán-Burboa et al, 2020). The seeds' good physical quality illustrates the minimal damage that genetic material from wild plants can present, allowing for a quick and easy determination of their germination potential.…”

Genetic Analyses of Seed Longevity in Capsicum annuum L. in Cold Storage Conditions

“…The nepenthesin aspartic proteases, which are produced by specialized cells in the lower part of the pitchers, are aimed primarily at the digestion of prey trapped by the plant [ 31 ]. Aspartic protease in guard cell 1 has recently been reported as a candidate gene for longevity in Capsicum [ 20 ]. Aspartic proteases mobilize seed-storage proteins and play a crucial role in the germination process and seed longevity [ 32 ].…”

“…According to the genebank information system (GBIS) of the IPK ( , accessed on 20 October 2022), there were 1241 accessions of Capsicum annuum L. available. C. annuum is the most economically important species of the genus Capsicum [ 20 ]. A recent report has shed considerable light on its evolution and trade history in addition to mapping genes related to its plant architecture, fruit quality and flower-related traits [ 21 ].…”

“…Differential gene expression analyses exhibited that aspartic protease in guard cell 1 (ASPG1) and homeobox protein 25 (HB25) expression were higher in long-lived accessions. In addition, a positive correlation between the amount of lignin and seed viability was demonstrated [ 20 ].…”