The Impact of Fruit Etiolation on Quality of Seeds in Tobacco

Abstract

Seed’s maturity and integrity are essential requirements for germination, and they rely on nutrients availability and a correct phytohormones’ balance. These aspects are prerequisites for prompt germination at the end of the dormancy period and strictly depend on chloroplast metabolism and photosynthesis. In the present work, capsules of Nicotiana tabacum were grown in dark during the whole post-anthesis period. Among others, photosynthetic rates, dormancy, and phytohormones levels in seeds were found to be significantly different with respect to controls. In particular, etiolated capsules had expectedly reduced photosynthetic rates and, when compared to controls, their seeds had an increased mass and volume, an alteration in hormones level, and a consequently reduced dormancy. The present findings show how, during fruit development, the presence of light and the related fruit’s photosynthetic activity play an indirect but essential role for reaching seeds maturity and dormancy. Results highlight how unripe fruits are versatile organs that, depending on the environmental conditions, may facultatively behave as sink or source/sink with associated variation in seed’s reserves and phytohormone levels.

The Influence of Blue and Red Light on Seed Development and Dormancy in Nicotiana tabacum L.

“…The readout of this assessment was performed by analyzing the seed quality in terms of the germination kinetics of seeds collected from both photomorphogenetic capsules (PC) and skotomorphogenetic capsules (SC). While SC seeds had an almost absent dormancy with no significant differences between the three conditions tested, consistent with previous studies performed under white light in N. tabacum L. [28], seeds developed in PC presented different behaviors depending on the type of light under which the seed maturation occurred. In particular, PC seeds from capsules developed under white and red light showed a clear dormancy phase, while, unexpectedly, in PC seeds from capsules developed under blue light, the dormancy was absent, showing a skotomorphogenetic-like behavior.…”

“…The influence of phytochromes on seed dormancy, affecting hormone biosynthesis, levels, and balance, is also taken into account. Considering previous observations [28], the reported data may have relevant applications in crop production or plant preservation for species where, as in tobacco, etiolation of fruits induces bigger and heavier seeds with reduced dormancy.…”

“…In more general terms, the whole process of reproduction, including seed development and maturation, from anthesis to pollination first and from fruit ripening to embryogenesis after, is regulated by electromagnetic signals leading to new individuals capable of preserving the species [11,[24][25][26][27]. It was previously observed that etiolated fruits of Nicotiana tabacum L. plants produce larger and heavier seeds with altered levels of hormones which are responsible for its absence of dormancy [28]. These observations were connected to a change in the balance between the sink role of fruits, gaining photosynthates from leaves, and their "self-source" ability, by which fruits produce photosynthates through their photosynthetic parenchyma [28].…”

“…It was previously observed that etiolated fruits of Nicotiana tabacum L. plants produce larger and heavier seeds with altered levels of hormones which are responsible for its absence of dormancy [28]. These observations were connected to a change in the balance between the sink role of fruits, gaining photosynthates from leaves, and their "self-source" ability, by which fruits produce photosynthates through their photosynthetic parenchyma [28]. In the present study, we focused our investigation by narrowing the visible band to the red (peak at 650 nm) and blue (peak at 430 nm) regions of the electromagnetic spectrum.…”

Epipactis tremolsii Seed Diversity in Two Close but Extremely Different Populations: Just a Case of Intraspecific Variability?

“…Therefore, our objective was to characterize seed morphology and weight, considering their ecological and functional importance. Preliminary microscopical observations, together with the scientific literature on the topic, suggested that seeds may differ among the two studied populations depending on the peculiar growth conditions characterizing one of them (PPS) [ 16 , 24 , 25 , 26 , 27 ]. To characterize seeds produced by PPS, a second population of the same species geographically close, and sharing the same climatic and ecological conditions (except for the soil pollution), was chosen for comparison (PCS hereafter, which stands for “plants growing on the control site”).…”