Cytohistological and cytochemical features of the seeds of Malus domestica Borkh exposed to spring frosts

Abstract

Malus domestica Borkh cv. Golden Delicious trees, exposed to spring frost, showed the occurrence of seeds with white (W), spotted (S) and black (B) integuments, with a different distribution, amount and damage in shedding and non-shedding fruits at several times after anthesis. While B seeds were completely degenerated, the S seeds showed hystological and cytochemical features that included a precocious embryo development stage, an embryonal cells shrinkage, an absence of reserves in the suspensor, endosperm and integuments, and a probable block of the routing of reserves, as a consequence of spring frost damages. All these features are the same occurring in seeds undergoing to natural abscission phenomenon and in the W seeds of shedding fruits observed in previous years. The S seeds damage is certainly attributable to meteorological events, because the S seeds were never found until the occurrence of the spring frosts. On the contrary, the damage in theW seeds, which do not show external symptoms in shedding fruits, may be due on the one hand to meteorological stress, and on the other hand to endogenous stress caused by natural abscission process. At 60 days post anthesis, at the end of fruit-set, the ripening fruits show a mean number of five well developed W seeds in normal cytohistological conditions. The data are discussed in relation to the general problem of natural abscission of immature fruits.

Arsenic-induced morphogenic response in roots of arsenic hyperaccumulator fern Pteris vittata

“…Similar effects on root anatomy have been pointed out in other plant systems following cadmium exposure (for a recent erudite review see [18]), in Arabidopsis Cu-treated seedlings [19] and in Malus immature fruits in which precocious cell differentiation was related to both developmental and environmental stress [20,21]. Our results also show that 250-334 M of As induce an increase in the frequency and in the length of root hairs.…”

Pre‐dispersal seed predation could help explain premature fruit drop in a tropical forest

“…For example, changes in resource availability, through mechanisms such as herbivory (Stephenson, 1980), leaf shading (Einhorn & Arrington, 2018) and drought (Nussbaumer et al, 2020; Pérez‐Pérez et al, 2008; Reichardt et al, 2020), can trigger premature fruit drop due to competition for resources among fruits (Bawa & Webb, 1984; Goubitz et al, 2002; Stephenson, 1981). Developmental or genetic abnormalities (Bradbury, 1929; Forino et al, 1987; Kraus, 1915), pollen quality (Goubitz et al, 2002) and damage to fruits through abiotic means, for example frost (Rodrigo, 2000; Rodrigo et al, 2006; Tagliasacchi et al, 2006), can trigger an individual to drop fruits which are unlikely to reach maturity and thereby minimise the cost to the parent plant (Stephenson, 1981). Damage by natural enemies can also lead to premature drop, often through seed/fruit predation or pathogen attack (Akinsanmi et al, 2016; Boucher & Sork, 1979; Planes et al, 2014).…”