Ultrastructural aspects of the embryo and different endosperm compartments, inEruca sativaHill cv. Nemat (Brassicaceae) during Heart and Torpedo stages

Abstract

Vol. 63, no. 2: 197-210, 2010 The John Bingham Laboratory, NIAB. Huntingdon Road, Cambridge CB3 0LE, UK.Abstract -These observations are the fi rst on the ultrastructure of the embryo and the endosperm of Eruca sativa Hill. We investigated the cv. Nemat, which is characterized by a particularly high amount of lipids and glucosinolates. Our observations suggested that the thick and abundant micropylar endosperm, completely surrounding the suspensor, may be the main active source of nutrients for the embryo. This endosperm, like the central chamber endosperm, is particularly rich in functional chloroplasts and cellularizes later with respect to the other previously investigated Brassicaceae. The last (distal with respect to the embryo) suspensor cell exhibits important features related to the passage of nutrients, such as wall ingrowths. In fact these ingrowths appear as highly convoluted labyrinthine wall projections. Such ultrastructural features are typical of transfer cells. The accumulation stage in E. sativa cv. Nemat appears to occur early (Heart stage of embryo development, as Brassica napus). The endosperm compartment called Chalazal Endosperm Cyst (CEC), contributes actively to the embryo trophism during the Heart and Torpedo stages. This function is evident because of the high number of chloroplasts in the cyst and for the observed continuity between the CEC and the other endosperm compartments (CC endosperm and micropylar endosperm) in cv. Nemat. The morphology of the CEC appeared to be more similar to the pyriform shape sensu Brown et al., but with a more fl attened base with respect to the proposed examples, and without labyrinthine wall. The Chalazal Chamber appeared to be more similar to the Brown's type B in E. sativa. The presence of chloroplasts with a well developed thylakoid system indicates an active photosynthetic activity by the majority of the seed tissues. E. sativa leaves are normally harvested for food, while the seeds of cv. Nemat appear to be particularly rich in oil. The premature independence of seeds and fruits from the necessity of absorbing nutrients from the rest of the plant, could indicate the possibility of harvesting both leaves (earlier) and seeds (later) in this plant without compromising a full seed maturation.

Endoreplication and its consequences in the suspensor of Pisum sativum

“…They facilitate the transport of dissolved substances by increasing the contact surface of cells. This kind of cell walls was described in suspensors of numerous plant species, including Phaseolus, Capsella, Arabidopsis, Epilobium, Antirrhinum, Lathyrus, Scrophularia, Stellaria, Diplotaxis, Tropaeolum, Alyssum, Medicago, Alisma, Paphiopedilum, Sedum, Sempervivum, Jovibarba, Eruca , and Chenopodium (Alessio et al 2010; Kozieradzka-Kiszkurno et al 2012; López-Fernández and Maldonado 2013). In Pisum sativum and in Vicia faba , the suspensors have a very similar construction with cell wall ingrowths along their surfaces, which allow them to maintain contact with endosperm (Marinos 1970a, b; Johansson and Walles 1994).…”

Salt-Affected Rocket Plants as a Possible Source of Glucosinolates

“…For example, focusing on salt stress, salinity enhanced lycopene, vitamin C, and total phenolic concentration in tomato plants [ 17 ]. Plant species belonging to Brassicaceae are a natural source of glucosinolates, and Eruca sativa showed variation in glucosinolate concentration on the basis of genetic variability, as in the case of Eruca sativa cultivar Nemat [ 18 ].…”