Fruit dehiscence mechanism and release of dimorphic seeds with different germination properties in Commelina erecta.

Commelina erecta is a successful weed species. The aims of this study were to analyse the morpho-anatomy of the fruit and dimorphic seeds of the weed C. erecta, the dynamics and type of dormancy, and water entry. Flowers and fruits at different development stages were processed using standard anatomical techniques. Besides, experiments of imbibition, germinability and water entry were performed on both seed types. In the fruit of C. erecta, free and coated seeds are developed within dehiscent and indehiscent carpels, respectively. Dehiscent carpels open through a region of mechanical weakness in the dorsal vascular bundle. This region does not form in the indehiscent carpel. The main anatomical differences between the two seed types were observed in the testa and in the number of covering layers. Imbibition experiments showed that the covering of both seed types is water permeable, so these seeds lack physical dormancy and may exhibit physiological dormancy. Germinability experiments showed that the dormancy in free seeds is variable throughout the reproductive season, whereas, in coated seeds, it is high throughout the reproductive season. The embryotega is an area where the hardness of the seed coat is interrupted and facilitates water entry. Differences in the morpho-anatomy of carpels result in the formation of dimorphic seeds with different covering layers and different germination properties. These different properties allow some seeds germinate immediately after falling from the mother plant, and others to be incorporated into the seed bank. These results are useful for designing weed management strategies in agroecosystems.

In Vitro Antifungal Screening of Argentine Native or Naturalized Plants against the Phytopathogen Monilinia fructicola.

BACKGROUND: One of the main problems that fruit health has gone through in recent years is the problematic eradication of their fungal pathogens during crops or the post-harvest stage. This concerns the whole world because it represents huge production losses, fruit export restrictions, and consumer distrust. Consequently, new alternatives are sought to avoid the increasing use of fungicides that cause important damage to fruit consumers and the environment. One of the alternatives to solve this problem could be exploring plants and their active compounds applied to the treatment of fruit health. MATERIALS AND METHODS: This article describes peach production worldwide and particularly in Argentina, in addition to the main fungal rot that causes the greatest economic losses. Furthermore, experimental in-vitro studies of 69 extracts obtained from 18 plants growing in the central region of Argentina were displayed against the devastating fungus Monilinia fructicola, which greatly affects stone fruits. A simple and effective method developed in agar plate was applied to evaluate a large number of samples in a short time. RESULTS: The results showed that approximately 36% of the samples tested were strongly active against this pathogen, 12% were moderately active, and 52% demonstrated to be inactive. CONCLUSION: These findings support the possible use of natural products for fruit health and the importance of deepening in this field of science.

A comparative approach to understanding the ovule, seed, and fruit development in Bulbostylis (Cyperaceae: Cyperoideae: Abildgaardieae).

In the present work, we study the ovule, seed, and fruit development in six Bulbostylis species in order to characterize the genus in a comparative approach and to identify the characteristics that can be used in taxonomy and phylogeny. Flowers and fruits at different developmental stages were analyzed using LM and SEM after processing according to standard techniques. The species studied have the following: anatropous and bitegmic ovules, weak crassinucellar ovules, obturator of integumentary origin, monosporic embryo sac of the Polygonum type, nuclear endosperm, hypostase formation, seed coat formed by tanniferous endotegmen and exotesta, and Bulbostylis-type embryo. On the other hand, the pericarp development constitutes the main variation within Bulbostylis since the cells of the exocarp may or may not present starch grains, and their inner periclinal walls may be slightly or deeply concave depending on the degree of development of the mesocarp sclereids. In a taxonomic context, the results herein obtained are in conflict with studies which suggest infrageneric groupings based on fruit micromorphology, and also with the relationship among the Bulbostylis species based on molecular analysis. This work contributes to a better understanding of the reproductive anatomy and embryology in Bulbostylis, and reveals the first insights about the origin of multiple embryos in Cyperaceae. Given the frequent presence of polyembryony in Bulbostylis, and the poor mention of this condition in the family, this work highlights an aspect in the anatomy of Cyperaceae that must be re-explored.