Next Article in Journal
Inflammasomes as Targets for Adjuvants
Previous Article in Journal
Neurological Aspects of HIV-1/HTLV-1 and HIV-1/HTLV-2 Coinfection
Previous Article in Special Issue
CgSCD1 Is Essential for Melanin Biosynthesis and Pathogenicity of Colletotrichum gloeosporioides
Open AccessArticle

Persistent Calyxes in Postbloom Fruit Drop: A Microscopy and Microanalysis Perspective

1
Center of Nuclear Energy in Agriculture, University of São Paulo, Piracicaba 13400-970, Brazil
2
“Luiz de Queiroz” College of Agriculture, University of São Paulo, Piracicaba 13418-900, Brazil
3
The Brazilian Fund for Citrus Protection, Araraquara 14807-040, Brazil
*
Authors to whom correspondence should be addressed.
Pathogens 2020, 9(4), 251; https://doi.org/10.3390/pathogens9040251
Received: 27 February 2020 / Revised: 19 March 2020 / Accepted: 21 March 2020 / Published: 28 March 2020
Citrus postbloom fruit drop, caused by Colletotrichum spp., is an important disease in the Americas. The pathogen infects citrus flowers, produces orange-brown lesions on petals, and may cause the abscission of young fruit. In diseased flowers, the calyxes remain attached to the peduncle after the young fruit drop. No anatomical and microanalysis studies have been conducted to determine whether calyx tissues can be infected by Colletotrichum spp. and why calyxes remain attached to the peduncle. Based on light microscopy, we demonstrate that the ovary abscission zone exhibits a separation region composed of layers of thickened lignified walled cells, indicating that abscission involves the disruption of cell walls. The first layers of the protective zone (PZ) are composed of densely packed cells with suberized walls produced by the wound meristem. Beneath the PZ, there is a compact mass of small cells that accumulate starch grains. X-ray fluorescence microanalysis (µ-XRF) confirmed the increased accumulation of calcium in the receptacle of the persistent calyxes compared to non-inoculated citrus flowers. Moreover, the peduncle pith and the receptacle exhibit hypertrophied cells with thick walls that may be related to calyx retention. Fungal structures are not observed inside the persistent calyx tissues. View Full-Text
Keywords: calcium oxalate crystals; citrus; fungal disease; starch; µ-XRF calcium oxalate crystals; citrus; fungal disease; starch; µ-XRF
Show Figures

Figure 1

MDPI and ACS Style

Rodrigues Marques, J.P.; Bellato Spósito, M.; Amorim, L.; Sgarbiero Montanha, G.; Silva Junior, G.J.; Pereira de Carvalho, H.W.; Appezzato-da-Glória, B. Persistent Calyxes in Postbloom Fruit Drop: A Microscopy and Microanalysis Perspective. Pathogens 2020, 9, 251.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

1
Search more from Scilit
 
Search
Back to TopTop