Developmental features of cotton fibre middle lamellae in relation to cell adhesion and cell detachment in cultivars with distinct fibre qualities

Abstract

BackgroundCotton fibre quality traits such as fibre length, strength, and degree of maturation are determined by genotype and environment during the sequential phases of cotton fibre development (cell elongation, transition to secondary cell wall construction and cellulose deposition). The cotton fibre middle lamella (CFML) is crucial for both cell adhesion and detachment processes occurring during fibre development. To explore the relationship between fibre quality and the pace at which cotton fibres develop, a structural and compositional analysis of the CFML was carried out in several cultivars with different fibre properties belonging to four commercial species: Gossypium hirsutum, G. barbadense, G. herbaceum and G. arboreum.ResultsCotton fibre cell adhesion, through the cotton fibre middle lamella (CFML), is a developmentally regulated process determined by genotype. The CFML is composed of de-esterified homogalacturonan, xyloglucan and arabinan in all four fibre-producing cotton species: G. hirsutum, G. barbadense, G. herbaceum and G. arboreum. Conspicuous paired cell wall bulges are a feature of the CFML of two G. hirsutum cultivars from the onset of fibre cell wall detachment to the start of secondary cell wall deposition. Xyloglucan is abundant in the cell wall bulges and in later stages pectic arabinan is absent from these regions.ConclusionsThe CFML of cotton fibres is re-structured during the transition phase. Paired cell wall bulges, rich in xyloglucan, are significantly more evident in the G. hirsutum cultivars than in other cotton species.

Metabolism of polysaccharides in dynamic middle lamellae during cotton fibre development

“…It is not altogether clear whether these bulges represent points of adherence involved in postgenital fusion, or whether they alternatively mark the onset of CFML dissolution eventually leading to detachment. What was observed by Hernandez-Gomez et al (2017) was that xyloglucan accumulated and the arabinan epitope LM13 disappeared from the paired cell wall bulges, coinciding with the transitional phase preceding secondary cell wall deposition and fibre detachment. Cell wall polymer dynamics is affected by both the rate of deposition and the rate of degradation.…”

“…While the cotton species and varieties studied here did not develop in perfect synchrony, the transition was remarkably consistent using the peak in easily extractable callose as a marker of the transition (Fig.1). However, early developmental events differed greatly in particular among varieties as demonstrated in the studies of the CFML by Hernandez-Gomez et al (2017). The observed cell wall metabolic processes are incompletely understood at present, and it is not altogether clear which processes contribute to adhesion and which to detachment.…”

“…MUR3 and CslC4 were quite lowly expressed in G. barbadense PimaS7 but the CoMPP analyses did not indicate absence of CDTA-extractable xyloglucan in PimaS7. The CoMPP-data suggests that this xyloglucan population existed from CFML deposition onwards and that its detection by Hernandez-Gomez et al (2017), in particular during CFML metabolism, is most likely a result of improved antibody accessibility. CDTA extractable xyloglucan declines sharply while the NaOH extractable xyloglucan declines more slowly.…”

“…A detailed immunohistochemical investigation of CFML by Hernandez-Gomez et al (2017) revealed the occurrence of bulges in the CFML that appeared as pairwise spots in one cultivar (FM966) but were present in all of four varieties investigated. It is not altogether clear whether these bulges represent points of adherence involved in postgenital fusion, or whether they alternatively mark the onset of CFML dissolution eventually leading to detachment.…”

Distribution of cell-wall polysaccharides and proteins during growth of the hemp hypocotyl

“…The structural and compositional analysis of the middle lamella reveals that it is composed of various sugars, such as homogalacturonan, xyloglucan, and arabinan. While xyloglucan is abundant in bulges of the cell wall, arabinans are absent in these regions (Hernandez-Gomez et al 2017). Modifications in arabinan levels were also observed during floral abscission, as a strong increase of xyloglucan, galactan, and arabinan was observed during fruit development in tomato (Iwai et al 2013).…”