The structural characteristics and component differences of proanthocyanidins in brown and white cotton fibres were identified by nuclear magnetic resonance (NMR) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) analyses. Proanthocyanidins in brown and white cotton fibres were found to contain mainly procyanidin (PC) and prodelphidin (PD) units with 2, 3-cis form (epigallocatechin and epicatechin). However, part of the proanthocyanidins in the white cotton fibres were modified by acylation and were constitutively different from the proanthocyanidins in brown cotton fibres. The relative amount of PD was similar to that of PC in white cotton fibres, while proanthocyanidins in brown cotton fibres consisted mainly of PD units with a relative ratio of 9:1. In brown cotton fibres, the proanthocyanidin monomeric composition was consistent with the expression profiles of proanthocyanidin synthase genes, suggesting that anthocyanidin reductase represented the major flow of the proanthocyanidin biosynthesis pathway. In addition, the structural characteristics and component differences of proanthocanidins in brown and white cotton fibres suggested that quinones, the oxidation products of proanthocyanidins, were the direct contributors to colour development in brown cotton fibre. This was demonstrated by vanillin-HCl staining and Borntrager's test. Collectively, these data demonstrated that the biosynthesis of proanthocyanidins is a crucial pigmentation process in brown cotton fibre, and that quinones may represent the main pigments contributing to formation of the the brown colour. This study revealed the molecular basis of pigmentation in brown cotton fibres, and provided important insights for genetic manipulation of pigment production in cotton fibres.
Verticillium wilt caused by Verticillium dahliae is a common soil-borne disease worldwide, affecting many economically important crop species. Soil microbes can influence plant disease development. We investigated rhizosphere and endosphere microbiomes in relation to cotton cultivars with differential susceptibility to Verticillium wilt. Soil samples from nine cotton cultivars were assessed for the density of V. dahliae microsclerotia; plants were assessed for disease development. We used amplicon sequencing to profile both bacterial and fungal communities. Unlike wilt severity, wilt inoculum density did not differ significantly among resistant and susceptible cultivars. Overall, there were no significant association of alpha diversity indices with wilt susceptibility. In contrast, there were clear differences in the overall rhizosphere and endosphere microbial communities, particularly bacteria, between resistant and susceptible cultivars. Many rhizosphere and endosphere microbial groups differed in their relative abundance between resistant and susceptible cultivars. These operational taxonomic units included several well-known taxonomy groups containing beneficial microbes, such as Bacillales, Pseudomonadales, Rhizobiales, and Trichoderma, which were higher in their relative abundance in resistant cultivars. Greenhouse studies with sterilized soil supported that beneficial microbes in the rhizosphere contribute to reduced wilt development. These findings suggested that specific rhizosphere and endosphere microbes may contribute to cotton resistance to V. dahliae.
Verticillium wilt is a soil-borne disease, and severely limits the development of cotton production. To investigate the role of endophytic fungi on Verticillium wilt, CEF-818 (Penicillium simplicissimum), CEF-714 (Leptosphaeria sp.), CEF-642 (Talaromyces flavus.) and CEF-193 (Acremonium sp.) isolated from cotton roots were used to assess their effects against cotton wilt disease caused by a defoliating V. dahliae strain Vd080. In the greenhouse, all treatments significantly reduced disease incidence and disease index, with the control efficacy ranging from 26% (CEF-642) to 67% (CEF-818) at 25 days (d) after inoculation. In the disease nursery, compared to controls (with disease incidence of 33.8% and disease index of 31), CEF-818, CEF-193, CEF-714 and CEF-642 provided a protection effect of 69.5%, 69.2%, 54.6% and 45.7%, respectively. Especially, CEF-818 and CEF-714 still provided well protection against Verticillium wilt with 46.9% and 56.6% or 14.3% and 33.7% at the first peak of the disease in heavily infected field, respectively (in early July). These results indicated that these endophytes not only delayed but also reduced wilt symptoms on cotton. In the harvest, the available cotton bolls of plant treated with CEF-818 and CEF-714 increased to 13.1, and 12.2, respectively. And the seed cotton yield significantly increased after seed bacterization with CEF-818 (3442.04 kg/ha) compared to untreated control (3207.51 kg/ha) by 7.3%. Furtherly, CEF-818 and CET-714 treatment increased transcript levels for PAL, PPO, POD, which leads to the increase of cotton defense reactions. Our results indicate that seed treatment of cotton plants with CEF-818 and CET-714 can help in the biocontrol of V. dahliae and improve seed cotton yield in cotton fields. This study provided a better understanding of cotton-endophyte interactions which will aid in developing effective biocontrol agents for Verticillium wilt of cotton in futhre.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.