Use of Lentinan To Control Sharp Eyespot of Wheat, and the Mechanism Involved

Abstract

Lentinan (LNT), a complex polysaccharide with a β-(1→3)-linked backbone of d-glucose residues, has been reported to inhibit plant diseases. Our objective was to explore the efficacy and action mechanism of LNT used as a seed dressing to control sharp eyespot of wheat. Seed dressing promoted wheat growth. At control germination rates of 50%, 8 g of LNT/100 kg of seeds of the Jimai 22, Shannong 23, and Luyuan 502 cultivars significantly increased seed germination to 54%, 52%, and 51%, respectively. Seven days after emergence, the heights and root activity of wheat treated with LNT were significantly greater than those of controls. These effects were dose-dependent. At this time, the plant heights of Jimai 22, Shannong 23, and Luyuan 502 cultivars were 9.52, 8.52, and 10.52 cm, respectively, significantly higher than that of the controls. LNT prevented the development of wheat sharp eyespot. In the highly susceptible Jimai 22 cultivar, sharp eyespot development was reduced by 33.7%, 31.9%, and 30.4% at 7, 14, and 21 days after germination. LNT somewhat increased phenylalanine ammonia-lyase, peroxidase, and superoxide dismutase activity; reduced the malondialdehyde content; increased chlorophyll a and b levels; and enhanced the root vigor of wheat. These effects peaked 7 days after germination. LNT increased transcription of the genes encoding alternative oxidase (AOX) and β-1,3-glucanase (GLU), the salicylic acid signaling pathway-related gene NbPR1a, and the sharp eyespot resistance-related gene RS33. A significant dose-effect relationship was evident in terms of AOX transcription; we thus speculate that AOX may be the target gene.

Development and Application of Seed Coating Agent for the Control of Major Soil-Borne Diseases Infecting Wheat

“…In wheat-producing regions, more than 30 kinds of pests and diseases occur on wheat every year, of which soil-borne diseases are one of the greatest constraints to wheat productivity [4]. Wheat sharp eyespot caused by Rhizoctonia cerealis van der Hoeven [5], root rot by Bipolaris sorokiniana [6], and wheat take-all by Gaeumammomyces graminis var. tritici [7] are the important typical soil-borne diseases threatening wheat production worldwide.…”

Use of Lentinan and Fluopimomide to Control Cotton Seedling Damping-Off Disease Caused by Rhizoctonia solani

“…Examples include, chitosan oligosaccharide (COS) obtained by hydrolysis of chitosan, which can be used as an effective inducer of plant immunity [37]; oligosaccharides can seriously reduce the severity of cucumber mosaic virus (CMV) [38]; kelp polysaccharides can induce tobacco resistance to carrot soft rot Erwinia [39], and also significantly increase expression levels of defense-related genes LOX and GST in grape leaf cells [40]; LNT can regulate plant growth, induce the activation of the plant defense response, enhance the plant's resistance against diseases, and thereby induce the plant's resistance to plant viruses and fungal diseases [41,42]. In addition, Ganoderma Lucidum polysaccharide can effectively control cotton fusarium wilt [9] and LNT can effectively control sharp eyespot of wheat [32].…”

“…Hexaconazole (CAS: 79983-71-4, 96.7% purity), pyraclostrobin (CAS: 175013-18-0, 98.0% purity), fludioxonil (CAS: 131341-86-1, 98.0% purity), carbendazim (CAS: 10605-21-7, 98.0% purity), difenoconazole (CAS: 119446-68-3, 97% purity) and fluopimomide (CAS: 1309859-39-9, 98.0% purity) were provided from College of Plant Protection, Key Laboratory of Pesticide Toxicology and Application Technique, Shandong Agricultural University, Tai'an, Shandong, China. Extraction and purification of LNT were performed according to Zhang et al [9]. Carbendazim and other fungicides stock solutions (1 × 10 4 mg L −1 ) were prepared with 3% hydrochloric acid and acetone, respectively, and stored at 4 • C.…”

“…CMDA (µmol L −1 ) = 6.45 (A 532 − A 600 ) − 0.56 A 450 , this yielded absolute MDA concentrations (µmol g −1 R. solani) [35]. Cotton leaf tissue exposed to 100 mg L −1 LNT was collected at 7 days after seedling emergence and stored at −80 • C. RNA extraction was performed as described by Zhang et al [9]. Draw a standard curve using a series of standards with known initial copy numbers to establish a linear relationship between the Ct value and the logarithm of the initial template amount.…”

“…Lentinan (LNT) is a new type of natural functional polysaccharide isolated from Lentinus edodes fruiting body that can reduce damage caused by oxygen free radicals to organelles and has a good inhibitory effect on plant diseases [9]. Lentinan could promote the elongation of the roots but has no effect on dry weight since the concentration of lentinan in plant is low [10].…”