Development of Root Hairs is aligned with the Tolerance Trait of Cotton against the Infections of Rotylenchulus Reniformis, Plant Parasitic Nematode

Abstract

Plant parasitic nematodes (PPN) are major cotton pathogens, causing the annual yield of up to 10 % annually. Lately, reniform nematode (RN, Rotylenchulus reniformis) has become a major threat to the cotton farming industry across the southeastern US region. However, current pest management programs lack a) resistant cultivar, b) efficacious rotation crop, and c) effective and low cost nematicide, and is in urgent need of breakthrough but it is not necessarily forthcoming due to a narrow genetic diversity in the cotton cultivars and germplasm, as well as little knowledge on the pathophysiology of cotton-PPN interactions. Generally used to tag or probe stained targeted materials, fluorescent chemical compounds are useful in most -if not all- areas of basic and applied sciences. Epi-fluorescence microscopy unveiled that RN produce autofluorescence compounds in intestinal areas. Characterization techniques were implemented to better understand multifluorescent molecule including observational studies to determine autofluorescence resides in intestinal tract and affluent throughout lifecycle. Stabilization tests incubating autofluorescence in various H2O2, DTT and pH concentrations using the Cytation 3 Image Reader TM, showed to be overall stable. Structural identification using high performance liquid chromatography, mass septectomy and nuclear magnetic resonance was found to be Sulfonium, [(17β) -3-ethoxyestra-1,3,5(10)-trien-17-yl]ethylmethyl-(9CI). Hypersensitive response (HR) is the most eminent and effective innate defense system in plants, characterized by the rapid programed cell death around the infection/feeding sites. It has long been proposed in the research field of nematology that HR is developed upon and limits the establishment and spread of PPN infections. However, our real-time ‘live’ imaging between RN and cotton lines of tolerant, hypersensitive and susceptible phenotypes has failed to corroborate the old hypothesis. Instead, we observed that the tolerance line developed significant increased numbers of root hairs compared to hypersensitive and susceptible lines, suggesting that root growth and/or root hair development are related to plant tolerance against PPN infections. Moving forward, we have employed a system biology approach to discern i) the tolerance associated genes and ii) if those genes are involved in root morphology by analyzing differential transcriptomes between the tolerant and susceptible cotton lines before and after nematode infections.