ABSTRACT
Domesticated strawberry is susceptible to sudden frost episodes, limiting the productivity of this cash crop in regions, where they are grown during early spring. In contrast, the ancestral woodland strawberry (Fragaria vesca) has successfully colonised many habitats of the Northern Hemisphere. Thus, this species seems to harbour genetic factors promoting cold tolerance. Screening a germplasm established in frame of the German Gene Bank for Crop Wild Relatives we identified, among 70 wild accessions, a pair contrasting with respect to cold tolerance. By following the physiological, biochemical, molecular, and metabolic responses of this contrasting pair, we identified the transcription factor Cold Box Factor 4 and the dehydrin Xero-2 as molecular markers associated with superior tolerance to cold stress. Overexpression of GFP fusions with Xero-2 in tobacco BY-2 cells conferred cold tolerance to these recipient cells. A detailed analysis of the metabolome for the two contrasting genotypes allows to define metabolic signatures correlated with cold tolerance versus cold stress. This work provides a proof-of-concept for the value of crop wild relatives as genetic resources to identify genetic factors suitable to increase the stress resilience of crop plants.
ABSTRACT
In this study we tested the hypotheses that root classes would exhibit distinctive anatomical and architectural responses to drought stress, and that those responses would vary along the root axes. The root systems of four maize (Zea mays L.) sweet corn genotypes designated SC1, SC2, SC3 and SC4 were phenotyped under well-watered and drought treatments in greenhouse mesocosms, permitting increasing stratification of moisture availability as the drought progressed. Anatomical and architectural responses to drought were evaluated for each root class. Lignin distribution was assessed by image processing of UV-illuminated root cross-sections acquired by laser ablation tomography. The two cultivars with less biomass reduction under drought, SC3 and SC4, substantially enhanced lateral root development along the apical segments of axial roots when plants were grown with drought stress. These segments grew into the deeper part of the mesocosm where more moisture was available. Apical segments of the axial and large lateral roots from drought-stressed plants were thicker and had greater theoretical axial water conductance than basal segments, especially in SC3 and SC4. Basal segments of crown roots of SC3 and SC4 showed increased lignification of the stele under drought. Root anatomical and architectural responses to drought are complex and vary among cultivars and root classes, and along root axes. Drought-induced proliferation of lateral roots on apical segments of axial roots would be expected to enhance deep water acquisition, while lignification of axial roots could help preserve axial water transport.
Subject(s)
Droughts , Zea mays , Biomass , Plant Roots , WaterABSTRACT
BACKGROUND: The isolation of high-quality RNA from strawberry leaves and fruits is notoriously cumbersome. Both tissues are extremely rich in active secondary metabolites, as phenolics and pigments that inevitably perturb the isolation of RNA. Many protocols have been developed to address this problem. However, they are either costly, or time-consuming, in particular for high number of many plant samples. We describe here a new method with an easy-to-handle approach to obtain high-quality RNA from strawberry leaves and fruits. The method, referred to as double lysis, uses a novel combination of CTAB and Trizol protocols. RESULTS: Compared to conventional Trizol-dependent protocols, either used individually, or in a commercial spin-column kit, the new method yields RNA at lower costs, but of significantly improved quality. The RNA obtained by double lysis was very pure as indicated by 260/280 ratios of 2.06 (leaves) and 2.07 (fruits), while 260/230 ratio was 2.07 and 1.75, respectively. Also visually, RNA sediments from double lysis showed a white color, indicative of efficient elimination of polyphenolics and pigments. In contrast, traditional Trizol method produced reddish precipitates. The purity of RNA isolated by double lysis enabled successful removal of genomic DNA and, thus, allowed for more efficient cDNA synthesis and RT-PCR. In addition, the suggested method is able to yield RNA with fully preserved integrity from strawberry leaves, fruits in addition to petals and roots. CONCLUSION: Double lysis is a new RNA isolation protocol developed through the integrative coupling of CTAB and Trizol reagents. The method is cost-effective, robust, time-saving, and can cope even with recalcitrant plant tissues with high contents of phenolics and pigments, such as strawberry leaves and fruits.
