Leaf Carbon Isotope Discrimination as an Accurate Indicator of Water-Use Efficiency in Sunflower Genotypes Subjected to Five Stable Soil Water Contents

Leaf carbon isotope discrimination (CID ) has been suggested as an indirect tool for breeding for water‐use efficiency (WUE ) in various crops. This work focused on assessing phenotypic correlations between WUE and leaf CID and analysing genotypic variability in four sunflower genotypes grown in a greenhouse in pots with five different stable levels of soil water content (SWC ). We measured WUE at whole plant and leaf (intrinsic) level. At whole plant level, WUE was derived from the ratio of total dry aerial biomass (BM ) to cumulative water transpired (CWT ). At leaf level, intrinsic WUE was calculated as the ratio of light‐saturated CO 2 assimilation to stomatal conductance (A /gs) in younger expanded leaves. Significant differences among the four genotypes and the five SWC s were observed for whole plant and leaf WUE and CID . Strong negative correlations were observed between whole plant WUE and CID as well as between intrinsic WUE and CID with decreasing water availability. No relationships appeared between BM production and WUE or CID . Our results can help agronomists and breeders to evaluate sunflower lines with high WUE for adaptation to drought conditions and for reducing water consumption and crop water needs. Leaf CID appears to be a pertinent and valuable trait to select sunflower genotypes with high WUE

Hydraulic conductivity and contribution of aquaporins to water uptake in roots of four sunflower genotypes

This article evaluates the potential of intraspecific variation for whole-root hydraulic properties in sunflower. We investigated genotypic differences related to root water transport in four genotypes selected because of their differing water use efficiency (JAC doi: 10.1111/jac.12079. 2014). We used a pressure-flux approach to characterize hydraulic conductance (L 0 ) which reflects the overall water uptake capacity of the roots and hydraulic conductivity (Lp r ) which represents the root intrinsic water permeability on an area basis. The contribution of aquaporins (AQPs) to water uptake was explored using mercuric chloride (HgCl2), a general AQP blocker. There were considerable variations in root morphology between genotypes. Mean values of L 0 and Lp r showed significant variation (above 60% in both cases) between recombinant inbred lines in control plants. Pressure-induced sap flow was strongly inhibited by HgCl2 treatment in all genotypes (more than 50%) and contribution of AQPs to hydraulic conductivity varied between genotypes. Treated root systems displayed markedly different L 0 values between genotypes whereas Lp r values were similar. Our analysis points to marked differences between genotypes in the intrinsic aquaporin-dependent path (Lp r in control plants) but not in the intrinsic AQP-independent paths (Lp r in HgCl2 treated plants). Overall, root anatomy was a major determinant of water transport properties of the whole organ and can compensate for a low AQP contribution. Hydraulic properties of root tissues and organs might have to be taken into account for plant breeding since they appear to play a key role in sunflower water balance and water use efficiency

Analyse évolutive et fonctionnelle d une famille de facteurs de transcription à domaine TCP chez les plantes

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Supplementary File 4 (ML tree with bootstrap support)

Same phylogenetic tree as in supplementary file 3 including bootstrap from 100 replicates as branch support (newick format)

Records of Host-pathogen associations used in the study

We analyzed the 7101 records from the fungus-host distribution database (https://nt.ars-grin.gov/fungaldatabases/fungushost/fungushost.cfm) that served as a basis for our study on the Sclerotiniaceae. Host species were classified as crops (crop) according to the USDA Natural Resources Conservation Service database (https://plants.usda.gov/npk/main), other cultivated plants (cult), ornamental plants (orn) and “others”, including largely wild plant species (wild). A total of 37% of the Fungus-Host database entries were from the USA (US), 17% from Europe (Eur), leaving a total of 46% of the entries that were neither from the USA or Europe (Afr, Africa; Asia; Can, Canada; Oce, Oceania; SA, South America; ?, others). These distributions do not reveal a strong bias towards crops or USA/Europe records in the records used for this analysis

Data from: Shifts in diversification rates and host jump frequencies shaped the diversity of host range among Sclerotiniaceae fungal plant pathogens

The range of hosts that a parasite can infect in nature is a trait determined by its own evolutionary history and that of its potential hosts. However, knowledge on host range diversity and evolution at the family level is often lacking. Here, we investigate host range variation and diversification trends within the Sclerotiniaceae, a family of Ascomycete fungi. Using a phylogenetic framework, we associate diversification rates, the frequency of host jump events, and host range variation during the evolution of this family. Variations in diversification rate during the evolution of the Sclerotiniaceae define three major macro-evolutionary regimes with contrasted proportions of species infecting a broad range of hosts. Host-parasite co-phylogenetic analyses pointed towards parasite radiation on distant hosts long after host speciation (host jump or duplication events) as the dominant mode of association with plants in the Sclerotiniaceae. The intermediate macro-evolutionary regime showed a low diversification rate, high frequency of duplication events, and the highest proportion of broad host range species. Our findings suggest that the emergence of broad host range fungal pathogens results largely from host jumps, as previously reported for oomycete parasites, probably combined with low speciation rates. These results have important implications for our understanding of fungal parasites evolution and are of particular relevance for the durable management of disease epidemics

Supplementary Table 1

List of Sclerotiniaceae and Rutstroemiaceae species used for phylogenetic analysis and their corresponding host range. 1 refers to position in the tree shown in Figure 1; 2 refers to the code used in RASP analysis (Sup. Figure 5). NA, not applicable; Rutst., Rutstroemiaceae; Sclero. Sclerotiniaceae

Supplementary File 3 (ML tree with SH-aLRT support)

Phylogenetic tree of 200 Leotiomycete species including 161 Sclerotiniaceae and Rutstroemiaceae species used in Figure 1, obtained by maximum likelihood approach and featuring SH-aLRT branch support (newick format)

Supplementary File 5 (Chronotree Sclerotiniaceae)

Time calibrated phylogenetic tree of the 105 Sclerotiniaceae species used in Figure 2

Supplementary File 2 (ITS multiple sequence alignment)

Curated multiple ITS sequence alignment for 200 Leotiomycete species, including 105 Sclerotiniaceae and 56 Rutstroemiaceae species. This alignment includes 797 informative sites and was used to generate the phylogenetic tree shown in Figure 1 and downstream analyses (fasta format)