
TY  - JOUR
A1  - Garthwaite, Alaina J. 
A1  - Bothmer, Roland von 
A1  - Colmer, Timothy D. 
T1  - Diversity in root aeration traits associated with waterlogging tolerance in the genus <emph type="2">Hordeum</emph>
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 2003
VL  - 30
IS  - 8
SP  - 875
EP  - 889
KW  - adventitious roots, aerenchyma, diversity, Hordeum vulgare, O2-deficiency, radial O2 loss, root porosity, wild Triticeae.
UR  - https://doi.org/10.1071/FP03058 
N2  - Growth, root aerenchyma, and profiles of radial O2 loss (ROL) along adventitious roots were evaluated in 35 &#39;wild&#39; Hordeum accessions and cultivated barley (H. vulgare L. ssp. vulgare) when grown in stagnant nutrient solution (deoxygenated and containing 0.1% agar). When grown in stagnant solution, accessions from wetland and &#39;intermediate&#39; habitats were superior, compared with accessions from non-wetland habitats, in maintaining relative growth rate, tillering, and adventitious root mass. Constitutive aerenchyma formation in adventitious roots was &#8805; 10% in 22 accessions (cf. H. vulgare at 2%). When grown in stagnant solution, aerenchyma was &#8805;  20% in the adventitious roots of 14 accessions (cf. H. vulgare at 12%). Variation among the accessions in the volume of aerenchyma formed when grown in aerated or stagnant solution was not determined by the waterlogging regime of the species&#39; natural habitat. However, the genus Hordeum comprises four genomes and when grown in stagnant solution accessions with the X genome formed, on average, 22% aerenchyma in adventitious roots (50 mm behind apex), whereas those with the H genome averaged 19%, and those with the Y or I genomes averaged 16 and 15%, respectively. Sixteen accessions formed a barrier to ROL in the basal region of adventitious roots when grown in stagnant solution. The formation of a barrier to radial O2 loss was predominant in accessions from wet habitats, and absent in accessions from non-wetland habitats. In addition, this trait was only present in accessions with the X or H genomes. The combination of aerenchyma and a barrier to ROL enhances the longitudinal diffusion of O2 within roots towards the apex. The possibility of a link between having a barrier to ROL and the X or H genomes in Hordeum species might, in future studies, enable a genetic analysis of this important trait. 
ER  -

