Garthwaite Alaina J, Bothmer Roland von, Colmer Timothy D
School of Plant Biology, Faculty of Natural and Agricultural Sciences, The University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009, Australia.
Genetic Resources Group, Department of Crop Sciences, Swedish University of Agricultural Sciences, SE-230 53 Alnarp, Sweden.
Funct Plant Biol. 2003 Sep;30(8):875-889. doi: 10.1071/FP03058.
Growth, root aerenchyma, and profiles of radial O loss (ROL) along adventitious roots were evaluated in 35 'wild' 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 'intermediate' 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 ≥10% in 22 accessions (cf. H. vulgare at 2%). When grown in stagnant solution, aerenchyma was ≥ 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' 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 O 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 O 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.
在35份“野生”大麦种质和栽培大麦（H. vulgare L. ssp. vulgare）于停滞营养液（脱氧并含有0.1%琼脂）中生长时，对其生长、根通气组织以及不定根上径向氧损失（ROL）的分布情况进行了评估。当在停滞溶液中生长时，来自湿地和“中间”生境的种质在维持相对生长速率、分蘖和不定根质量方面优于来自非湿地生境的种质。22份种质的不定根中组成型通气组织形成率≥10%（相比之下，栽培大麦为2%）。当在停滞溶液中生长时，14份种质的不定根中通气组织≥20%（相比之下，栽培大麦为12%）。在通气或停滞溶液中生长时，种质间通气组织形成量的差异并非由该物种自然生境的涝渍状况决定。然而，大麦属包含四个基因组，当在停滞溶液中生长时，具有X基因组的种质不定根（根尖后50毫米处）平均形成22%的通气组织，具有H基因组的种质平均为19%，具有Y或I基因组的种质分别平均为16%和15%。16份种质在停滞溶液中生长时在不定根基部区域形成了ROL屏障。在停滞溶液中生长时，径向氧损失屏障的形成在来自湿润生境的种质中占主导，而在来自非湿地生境的种质中不存在。此外，该性状仅存在于具有X或H基因组的种质中。通气组织和ROL屏障的组合增强了根内氧气向根尖的纵向扩散。在未来的研究中，大麦物种中ROL屏障与X或H基因组之间存在联系的可能性或许能够对这一重要性状进行遗传分析。
