Novel barley (Hordeum vulgare L.) germplasm resistant to acidic soil

Abstract

Improving the resistance of barley (Hordeum vulgare L.) to acidic soils is an important goal of several barley breeding programs around the world. The identification and utilisation of novel barley sources resistant to aluminium (Al) may provide a significant and rapid advance towards that goal. Barley standards and screening protocols for selecting barley germplasm resistant to Al in nutrient solution and acidic soil were reevaluated. The assays used were quantitative in nature and were suitable for genotypic- and seedling-based selections. Although there was a broad agreement between the solution culture assays and soil assays in the ranking of genotypes it obscured the fact that misclassification of genotypes is common. Brindabella was shown to be better suited than Dayton (the current barley standard resistant to Al) as the Australian standard for resistance to acidic soils. A seedling-based Al pulse-recovery assay and an acidic soil assay were used to characterise 41 genotypes from the South and East Asian Barley Core Collection (SEA-BCC). In addition, in the acidic soil assays several standard barley and wheat genotypes were included. Three SEA-BCC genotypes were more resistant than Dayton to acidic soil while several others were similar to Dayton. The most resistant SEA-BCC genotypes Honen, Ohichi and Zairai Tanbo were of Japanese origin. Misclassification of barley genotypes and wheat genotypes for resistance to soil acidity between solution culture and acid soil assay provided strong evidence for the unsuitability of solution culture assay. Although in solution culture several barley genotypes were sensitive relative to wheat, in acidic soil they were not different from wheat. While the quest for resistant barley to acidic soils similar or better than resistant wheat still continues, it may be an unnecessary endeavour.

Enhancing the aluminium tolerance of barley by expressing the citrate transporter genes SbMATE and FRD3

“…This stimulation of growth in acid conditions by low levels of Al 3+ has been observed previously and is interpreted as Al 3+ alleviating H + toxicity ( Kinraide et al , 1992 ). Moroni et al (2010) screened a range of cereal genotypes for Al 3+ tolerance and concluded that the rankings differed between hydroponic and field trials because barley appeared more tolerant in soil than the hydroponic screens. While the present study found broad agreement between the results in hydroponics and short soil experiments, longer field trials will be necessary to assess how effective these transgenes are in improving grain yield on acid soils.…”

The barley MATE gene, HvAACT1, increases citrate efflux and Al3+ tolerance when expressed in wheat and barley

“…Barley is among the most Al 3+ -sensitive cereal crops and, although genotypic variation exists within this species, Al 3+ -tolerant genotypes are more sensitive than Al 3+ -tolerant wheat plants. A seedling-based screen of diverse barley genotypes identified the cultivars Kearney and 'Golden Promise' as being Al 3+ sensitive and 'Dayton' and several Japanese cultivars as being among the most tolerant (Moroni et al, 2010). Hexaploid wheat has a greater variation in Al 3+ tolerance than barley, with differences in root growth that can vary by .10-fold in short-term growth assays or in field screens (Rengel and Jurkic, 1992;Bona et al, 1993;Ryan et al, 1995;Pinto-Carnide and Guedes-Pinto, 1999;Garvin and Carver, 2003;Tang et al, 2003;Raman et al, 2008;Dai et al, 2009).…”

Biotechnological Solutions for Enhancing the Aluminium Resistance of Crop Plants

“…Even barley, which is considered one of the most Al 3+ -sensitive of the small-grained Triticeae, displays significant genotypic variability. A seedling-based screen of barley lines in the South and East Asian Barley Core Collection identified Kearney and Golden Promise as sensitive to Al 3+ while Dayton and several Japanese cultivars (Honen, Ohichi and Zairai Tanbo) were among the most resistant (Moroni et al 2010). A greater variation occurs in hexaploid or bread wheat where differences in root growth can vary by ten-fold or more in short-term growth assays or in field screens (Bona et al 1993;Cosic et al 1994;Dai et al 2009;Foy 1996;Garvin and Carver 2003;Pinto-Carnide and Guedes-Pinto 1999;Raman et al 2008;Rengel and Jurkic 1992;Ryan et al 1995a;Tang et al 2003).…”