Performance of wheat crops with different chromosome ploidy: root-sourced signals, drought tolerance, and yield performance

Abstract

Pot-culture experiments were carried out to estimate the role of non-hydraulic root signals (nHRS) and the relation of these signals to drought tolerance and grain yield formation under drought stress in six wheat varieties. These were two modern hexaploid wheat (Triticum aestivum L., AABBDD) Plateau602 and Longchun8139-2, two diploid wheat (Triticum monococcum L., AB) MO1 and MO4, and two tetraploid wheat (Triticum dicoccum Schuebl L., AABB) DM22 and DM31. In the two diploid relatives, the nHRS was switched on and off at a soil water content (SWC) of approximately 53-45% field water capacity (FWC). In contrast, in the modern hexaploid varieties, Longchun8139-2 and Plateau602 the nHRS occurred between a SWC of about 71 and 35% FWC, a much wider soil moisture range. The two tetraploid relatives, DM22 and DM31, were generally intermediate. The nHRS threshold range in SWC also narrowed as all six varieties went through successive developmental stages from shooting to grain filling. The two hexaploid wheat varieties had the longest duration of survival after the water supply ceased, and the best yield stability under drought stress, similar to with tetraploid wheat varieties; the diploid wheat varieties were least robust. These two parameters were both significantly correlated with the nHRS soil moisture threshold range (r=0.9456** and 0.8608*, respectively). Based on these patterns, we propose a "triple Z" model to describe the features of non-hydraulic stomatal sensitivity versus soil drought in wheat growth.

Chromosome doubling can increase heat tolerance in Lonicera japonica as indicated by chlorophyll fluorescence imaging

“…Compared to diploids, chromosome doubling (polyploidy) is often associated with increases in leaf thickness and area (Xu et al 2010) as well as in numbers of shoots and flowers (Xiong et al 2006, Li et al 2009). These anatomical and morphological variations generally lead to different physiological traits and ecological adaptations, e.g., higher drought tolerance (Li et al 1996, Xiong et al 2006, Li et al 2009).…”

“…These anatomical and morphological variations generally lead to different physiological traits and ecological adaptations, e.g., higher drought tolerance (Li et al 1996, Xiong et al 2006, Li et al 2009). Chromosome doubling can increase drought resistance in Lonicera japonica in relation to leaf anatomy improvement (Li et al 2009).…”

Regulation of root system behavior by abiotic stress

“…It has been suggested that the reduction of the lateral roots formation may be caused by the suppression of the activation of the lateral root's meristem, not because of the reduction of the initiation in the lateral root per se (9,10). Mutants with alterations in the development of lateral roots respond differently to drought stress (9,13). Suppression of the development of lateral roots by drought has been widely accepted as an adaptive response to ensure the plant's survival under unfavorable growing conditions (13).…”

“…Mutants with alterations in the development of lateral roots respond differently to drought stress (9,13). Suppression of the development of lateral roots by drought has been widely accepted as an adaptive response to ensure the plant's survival under unfavorable growing conditions (13). Nevertheless new lateral root formation and/or lateral root growth as well as the differentiation/elongation of root hairs lead to a considerable increase of the overall absorption surface (11).…”

“…The decrease in water potential of roots, not leaves, caused by salinity is the factor that triggers the production of ABA in different species (23). A condition of mild osmotic stress also inhibits the lateral root's formation in a dependent way of ABA (9,10,13,24). For the case of Arabidopsis, the reduced water availability dramatically inhibits the formation of lateral roots of the lateral primordium, while the initiation of lateral roots is not affected.…”