Differential response of wild and cultivated wheats to water deficits during grain development: changes in soluble carbohydrates and invertases

Abstract

Wheat, staple food crop of the world, is sensitive to drought, especially during the grain-filling period. Water soluble carbohydrates (WSCs), stem reserve mobilization and higher invertase activity in the developing grains are important biochemical traits for breeding wheat to enhance tolerance to terminal drought. These traits were studied for three accessions of Triticum dicoccoides(a tetraploid wheat progenitor species) -acc 7054 (EC 171812), acc 7079 (EC 171837) and acc 14004 (G-194-3 M-6 M) selected previously on the basis of grain filling characteristics. Check wheat cultivars-PBW-343 (a popular bread wheat cultivar for irrigated environments) and C-306 (widely adapted variety for rain-fed agriculture) were also included in this set. Analysis of variance revealed significant genotypic differences for the content of water soluble carbohydrates, activity of acid invertase and alkaline invertase. Acc 7079 was found to be a very efficient mobilizer of water soluble carbohydrates (236.43 mg g -1 peduncle DW) when averaged over irrigated and rain-fed conditions. Acid invertase activity revealed marked genotypic differences between wild and cultivated wheats. Alkaline invertase activity was highest in Acc 7079 when pooled across both the environments. On the whole, acc 7079 qualifies as a suitable donor for enhancing tolerance of bread wheat to terminal drought. The association of physiobiochemical differences observed with grain filling attributes on one hand and molecular markers on the other could be of use in improving wheat for water stress conditions.

A proteomic analysis of grain yield-related traits in wheat

“…Invertases were shown to have a role in the control of cell differentiation and plant development ( Silva and Ricardo 1992 ; Sturm 1999 ). For example, in a study on water-soluble carbohydrate and remobilization to the grains, significant difference of acid invertase activity was reported between wild and cultivated wheats ( Yadhu et al 2015 ). Functional analyses have shown that the rice GRAIN INCOMPLETE FILLING 1 gene encodes a cell wall invertase which has a role in carbon partitioning during early grain filling ( Wang et al 2008 ).…”

Bread wheat progenitors: Aegilops tauschii (DD genome) and Triticum dicoccoides (AABB genome) reveal differential antioxidative response under water stress

“…T. dicoccoides accession 7079 revealed highest constitutive levels of APX and GR. It had suffered lower membrane damage, maintained higher proline content in leaves at tillering stage, exhibited efficient mobilization of stem reserves and higher acid and alkaline invertase activity in developing grain (Suneja et al 2015). In addition to higher constitutive levels, metabolic plasticity in terms of a modest increase in the activity of SOD, APX and GR was evident in T. dicoccoides accession 7054 which eventually translated into a 16% increase in grain weight under water stress conditions.…”

“…Accession 14004 had shown greater membrane stability but a relatively poorer phenotypic response (Suneja 2014). These T. dicoccoides accessions had also been evaluated for the activity of key carbohydrate metabolizing enzymes under irrigated and rain-fed conditions (Suneja et al 2015).…”

Staying Alive or Going to Die During Terminal Senescence—An Enigma Surrounding Yield Stability

“…Moreover, a significant drop in peduncle elongation further increased floret sterility under drought stress mainly due to a shortage of assimilates and competition between stem and ear for the depleted assimilate pool ( Jagadish et al, 2010 ). Two key processes that could determine the viability of reproductive organs and thereby grain numbers are the availability of sufficient amounts of sugars through maintained photosynthesis and efficient sucrose cleavage pathway to channel gradients of hexoses to the developing reproductive tissues ( Ji et al, 2010 ; Dolferus et al, 2011 ; Suneja et al, 2015 ). Hence, mechanisms that impact grain numbers through key physiological events including altered male and female gametophyte development, pollen and ovule viability, fertilization events and optimum seed filling are key drivers for maintaining yield under stress (Figure 1 ).…”