Participation of Green Organs to Grain Filling in Triticum turgidum var durum Grown under Mediterranean Conditions

Abstract

In wheat, flag leaf, stem, chaff and awns contribute to grain filling through photosynthesis and/or re-mobilization. Environmental and genetic effects on the relative contribution of each organ were examined by analyzing the consequences of sink-source manipulations (shading and excision) and by comparing carbon isotope discrimination (Δ) values in dry matter (at maturity) and sap (two weeks after anthesis) in six durum wheat genotypes grown in two contrasting seasons. The contribution of flag leaf, stem, chaff and awns to grain filling, estimated by sink-source manipulations, highly varied with the season. The contribution of ear photosynthesis and re-mobilization from the stem increased with post-anthesis water stress. They showed a large genetic variation that was, however, not clearly associated to morphological characteristics of ear and stem. Isotopic imprints of chaff on grain Δ were identified as a possible surrogate of the destructive and cumbersome sink-source manipulations to evaluate the contribution of carbon assimilated in ears or re-mobilized from stem. This might facilitate screening of genetic resources and allow the combining of favourable drought tolerance mechanisms in wheat.

Potential Effects of Awn Length Variation on Seed Yield and Components, Seed Dispersal and Germination Performance in Siberian Wildrye (Elymus sibiricus L.)

“…The contribution of awns to kernel filling and grain yield was also supported by Rut Sachez-Bragado et al [14]. In contrast, awns showed no significant or lower contribution to grain filling and grain yield increment compared to flag leaves when awn removal experiments were performed [30]. These results indicate that the contribution of awns on seed yield depends not only on its direct and indirect interactions with seed yield components but also on morphological features of awns.…”

Mechanisms Regulating the Dynamics of Photosynthesis Under Abiotic Stresses

“…Additionally, the impaired expression of SGR (STAY-GREEN), a chloroplast targeted protein that act as key regulator of Chl degradation and NYC1 (NON-YELLOW COLORING 1) under heat and drought stress inhibit the process of chlorophyll degradation and retention in green soybean seeds. In wheat, the relative contribution of ear (spike and awns) to grain filling is severely affected by drought stress, for instance the CO 2 assimilation is reduced due drought and eventually disturb the rate of photosynthesis (Kottmann et al, 2014 ; Merah et al, 2018 ). Ashraf and Harris ( 2013 ) reported that Chl content assimilation does not show a positive correlation with drought condition in wheat plants, suggesting that it may be due to variation in Chl synthesis among the cultivars mediated by the alteration in the activities of specific enzymes involved in the biosynthesis of Chl (Ashraf and Harris, 2013 ).…”

Grain yield, agronomic traits, and protein content of two- and six-row barley genotypes under terminal drought conditions

“…Dry matter for grain filling is a result of a post-anthesis photosynthetic activity and remobilization of storage reserves deposited prior to anthesis. If climatic conditions (predominantly water scarcity and enhanced temperatures) are limiting, the contribution of current photosynthesis to grain filling declines and the remobilization of stored carbohydrates from senescent tissues increases (Merah et al, 2017). During the vegetative and early reproductive stages of cereal development, assimilated C is temporarily stored as carbohydrate in vegetative RESEARCH sink tissues, such as the stem and leaf sheaths, and those reserves are subsequently remobilized for the transport to reproductive sink tissues and filling the grain during the later stages of plant development (Scofield et al, 2009).…”