Genetic Evidence for the Role of a Rice Vacuolar Invertase as a Molecular Sink Strength Determinant

Abstract

BackgroundRice is a major crop feeding the majority of the global population, and increasing its sink strength is one of the modes to alleviate the declining availability of food for the rapidly growing world population. We demonstrate a role for an important rice vacuolar invertase isoform, OsINV3, in sink strength determination.ResultsOsINV3 mutants showed shorter panicles with lighter and smaller grains, owing to a smaller cell size on the outer and inner surfaces of the palea and lemma as observed by scanning electron microscopy. Further, strong promoter::GUS expression was observed in the palea, lemma and the rachis branches in the young elongating panicles, which supported the role of OsINV3 in cell expansion and thus, in spikelet size and panicle length determination. Size of the spikelet was found to directly influence the grain weight, which was confirmed by the lack of differences in weights of hulled grain for differently segregated alleles in the heterozygous lines. Assessment of field grown mutants not only revealed a drastic reduction in the percentage of ripened grain, 1000-grain weight and final yield, but also significantly reduced partitioning of assimilates to the panicles, whereby the total dry weight remained unaffected. Determination of the non-structural carbohydrate contents revealed a lower hexose-to-sucrose ratio in the panicles of the mutants from panicle initiation to 10 days after heading, a stage that identifies as the critical pre-storage phase of grain filling, whereas the starch contents were not affected. In addition, strong promoter::GUS expression was observed in the dorsal end of ovary during the pre-storage phase until 6 days after flowering, highlighting a function for OsINV3 in monitoring the initial grain filling stage.ConclusionsOsINV3 was found to regulate spikelet size by playing a key role in cell expansion, driving the movement of assimilates for grain filling by modulating the hexose-to-sucrose ratio, contributing in grain weight determination and thus, the grain yield.Electronic supplementary materialThe online version of this article (10.1186/s12284-018-0201-x) contains supplementary material, which is available to authorized users.

Acid invertase confers heat tolerance in rice plants by maintaining energy homoeostasis of spikelets

“…Invertases cleave sucrose into hexoses, which provide cells with fuel for respiration as well as with both carbon and energy for the synthesis of numerous different compounds (Goetz et al, ; Roitsch & Gonzalez, ). Furthermore, invertases are also involved in the long‐distance transport of sucrose by generating the necessary sucrose concentration gradient between phloem loading and unloading sites (Hu et al, ; Morey et al, ; Roitsch, Bittner, & Godt, ). This suggests that invertases are key metabolic enzymes involved in various aspects of the plant life cycle and the plant response to environmental stimuli (Chang et al, ; Naseem, Kunz, & Dandekar, ; Qin et al, ; Roitsch, Balibrea, Hofmann, Proels, & Sinha, ; Wang & Ruan, ).…”

Role of Triose Phosphate Utilization in photosynthetic response of rice to variable carbon dioxide levels and plant source-sink relations

“…5), suggesting that morphology-based phenotypic plasticity causing variation in C 501 source-sink ratio can affect TPU. A recent study also reported the effect of sink strength on 502 sucrose partitioning that may be used to increase grain yield in rice (Morey et al, 2018). More This study provided new insights into the effect of C source-sink relationships on rice 507 photosynthesis and in particular, its parameter TPU.…”

Functional Characterization of Invertase Inhibitors PtC/VIF1 and 2 Revealed Their Involvements in the Defense Response to Fungal Pathogen in Populus trichocarpa

“…The hexoses released by CWI or VI not only served as core metabolites and nutrient sources but also acted as key signaling molecules to impact on gene expression during developmental transitions and responding to environmental cues (Rolland et al, 2006;Ruan, 2014). The basic functions of VI in photoassimilate partitioning, cell expansion, and osmotic regulation have been implemented widely in a variety of plants (Klann et al, 1996;Kohorn et al, 2006;Sergeeva et al, 2006;Yu et al, 2008;Nägele et al, 2010;Morey et al, 2018). Suppression of VI activities showed a decrease of cold-induced sweetening (CIS), leading to improved processing qualities of potato tubers (Bhaskar et al, 2010;Zhu et al, 2016).…”