Characterisation of a rice vacuolar invertase isoform, OsINV2, for growth and yield-related traits

Abstract

OsINV2, a rice vacuolar invertase isoform, was assessed for its functional roles in plant growth and development with key focus on its agronomic traits such as grain weight, grain filling percentage, grain number and dry weights at various stages until harvest. Lack of differences between the wild-type and the mutants with respect to any of the aforementioned traits tested revealed a possibility of functional compensation of OsINV2 in the mutants conceivably by its isoform. This was confirmed by OsINV2 promoter::GUS studies, where its spatial and temporal expression in the panicle elongation stages showed that although OsINV2 expression was observed from the stage with young panicles ~1 cm in length to the flag leaf stage, significant differences with respect to panicle and spikelet phenotypes between the wild-type and the mutant were not present. However, complement lines displaying an overexpression phenotype of OsINV2 possessed a higher stem non-structural carbohydrate content under both monoculm and normal tillering conditions. A trade-off between the spikelet number and grain weight in the complement lines grown under monoculm conditions was also observed, pointing towards the necessity of OsINV2 regulation for grain yield-related traits.

OsINV3 and Its Homolog, OsINV2, Control Grain Size in Rice

“…In our study, the double mutant INV3 KO INV2 KO showed a grain size smaller than both INV3 KO and INV2 KO (Figure 9), suggesting that in the absence of OsINV3, it is possible to detect a role of OsINV2 in the regulation of grain size. As reported previously, the functions of OsINV2 were redundantly encoded in OsINV3 [42]. Our results show for the first time that OsINV2 regulates grain size in the absence of OsINV3.…”

“…Our results show that INV3 KO causes small grain size (Figures 5 and 6), suggesting that OsINV3 positively regulates grain size by causing cell expansion resulting in an increase in grain length and grain-width. Genetic data showed that INV2 KO did not cause any change in grain size by itself (Figures 8 and 9), but still plays important regulatory role in traits related to grain yield [42]. In our study, the double mutant INV3 KO INV2 KO showed a grain size smaller than both INV3 KO and INV2 KO (Figure 9), suggesting that in the absence of OsINV3, it is possible to detect a role of OsINV2 in the regulation of grain size.…”

“…The previously reported alleles of OsINV3 have been shown to cause small grain size [40,41]. On the other hand, OsINV2 was reported to be a functionally redundant vacuolar invertase isoform and showed no significant changes in key agronomic and physiological traits [42]. Both OsINV3 and OsINV2 play key roles in regulating traits related to grain yield in plant growth and development.…”

Meta-QTL and haplo-pheno analysis reveal superior haplotype combinations associated with low grain chalkiness under high temperature in rice

“…Our study identified OsINV2 as one of the candidate genes in MQTL 4.4 [contributed by QTLs qDPGWC, qPGWC, qWCR4.1, qWCR4.2, qch ( Peng et al., 2014a ; Wang et al., 2016 ; Yun et al., 2016 ; Edwards et al., 2017 )]. OsVIN2 and its homologue OsVIN3 regulate the sink size by controlling hexose to sucrose ratio and drive cell expansion by turgor generated due to influx of osmotic solutes ( Koch, 2004 ; Sergeeva et al., 2006 ; Morey et al., 2019 ). Consequently, vin2 and vin3 mutations lead to decreased seed size and shorter and lighter panicles ( Morey et al., 2018 ; Lee et al., 2019 ; Morey et al., 2019 ; Xu et al., 2019 ; Deng et al., 2020 ).…”

Cloning and functional analysis of soluble acid invertase 2 gene (SbSAI-2) in sorghum

“…Because the sorghum genetic transformation efficiency is relatively lower, rice was selected as the receptor material to validate the function of SbSAI-2 gene in this study. Morey et al (2019) evaluated the functional role of rice soluble acid invertase isoform OsVIN2 in plant growth and development, studied the differences between important agronomic traits such as grain weight, grain filling rate, grain number and dry weight at various stages of growth and development, and found that there were no significant differences between the wild type and the mutant in terms of the agronomic traits tested. In the mutant, the non-structural carbohydrates in the stem will increase after the correct OsVIN2 gene was transformed, and the overexpression line has a higher number of spikelets, but the grain weight was reduced.…”