Dataset Information

Phenotypic, Anatomical, and Diel Variation in Sugar Concentration Linked to Cell Wall Invertases in Common Bean Pod Racemes under Water Restriction.

ABSTRACT: The common bean (Phaseolus vulgaris L.) pod wall is essential for seed formation and to protect seeds. To address the effect of water restriction on sugar metabolism in fruits differing in sink strength under light-dark cycles, we used plants of cv. OTI at 100% field capacity (FC) and at 50% FC over 10 days at the beginning of pod filling. Water restriction intensified the symptoms of leaf senescence. However, pods maintained a green color for several days longer than leaves did. In addition, the functionality of pods of the same raceme was anatomically demonstrated, and no differences were observed between water regimes. The glucose and starch concentrations were lower than those of sucrose, independent of pod wall size. Remarkably, the fructose concentration decreased only under water restriction. The cell wall invertase activity was twofold higher in the walls of small pods than in those of large ones in both water regimes; similar differences were not evident for cytosolic or vacuolar invertase. Using bioinformatics tools, six sequences of invertase genes were identified in the P. vulgaris genome. The PvINVCW4 protein sequence contains substitutions for conserved residues in the sucrose-binding site, while qPCR showed that transcript levels were induced in the walls of small pods under stress. The findings support a promising strategy for addressing sink strength under water restriction.

SUBMITTER: Chavez Mendoza K

PROVIDER: S-EPMC9268661 | biostudies-literature | 2022 Jun

REPOSITORIES: biostudies-literature

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Phenotypic, Anatomical, and Diel Variation in Sugar Concentration Linked to Cell Wall Invertases in Common Bean Pod Racemes under Water Restriction.

Chavez Mendoza Karla K Peña-Valdivia Cecilia Beatriz CB Hernández Rodríguez Martha M Vázquez Sánchez Monserrat M Morales Elías Norma Cecilia NC Jiménez Galindo José Cruz JC García Esteva Antonio A Padilla Chacón Daniel D

Plants (Basel, Switzerland) 20220621 13

The common bean (<i>Phaseolus vulgaris</i> L.) pod wall is essential for seed formation and to protect seeds. To address the effect of water restriction on sugar metabolism in fruits differing in sink strength under light-dark cycles, we used plants of cv. OTI at 100% field capacity (FC) and at 50% FC over 10 days at the beginning of pod filling. Water restriction intensified the symptoms of leaf senescence. However, pods maintained a green color for several days longer than leaves did. In addit ...[more]

PMID: 35807573

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Project description:Seed shattering in crops is a key domestication trait due to its relevance for seed dispersal, yield, and fundamental questions in evolution (e.g., convergent evolution). Here, we focused on pod shattering in common bean (Phaseolus vulgaris L.), the most important legume crop for human consuption in the world. With this main aim, we developed a methodological pipeline that comprises a thorough characterization under field conditions, including also the chemical composition and histological analysis of the pod valves. The pipeline was developed based on the assumption that the shattering trait itself can be treated in principle as a "syndrome" (i.e., a set of correlated different traits) at the pod level. We characterized a population of 267 introgression lines that were developed ad-hoc to study shattering in common bean. Three main objectives were sought: (1) to dissect the shattering trait into its "components," of level (percentage of shattering pods per plant) and mode (percentage of pods with twisting or non-twisting valves); (2) to test whether shattering is associated to the chemical composition and/or the histological characteristics of the pod valves; and (3) to test the associations between shattering and other plant traits. We can conclude the following: Very high shattering levels can be achieved in different modes; shattering resistance is mainly a qualitative trait; and high shattering levels is correlated with high carbon and lignin contents of the pod valves and with specific histological charaterstics of the ventral sheath and the inner fibrous layer of the pod wall. Our data also suggest that shattering comes with a "cost," as it is associated with low pod size, low seed weight per pod, high pod weight, and low seed to pod-valves ratio; indeed, it can be more exaustively described as a syndrome at the pod level. Our work suggests that the valve chemical composition (i.e., carbon and lignin content) can be used for a high troughput phenotyping procedures for shattering phenotyping. Finally, we believe that the application of our pipeline will greatly facilitate comparative studies among legume crops, and gene tagging.

Project description:In common bean (Phaseolus vulgaris L.), leaf photosynthesis is significantly reduced under drought conditions. Previous studies have shown that some drought-tolerant cultivars use the pod walls to compensate the decreased photosynthesis rate in leaves by acting as temporary reservoirs of carbohydrates to support seed filling. Here, we describe a comprehensive molecular characterization of sucrose synthase (SUS, EC 2.4.1.13) gene family through a genome-wide analysis and evaluated the effects of terminal drought on reproductive structures, specifically the pod walls. Seven PvSUS genes were located on six different chromosomes and had 8-16 intron-exon structures (8-16 exons). The PvSUS protein sequences revealed conserved catalytic domains, with molecular weights ranging from 90.5 kDa to 105.1 kDa and lengths from 799 to 929 amino acids. Phylogenetic analysis grouped these sequences into three main clusters with seven subgroups, indicating divergence from SUS sequences in other plant species. Using a docking sequence, we predicted three-dimensional (3-D) structures and evaluated the active sites. Bioinformatics analysis of promoter regions suggested that PvSUS genes may respond to light, hormone signaling, and stress stimuli. Greenhouse experiments were conducted using the cv. OTI, identified as having intermediate drought tolerance. Plants at the R8 growth stage were maintained with regular irrigation at 100% field capacity (FC) or with water restriction to maintain 50% of field capacity. Pods were harvested 5 days, 10 days, 15 days, and 20 days after anthesis. An increase in PvSUS activity under water restriction was associated with higher levels of fructose, while sucrose concentration also increased. qRT-PCR analysis revealed that PvSUS1, PvSUS3, and PvSUS4 were strongly expressed during seed development under water restriction. The fluorescent sucrose analog esculin indicated that transport across the plasma membrane might contribute to the increase in the pith cell diameter of pedicels. The results provide a systematic overview of the PvSUS gene family in P. vulgaris, offering a framework for further research and the potential functional application of PvSUS genes.

Project description:Nectar composition varies between species, depending on flowering time and pollinator type, among others. Various models of the biochemical and molecular mechanisms underlying nectar production and secretion have been proposed. To gain insights into these mechanisms, day- and night-flowering tobacco (Nicotiana) species with high or low proportions of hexoses in the nectar were analyzed. Nectar and nectaries were simultaneously collected, throughout the day and night. Soluble sugars and starch were determined and the activity and expression level of cell wall invertase (CW-INVs) were measured in nectaries. Nectaries and nectar of the five Nicotiana species contained different amounts of sucrose, glucose, and fructose. CW-INV activity was detected in the nectaries of all Nicotiana species and is probably involved in the hydrolysis of sucrose in the nectary tissue and during nectar secretion. The larger differences in the sucrose-to-hexose-ratio between nectaries and nectar in diurnal species compared to nocturnal species can be explained by higher sucrose cleavage within the nectaries in night-flowering species, and during secretion in day-flowering species. However, cell wall invertase alone cannot be responsible for the differences in sugar concentrations. Within the nectaries of the Nicotiana species, a portion of the sugars is transiently stored as starch. In general, night-flowering species showed higher starch contents in the nectaries compared to day-flowering species. Moreover, in night flowering species, the starch content decreased during the first half of the dark period, when nectar production peaks. The sucrose concentrations in the cytoplasm of nectarial cells were extrapolated from nectary sucrose contents. In day-flowering species, the sucrose concentration in the nectary cytoplasm was about twice as high as in nectar, whereas in night-flowering species the situation was the opposite, which implies different secretion mechanisms. The secreted nectar sugars remained stable for the complete flower opening period, which indicates that post-secretory modification is unlikely. On the basis of these results, we present an adapted model of the mechanisms underlying the secretion of nectar sugars in day- and night-flowering Nicotiana.

Project description:Background and aimsCoordination of sugar transport and metabolism between developing seeds and their enclosing fruit tissues is little understood. In this study the physiological mechanism is examined using two genotypes of asparagus bean (Vigna unguiculata ssp. sesquipedialis) differing in pod wall and seed growth rates. Pod growth dominates over seed growth in genotype 'Zhijiang 121' but not in 'Zhijiang 282' in which a 'bulging pod' phenotype is apparent from 8 d post-anthesis (dpa) onward.MethodsSeed and pod wall growth rates and degree of pod-bulging were measured in the two genotypes together with assays of activities of sucrose-degrading enzymes and sugar content in pod wall and seed and evaluation of cellular pathways of phloem unloading in seed coat using a symplasmic fluorescent dye, 5(6)-carboxyfluorescein (CF).Key resultsActivities of cell wall, cytoplasmic and vacuolar invertases (CWIN, CIN and VIN) were significantly smaller in pod walls of '282' than in '121' at 10 dpa onwards. Low INV activities were associated with weak pod wall growth of '282'. In seed coats, CF was confined within the vasculature in '282' but moved beyond the vasculature in '121', indicating apoplasmic and symplasmic phloem unloading, respectively. Higher CWIN activity in '282' seed coats at 6-8 dpa correlated with high hexose concentration in embryos and enhanced early seed growth. However, CWIN activity in '282' decreased significantly compared with '121' from 10 dpa onwards, coinciding with earlier commencement of nuclei endoreduplication in their embryos.ConclusionsThe study shows genotypic differences between 'bulging pod' and 'non-bulging' phenotypes of asparagus bean in sucrose metabolism in relation to the pathway of phloem unloading in developing seed coats, and to pod and seed growth. Low INV activity in pod wall corresponds to its shortened and weak growth period; by contrast, the apoplasmic path in the seed coat is associated with high CWIN activity and strong early seed growth.

Dataset Information

Phenotypic, Anatomical, and Diel Variation in Sugar Concentration Linked to Cell Wall Invertases in Common Bean Pod Racemes under Water Restriction.

Publications

Phenotypic, Anatomical, and Diel Variation in Sugar Concentration Linked to Cell Wall Invertases in Common Bean Pod Racemes under Water Restriction.

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