Sucrose Efflux Mediated by SWEET Proteins as a Key Step for Phloem Transport

Chen, Lei; Qu, Xiao Qing; Hou, Bi Huei; Sosso, Davide; Osorio, Sonia; Fernie, Alisdair R.; Frommer, Wolf B.

doi:10.1126/science.1213351

Cited by 1,083 publications

(1,389 citation statements)

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“…Other studies have also found consistency in nectar sugar concentration between different varieties of OSR (Mohr & Jay, 1990; Mesquida et al ., 1991; Pierre et al ., 1996). While it is known that the family of SWEET protein transporters in plants, including brassicas, facilitate the diffusion of sucrose from photosynthetic to heterotrophic cells, such as nectaries, down a concentration gradient (Chen et al ., 2012; Chen, 2014; Lin et al ., 2014), little is known about the regulation of concentration in nectar sugar, and this is an emerging area of research.…”

Section: Discussionmentioning

confidence: 99%

Oilseed rape (Brassica napus) as a resource for farmland insect pollinators: quantifying floral traits in conventional varieties and breeding systems

et al. 2017

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Oilseed rape (OSR; Brassica napus L.) is a major crop in temperate regions and provides an important source of nutrition to many of the yield‐enhancing insect flower visitors that consume floral nectar. The manipulation of mechanisms that control various crop plant traits for the benefit of pollinators has been suggested in the bid to increase food security, but little is known about inherent floral trait expression in contemporary OSR varieties or the breeding systems used in OSR breeding programmes. We studied a range of floral traits in glasshouse‐grown, certified conventional varieties of winter OSR to test for variation among and within breeding systems. We measured 24‐h nectar secretion rate, amount, concentration and ratio of nectar sugars per flower, and sizes and number of flowers produced per plant from 24 varieties of OSR representing open‐pollinated (OP), genic male sterility (GMS) hybrid and cytoplasmic male sterility (CMS) hybrid breeding systems. Sugar concentration was consistent among and within the breeding systems; however, GMS hybrids produced more nectar and more sugar per flower than CMS hybrid or OP varieties. With the exception of ratio of fructose/glucose in OP varieties, we found that nectar traits were consistent within all the breeding systems. When scaled, GMS hybrids produced 1.73 times more nectar resource per plant than OP varieties. Nectar production and amount of nectar sugar in OSR plants were independent of number and size of flowers. Our data show that floral traits of glasshouse‐grown OSR differed among breeding systems, suggesting that manipulation and enhancement of nectar rewards for insect flower visitors, including pollinators, could be included in future OSR breeding programmes.

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Section: Discussionmentioning

confidence: 99%

Oilseed rape (Brassica napus) as a resource for farmland insect pollinators: quantifying floral traits in conventional varieties and breeding systems

et al. 2017

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“…Carbohydrate is transported as sucrose to sink tissues through the phloem. The key step for phloem loading is sucrose efflux, which is mediated by SWEET proteins (32). We determined that SWEET15/SAG29 is induced in senescing Arabidopsis leaves.…”

Section: Phosphorylation Of Abfs By Snrk2s Facilitates Aba-induced Sag12mentioning

confidence: 98%

ABA receptor PYL9 promotes drought resistance and leaf senescence

Zhao

Chan

Gao

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

495

402

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Drought stress is an important environmental factor limiting plant productivity. In this study, we screened drought-resistant transgenic plants from 65 promoter-pyrabactin resistance 1-like (PYL) abscisic acid (ABA) receptor gene combinations and discovered that pRD29A::PYL9 transgenic lines showed dramatically increased drought resistance and drought-induced leaf senescence in both Arabidopsis and rice. Previous studies suggested that ABA promotes senescence by causing ethylene production. However, we found that ABA promotes leaf senescence in an ethylene-independent manner by activating sucrose nonfermenting 1-related protein kinase 2s (SnRK2s), which subsequently phosphorylate ABA-responsive element-binding factors (ABFs) and Related to ABA-Insensitive 3/VP1 (RAV1) transcription factors. The phosphorylated ABFs and RAV1 up-regulate the expression of senescence-associated genes, partly by up-regulating the expression of Oresara 1. The pyl9 and ABA-insensitive 1-1 single mutants, pyl8-1pyl9 double mutant, and snrk2.2/3/6 triple mutant showed reduced ABA-induced leaf senescence relative to the WT, whereas pRD29A::PYL9 transgenic plants showed enhanced ABA-induced leaf senescence. We found that leaf senescence may benefit drought resistance by helping to generate an osmotic potential gradient, which is increased in pRD29A::PYL9 transgenic plants and causes water to preferentially flow to developing tissues. Our results uncover the molecular mechanism of ABA-induced leaf senescence and suggest an important role of PYL9 and leaf senescence in promoting resistance to extreme drought stress.drought stress | abscisic acid | PYL | dormancy | Arabidopsis C ell and organ senescence causes programmed cell death to regulate the growth and development of organisms. In plants, leaf senescence increases the transfer of nutrients to developing and storage tissues. Recently, studies on transgenic tobacco showed that delayed leaf senescence increases plant resistance to drought stress (1). However, the senescence and abscission of older leaves and subsequent transfer of nutrients are known to increase plant survival under abiotic stresses, including drought, low or high temperatures, and darkness (2, 3). Senescence mainly develops in an age-dependent manner and is also triggered by environmental stresses and phytohormones, such as abscisic acid (ABA), ethylene, salicylic acid, and jasmonic acid, but delayed by cytokinin (4).Senescence-associated genes (SAGs) are induced by leaf senescence. The expression of SAGs is tightly controlled by several senescence-promoting, plant-specific NAC (NAM, ATAF1, and CUC2) transcription factors, such as Oresara 1 (ORE1) (5), Oresara 1 sister 1 (ORS1) (6), and AtNAP (7). Environmental stimuli and phytohormones may regulate leaf senescence through NACs. Phytochrome-interacting factor 4 (PIF4) and PIF5 transcription factors promote dark-induced senescence by activating ORE1 expression (8). The expression of ORE1, AtNAP, and OsNAP (ortholog of AtNAP) is up-regulated by ABA by an unknown molecular m...

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“…The functions of transporting glucose and sucrose are identified in most well-studied SWEETs currently (Chen et al 2010;Chen et al 2012). For example, AtSWEET1 is involved in the regulation of glucose uptake and efflux (Chen et al 2010;Sonnewald 2011).…”

Section: Introductionmentioning

confidence: 99%

“…For example, AtSWEET1 is involved in the regulation of glucose uptake and efflux (Chen et al 2010;Sonnewald 2011). OsSWEET11 and OsSWEET14 are the low affinity transport sucrose carriers that may be involved in the phloem sucrose loading process (Chen et al 2012;Chen 2014). AtSWEET1/4/5 may directly involve in the transport of sugar to regulate the osmotic active substances, or participate in cell wall sugar loading (Bauer et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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A genome-wide analysis of SWEET gene family in cotton and their expressions under different stresses

et al. 2018

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Background: The SWEET (Sugars will eventually be exported transporters) gene family plays multiple roles in plant physiological activities and development process. It participates in reproductive development and in the process of sugar transport and absorption, plant senescence and stress responses and plant-pathogen interaction. However, thecomprehensive analysis of SWEET genes has not been reported in cotton.

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Sucrose Efflux Mediated by SWEET Proteins as a Key Step for Phloem Transport

Cited by 1,083 publications

References 52 publications

Oilseed rape (Brassica napus) as a resource for farmland insect pollinators: quantifying floral traits in conventional varieties and breeding systems

Oilseed rape (Brassica napus) as a resource for farmland insect pollinators: quantifying floral traits in conventional varieties and breeding systems

ABA receptor PYL9 promotes drought resistance and leaf senescence

A genome-wide analysis of SWEET gene family in cotton and their expressions under different stresses

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