The turnip(Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the ne...The turnip(Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the next spring for flowering and seeds. FLOWERING LOCUS C(FLC) is a MADS-box transcription factor that acts as a major repressor of floral transition by suppressing the flowering promoters FT and SOC1. Here we show that vernalization effectively represses tuber formation and promotes flowering in Tibetan turnip. We functionally characterized four FLC homologues(BrrFLC1,FLC2, FLC3, and FLC5), and found that BrrFLC2 and BrrFLC1 play a major role in repressing flowering in turnip and in transgenic Arabidopsis. In contrast, tuber formation was correlated with BrrFLC1 expression in the hypocotyl and was repressed under cold treatment following the quantitative downregulation of BrrFLC1. Grafting experiments of non-vernalized and vernalized turnips revealed that vernalization independently suppressed tuberization in the tuber or hypocotyl of the rootstock or scion, which occurred in parallel with the reduction in BrrFLC1 activity. Together, our results demonstrate that the Tibetan turnip is highly responsive to cold exposure, which is associated with the expression levels of BrrFLC genes.展开更多
In flowering plants,sexual reproductive success depends on the production of viable pollen grains.However,the mechanisms by which QUA QUINE STARCH(QQS)regulates pollen development and how transcriptional activators fa...In flowering plants,sexual reproductive success depends on the production of viable pollen grains.However,the mechanisms by which QUA QUINE STARCH(QQS)regulates pollen development and how transcriptional activators facilitate the transcription of QQS in this process remain poorly understood.Here,we demonstrate that INDUCER OF CBF EXPRESSION 1(ICE1),a basic helix–loop–helix(b HLH)transcription factor,acts as a key transcriptional activator and positively regulates QQS expression to increase pollen germination and viability in Arabidopsis thaliana by interacting with INDETERMINATE DOMAIN14(IDD14).In our genetic and biochemical experiments,overexpression of ICE1 greatly promoted both the activation of QQS and high pollen viability mediated by QQS.IDD14 additively enhanced ICE1 function by promoting the binding of ICE1 to the QQS promoter.In addition,mutation of ICE1 significantly repressed QQS expression;the impaired function of QQS and the abnormal anther dehiscence jointly affected pollen development of the ice1-2 mutant.Our results also showed that the enhancement of pollen activity by ICE1 depends on QQS.Furthermore,QQS interacted with CUT1,the key enzyme for long-chain lipid biosynthesis.This interaction both promoted CUT1 activity and regulated pollen lipid metabolism,ultimately determining pollen hydration and fertility.Our results not only provide new insights into the key function of QQS in promoting pollen development by regulating pollen lipid metabolism,but also elucidate the mechanism that facilitates the transcription of QQS in this vital developmental process.展开更多
基金supported by the National Science Foundation of China(No.31500221,31590823 and 31601999)the West Light Foundation of the Chinese Academy of Sciences by XXK
文摘The turnip(Brassica rapa var. rapa) is a biennial crop that is planted in late summer/early fall and forms fleshy tubers for food in temperate regions. The harvested tubers then overwinter and are planted again the next spring for flowering and seeds. FLOWERING LOCUS C(FLC) is a MADS-box transcription factor that acts as a major repressor of floral transition by suppressing the flowering promoters FT and SOC1. Here we show that vernalization effectively represses tuber formation and promotes flowering in Tibetan turnip. We functionally characterized four FLC homologues(BrrFLC1,FLC2, FLC3, and FLC5), and found that BrrFLC2 and BrrFLC1 play a major role in repressing flowering in turnip and in transgenic Arabidopsis. In contrast, tuber formation was correlated with BrrFLC1 expression in the hypocotyl and was repressed under cold treatment following the quantitative downregulation of BrrFLC1. Grafting experiments of non-vernalized and vernalized turnips revealed that vernalization independently suppressed tuberization in the tuber or hypocotyl of the rootstock or scion, which occurred in parallel with the reduction in BrrFLC1 activity. Together, our results demonstrate that the Tibetan turnip is highly responsive to cold exposure, which is associated with the expression levels of BrrFLC genes.
基金supported by the National Science Foundation of China(Grant Nos.32170385,32200306,and 31500221)the Second Tibetan Plateau Scientific Expedition and Research(STEP)program(Grant No.2019QZKK0502)。
文摘In flowering plants,sexual reproductive success depends on the production of viable pollen grains.However,the mechanisms by which QUA QUINE STARCH(QQS)regulates pollen development and how transcriptional activators facilitate the transcription of QQS in this process remain poorly understood.Here,we demonstrate that INDUCER OF CBF EXPRESSION 1(ICE1),a basic helix–loop–helix(b HLH)transcription factor,acts as a key transcriptional activator and positively regulates QQS expression to increase pollen germination and viability in Arabidopsis thaliana by interacting with INDETERMINATE DOMAIN14(IDD14).In our genetic and biochemical experiments,overexpression of ICE1 greatly promoted both the activation of QQS and high pollen viability mediated by QQS.IDD14 additively enhanced ICE1 function by promoting the binding of ICE1 to the QQS promoter.In addition,mutation of ICE1 significantly repressed QQS expression;the impaired function of QQS and the abnormal anther dehiscence jointly affected pollen development of the ice1-2 mutant.Our results also showed that the enhancement of pollen activity by ICE1 depends on QQS.Furthermore,QQS interacted with CUT1,the key enzyme for long-chain lipid biosynthesis.This interaction both promoted CUT1 activity and regulated pollen lipid metabolism,ultimately determining pollen hydration and fertility.Our results not only provide new insights into the key function of QQS in promoting pollen development by regulating pollen lipid metabolism,but also elucidate the mechanism that facilitates the transcription of QQS in this vital developmental process.
