Weichang Hu1,2, Xiuting Hua1,2, Qing Zhang1,2, Jianping Wang1,3, Qiaochu Shen1,2, Xingtan Zhang1,2, Kai Wang1,2, Qingyi Yu4, Yann-Rong Lin5, Ray Ming1,6, Jisen Zhang7,8. 1. Center for Genomics and Biotechnology, Haixia Institute of Science and Technology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. 2. Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. 3. Agronomy Department, University of Florida, Gainesville, FL, 32610, USA. 4. Texas A&M AgriLife Research, Department of Plant Pathology and Microbiology, Texas A&M University System, Dallas, TX, 75252, USA. 5. Department of Agronomy, National Taiwan University, Taipei, 100, Taiwan. 6. Department of Plant Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA. 7. Center for Genomics and Biotechnology, Haixia Institute of Science and Technology, Fujian Provincial Key Laboratory of Haixia Applied Plant Systems Biology, College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. zjisen@126.com. 8. Key Laboratory of Sugarcane Biology and Genetic Breeding, Ministry of Agriculture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China. zjisen@126.com.
Abstract
BACKGROUND: The SWEET (Sugars Will Eventually be Exported Transporters) gene family is a recently identified group of sugar transporters that play an indispensable role in sugar efflux, phloem loading, plant-pathogen interaction, nectar secretion, and reproductive tissue development. However, little information on Saccharum SWEET is available for this crop with a complex genetic background. RESULTS: In this study, 22 SWEET genes were identified from Saccharum spontaneum Bacterial Artificial Chromosome libraries sequences. Phylogenetic analyses of SWEETs from 11 representative plant species showed that gene expansions of the SWEET family were mainly caused by the recent gene duplication in dicot plants, while these gene expansions were attributed to the ancient whole genome duplication (WGD) in monocot plant species. Gene expression profiles were obtained from RNA-seq analysis. SWEET1a and SWEET2s had higher expression levels in the transitional zone and maturing zone than in the other analyzed zones. SWEET1b was mainly expressed in the leaf tissues and the mature zone of the leaf of both S. spontaneum and S. officinarum, and displayed a peak in the morning and was undetectable in both sclerenchyma and parenchyma cells from the mature stalks of S. officinarum. SsSWEET4a\4b had higher expression levels than SWEET4c and were mainly expressed in the stems of seedlings and mature plants. SWEET13s are recently duplicated genes, and the expression of SWEET13s dramatically increased from the maturing to mature zones. SWEET16b's expression was not detected in S. officinarum, but displayed a rhythmic diurnal expression pattern. CONCLUSIONS: Our study revealed the gene evolutionary history of SWEETs in Saccharum and SWEET1b was found to be a sucrose starvation-induced gene involved in the sugar transportation in the high photosynthetic zones. SWEET13c was identified as the key player in the efflux of sugar transportation in mature photosynthetic tissues. SWEET4a\4b were found to be mainly involved in sugar transportation in the stalk. SWEET1a\2a\4a\4b\13a\16b were suggested to be the genes contributing to the differences in sugar contents between S. spontaneum and S. officinarum. Our results are valuable for further functional analysis of SWEET genes and utilization of the SWEET genes for genetic improvement of Saccharum for biofuel production.
BACKGROUND: The SWEET (Sugars Will Eventually be Exported Transporters) gene family is a recently identified group of sugar transporters that play an indispensable role in sugar efflux, phloem loading, plant-pathogen interaction, nectar secretion, and reproductive tissue development. However, little information on Saccharum SWEET is available for this crop with a complex genetic background. RESULTS: In this study, 22 SWEET genes were identified from Saccharum spontaneum Bacterial Artificial Chromosome libraries sequences. Phylogenetic analyses of SWEETs from 11 representative plant species showed that gene expansions of the SWEET family were mainly caused by the recent gene duplication in dicot plants, while these gene expansions were attributed to the ancient whole genome duplication (WGD) in monocot plant species. Gene expression profiles were obtained from RNA-seq analysis. SWEET1a and SWEET2s had higher expression levels in the transitional zone and maturing zone than in the other analyzed zones. SWEET1b was mainly expressed in the leaf tissues and the mature zone of the leaf of both S. spontaneum and S. officinarum, and displayed a peak in the morning and was undetectable in both sclerenchyma and parenchyma cells from the mature stalks of S. officinarum. SsSWEET4a\4b had higher expression levels than SWEET4c and were mainly expressed in the stems of seedlings and mature plants. SWEET13s are recently duplicated genes, and the expression of SWEET13s dramatically increased from the maturing to mature zones. SWEET16b's expression was not detected in S. officinarum, but displayed a rhythmic diurnal expression pattern. CONCLUSIONS: Our study revealed the gene evolutionary history of SWEETs in Saccharum and SWEET1b was found to be a sucrose starvation-induced gene involved in the sugar transportation in the high photosynthetic zones. SWEET13c was identified as the key player in the efflux of sugar transportation in mature photosynthetic tissues. SWEET4a\4b were found to be mainly involved in sugar transportation in the stalk. SWEET1a\2a\4a\4b\13a\16b were suggested to be the genes contributing to the differences in sugar contents between S. spontaneum and S. officinarum. Our results are valuable for further functional analysis of SWEET genes and utilization of the SWEET genes for genetic improvement of Saccharum for biofuel production.
Authors: Yuan Hu Xuan; Yi Bing Hu; Li-Qing Chen; Davide Sosso; Daniel C Ducat; Bi-Huei Hou; Wolf B Frommer Journal: Proc Natl Acad Sci U S A Date: 2013-09-11 Impact factor: 11.205
Authors: Anke Reinders; Alicia B Sivitz; Alex Hsi; Christopher P L Grof; Jai M Perroux; John M Ward Journal: Plant Cell Environ Date: 2006-10 Impact factor: 7.228