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Environmental and Genetic Determinants of Seed Quality and Performance (From W1168)
A.B. Downie, R.L. Geneve, S.E. Perry, C.C. Baskin
Department of Horticulture
Seeds are the primary entities for propagation of food, feed, fiber, bio-fuel, and ornamental plants. America produces copious quantities of seed to grow a vast array of plants whose natural and agro-ecological niches are exceptionally diverse and in environmental conditions that are not always favorable for their germination, emergence, establishment, and persistence.
The underlying principles that influence successful plant propagation are biologically based, as are the solutions to overcoming problems that limit establishment of desirable species. Whether at the level of the individual seed, variety, field, habitat, or ecosystem, the needs for seed biology research transcend individual geographic regions.
This multistate project has had, and will continue to have, an important role in capitalizing on research opportunities that will successfully address various biological processes that enhance seed performance. Many productive research collaborations have been initiated through this multistate project, and the wide array of seed biology expertise among W-1168 participants synergistically stimulates new approaches leading to relevant new biological insights. The outcomes from these collaborations foster technical innovations applicable to the wide range of crops and natural species.
2009 Project Description
Our overall goal is to understand the ecology, biogeography and evolution of seed dormancy and germination.
A concentrated effort to examine the seed dormancy mechanism of species present in biogeographical regions identified as underrepresented in the 1998 book, Seeds: Ecology, biogeography, and evolution of dormancy and germination has resulted in publications in 2009 on several species from the USA as well as species from other countries including Taiwan, Japan, China, Australia Dodonaea), and Europe (forest herbs). Web page for the W-2168 was set up that links to all member's labs (http://www.seedresearchers.com).
The Perry lab has continued to probe mechanisms underpinning plant embryogenesis by identifying genes directly and indirectly regulated by the DNA-binding MADS-factor AGL15. AGL15 accumulation correlates with competence for somatic embryogenesis. Understanding somatic embryo development is fascinating from the basic viewpoint of determining how a cell can dedifferentiate and redifferentiate in embryo mode, as well as having practical aspects to promote regeneration of value-added transgenic plants by somatic embryogenesis.
One route to contribute to determination of mechanisms of somatic embryo development is to determine genes controlled by transcriptional regulators that promote this process, such as AGL15. We have globally mapped where AGL15 associates with DNA in vivo, resulting in around 2000 binding sites. We have combined this information with expression microarray data to determine perturbations in the transcriptome in response to increased or decreased AGL15. This has allowed us to identify genes that are likely to be directly expressed in response to AGL15 as well as genes directly repressed by AGL15, resulting in around 200 genes with a direct, consistent and significant response to AGL15. Interestingly, other transcriptional regulators are overrepresented in the directly expressed list, but not the directly repressed list. DNA motifs that AGL15 recognizes are overrepresented in the fragments identified as bound by AGL15. We published this work in The Plant Cell in 2009. Currently we are focusing on confirmation of select direct targets of AGL15 (and the redundant AGL18) and to determine the function of regulated genes.
Finally we are developing tools to allow us to extend the gene regulation network underlying embryogenesis by looking at genes regulated by some AGL15 targets that encode transcriptional regulators. The data obtained has also led to collaborations resulting in a publication in the Journal of Experimental Botany in 2009 and an ongoing collaboration with a researcher at the University of Wisconsin-Madison.
Workshop "A short-course on seed dormancy and germination with emphasis on Hawaiian species" University of Hawaii, Manoa, 31 July 2009.
Workshop "Future research objectives for studies on seed dormancy and germination in the Junggar Desert, northwest China." Xinjiang Agriculture University, Urumqi, China, 27 June 2009.
Lecture: "Seed dormancy profile for the Xishuangbanna Tropical Seasonal Rainforest Dynamics Plot: First approximation" Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Kunming, China. 24 December 2009.
Lecture. "Variation in seed dormancy/germination within and between individuals and populations" Chinese Academy of Sciences, Xishuangbanna Tropical Botanical Garden, Kunming, China. 24 December 2009.
Lecture. "The ecology of the federally-endangered species Solidago shortii" Xinjiang Agricultural University, Urumqi, China. 17 June 2009.
Lecture. "How seed dormancy studies serve plant conservation: Using information on biogeography and phylogeny of seed dormancy to facilitate propagation of plant species for restoration" Lyon Arboretum, University of Hawaii, Manoa, 3 August 2009.
Symposium talk. "Seed dormancy and germination of Hawaiian montane species: meeting common goals of basic science and conservation" Hawaii Conservation Conference, Honolulu, HI, 30 July 2009.
Lecture. "Seed germination ecology in a specific habitat: Cedar glades" Xinjiang Agricultural University, Urumqi, China. 17 June 2009. Lecture. "Seed dormancy and germination of cedar glade plants" Cedars of Lebanon Annual Wildflower Weekend, Lebanon, TN, 2 May 2009. Invited poster. "Classification and phylogeny of seed dormancy", Xishuangbanna International Symposium II.
Biodiversity Conservation: Research Imperatives for Scientific Institutions" Chinese Academy of Sciences, Institute of Botany, Xishuangbanna Tropical Botanical Garden, Menglum (Yunnan Province), P. R. China, 1-2 January 2009. The membership was expanded, an official name for the W-2168 that will not change each time we go through a re-write, was adopted, a webpage for the group was established.
Limited numbers of studies have been performed to globally identify direct targets of plant transcription factors. Consequently not much is known about the number or types of targets that a specific factor controls. We have found that while many sites are occupied by a given transcription factor in vivo relatively few interactions between a transcriptional regulator and DNA result in significant changes in gene expression of the nearby gene. There are numerous possible reasons, but it seems important to assess the impact of DNA-protein interaction.
Analysis of genes directly and indirectly controlled by AGL15 has led us to investigate hormone interactions involved in control of somatic embryo development. We are currently using combinations of mutants, hormones and inhibitor treatments to tease apart how different hormones cross-talk in control of somatic embryo development. We have extended our work in Arabidopsis and demonstrated that ectopic expression of AGL15 in soybean can promote somatic embryogenesis in this important crop.
Baskin, C. C., C. T. Chien, S. Y. Chen and J. M. Baskin. 2009. Epicotyl morphophysiological dormancy in seeds of Daphniphyllum glaucescens, a woody member of the Saxifragales. International Journal of Plant Sciences 170: 174-181.
Jayasuriya, K. M. G. G., J. M. Baskin, R. L. Geneve, C. C. Baskin. 2009. Phylogeny of Seed Dormancy in Convolvulaceae, Subfamily Convolvuloideae (Solanales). Annals of Botany 103: 45-63.
Jayasuriya, K. M. G. G., J. M. Baskin, R. L. Geneve, C. C. Baskin. 2009. A proposed mechanism for physical dormancy break in seeds of Ipomoea lacunosa (Convolvulaceae). Annals of Botany 103: 433-445.
Phartyal, S. S., T. Kondo,Y. Hoshino, C.C. Baskin and J.M. Baskin. 2009. Morphological dormancy in seeds of the autumn-germinating shrub Lonicera caerulea var. emphyllocalyx (Caprifoliaceae). Plant Species Biology 24: 20-26.
Jayasuriya, K. M. G. G., J. M. Baskin, R. L. Geneve and C. C. Baskin. 2009. Sensitivity cycling and mechanism of physical dormancy break in seeds of Ipomoea hederacea (Convolvulaceae). International Journal of Plant Sciences 170: 429-443.
Jayasuriya, K. M. G. G., J. M. Baskin and C. C. Baskin. 2009. Sensitivity cycling and its ecological role in seeds with physical dormancy. Seed Science Research 19: 3-13.
Yang, H., C.C. Baskin, J. M. Baskin, Z. Cao, X. Zhu1, Z. Huang, M. Dong. 2009. Responses of caryopsis germination, early seedling growth and ramet clonal growth of Bromus inermis to soil salinity. Plant and Soil 316: 265-275.
Phartyal, S. S. T. Kondo, J. M. Baskin and C.C. Baskin. 2009. Temperature requirements differ for the two stages of seed dormancy-break in Aegopodium podagraria (Apiaceae), A species with deep complex morphophysiological dormancy. American Journal of Botany 96: 1086-1095.
Graae, B. J., K. Verheyen, A. Kolb, S. Van Der Veken, T. Heinken, O. Chabrerie, M. Diekmann, K. Valtinat, R. Zindel, E. Karlsson, L. Strom, G. Decocq, M. Hermy and C.C. Baskin. 2009. Germination requirements and seed mass of slow- and fast-colonizing temperate forest herbs along a latitudinal gradient. Ecoscience 16: 248-257.
Baskin, C. C., S.-Y. Chen, C.-T. Chien and J. M. Baskin. 2009. Overview of seed dormancy in Viburnum (Caprifoliaceae). Propagation of Ornamental Plants 9: 115-121.
Sun, H. Z., J. J. Lu, D. Y. Tan, J. M. Baskin and C. C. Baskin. 2009. Dormancy and germination characteristics of the trimorphic achenes of Garhadiolus papposus (Asteraceae), an annual ephemeral from the Junggar Desert, northwest China. South African Journal of Botany 75: 537-545.
Turner, S. R., A. Cook, J. M. Baskin, C. C. Baskin, K. J. Steadman and K. W. Dixon. 2009. Identification and characterization of the water gap in the physically dormant seeds of Dodonaea petiolaris: a first report for Sapindaceae. Annals of Botany 104: 833-844.
Turner, S. R., L. E. Commander, J. M. Baskin, C. C. Baskin and K. W. Dixon. 2009. Germination behaviour of Astroloma xerophyllum (Ericaceae), a species with woody indehiscent endocarps. Botanical Journal of the Linnean Society 160: 299-311.
Hu, X.W., Y. R. Wang, Y. P. Wu and C.C. Baskin. 2009. Role of the lens in controlling water uptake in seeds of two Fabaceae (Papilionoideae) species treated with sulphuric acid and hot water. Seed Science Research 19: 73-80.
Jayasuriya, K. M. G. G., J. M. Baskin, D. M. TeKrony, and C. C. Baskin. 2009. Sensitivity cycling to physical dormancy break and seed vigour of two Ipomoea species (Convolvulaceae). Seed Science Research 19: 249-259.
Hall, S., C. Barton, C. C. Baskin. 2009. Topsoil seed bank of an oak-hickory forest in eastern Kentucky as a Restoration Tool on Surface Mines. Restoration Ecology DOI: 10.1111/j.1526-100X.2008.00509.x
Hall, S. L., C. D. Barton and C. C. Baskin. 2009. Seed viability in stockpiled topsoil on a surface mine in Appalachia. Ecological Restoration 27:381-383.
Wang, J. H., C. C. Baskin, W. Chen and G. Z. Du. 2009 Variation in seed germination between populations of five sub-alpine woody species from eastern Qinghai-Tibet Plateau following dry storage at low temperatures. Ecological Research DOI 10.1007/s11284- 009-0643-0
Zheng, Z., S. Zhang, G. Yang, Y. Tang, J. M. Baskin, C. C. Baskin and L. Yang. 2009. Abundance and distribution of cavity trees in an old-growth subtropical montane evergreen broad-leaved forest. Canadian Journal of Forest Research 39: 2234-2245.
Graae, B. J., K. Verheyen, A. kolb, S. Van Der Veken, H. Heinken, O. Chabrerie, M. Diekmann, K. Valtinat, R. Zindel, E. Karlsson, L. Strom, G. Decocq, M. Hermy and C. C. Baskin. 2009. Germination requirements and seed mass of slow- and fast-colonizing temperate forest herbs along a latitudinal gradient. Ecoscience 16: 248-257.
Chen, S.-Y., Chien, C.-T., Baskin, J. M. and Baskin, C. C. 2009. Storage behavior and changes in concentrations of abscisic acid and gibberellins during dormancy break and germination in seeds of Phellodendron amurense var. wilsonii (Rutaceae). Tree Physiology 30: 275-284.
Geneve, R.L. (2009). Physical seed dormancy in selected Caesalpinioid legumes from eastern North America. Propagation of Ornamental Plants 9:129-134.
Jayasuriya, K.M.G., Baskin, J.M., Geneve, R.L. and Baskin, C.C. (2009). A proposed mechanism of physical dormancy break in sensitive and insensitive seeds of Ipomoea lacunosa (Convolvulaceae). Annals of Botany 103:433-445.
Jayasuriya, K.M.G., Baskin, J.M., Geneve, R.L. and Baskin, C.C. (2009). Phylogeny of seed dormancy in Convolvulaceae, subfamily Convolvuloideae (Solanales). Annals of Botany 103:45-63.
Zheng, Y., Ren, N., Wang, H., Stromberg, A.J. and Perry, S.E. 2009. Global Identification of Targets of the Arabidopsis MADS Domain Protein AGAMOUS-Like15. The Plant Cell 21, 2563-2577.
Nakaminami, K., Hill, K., Perry, S.E., Sentoku, N., Long, J.A. and Karlson, D.T. 2009. Arabidopsis Cold Shock Domain Proteins: Relationships to Floral and Silique Development. Journal of Experimental Botany 60, 1047-1062.