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Selective Deactivation of Gibberellins below the shoot apex is Critical to Flowering but Not to Stem Elongation of Lolium

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Molecular Plant 2008年第2期1卷 295-307页

作者： Rod W. King Lewis N. Mander Torben Asp Colleen R MacMillan Cheryl A. Blundell Lloyd T. Evans CSIRO Plant Industry Canberra ACT 2600 Australia Research School of Chemistry Australian National University Canberra ACT 0200 Australia Department of Genetics and-Biotechnology University of Aarhus 4200 Slagelse Denmark Present Address: ENSIS PO Box E 4008 Kingston ACT 2604 Australia

Gibberellins （GAs） cause dramatic increases in plant height and a genetic block in the synthesis of GA1 explains the dwarfing of Mendel＇s pea. For flowering, it is GAs which is important in the long-day （LD） responsive grass, Loliurn. As we show here, GA1 and GA4 are restricted in their effectiveness for flowering because they are deactivated by C-2 hydroxylation below the shoot apex. In contrast, GAs is effective because of its structural protection at C-2. Excised vegetative shoot tips rapidly degrade [14C]GA1, [14C]GA4, and [14C]GA20 （〉80% in 6 h）, but not [14C]GAs. CoincidentaUy, genes encoding two 2β-oxidases and a putative 16-17-epoxidase were most expressed just below the shoot apex （〈3 mm）. Further down the immature stem （〉4 mm）, expression of these GA deactivation genes is reduced, so allowing GA1 and GA4 to promote sub-apical stem elongation. Subsequently, GA degradation declines in florally induced shoot tips and these GAs can become active for floral development. Structural changes which stabilize GA4 confirm the link between florigenicity and restricted GA 2β-hydroxylation （e.g. 2α-hydroxylation and C-2 di-methylation）. Additionally, a 2-oxidase inhibitor （Trinexapac Ethyl） enhanced the activity of applied GA4, as did limiting C-16,17 epoxidation in 16,17-dihydro GAs or after C-13 hydroxylation. Overall, deactivation of GA1 and GA4 just below the shoot apex effectively restricts their florigenicity in Loliurn and, conversely, with GAs, C-2 and C-13 protection against deactivation allows its high florigenicity. Speculatively, such differences in GA access to the shoot apex of grasses may be important for separating floral induction from inflorescence emergence and thus could influence their survival under conditions of herbivore predation.

关键词： Selective Deactivation shoot apex Stem Elongation of Lolium

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Comprehensive Pattern of Primordium Initiation in shoot apex of Wheat

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Acta Botanica Sinica 2002年第3期44卷 273-278页

作者：李存东曹卫星张月辰南京农业大学农业部作物生长调控重点开放实验室南京210095 河北农业大学农学院河北保定071001

The time course of the initiation of different types of apical primordia on the stem of wheat (Triticum aestivum L.) was investigated to establish a comprehensive pattern of apical primordium development and quantitative dynamic relationships among different primordium initiation. The results showed that the initiation of leaf and bracteal primordia took the S shape, and that of spikelet and floret took the rise stage of parabolic shape in relation to GDD (growing degree days after sowing) in wheat. The bracteal was much like vegetative rather than reproductive organ in terms of the dynamic pattern of primordium initiation. The progress of spikelet and floret primordium initiation could well reflect the characteristics of different genotypes and the impact of different ecological environments on wheat apical development. The integrated model of different primordium initiation in shoot of wheat was an S_shaped curvilinear, and could be divided into three sub_models. The number of leaf primordia was affected by both genotype and environment, while the numbers of bracteal, spikelet and floret primordia were affected mainly by environmental factors. Measured with mean thermochron, the rates of initiation of leaf, bracteal and spikelet primordia in normal planting were the highest among all the sowing date treatments. In contrast to the relationships among leaf, bracteal, spikelet and their initiation duration, the correlation between the number of floret and its initiation duration was highly significant.

关键词： wheat shoot apex primordium initiation comprehensive pattern dynamic characteristics

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Molecular Cloning and Analysis of LEA14L2 Gene from Rubber Tree( Hevea brasiliensis Muell. Arg. )

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Agricultural Biotechnology 2013年第5期2卷 4-8页

作者： Zhi ZOU Lifu YANG Feng AN Zhenhui WANG Kun YUAN Key Laboratory of Biology and Genetic Resources of Rubber Tree Ministry of Agriculture/Rubber Research InstituteChinese Academy of Tropical Agricultural Sciences

Using an isotig encoding a putative polypeptide with high similarity to Arabidopsis LEA14 as a query, a 613 bp long cDNA was in silico cloned from the transeriptome data of rubber tree. The sequence nominated as HbLEA14L2 contains an ORF of 456 bp with 3 bp 5＇ UTR and 154 bp 3＇ UTR. Subsequently, a 464 bp eDNA and an 834 bp genome sequence containing this ORF was amplified and sequenced. Sequence analysis suggested that HbLEA14L2 has one intron and encodes 151 amino acids with a theoretical molecular weight of 16.55 kDa, isoleetric point of 4.93 and GRAVY value of -0.022, indicating a cytoplasmle localization pattern; HbLEA14L2 protein contains a conserved LEA_2 domain and belongs to LEA_2 subfamily, sharing 91%, 76%, 75%, 72% and 63% similarity with the homologous proteins in castor bean, leafy spurge, poplar, cotton, and Arabidopsis, respectively. Swiss-Model indicated that the tertiary structure of HbLEA14L2 is consisted of one α-helix and seven β-sheets, which was proposed to serve as a regulatory protein to prevent cellular desiccation.

关键词： Hevea brasiliensis Muell. Arg. Arabidopsis thaliana LEA14 shoot apex

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