The Tomato Hybrid Proline-rich Protein regulates the abscission zone competence to respond to ethylene signals

The Tomato Hybrid Proline-rich Protein(THyPRP)gene was specifically expressed in the tomato(Solanum lycopersicum)flower abscission zone(FAZ),and its stable antisense silencing under the control of an abscission zone(AZ)-specific promoter,Tomato Abscission Polygalacturonase4,significantly inhibited tomato pedicel abscission following flower removal.For understanding the THyPRP role in regulating pedicel abscission,a transcriptomic analysis of the FAZ of THyPRP-silenced plants was performed,using a newly developed AZ-specific tomato microarray chip.Decreased expression of THyPRP in the silenced plants was already observed before abscission induction,resulting in FAZ-specific altered gene expression of transcription factors,epigenetic modifiers,post-translational regulators,and transporters.Our data demonstrate that the effect of THyPRP silencing on pedicel abscission was not mediated by its effect on auxin balance,but by decreased ethylene biosynthesis and response.Additionally,THyPRP silencing revealed new players,which were demonstrated for the first time to be involved in regulating pedicel abscission processes.These include:gibberellin perception,Ca2+-Calmodulin signaling,Serpins and Small Ubiquitin-related Modifier proteins involved in post-translational modifications,Synthaxin and SNARE-like proteins,which participate in exocytosis,a process necessary for cell separation.These changes,occurring in the silenced plants early after flower removal,inhibited and/or delayed the acquisition of the competence of the FAZ cells to respond to ethylene signaling.Our results suggest that THyPRP acts as a master regulator of flower abscission in tomato,predominantly by playing a role in the regulation of the FAZ cell competence to respond to ethylene signals.

Phloem-Mobile AuxlIAA Transcripts Target to the Root Tip and Modify Root Architecture

In plants, the phloem is the component of the vascular system that delivers nutrients and transmits signals from mature leaves to developing sink tissues. Recent studies have identified proteins, mRNA, and small RNA within the phloem sap of several plant species. It is now of considerable interest to elucidate the biological functions of these potential long-distance signal agents, to further our understanding of how plants coordinate their developmental programs at the whole-plant level. In this study, we developed a strategy for the functional analysis of phloem-mobile mRNA by focusing on IAA transcripts, whose mobility has previously been reported in melon （Cucumis melo cv. Hale＇s Best Jumbo）. Indoleacetic acid （IAA） proteins are key transcriptional regulators of auxin signaling, and are involved in a broad range of developmental processes including root development. We used a combination of vasculature-enriched sampling and hetero-grafting techniques to identify IAA18 and IAA28 as phloemmobile transcripts in the model plant Arabidopsis thaliana. Micro-grafting experiments were used to confirm that these IAA transcripts, which are generated in vascular tissues of mature leaves, are then transported into the root system where they negatively regulate lateral root formation. Based on these findings, we present a model in which auxin distribution, in combination with phloem-mobile Aux/IAA transcripts, can determine the sites of auxin action.

Quantitative Trait Loci Analysis Identifies a Prominent Gene Involved in the Production of Fatty Acid-Derived Flavor Volatiles in Tomato

To gain insight into the genetic regulation of lipid metabolism in tomato, we conducted metabolic trait loci （mQTL） analysis following the lipidomic profiling of fruit pericarp and leaf tissue of the Solanum pennellii introgression lines （IL）. To enhance mapping resolution for selected fruit-specific mQTL, we profiled the lipids in a subset of independently derived S. pennellii backcross inbred lines, as well as in a nearsogenic sub-iL population. We identified a putative lecithin：cholesterol acyltransferase that controls the levels of several lipids, and two members of the class III lipase family, LIP1 and LIP2, that were associated with decreased levels of diacylglycerols （DAGs） and triacylglycerols （TAGs）. Lipases of this class cleave fatty acids from the glycerol backbone of acylglycerols. The released fatty acids serve as precursors of flavor volatiles. We show that LIP1 expression correlates with fatty acid-derived volatile levels. We further confirm the function of LIP1 in TAG and DAG breakdown and volatile synthesis using transgenic plants. Taken together, our study extensively characterized the genetic architecture of Upophilic compounds in tomato and demonstrated at molecular level that release of free fatty acids from the glycerol backbone can have a major impact on downstream volatile synthesis.

1-MCP处理提高不同成熟度Spadona梨贮后品质的研究

Spadona梨是一种不需要低温诱导乙烯生成的热带水果。本研究采用乙烯抑制剂1-甲基环丙烯（1-MCP）对不同成熟阶段的梨果实进行处理，以期进一步了解其成熟过程中乙烯的作用，同时提高梨果实贮藏后的品质。

菜豆“水分利用效率黄金时段”量化解析方法的建立及应用

植物水分利用效率(water use efficiency,WUE)的“黄金时段”(golden hour,GH)指植物能够以较少的水分消耗生产较多干物质的时间段,而此时段的WUE相关性状被称为“黄金WUE”性状(GHW性状)。本研究中利用WUE模型推导发现试验材料菜豆(Phaseolus vulgaris L.)的冠层导度(蒸腾速率与饱和蒸气压差的比值)可用于反演光合速率,并通过常规低通量的冠层气体交换参数测量进行了验证。基于此,开发了基于“Plantarray”高通量生理表型系统解析菜豆不同品种GHW性状的方法。该方法以GHW时段的累积冠层导度(AccGHW)及其占全天的比重(fGHW)、估算的WUE(WUEe)等作为综合量化参数,并从24份国内外菜豆种质中筛选得到了GHW性状上差异显著的优劣系。