TaTPP-7A positively feedback regulates grain filling and wheat grain yield through T6P-SnRK1 signalling pathway and sugar–ABA interaction

Grain size and filling are two key determinants of grain thousand-kernel weight (TKW) and crop yield, therefore they have undergone strong selection since cereal was domesticated. Genetic dissection of the two traits will improve yield potential in crops. A quantitative trait locus significantly associated with wheat grain TKW was detected on chromosome 7AS flanked by a simple sequence repeat marker of Wmc17 in Chinese wheat 262 mini-core collection by genome-wide association study. Combined with the bulked segregant RNA-sequencing (BSR-seq) analysis of an F₂ genetic segregation population with extremely different TKW traits, a candidate trehalose-6-phosphate phosphatase gene located at 135.0 Mb (CS V1.0), designated as TaTPP-7A, was identified. This gene was specifically expressed in developing grains and strongly influenced grain filling and size. Overexpression (OE) of TaTPP-7A in wheat enhanced grain TKW and wheat yield greatly. Detailed analysis revealed that OE of TaTPP-7A significantly increased the expression levels of starch synthesis- and senescence-related genes involved in abscisic acid (ABA) and ethylene pathways. Moreover, most of the sucrose metabolism and starch regulation-related genes were potentially regulated by SnRK1. In addition, TaTPP-7A is a crucial domestication- and breeding-targeted gene and it feedback regulates sucrose lysis, flux, and utilization in the grain endosperm mainly through the T6P-SnRK1 pathway and sugar–ABA interaction. Thus, we confirmed the T6P signalling pathway as the central regulatory system for sucrose allocation and source–sink interactions in wheat grains and propose that the trehalose pathway components have great potential to increase yields in cereal crops.     

Oxide-Based Solid-State Batteries: A Perspective on Composite Cathode Architecture

The garnet-type phase Li₇La₃Zr₂O₁₂ (LLZO) attracts significant attention as an oxide solid electrolyte to enable safe and robust solid-state batteries (SSBs) with potentially high energy density. However, while significant progress has been made in demonstrating compatibility with Li metal, integrating LLZO into composite cathodes remains a challenge. The current perspective focuses on the critical issues that need to be addressed to achieve the ultimate goal of an all-solid-state LLZO-based battery that delivers safety, durability, and pack-level performance characteristics that are unobtainable with state-of-the-art Li-ion batteries. This perspective complements existing reviews of solid/solid interfaces with more emphasis on understanding numerous homo- and heteroionic interfaces in a pure oxide-based SSB and the various phenomena that accompany the evolution of the chemical, electrochemical, structural, morphological, and mechanical properties of those interfaces during processing and operation. Finally, the insights gained from a comprehensive literature survey of LLZO–cathode interfaces are used to guide efforts for the development of LLZO-based SSBs.     

海甘蓝种子成熟过程中脂肪酸含量以及脱落酸和山梨醇的效应

海甘蓝种子在成熟过程中,棕榈酸、硬脂酸和亚麻酸的含量不断下降,而二十碳烯酸和芥酸的含量呈上升趋势。选用开花后２５～２７ｄ的海甘蓝幼胚分别在含不同浓度的ＡＢＡ或高渗透剂的培养基中培养１～３ｄ,发现其各种脂肪酸的变化趋势和种子自然成熟过程中脂肪酸的变化相似,说明ＡＢＡ或高渗透剂可能是种子成熟过程中各种脂肪酸合成和相互转化所需的条件。     

Characterization of a 46 kda insect chitinase from transgenic tobacco

A 46 kDa Manduca sexta (tobacco hornworm) chitinase was isolated from leaves of transgenic tobacco plants containing a recombinant insect chitinase cDNA, characterized, and tested for insecticidal activity. The enzyme was purified by ammonium sulfate fractionation, Q-Sepharose anion-exchange chromatography and mono-S cation-exchange chromatography. Although the gene for the chitinase encoded the 85 kDa full-length chitinase as previously reported by Kramer et al. [Insect Biochem. Molec. Biol. 23, 691–701 (1993)], the enzyme is produced in tobacco as a 46 kDa protein that is approximately four-fold less active than the 85 kDa chitinase. The N-terminal amino acid sequence of the 46 kDa chitinase is identical to that of the 85 kDa chitinase. The former enzyme is not glycosylated, whereas the latter contains approximately 25% carbohydrate. The pH and temperature optima of the 46 kDa chitinaseare similar to those of the 85 kDa chitinase. The former enzyme is more basic than the latter. The 46 kDa chitinase likely consists of the N-terminal catalytic domain of the 85 kDa chitinase and lacks the C-terminal domain that contains several potential sites for glycosylation. The 46 kDa chitinase is expressed in a number of plant organs, including leaves, flowers, stems and roots. Enzyme levels are higher in leaves and flowers than in stems and roots, and leaves from the middle portion of the plant have more chitinase than leaves from the top and bottom portions. Little or no enzyme is secreted outside of the plant cells because it remains in the intracellular space, even though its transit sequence is processed. When fed at a 2% dietary level, the 46 kDa chitinase caused 100% larval mortality of the merchant grain beetle, Oryzaephilis mercator. The results of this study support the hypothesis that insect chitinase is a biopesticidal protein for insect pests feeding on insect chitinase gene-containing transgenic plants.     

The role of Ca2+ in progesterone-induced germinal vesicle breakdown of Xenopus laevis oocytes: the synergic effects of microtubule depolymerization and Ca2+

 By monitoring ⁴⁵Ca²⁺ influx and efflux from oocytes a transient increase followed by a transient decrease in the Ca²⁺-content of progesterone-treated oocytes was observed. Chelation of intracellular Ca²⁺ with EGTA or BAPTA-type buffers inhibited progesterone-induced GVBD. Buffers with a mid-range K_d (∼1.5 μm) were most effective in inhibiting GVBD whereas buffers with a K_d above or below this value were less effective. These observations indicate that intracellular Ca²⁺, probably in the form of a localized release, is required for progesterone-induced oocyte maturation. However, Ca²⁺ alone was insufficient to induce GVBD. When the effects of nocodazole and taxol upon this Ca²⁺-requirement were tested, we observed that taxol-induced microtubule polymerization not only delayed progesterone-induced GVBD but also completely inhibited it in combination with BAPTA-AM. Conversely, nocodazole-induced microtubule depolymerization in combination with ionophore A23187 not only accelerated progesterone-induced GVBD, but also induced GVBD in the absence of progesterone. The combined treatment of oocytes with nocodazole and InsP_3, or with cold treatment and ionophore A23187 also induced GVBD in the absence of progesterone. Thus, Ca²⁺ and microtubule depolymerization synergistically promote GVBD. In both nocodazole- and cold-treated oocytes, the GV was displaced to the periphery of the oocyte and underwent GVBD when treated with A23187. However, when the GV was displaced to the cortex by a centrifugal force under conditions that would not cause microtubule depolymerization and the oocyte was treated with A23187, oocytes did not undergo GVBD. Received: 19 January 1996 / Accepted: 21 May 1996     

Factors affecting Citrus tree isozyme-gene expression

Ten enzymatic systems of Citrus species and cultivars have been evaluated for identification purposes and for genetic variability studies. The following factors that could affect their expression were studied: season of sampling, location, rootstock, position of the branch, infection, and age of the tree. Differences involving the presence-absence of the Cu/Zn SOD within the same tree were found. This difference is mainly related to the position of the leaf relative to the sunlight. No change was observed at any of the ten enzymatic systems assayed regarding the location, the rootstock, the growing condition, the season, or the infection with most virus and virus-like pathogens. Viroids induced noticeable changes on 6PG and PRXa zymograms in C. medica. A new peroxidase (not present in healthy plants) was detected that could be related to appearance of symptoms. This may induce errors when trees without sanitary control are characterized by this enzymatic system. On the other hand, it provides a new possibility for studying the plant response to the presence of viroids. An effect of age, from 3 months up to 12 years, was observed on citrange Troyer and mandarin Cleopatra PRX, MDH and 6PG patterns. An important change occurs around the first year, most likely related to the end of the seedling stage. This is followed by a long transition phase, the end of which (around 9 years later) coincides with a change in the PRX pattern. These age-related changes seem to involve post-translational modifications of pre-existing isozymes.     

Evidence for the involvement of ethylene in the expression of specific RNAs during maturation of the orange,a non-climacteric fruit

Twelve cDNAs corresponding to mRNAs inducible by ethylene were isolated by differential screening of a cDNA library from ethylene-treated Citrus sinensis fruits. Northern analysis of RNA extracted from flavedo of ethylene-treated fruits and from fruits at different maturation stages showed that some of the mRNAs corresponding to these cDNAs were regulated both by ethylene treatment and during fruit maturation. The effect of exogenous ethylene on leaves and of endogenous ethylene on flowers showed that gene induction was not restricted to the flavedo tissue. The possible role of ethylene during maturation of the non-climacteric Citrus fruit is discussed.     

Thein vitro effect of theophylline on 17α, 20ß-dihydroxy-4-pregnen-3-one-induced germinal vesicle breakdown in the catfish,Clarias batrachus

The effects of theophylline (a phosphodiesterase inhibitor) and cAMP on 17α, 20ß-dihydroxy-4-pregnen-3-one-induced germinal vesicle breakdown was investigatedin vitro in catfish (Clarias batrachus) oocytes. Folliculated oocytes incubated with 17α, 20ß-dihydroxy-4-pregnen-3-one at the concentration of 1 μg/ml induced 93.2 ± 2.23% germinal vesicle breakdown. When the oocytes were prestimulated with 17α,20ß-dihydroxy-4-pregnen-3-one for 6 h and then treated with different concentrations of theophylline, there was a significant drop in the frequency of germinal vesicle breakdown at the concentrations 2.0, 1.5 and 1.0 mM. However, theophylline was found to be incapable of inhibiting germinal vesicle breakdown at its lowest concentration (0.5 inM). In the time course study, significant inhibition of germinal vesicle breakdown was recorded when 1 mM theophylline was added up to 30 h of 17α,20ß-dihydroxy-4-pregnen-3-one Stimulation but the inhibitory effect of theophylline gradually (time dependent manner) declined if the stimulatory time of 17α,20ß-dihydroxy-4-pregnen-3-one was increased. A similar inhibition of germinal vesicle breakdown was also recorded with various concentrations of cAMP. Except 0.5 mM, all the higher concentrations of cAMP significantly inhibited 17α,20ß-dihydroxy-4-pregnen-3-one induced germinal vesicle breakdown.     

Flight initiation byProstephanus truncatus in relation to time of day, temperature, relative humidity and starvation

Studies were carried out in the laboratory on the influences of time of day, temperature, relative humidity and starvation on flight initiation byProstephanus truncatus (Horn) (Coleoptera: Bostrichidae). Flight occurred throughout the 12 h photophase and at the beginning of the scotophase but peaked at 2–0 h before darkness. Temperature exerted a significant effect on flight. The frequency of flight take-off increased with temperature over the range 20–30°C but declined sharply at 35°C. Flight activity increased with starvation up to a maximum at 2 days after which it began to decline.