全球气候变暖强烈影响树线交错带植物的生活史策略,异龄叶大小-出叶强度权衡关系是常绿植物生活史策略的重要内容.以川西树线交错带的岷江冷杉(Abies faxoniana)幼苗为例,研究气候变暖对异龄叶大小与出叶强度关系的影响.通过开顶箱(Open-top chamber,OTC)对川西王朗自然保护区树线交错带的岷江冷杉进行模拟增温,采用标准化主轴估计(Standardized major axis estimation,SMA)方法研究了叶大小(单叶质量、单叶面积)与出叶强度(基于茎生物量、茎体积)间异速生长关系对长期增温的响应及其年际变化.结果表明:使用不同参数表征叶大小与出叶强度得到的结果存在差异;多年生小枝上存在单叶质量-出叶强度的负等速权衡关系,共同主轴随小枝年龄增加而向下漂移;长期增温并不影响单叶质量与出叶强度的异速生长关系,不同年龄小枝的异速生长常数对增温具有差异性响应.增温处理中当年生小枝在相同单叶质量下的出叶强度更低,以换取叶片总数的增加,使小枝具有更大的可塑性而适应增温.本研究提供了岷江冷杉幼苗协调异龄叶大小与出叶强度从而适应长期增温的证据,为评估树木生长随气候变化而加速提供了理论参考.

Whether photosynthesis has improved with increasing yield in major crops remains controversial. Research in this area has often neglected to account for differences in light intensity experienced by cultivars released in different years. Light intensity is expected to be positively associated with photosynthetic capacity and the resistance of the photosynthetic apparatus to high light but negatively associated with light-utilization efficiency under low light. Here, we analyzed the light environment, photosynthetic activity, and protein components of leaves of 26 winter wheat cultivars released during the past 60 years in China. Over time, light levels on flag leaves significantly decreased due to architectural changes, but photosynthetic rates under high or low light and the resistance of the photosynthetic apparatus to high light remained steady, contrary to expectations. We propose that the difference between the actual and expected trends is due to breeding. Specifically, breeding has optimized photosynthetic performance under high light rather than low light. Moreover, breeding selectivity altered the stoichiometry of several proteins related to dynamic photosynthesis, canopy light distribution, and photoprotection. These results indicate that breeding has significantly altered the photosynthetic mechanism in wheat and its response to the light environment. These changes likely have helped increase wheat yields.

为了更好地利用与改良品质较差小麦面粉的加工品质,将面包、面条加工品质较优与较劣的面粉按不同比例进行配粉,分析不同配粉比例对面粉理化特性和面包、面条品质的影响.结果表明,配粉能够显著改善品质较劣面粉的理化特性及其加工面包、面条的品质,优质面粉添加比例为30％时就可以明显改善面粉的理化特性,添加比例为50％时面包、面条品质提升效果最明显.配粉后,面粉蛋白质、沉淀值、干面筋含量、面筋指数以及面团形成时间、稳定时间、粉质质量指数、吸水率、稀懈值与面包、面条评分呈极显著正相关关系.

Plants are intermittently exposed to high intensity light; however, it is unknown how the photosynthetic apparatus of cultivated crops, such as wheat (Triticum aestivum L.), acclimatizes to intermittent high light conditions. To address this question, we grew wheat plants under constant high light (800 mu mol m(-2)s(-1); 100%H), constant low light (100 mu mol m(-2)s(-1); 0%H), 1 day high light followed by 3 days low light (25%H), or 1 day high light followed by 1 day low light (50%H) for 4 weeks. We analyzed seedling growth and the activity and photosensitivity of the photosynthetic apparatus in leaves. Compared with 0%H plants, there was no difference in photosynthetic electron transfer rate or thylakoid membrane protein levels in 25%H plants, but the Rubisco protein levels and photosynthetic carbon fixing capacity were higher. A higher proportion of exposure to high light (50%H) did not further improve the photosynthetic carbon fixing capacity, but it increased the photosynthetic electron transfer rate and photosynthetic protein levels in thylakoid membranes and enhanced the tolerance of the photosynthetic apparatus to high light. Therefore, the acclimation of photosynthesis to intermittent high light exposure depends on the proportion and duration of the high light exposure. Furthermore, during intermittent high light exposure, wheat preferentially invested in photosynthetic carbon assimilation vs the electron transfer reaction and photoprotection. This photosynthetic acclimation strategy maximizes carbon assimilation under intermittent high light conditions.

植物生长调节剂在植物抵御逆境胁迫过程中发挥着重要作用,但尚不清楚同种植物中不同植物生长调节剂对逆境下光抑制的影响有何差异.本实验研究了不同浓度的6种植物生长调节剂(脱落酸、乙烯利、2,4-表油菜素内酯、水杨酸、生长素和细胞分裂素)对黄瓜(Cucumis sativus)栽培过程中常见逆境胁迫(常温强光和低温弱光)下光系统Ⅱ(PSⅡ)和光系统Ⅰ(PSⅠ)光抑制的影响.结果表明,适当浓度的脱落酸、乙烯利和2,4-表油菜素内酯显著缓解了常温强光下黄瓜叶片PSⅡ光抑制;仅2,4-表油菜素内酯显著缓解了低温弱光下黄瓜叶片PSⅡ光抑制.适当浓度的乙烯利和2,4-表油菜素内酯显著缓解了低温弱光导致的黄瓜叶片PSⅠ光抑制.水杨酸、生长素和细胞分裂素对常温强光和低温弱光胁迫下黄瓜叶片PSⅠ和PSⅡ光抑制均没有明显影响.综上所述,脱落酸、乙烯利和2,4-表油菜素内酯可以增强黄瓜叶片光合机构对常温强光的抗性,而乙烯利和2,4-表油菜素内酯可以增强黄瓜叶片光合机构对低温弱光的抗性.尤其是2,4-表油菜素内酯对常温强光和低温弱光下PSⅠ和PSⅡ的光抑制均有明显的缓解作用.

前期研究发现线粒体交替氧化酶（AOX）呼吸途径对叶绿体光系统II（PSII）的光抑制有明显的缓解作用。线粒体内另一条呼吸途径——细胞色素氧化酶（COX）呼吸途径是否也具有光保护作用尚不清楚。该文通过荧光快速诱导动力学和荧光淬灭分析,解析了烟草（Nicotianatabacum）叶片中COX途径对PSII光保护的贡献及其与AOX途径的关系。结果表明,强光处理后PSII活性在所有叶片中均下降。AOX途径受抑明显加速了叶片PSII活性的下降。而当COX途径受抑后,叶片PSII活性的下降与水处理的对照叶片无明显差异。当AOX途径与COX途径同时受抑时,叶片PSII活性的下降比单独抑制AOX途径时更严重。此外,呼吸电子传递受抑均导致叶片非光化学淬灭（NPQ）增加,AOX途径受抑导致的NPQ上调比COX途径受抑时更明显, AOX和COX途径同时受抑时NPQ的增幅最大。上述结果表明,烟草叶片中COX途径和AOX途径均参与PSII的光保护。当COX途径受抑时,其光保护功能可以被AOX途径和NPQ补偿,而AOX途径的光保护作用不能被COX途径和NPQ完全补偿。

Drought is a key threat to maize growth and yield. Understanding the mechanism of immature tassel (IT) response to long term drought is of paramount importance. Here, the maize inbred line PH6WC was tested under well-watered (CK) and two water deficit treatments (WD1 and WD2). The final IT length in the WD1 and WD2 treatments decreased by nearly 6.2% and 21.2% compared to the CK, respectively, and the average accumulation rate IT dry matter was 1.5-fold and 1.8-fold slower, respectively. Furthermore, RNA sequencing analysis was conducted on the IT sampled at 30 days after the WD treatments. In total, the cellular component in gene ontology (GO) analysis suggested that the differentially expressed genes were significantly enriched in three common terms (apoplast, plant-type cell wall, and anchored component of membrane) among the CK vs WD1, CK vs WD2, and WD1 vs WD2 comparisons. Next, a co-expression network analysis identified 44 modules that contained global expression genes. Finally, by combining the GO analysis with modules, nine genes involved in carbohydrate metabolism and the antioxidant system were screened out, and the six corresponding physiological parameters were all significantly increased under the WD treatments. These results showed that, although the IT length and dry matter decreased, the IT enhanced the adaptation to drought by regulating their own genetic and physiological changes.

The mitochondrial alternative pathway (AP) represents an important photoprotective mechanism for the chloroplast, but the temperature sensitivity of its photoprotective role is unknown. In this study, using theaox1aArabidopsis mutant, the photoprotective role of the AP was verified under various temperatures, and the mechanism underlying the temperature sensitivity of the AP's photoprotective role was clarified. It was observed that the photoprotective role of the AP increased with rising temperature but was absent at low temperature. The photoprotective role of the AP was severely reduced under non-photorespiratory conditions. Disturbance of the AP inhibited the conversion of glycine to serine in mitochondria, which may restrain upstream photorespiratory metabolism and aggravate photoinhibition. With rising temperatures, photorespiration accelerated and the restraint of photorespiration caused by disturbance of the AP also increased, determining the temperature sensitivity of the AP's photoprotective role. We also verified that not only the AP but also the cytochrome pathway in mitochondria contributes to photoprotection by maintaining photorespiration.

Wheat cultivars that produce good-quality bread and noodles are important for the food industry and starch physicochemical properties greatly influence the reprocessing quality. In this study, six types of cultivars differing in bread and noodle quality were compared for starch characteristics and for future quality improvement. All six types exhibited significantly different starch physicochemical properties including starch components, amylopectin chain length distribution, granule size and distribution, pasting, swelling, and gelatinization. Most parameters investigated were significantly correlated with bread- and noodle-making performance, confirming significant effects of starch properties on wheat end-use quality. The ratio of amylopectin/amylose contents, proportion of amylopectin short chains (2 <= DP <= 10), amount of C-type starch granules, pasting peak viscosity and gelatinization conclusion temperature (T-c) were effective indicators for improvement of wheat processing quality, and cultivars with those parameters in ranges of 2.1-2.6, 47.8-51.0%, 36.2-46.7%, 2890-3450 cP, and 68.5-69.6 degrees C, respectively, would yield superior bread- and/or noodle-making quality.

选取河南省的区试对照品种周麦18与郑麦7698进行光合性能比较研究,分析郑麦7698高产原因,旨在为小麦高产育种提供理论指导.结果 表明,郑麦7698在开花后0～36 d旗叶的总光合速率均显著高于周麦18(平均提高40.0％),在开花后6～18d穗的总光合速率均显著高于周麦18(整个测定时期平均提高17.2％).郑麦7698穗层光合有效辐射截获率显著高于周麦18(提高29.6％).与周麦18相比,郑麦7698能够保持更高的叶绿素含量、最大光合速率、表观量子效率、最大羧化效率和RuBP最大再生速率,保证了郑麦7698在灌浆后期较慢的衰老速率.上述因素致使郑麦7698比周麦18有更高的籽粒灌浆能力,最终导致郑麦7698具有较高的千粒质量和穗粒数,分别较周麦18显著提高3.5％和8.0％,进而使得籽粒产量较周麦18显著提高9.1％.

Because of the need for agriculture and landscaping, many overwintering evergreen and biennial species that maintain green leaves over winter were introduced to higher latitudes. The green leaves of introduced overwintering species have to withstand a harsher winter, especially lower temperature, than in their native region of origin. Although the responses and adaptability of photosynthetic apparatus to winter conditions in native overwintering species were widely studied, the experimental results on the introduced overwintering species are very limited. Here, the photosynthetic adaptability during winter was analyzed in two native overwintering species, pine (woody plants), winter wheat (herb), and two introduced overwintering species, bamboo (woody plants), lilyturf (herb). The native species exhibited higher capacity for photosynthetic CO 2 fixation and lower susceptibility for photoinhibition than introduced species during winter. Photosynthesis related proteins, such as PsbA, PsaA, Rubisco and Lhcb1, were marginally affected in native species, but significantly degraded in introduced species during winter. More interestingly, the PSII photoinhibition was mainly caused by up-regulation of photoprotection mechanism, non-photochemical quenching, in native species, but by photodamage in introduced species. This study indicates that the growth and survival of introduced overwintering species is limited by their photosynthetic adaptability to the harsher winter conditions at high latitudes.

Jerusalem artichoke (Helianthus tuberosus L.) is an important energy crop for utilizing coastal marginal land. This study was to investigate waterlogging tolerance of Jerusalem artichoke through photosynthetic diagnose with emphasis on photosystem II (PSII) and photosystem I (PSI) performance. Potted plants were subjected to severe (liquid level 5 cm above vermiculite surface) and moderate (liquid level 5 cm below vermiculite surface) waterlogging for 9 days. Large decreased photosynthetic rate suggested photosynthesis vulnerability upon waterlogging. After 7 days of severe waterlogging, PSII and PSI photoinhibition arose, indicated by significant decrease in the maximal photochemical efficiency of PSII (Fv/Fm) and PSI (△MR/MR0), and PSI seemed more vulnerable because of greater decrease in △MR/MR0 than Fv/Fm. In line with decreased △MR/MR0 and unchanged Fv/Fm after 9 days of moderate waterlogging, the amount of PSI reaction center protein rather than PSII reaction center protein was lowered, confirming greater PSI vulnerability. According to positive correlation between △MR/MR0 and efficiency that an electron moves beyond primary quinone and negative correlation between △MR/MR0 and PSII excitation pressure, PSI inactivation elevated PSII excitation pressure by depressing electron transport at PSII acceptor side. Thus, PSI vulnerability induced PSII photoinhibition and endangered the stability of whole photosynthetic apparatus under waterlogging. In agreement with photosystems photoinhibition, elevated H2O2 concentration and lipid peroxidation in the leaves corroborated waterlogging-induced oxidative stress. In conclusion, Jerusalem artichoke is a waterlogging sensitive species in terms of photosynthesis and PSI vulnerability. Consistently, tuber yield was tremendously reduced by waterlogging, confirming waterlogging sensitivity of Jerusalem artichoke.

Bisphenol A (BPA), a widely distributed pollutant, suppresses photosynthesis in leaves. In previous studies on higher plants, the plants were treated by BPA through irrigation to root. This method cannot distinguish whether the BPA directly suppresses photosynthesis in leaves, or indirectly influences photosynthesis through affecting the function of root. Here, only the leaves but not the roots of cucumber were infiltrated with BPA solution. The photosystem II and I (PSII, PSI) were insensitive to BPA under darkness. BPA aggravated the PSII but not the PSI photoinhibition under light. BPA also inhibited CO2 assimilation, and the effect of BPA on PSII photoinhibition disappeared when the CO2 assimilation was blocked. The H2O2 accumulated in BPA-treated leaves under light. And the BPA-caused PSII photoinhibition was prevented under low (2%) O-2. We also proved that the BPA-caused PSII photoinhibition depend on the turnover of D1 protein. In conclusion, this study proved that BPA could directly suppress photosynthesis in leaves, however, BPA does not damage PSII directly, but inhibits CO2 assimilation and over-reduces the electron transport chain under light, which increases the production of reactive oxygen species (H2O2), the over-accumulated ROS inhibits the turnover of D1 protein and consequently aggravates PSII photoinhibition.

强光等逆境下光系统活性的下降被称为光抑制.高等植物中光系统Ⅰ (PSⅠ)和光系统Ⅱ(PSⅡ)都会发生光抑制.目前PSⅡ光抑制对PSⅠ的影响已被广泛研究,而PSⅠ光抑制对PSⅡ的影响研究较少,这主要是因为没有专一性诱导PSⅠ光抑制的方法.有研究报道,常温频闪光可以较为专一地伤害PSⅠ.本研究发现持续光处理3h和频闪光处理4h小麦叶片PSⅡ最大光化学效率(Fv/Fm)降低的幅度相同.当PSⅡ光抑制相同时,频闪光处理叶片的PSⅡ实际光化学效率[Y(Ⅱ)]和非光化学淬灭(NPQ)都明显低于持续光处理叶片,而且只有频闪光处理叶片发生了PSⅠ光抑制.因为两种光处理导致PSⅡ光抑制程度相同,所以叶片光合机构活性的差异主要是由PSⅠ光抑制引起的.PSⅠ光抑制不仅限制PSⅡ向下游的电子传递,而且会使PSⅡ最重要的光保护机制NPQ失活.此外,本研究还发现持续光处理下Y(Ⅱ)下降是由PSⅡ反应中心伤害导致的,而频闪光处理下Y(Ⅱ)降低主要是由PSⅡ反应中心关闭造成的.因此,本研究表明:PSⅠ光抑制会抑制PSⅡ电子向下游的传递,并且抑制NPQ活性,从而加重PSⅡ光抑制.

[目的]探讨叶片蜡质含量对干旱胁迫下小麦光合特性的影响.[方法]本研究以一对小麦近等基因系多蜡质品系JM205和少蜡质品系JM204为试验材料,将二者种植在同一盆中,在人工气候室采用逐渐干旱的方式模拟田间干旱过程中的土壤水分变化.随着干旱处理时间的延长,土壤相对含水量逐渐降低,同步测定了不同土壤相对含水量下小麦旗叶的水势、光合气体交换参数及荧光参数.[结果]轻度干旱胁迫(土壤相对含水量在60％-49％)下,多蜡质品系JM205与少蜡质品系JM204旗叶的光合速率(Pn)无显著差异,随着干旱程度的加重,多蜡和少蜡质品系的光合速率都逐渐降低,但少蜡质品系JM204下降幅度更大.在中度干旱胁迫(土壤相对含水量在49％-32％)下,多蜡质品系比少蜡质品系具有较高的水势和较大的气孔开度,因此CO2供应充足,光合速率更高;少蜡质品系的PSⅡ实际光化学效率(ΦPS Ⅱ)和最大光化学效率(Fv/Fm)较多蜡质品系下降更快,说明少蜡质品系PSⅡ电子传递受阻情况和光抑制比多蜡质品系更严重;快速叶绿素荧光动力学曲线参数分析(JIP-test)发现PSⅡ电子传递受阻主要是因为受体侧QA到QB电子传递限制.在重度干旱胁迫(土壤相对含水量下降到32％以下)时,多蜡质与少蜡质品系的水势和光合能力都大幅下降且二者间没有明显差异.[结论]本研究表明,多蜡质品系JM205在中度干旱胁迫(土壤相对含水量49％-32％范围)下具有较高的光合优势;本研究为小麦抗旱性选育与利用提供了理论依据,并对进一步的研究提供了建议.

Fusarium fungi are soil-borne pathogens, and the pathological effects on plant photosystems remain unclear. This study aimed to deeply reveal pathological characterization in apple seedlings infected with Fusarium solani by investigating photosystems performance and interaction. Roots were immersed in conidial suspension for inoculation. Thereafter, prompt and delayed chlorophyll a fluorescence and modulated 820 nm reflection were simultaneously detected. After 30 days of infection, leaf relative water content and dry weight were remarkably decreased by 55.7 and 47.1%, suggesting that the infected seedlings were subjected to Fusarium-induced water deficit stress. PSI reaction center was more susceptible than PSII reaction center in infected seedlings due to greater decrease in the maximal photochemical efficiency of PSI than that of PSII, but PSI reaction center injury was aggravated slowly, as PSII injury could partly protect PSI by restricting electron donation. PSII donor and acceptor sides were also damaged after 20 days of infection, and the restricted electron donation induced PSII and PSI disconnection by blocking PSI re-reduction. In accordance with greater damage of PSI reaction center, PSI oxidation was also suppressed. Notably, significantly increased efficiency of electron transport from plastoquinone (PQ) to PSI acceptors (REo/ETo) after 20 days of infection suggested greater inhibition on PQ reduction than re-oxidation, and the protection for PSI acceptors might alleviate the reduction of electron transport efficiency beyond PQ upon damaged PSI reaction center. Lowered delayed fluorescence in microsecond domain verified PSII damage in infected seedlings, and elevated delayed fluorescence in sub-millisecond domain during PQ reduction process conformed to increased REo/ETo. In conclusion, F. solani infection depressed PSII and PSI performance and destroyed their coordination by inducing pathological wilting in apple seedlings. It may be a pathogenic mechanism of Fusarium to induce plant photosystems damage.

Honeysuckle (Lonicera japonica Thunb.) is a traditional medicinal plant in Chinese, and chlorogenic acid and luteolosid are its specific bioactive phenolic compounds. This study was to investigate leaf antioxidant responses in honeysuckle to saline stress with emphasis on phenolics through hydroponic experiments and field trials. NaCl stress did not stimulate antioxidant system including superoxide dismutase, ascorbate peroxidase, catalase and ascorbate, and had no significant effect on lipid peroxidation in the leaves. Consistently, no inhibition on photochemical capacity of photosystems suggested that reactive oxygen species (ROS) was maintained at a normal level under NaCl stress. However, leaf phenolic synthesis was activated by NaCl stress, indicated by elevated genes transcription and activity of phenylalanine ammonia-lyase and increased phenolics concentration. Specifically, leaf chlorogenic acid concentration was increased by 67.43% and 48.86% after 15 days of 150 and 300 mM NaCl stress, and the increase of luteolosid concentration was 54.26% and 39.74%. The accumulated phenolics hardly helped detoxify ROS in vivo in absence of oxidative stress, but the elevated phenolic synthesis might restrict ROS generation by consuming reduction equivalents. As with NaCl stress, soil salinity also increased concentrations of leaf phenolics including chlorogenic acid and luteolosid without exacerbated lipid peroxidation. In conclusion, leaf phenolics accumulation is a mechanism for the acclimation to saline stress probably by preventing oxidative stress in honeysuckle; leaf medicinal quality of honeysuckle can be improved by saline stress due to the accumulation of bioactive phenolic compounds.

The purpose of this study was to explore the effect of reducing nitric oxide (NO) in Rumex K-1 leaves on the photoprotection of photosystem II (PSII) under high temperature with strong light. Reducing the content of NO in Rumex K-1 leaves significantly aggravated the PSII photoinhibition and net degradation of D1 protein under high temperature with strong light, but not under high temperature in the darkness. The reduction of NO remarkably inhibited the electron transport of PSII in the leaves under high temperature and strong light, which resulted in an increase in excitation pressure and an over-accumulation of reactive oxygen species (ROS). The over-accumulation of ROS further damaged PSII. However, when the synthesis of D1 protein was inhibited, the D1 protein content and PSII activity were no longer influenced by reducing NO content in the leaves. The reduction of NO in leaves decreased the activities of ROS scavenger enzymes after treatment with high temperature and strong light for 2 h, which enhanced the over-accumulation of ROS to damage photosynthetic apparatus severely. All of these results suggest that NO was involved in the synthesis of D1 protein. Maintaining physiologically appropriate NO content in leaves will alleviate net degradation of D1 protein under high temperature with strong light to keep photosynthetic electrons flowing smoothly, which mitigates the accumulation of ROS in photosystems to avoid damage to the photosynthetic apparatus. Therefore, NO plays an important role in maintaining higher PSII photosynthetic performance under high temperature with strong light.

Drought stress leads to dramatic annual yield losses in wheat, while cuticular wax plays important roles in drought resistance; therefore, wax is vital for improving wheat drought tolerance and productivity. The wax confers essential ecophysiological functions, including the prevention of non-stomatal water loss and gas exchange, protection of plant from ultraviolet light or high irradiation, and other abiotic and biotic stress. Cutic-ular wax biosynthesis is very complex, and a number of genes involved in wax biosynthesis have been charac-terized recently mostly from model plantArabidopsis, as well as transcription factors (TFs) involved in the reg-ulation of wax biosynthesis. Cuticular wax biosynthesis is regulated transcriptionally, post-transcriptionally, and post-translationally; however, transcriptional regulation is considered to be the major regulatory mechanism. It has been indicated that drought can induce increased wax deposition, together with varied composition and morphology. Meanwhile, increased amounts of cuticular wax have been associated with improved drought tol-erance. Physiological studies in wheat found that wax signiifcantly increased the photosynthesis to transpiration ratio in greenhouse experiments, and increased grain and biomass yield in irrigated and rainfed ifeld experi-ments. The β-diketone pathway speciifc in wheat predominates in the reproductive stages. Despite its adaptive importance, the molecular mechanisms underlying variation in wheat wax especially for β-diketone and its as-sociation with drought tolerance remain to be investigated systematically.