Modeling Dynamics of Leaf Color Based on RGB Value in Rice

This paper was to develop a model for simulating the leaf color changes in rice （Oryza sativa L.） based on RGB （red, green, and blue） values. Based on rice experiment data with different cultivars and nitrogen （N） rates, the time-course RGB values of each leaf on main stem were collected during the growth period in rice, and a model for simulating the dynamics of leaf color in rice was then developed using quantitative modeling technology. The results showed that the RGB values of leaf color gradually decreased from the initial values （light green） to the steady values （green） during the first stage, remained the steady values （green） during the second stage, then gradually increased to the final values （from green to yellow） during the third stage. The decreasing linear functions, constant functions and increasing linear functions were used to simulate the changes in RGB values of leaf color at the first, second and third stages with growing degree days （GDD）, respectively; two cultivar parameters, MatRGB （leaf color matrix） and AR （a vector composed of the ratio of the cumulative GDD of each stage during color change process of leaf n to that during leaf n drawn under adequate N status）, were introduced to quantify the genetic characters in RGB values of leaf color and in durations of different stages during leaf color change, respectively; FN （N impact factor） was used to quantify the effects of N levels on RGB values of leaf color and on durations of different stages during leaf color change; linear functions were applied to simulate the changes in leaf color along the leaf midvein direction during leaf development process. Validation of the models with the independent experiment dataset exhibited that the root mean square errors （RMSE） between the observed and simulated RGB values were among 8 to 13, the relative RMSE （RRMSE） were among 8 to 10%, the mean absolute differences （da） were among 3.85 to 6.90, and the ratio of da to the mean observation values （Clap） were among 3.04 to 4.90%. In addition, the leaf color model was used to render the leaf color change over growth progress using the technology of visualization, with a good performance on predicting dynamic changes in rice leaf color. These results would provide a technical support for further developing virtual plant during rice growth and development.

Distribution of Leaf Color and Nitrogen Nutrition Diagnosis in Rice Plant

Greenness and nitrogen content of each leaf on main stem of different japonica and indica rice varieties under different nitrogen levels were investigated. Results showed that the fourth leaf from the top exhibited active changes with the change of plant nitrogen status. When the plant nitrogen content was low, its color and nitrogen content were obviously lower than those of the three top leaves. With the increase of plant nitrogen content, the color and nitrogen content of the fourth leaf increased quickly, and the differences of color and nitrogen content between the fourth leaf and the three top leaves decreased. So, the fourth leaf was an ideal indication of plant nutrition status. In addition, color difference between the fourth and the third leaf from the top was highly related to the plant nitrogen content regardless of the variety and development stage. Therefore, color difference between the fourth and the third leaf could be widely used for diagnosis of plant nutrition. Results also indicated that the minimized color difference between the fourth and the third leaf at the critical effective tillering, the emergence of the second leaf from the top, and the heading was the symbol of high yield. Plant nitrogen content of 27 g kg-1 DW for japonica rice and 25 g kg-1 DW for indica were the critical nitrogen concentrations.

Physiology and Biochemistry Changes of Euphorbia pulcherrima During Leaf Color Transformation

Reasons for the color change of E.pulcherrima were studied with physiological and biochemical paraments such as: chlorophyll,carotenoids,anthocyanin,Phenylalanine ammonia-lyase (PAL),pH of cell sap in leaves and soluble sugar content etc.The results showed that during the period of the leaf color transmittion of E.pulcherrima,the contents of plastid pigment,soluble sugar and pH of cells sap in leaves showed a high-low-high dynamic change,while the contents of anthocyanin and PAL activity showed the low-high...

Relationships between leaf color changes,pigment levels,enzyme activity,photosynthetic fluorescence characteristics and chloroplast ultrastructure of Liquidambar formosana Hance

Liquidambar formosana Hance is an attractive landscape tree species because its leaves gradually change from green to red,purple or orange in autumn.In this study,the red variety of L.formosana was used to establish a quantitative model of leaf color.Physiological changes in leaf color,pigment levels,enzyme activity,photosynthetic fluorescence characteristics and chloroplast ultrastructure were monitored.The relationship between leaf color and physiological structure indices was quantitatively analyzed to systematically explore the mechanisms behind leaf color.Our data showed that with a decrease in external temperatures,chloroplast numbers and sizes gradually decreased,thylakoid membranes became distorted,and chlorophyll synthesis was blocked and gradually decreased.As a result,chloroplast membranes could not be biosynthesized normally;net photosynthesis,maximum and actual photochemical efficiency,and rate of electron transfer decreased rapidly.Excess light energy caused leaf photoinhibition.With intensification of photoinhibition,leaves protected themselves using two mechanisms.In the first,anthocyanin synthesis was promoted by increasing chalcone isomerase and flavonoid glycosyltransferase activities and soluble sugar content so as to increase anthocyanin to filter light and eliminate reactive oxygen species to reduce photoinhibition.In the second,excessive light energy was consumed in the form of heat energy by increasing the non-photochemical quenching coefficient.These processes tuned the leaves red.

Modeling leaf color dynamics of winter wheat in relation to growth stages and nitrogen rates

The objective of this work was to develop a model for simulating the leaf color dynamics of winter wheat in relation to crop growth stages and leaf positions under different nitrogen(N) rates. RGB(red, green and blue) data of each main stem leaf were collected throughout two crop growing seasons for two winter wheat cultivars under different N rates. A color model for simulating the leaf color dynamics of winter wheat was developed using the collected RGB values. The results indicated that leaf color changes went through three distinct stages, including early development stage(ES), early maturity stage(MS) and early senescence stage(SS), with respective color characteristics of light green, dark green and yellow for the three stages. In the ES stage, the R and G colors gradually decreased from their initial values to steady values, but the B value generally remained unchanged. RGB values remained steady in the MS, but all three gradually increased to steady values in the SS. Different linear functions were used to simulate the dynamics of RGB values in time and space.A cultivar parameter of leaf color matrix(MRGB) and a nitrogen impact factor(FN) were added to the color model to quantify their respective effects. The model was validated with an independent experimental dataset. RMSEs(root mean square errors) between the observed and simulated RGB values ranged between 7.0 and 10.0, and relative RMSEs(RRMSEs)ranged between 7 and 9%. In addition, the model was used to render wheat leaves in three-dimensional space(3 D). The 3 D visualizations of leaves were in good agreement with the observed leaf color dynamics in winter wheat. The developed color model could provide a solid foundation for simulating dynamic crop growth and development in space and time.

Analysis of variation in temperature-responsive leaf color mutant lines induced from Gamma irradiation in rice(Oryza sativa L.)

Eight lines of temperature-responsive leaf colormutants induced by applying 300 Gy Gamma-ray irradiation to Thermo-sensitive genic malesterile line 2177s,were obtained through con-tinuous selection in seven generations..Theleaves of these lines started to become greenafter the fourth leaf extension,and except

A valine residue deletion in ZmSig2A, a sigma factor, accounts for a revertible leaf-color mutation in maize

A nuclear-encoded sigma(σ) factor is essential for the transcriptional regulation of plant chloroplastencoded genes. Five putative maize r factors have been identified by database searches, but their functions are unknown. We report a maize leaf color mutant etiolated/albino leaf 1(eal1) that was derived from space mutation breeding. The eal1 mutant displays etiolated or albino leaves that then gradually turn to normal green at the seedling stage. The changes in eal1 leaf color are associated with changes in photosynthetic pigment content and chloroplast development. Map-based cloning revealed that a single amino-acid deletion changing Val_(480)-Val_(481)-Val_(482) to Val_(480)-Val_(481), in the C-terminal domain σ_(4) of the putative σ factor ZmSig2A, is responsible for the eal1 mutation. In comparison with the expression level of the wild-type(WT) allele ZmSig2A^(+) in WT plants, much higher expression of the mutant allele ZmSig2A^(⊿V) in eal1 plants was detected before the eal1 plants turned to normal green. ZmSig2A shows the highest similarity to rice OsSig2A and Arabidopsis SIG2. Ectopic expression of ZmSig2A^(+) or ZmSig2A^(⊿V) driven by the cauliflower mosaic virus 35 S promoter rescued the pale green leaf of the sig2 mutant, but ectopic expression of ZmSig2A^(⊿V) driven by the SIG2 promoter did not. We propose that the Val deletion generated a new weak allele of ZmSig2A that cannot completely abolish the ZmSig2A function. Some genes involved in chloroplast development and photosynthesis-associated nuclear genes showed significant expression differences between eal1 and WT plants. We conclude that ZmSig2A encoding a r factor is essential for maize chloroplast development. The eal1 mutant with a weak allele of ZmSig2A represents a valuable genetic resource for investigating the regulation of ZmSig2A-mediated chloroplast development in maize.The eal1 mutation may be useful as a marker for early identification and elimination of false hybrids or transgene transmission in the application of genetic male sterility to commercial hybrid seed production.

A Review on Resistance to Biotic Stress in Leaf-Colored Plant

As sessile organisms, plants have to be subjected to insect attack. Over the long course of evolution, plants have produced many mechanisms to resist this biotic stress such as pigment accumulation. Pigment levels determined depth and distribution of leaf color, thereby indirectly or directly affecting the behavior of insect attack. Therefore, understanding the mechanism of mutual recognition between leaf color and insect will provide important theoretical insight for the cultivation and improvement of new cultivars. This paper outlines leaf-color formation and the effect of pigment on the behavior of insect attack, and explores the challenge of research in the interaction between leaf color and insect, as soon as the potential direction for future development. This will give a broad background for improvements of colored plants with resistance to insect attack.

Morphological Structure and Genetic Mapping of New Leaf-Color Mutant Gene in Rice (Oryza sativa)

Leaf-color mutations are a widely-observed class of mutations, playing an important role in the study of chlorophyll biosynthesis and plant chloroplast structure, function, genetics and development. A naturally-occurring leaf-color rice mutant, Baihuaidao 7, was analyzed. Mutant plants typically exhibited a green-white-green leaf-color progression, but this phenotype was only expressed in the presence of a stress signal induced by mechanical scarification such as transplantation. Prior to the appearance of white ~eaves, mutant plant growth, leaf color, chlorophyll content, and chloroplast ultrastructure appeared to be identical to those of the wild type. After the changeover to white leaf color, an examination of the mutated leaves revealed a decrease in total chlorophyll, chlorophyll a, chlorophyll b, and carotenoid content, a reduction in the number of chloroplast grana lamella and grana, and a gradual degradation of the thylakoid lamellas. At maturity, the mutant plant was etiolated and dwarfed compared with wild-type plants. Genetic analysis indicated that the leaf mutant character is controlled by a recessive nuclear gene. Genetic mapping of the mutant gene was performed using an F2 population derived from a Baihuaidao 7 ~ Jiangxi 1587 cross. The mutant gene was mapped to rice chromosome 11, positioned between InDel markers L59.2-7 and L64.8-11, which are separated by approximately 740.5 kb. The mutant gene is believed to be a new leaf-color mutant gene in rice, and is tentatively designated as gwgl.

Resources of Colored-leaf Trees and Their Phenological Ornamental Characteristics in Lhasa City

By using biological five points,expert consultation and fuzzy comprehensive evaluation,the species,phenological ornamental characteristics,and landscape application of colored-leaf trees in Lhasa City were surveyed systematically. The results show that there are 42 species of colored-leaf trees in Lhasa City,belonging to 31 genera and 18 families,of which there are 5,19,and 18 species of spring,autumn,and common colored-leaf trees,accounting for 11.90%,45.24% and 42.86% of total number of the investigated tree species respectively. It is clearly seen that there are too few species of spring colored-leaf trees in the city. There are 19 and 17 species of trees possessing red and yellow leaves,while the leaves of other 6 species of colored-leaf trees are shown in other colors,and the number of their species accounts for 45.24%,40.48% and 14.28% of total number of the investigated tree species respectively. The best ornamental periods of spring,autumn and common colored-leaf trees in Lhasa City average 38.4,41.8 and 251.8 d respectively. Prunus cerasifera Ehrhar f. atropurpurea Rehd.,Ulmus pumila L.,Populus × beijingensis W. Y. Hsu,and Salix alba are applied most frequently in Lhasa City,and their relative frequency is 18.67%,10.29%,9.91% and 8.95% respectively. According to the comprehensive assessment value of their ornamental characteristics,the ornamental characteristics of 15 species of colored-leaf trees in Lhasa City are good or very good,and there is a positive correlation between the comprehensive assessment value and relative frequency. Based on the investigation,the current application situation and problems of colored-leaf trees in Lhasa City were analyzed,and solutions to the problems were proposed.

Investigation and Application of Colored-leaf Plants in Tibet

For the quantitative analysis of colored-leaf plants in Tibet,the five-point sampling method is used for stratified investigation of garden plant communities in Tibet.(i)There are a total of 46 families,76 genera and 110 species of garden colored-leaf plants in Tibet,including 56 kinds of trees,40 kinds of bushes,9 kinds of herbs,4 kinds of vines and 1 kind of bamboo.There are too few colored-leaf herbs and bamboos,and there is a serious imbalance between evergreen and deciduous trees,between coniferous and broad leaved forests.(ii)The most widely applied families include Rosaceae(26),Salicaceae(12),Fabaceae(6),Aceraceae(5),Oleaceae(4)and Elaeagnaceae(4),accounting for 23.64%,10.91%,5.46%,4.55%,3.64% and 3.64% of the investigated colored-leaf plants,respectively.(iii)In terms of color,there are 55 kinds of red plants,43 kinds of yellow plants and 12 kinds of plants with other colors,accounting for 50.00%,39.09%and 10.91% of colored-leaf plants,respectively.There are 9 kinds of spring color leaf plants,63 kinds of autumn color leaf plants,29 kinds of constant color leaf plants,7 kinds of double color leaf plants and 2 kinds of spot color leaf plants,accounting for 8.18%,57.27%,26.36%,6.36% and 1.82% of colored-leaf plants,respectively,indicating that it is dominated by autumn color leaf and constant color leaf plants.(iv)In terms of importance value of trees,the top two are Salix alba(37.623)and Prunus cerasifera f.atropurpurea(26.063); in terms of importance value of bushes,the top three are Ligustrum × vicaryi Hort(22.577),Berberis thunbergii‘atropurpurea Nana'(18.987)and Platycladus orientalis Franco cv.Sieboldii(10.529); in terms of importance value of herbs,the top two are Taraxacum sherriffii(0.915)and Oxalis triangu laris cv.purpurea(0.326).(v)In terms of species abundance of colored-leaf plants,it is in the order of Nyingchi(94)> Lhasa(47)> Qamdo(43)> Shannan(34)> Xigaze(21)> Ali(7)> Nagqu(5).There are great differences between regions: it is highest in Nyingchi while it is lowest in Nagqu.Based on the main problems in the application of colored-leaf plants in Tibet,this paper makes the corresponding recommendations.

Colored-leaf Species Resources and Their Landscaping Application in Guang'an City

By investigating species, characteristics and landscaping application of colored-leaf species in Guang'an City, this paper proposed suggestions for the application of colored-leaf species in the local area.

Application of Colored-leaf Plants in Landscape Construction

With the gradual improvement of living standard, the public demands on landscaping have focused more on quality than on quantity, and plant furnishing has grown from singular green plants to colored-leaf plants with multiple layers. Confi guration of colored-leaf plants follows certain principles and patterns to enrich the beauty of plant landscaping, construct colorful urban green spaces, satisfy increasing application and aesthetic needs of the public, and reflect value of plant landscaping.

基于色差仪的茶树叶色量化研究

[目的]本试验旨在探讨不同叶色茶树群体的叶色关系及分布规律,确定茶树叶色定量描述的最佳色差仪参数,为叶色描述、分类提供理论依据。[方法]以120个茶树品种(或株系)为研究对象,用色差仪测定叶片的明度(L^(*))、红度(a^(*))、黄度(b^(*))、彩度(C^(*))、总色值(E^(*))、色调角(h)和饱和度(S^(*)),开展包括正态性检验、主成分分析、非参数多重比较、聚类分析和相关性分析的统计分析。[结果]由黄色、绿色到紫绿色,叶片的L^(*)、b^(*)、C^(*)、E^(*)和S^(*)值逐渐降低,a^(*)值先降后升。h值在绿色茶树中最大,紫绿色与黄色茶树没有显著差异。7个参数在绿色茶树中多为正态分布,而在黄色、紫绿色茶树中多为偏态,说明黄色和紫绿色茶树所受选择压力大于绿色茶树。主成分分析结果表明,不同颜色茶树群体之间主要是明度和饱和度存在差异,群体内主要是红绿度存在差异。多重比较结果显示,S^(*)值对不同品种(株系)茶树叶色的区分度最佳,a^(*)值最差。当欧式距离为8.78时,120个茶树品种(株系)被聚为3类,与目测法的分类一致。L^(*)、b^(*)、C^(*)、E^(*)和S^(*)值与叶绿素含量的相关性较强,相关系数都在0.70以上;a^(*)值与花色苷含量的相关性较强,相关系数为0.76。[结论]S^(*)值对不同品种茶树叶色区分度最佳,同时与叶绿素和花色苷含量均有较强的相关性,能够在一定程度上反映叶绿素与花色苷含量,可以选定饱和度S^(*)作为精准评价茶树叶片颜色的最佳色差仪参数。

水稻维生素B_1合成相关基因OsTHIC的功能研究

【目的】维生素B_(1)(vitamin B_(1), VB_(1))是生物所必需的微量元素,其作为多个酶的辅因子,参与重要的细胞代谢途径,而水稻中维生素B_(1)合成途径还有待深入研究。本研究旨在解析水稻维生素B_(1)合成相关基因OsTHIC的生物学功能。【方法】综合运用诱变技术、色素测定、Mutmap+、基因编辑及非靶向代谢组分析等手段克隆目的基因并解析其功能。【结果】从EMS诱变的水稻突变体库中发现一个心叶白化致死突变体wll1(white leaf and lethal 1)。wll1从四叶期开始出现心叶白化表型,白化表型逐渐扩展到其他叶片并导致幼苗死亡。与野生型相比,wll1的叶绿素含量与类胡萝卜素含量显著降低。利用Mutmap+及基因编辑技术,确定目的基因为维生素B_(1)合成相关基因OsTHIC。OsTHIC在叶片具有较高表达量,OsTHIC蛋白定位于叶绿体。wll1及OsTHIC的敲除突变体中维生素B_(1)含量均显著低于野生型,外施维生素B_(1)可以恢复wll1的突变表型。外施维生素B_(1)及OsTHIC突变均会影响维生素B_(1)合成相关基因的表达。非靶向代谢组测序分析表明,野生型与wll1差异代谢物在氨基酸的生物合成、辅因子的生物合成、ABC转运器及氨酰基-tRNA的生物合成等方面显著富集。【结论】OsTHIC通过调控维生素B_(1)含量,参与氨基酸合成等代谢过程,在水稻生长发育过程中发挥重要作用。

一份新的玉米永久性失绿突变体chs10的鉴定及基因克隆

【目的】利用60Co-γ射线处理自交系齐319获得了一份新的玉米叶色突变体,对该突变体进行遗传分析、基因定位与克隆,并对候选基因的功能进行初步分析。【方法】以该突变体为亲本,构建遗传分析群体和基因定位群体;通过图位克隆技术获得关键候选基因;利用生物信息学方法分析关键候选基因的结构和进化关系;通过qRT-PCR技术检测候选基因在不同组织中的表达差异;同时运用烟草瞬时表达技术对候选基因进行亚细胞定位表达分析。【结果】鉴定了一份玉米永久性失绿突变体chs10(Permanent chlorosis 10),chs10自V2时期开始,叶片从幼苗基部到顶部逐渐由绿转黄,后期的生长发育过程中不再复绿,并且,整个植株包括叶鞘、叶环、茎秆、苞叶和雄穗也均为黄色。该突变体受一对隐性核基因控制,可稳定遗传,植株生长发育正常,可正常授粉结实。突变基因被定位于玉米第10染色体长臂标记SNP-2和SNP-3之间约0.17 Mb范围内,确定了关键候选基因Zm00001d025860,qRT-PCR结果显示Zm00001d025860在玉米根、茎、叶和叶鞘中均有表达,但在叶片中高表达,亚细胞定位结果显示目标蛋白被定位在细胞膜和叶绿体中。利用STRING预测发现Zm00001d025860与卟啉结合蛋白GUN4基因互作,GUN4与叶绿素合成中的镁离子螯合酶(MgCh)具有反馈调节作用。【结论】Zm00001d025860基因的突变导致突变体chs10叶色的改变,并且Zm00001d025860可能通过参与叶绿素合成途径来调控叶色变化。突变体chs10的发现一方面丰富了玉米叶色突变体研究的基因资源,同时为解析镁离子螯合酶在叶绿素合成途径中的作用机理奠定了材料基础。

引种鸡爪槭光合特性及叶片呈色对异质生境的响应

探讨不同生境下引种鸡爪槭叶片呈色及光合特性,为其引种驯化、高效种植提供理论依据.以引种鸡爪槭4年生嫁接苗为研究对象,分析不同环境因子(海拔及坡向等)对各品种鸡爪槭(分别为红舞姬HWJ、橙之梦CZM、三季黄枫SJHF)叶片呈色、叶绿素荧光参数及光合特性的影响.低海拔阴坡生境下各品种鸡爪槭的叶绿素a(Chla)、叶绿素b(Chlb)、类胡萝卜素(Car)、叶绿素(Chls)、最大荧光(Fm)、初始羧化速率(α)、最大光化学效率(Fv/Fm)、表观量子效率(AQY)和最大净光合速率(P_(nmax))显著低于其他生境(p<0.05).在同一生境下,三季黄枫的P_(nmax),A_(nmax),α, AQY,Fv/Fm,光呼吸速率(Rp)均高于红舞姬、橙之梦,且三季黄枫在不同生境下AQY、Rp、光补偿点(LCP)、 CO_(2)补偿点(CCP)、暗呼吸速率(Rd)和饱和胞间CO_(2)摩尔分数(CSP)差异无统计学意义(p>0.05).品种间叶色参数L*,a*,b*值差异极有统计学意义(p<0.01),生境及生境与品种的交互作用对Chla, Chlb, Chls, Car, LSP, AQY, CSP,P_(nmax),A_(nmax),Fv/Fm和ETR产生极显著影响(p<0.01),其中pH值、土壤含水率、海拔和坡向是影响鸡爪槭光合特性的关键因子.生境间差异对引种鸡爪槭的光合特性均有显著影响,但在同一生境中,三季黄枫捕获、传递光能以及进行能量转化的光合色素质量分数均大于其他2个品种,表现出更强的环境适应性.

Genetic Analysis and Gene Mapping of Light Brown Spotted Leaf Mutant in Rice

A light brown spotted-leaf mutant of rice was isolated from an ethane methyl sulfonate （EMS）- induced IR64 mutant bank. The mutant, designated as Ibsll （light brown spotted-leaf 1）, displayed light brown spot in the whole growth period from the first leaf to the flag leaf under natural summer field conditions. Agronomic traits including plant height, growth duration, number of filled grains per panicle, seed-setting rate and 1000-grain weight of the mutant were significantly affected. Genetic analysis showed that the mutation was controlled by a single recessive gene, tentatively named Ibsll（t）, which was mapped to the short arm of chromosome 6. By developing simple sequence repeat （SSR） markers, the gene was finally delimited to an interval of 130 kb between markers RM586 and RM588. The Ibsll（t） gene is likely a novel rice spotted-leaf gene since no other similar genes have been identified near the chromosomal region. The genetic data and recombination populations provided will facilitate further fine-mapping and cloning of the gene.

基于色彩参数和高光谱参数估测风箱果属植物叶片色素含量

为快速、无损检测3种(品种)不同色系风箱果叶片色素含量及光合性能,在生长季内分别测定3种试材不同叶位叶片的色素含量、色彩参数、高光谱反射率,通过多元逐步回归、偏最小二乘回归分析建立叶片色素含量估算模型,并进行精度检验。结果表明,风箱果、金叶风箱果叶片光谱反射特性相似,紫叶风箱果在绿光峰值及近红外光处区别于前两者,三者光谱反射率表现为金叶风箱果>风箱果>紫叶风箱果。基于偏最小二乘构建的色素估算模型精度最高,其中,叶片色彩参数与风箱果总叶绿素、花色素苷及紫叶风箱果花色素苷含量建模和检验R2均在0.68以上,最高为0.89;高光谱参数与风箱果及金叶风箱果的叶绿素a、叶绿素b、总叶绿素、类胡萝卜素、花色素苷含量建模R2均在0.79以上,最高为0.98,检验R2均在0.64以上,最高为0.91。基于高光谱参数建立的叶片色素估算模型精度高于基于色彩参数所建模型;证实了偏最小二乘回归模型在3种(品种)色系风箱果叶片色素含量估算中的优越性,并构建了高精度的叶片色素估算模型。

Physiological and Transcriptomic Changes During Autumn Coloration and Senescence in Ginkgo biloba Leaves

Autumn leaf senescence and coloration is a complex process and a striking natural phenomenon.Here,through biology approach integrating transcriptomic analyses in Ginkgo biloba,we determined that the content of chlorophyll decreased during leaf senescence,while carotenoid components increased until late October in the turning stage(TS)and then decreased in the yellow leaf stage(YS).Simultaneously,chlorophyll biosynthesis genes exhibited significantly lower expression levels while chlorophyll degradation genes showed increased expression from the green leaf stage(GS)to YS.However,carotenoid biosynthesis-related genes showed enhanced expression,especially in TS.An analysis of the expression of genes related to senescence demonstrated that the expression levels of most abscisic acid-and jasmonic acid-related genes,autophagy,WRKY,and NAC genes increased,whereas cytoskeleton-,photosynthesis-,and antioxidation-related genes decreased from GS to YS.Furthermore,G.biloba seedlings exogenously treated with abscisic acid,jasmonic acid,or ultraviolet-B radiation all showed obvious color variation and senescence symptoms.We used these exogenously seedlings to further validate the function of several genes involved in chlorophyll biosynthesis and senescence.Taken together,these results contribute to the elucidation of the molecular mechanisms of leaf coloration and senescence in G.biloba as well as in the identification of candidate genes involved in this process.