Shoot Growth and Changes in the Mesophyll Cell Structure in the Biennial Needles of Abies sibirica Ledeb.

Structural aspects of source–sink relations in current-year and second-year shoots of Siberian fir were investigated. The period of linear growth of current-year shoots was accompanied by a decrease in the size of starch granules in chloroplasts and the number of mitochondria, as well as by the disappearance of lipid inclusions in the mesophyll cells of second-year needles. Growth processes did not affect seasonal changes in the structure of chloroplast grana in these cells. After the termination of shoot growth, large polysaccharide globules appeared in the cytoplasm of mesophyll cells in second-year needles. It is possible that the formation of these inclusions prevents the inhibition of the photosynthesis by starch, which was accumulated in chloroplasts.     

Metabolism of <Superscript>14</Superscript>C-glycine as a substrate for photorespiration of the leaf at different developmental stages of ephemeroides

The metabolism of ¹⁴C-glycine (a substrate for photorespiration) was studied in the light and in darkness under natural CO₂ concentration (0.03%) in the leaves of ephemeroides Scilla sibirica Haw. and Ficaria verna Huds. at different developmental stages. Using one and the same sample, potential photosynthesis (at 1% CO₂), true photosynthesis (at 0.03% CO₂), and leaf respiratory capacity were measured by the radiometric and manometric methods, respectively. All measurements were performed at 15°C, an average temperature during ephemer growth. It was found that, in the white zone of the Scilla leaf, the rate of CO₂ evolution resulting from metabolization of exogenous ¹⁴C-glycine was similar in the light and in darkness. In the green zone of the Scilla leaf and in the green leaf of Ficaria, both ¹⁴C-glycine absorption and ¹⁴CO₂ evolution were lower in the light as compared with darkness, which is explained by CO₂ reassimilation. In all treatments of both plant species, a specific inhibitor of glycine decarboxylase complex (GDC), aminoacetonitrile (5 mM) suppressed CO₂ evolution by 20–40%. It was concluded that in ephemeroides mitochondrial GDC, responsible for CO₂ evolution in photorespiration, is formed at the earliest stage of leaf development. This indicates that photorespiration can occur simultaneously with the development of the leaf photosynthetic activity. On the basis of the assumption that carbon losses in the form of CO₂ evolved during photorespiration comprise 25% of true photosynthesis, it was calculated that, in ephemer leaves, the highest rates of photorespiration and photosynthesis were attained during flowering when the leaf area was the largest and the rate of dark respiration was reduced by 1.5–2.0 times. The highest rates of dark respiration were observed in the beginning of growth. In senescing leaves by the end of the plant vegetation, potential photosynthesis and true photosynthesis were reduced, whereas dark respiration remained essentially unchanged. It is concluded that the high rates of potential and true photosynthesis are characteristic of ephemeroides when they complete their short developmental program in early spring (at 15°C); theoretically, photorespiration also occurs at a high rate during this period, when this process provides for a defense against the threat of photoinhibition at low temperature and high insolation.     

CO2 Exchange and Mesophyll Structure in Second-Year Needles of Abies sibirica Ledeb.

Seasonal changes in the net photosynthesis and dark respiration in second-year needles of Siberian fir were investigated. The functional state of needles was shown to determine the structural features of mesophyll cells. Current-year shoot growth is one of the major factors affecting the structure and functional activity of second-year needles during the growing period. The greatest changes occur in the number of mitochondria in mesophyll cells and the respiration rate of second-year needles. The rate of photosynthesis in second-year needles was shown to depend on the number of thylakoids in mesophyll chloroplasts.     

Basic Types of Structural Changes in the Leaf Mesophyll during Adaptation of Eastern Pamir Plants to Mountain Conditions

Quantitative characteristics of mesophyll structure were compared in leaves of eleven alpine plant species grown under natural conditions in the Eastern Pamirs at various altitudes, from 3800 to 4750 m. Basic types of changes in mesophyll structure, associated with plant adaptation to mountain conditions, were characterized. These changes manifested themselves in different numbers of cell layers and cell sizes in the palisade tissue and, as a consequence, in changed leaf thickness and cell number per unit of leaf area. Three plant groups were identified by the changes in the leaf structural characteristics depending on the type of mesophyll structure, ecological group of plant species, and altitude of plant habitat. The first group comprised alpine xerophytes with an isopalisade structure, in which the volume of palisade cells decreased and their number per unit of leaf area increased with the altitude of plant habitat. The number of mesophyll layers and leaf thickness decreased or did not change with altitude. The second group comprised subalpine plant species with a dorsoventral structure of mesophyll; these species occur below the line of continuous night frost. In these plant species, the number of mesophyll layers, leaf thickness, and cell number per unit of leaf area increased with altitude. The third group comprised mesophyte plants with a dorsoventral and homogenous mesophyll structure, which are encountered in a wide range of habitats, including the nival belt (from 4700 to 5000 m). In this group, cell volume increased and cell number per unit of leaf area decreased with altitude. We present a general scheme of leaf structural changes, which explains the changes in the quantitative characteristics of mesophyll as a function of altitude and highland environmental conditions.     

Ultrastructural Responses of Leaf Mesophyll and Trap Wall Cells of Utricularia Vulgaris to Cadmium

Ultrastructure of leaf mesophyll and two-layer trap wall of Utricularia vulgaris L. was studied after 24-h and 48-h treatment with different concentrations of cadmium. The treatment of plants with 0.25 g(Cd²⁺) m⁻³ caused different changes in the chloroplasts of the two organs. The thylakoids swelled in chloroplasts of leaf and the starch content increased in chloroplasts of traps. Higher concentrations of Cd (0.5 and 1.5 g m⁻³) caused osmiophilisation of thylakoids in the chloroplasts of both studied organs. The secretory cells in the trap wall was resistant to Cd. This revised version was published online in June 2006 with corrections to the Cover Date.     

Structural Adaptation of the Leaf Mesophyll to Shading

Structural characteristics of the mesophyll were studied in five boreal grass species experiencing a wide range of light and water supply conditions. Quantitative indices of the palisade and spongy mesophyll tissues (cell and chloroplast sizes, the number of chloroplasts per cell, the total cell and chloroplast surface area per unit leaf surface area) were determined in leaves of each of the species. The cell surface area and the cell volume in spongy mesophyll were determined with a novel method based on stereological analysis of cell projections. An important role of spongy parenchyma in the photosynthetic apparatus was demonstrated. In leaves of the species studied, the spongy parenchyma constituted about 50% of the total volume and 40% of the total surface area of mesophyll cells. The proportion of the palisade to spongy mesophyll tissues varied with plant species and growth conditions. In a xerophyte Genista tinctoria, the total cell volume, cell abundance, and the total surface area of cells and chloroplasts were 30–40% larger in the palisade than in the spongy mesophyll. In contrast, in a shade-loving species Veronica chamaedris, the spongy mesophyll was 1.5–2 times more developed than the palisade mesophyll. In mesophyte species grown under high light conditions, the cell abundance and the total cell surface area were 10–20% greater in the palisade mesophyll than in the spongy parenchyma. In shaded habitats, these indices were similar in the palisade and spongy mesophyll or were 10–20% lower in the palisade mesophyll. In mesophytes, CO₂ conductance of the spongy mesophyll accounted for about 50% of the total mesophyll conductance, as calculated from the structural characteristics, with the mesophyll CO₂ conductance increasing with leaf shading.     

The Heterogeneity of Structural and Functional Photosynthetic Characteristics of Mesophyll Chloroplasts in Various Parts of Mature or Senescing Leaf Blade of Two Maize (Zea Mays L.) Genotypes

Differences in ultrastructural parameters of mesophyll cell (MC) chloroplasts, contents of photosynthetic pigments, and photochemical activities of isolated MC chloroplasts were studied in the basal, middle, and apical part of mature or senescing leaf blade of two maize genotypes. A distinct heterogeneity of leaf blade was observed both for structural and functional characteristics of chloroplasts. In both mature and senescing leaves the shape of MC chloroplasts changed from flat one in basal part of leaf to nearly spherical one in leaf apex. The volume density of granal thylakoids decreased from leaf base to apex in both types of leaves examined, while the amount of intergranal thylakoids increased in mature leaves but decreased in senescing leaves. The most striking heterogeneity was found for the quantity of plastoglobuli, which strongly increased with the increasing distance from leaf base. The differences in chloroplast ultrastructure were accompanied by differences in other photosynthetic characteristics. The Hill reaction activity and activity of photosystem 1 of isolated MC chloroplasts decreased from leaf base to apex in mature leaves. Apical part of senescing leaf blade was characterised by low contents of chlorophyll (Chl) a and Chl b, whereas in mature leaves, the content of Chls as well as the content of total carotenoids (Car) slightly increased from basal to apical leaf part. This was reflected also in the ratio Chl (a+b)/total Car; the ratio of Chl a/b did not significantly differ between individual parts of leaf blade. Both genotypes examined differed in the character of developmental gradient observed along whole length of leaf blade.     

Intra-tissue Characteristics of Chloroplasts in the Lamina and Petiole of Mature Winter Leaf of Arum italicum Miller

Abstract: Laminae and petioles from mature winter leaves of Arum italicum were studied in order to obtain information on the sun—shade intra-tissue properties of chloroplasts. This inference was based on the: (1) micro- and submicroscopic characteristics of the chloroplasts, (2) cytochemical localizations of functional PS I and PS II, (3) pigment patterns and compositions, (4) immunolocalization of Rubisco, and (5) net photosynthesis. It was inferred that all the chloroplasts across the lamina had adaptations to intermediate shade conditions, without a sun-shade dimorphism between the palisade and the spongy tissues. In the petiole, where normally-structured chloroplasts were surprisingly present in the entire thickness of the organ, a structural and chemical dimorphism was found between the outer chlorenchyma and the inner aerenchyma where intermediate shade-type and extreme shade-type chloroplasts were present, respectively. However, some anomalies in the pigment composition were noted chiefly in the inner aerenchyma (low concentrations of β-carotene and lutein, absence of zeaxanthin, presence of unusual pigments, for instance lutein epoxide, lutein cis-isomer, and chlorophyllide a). The Rubisco immunolabelling in the outer chlorenchyma of the petiole was similar to that in the lamina, while it was very scant in the inner aerenchyma. Net photosynthesis in the petiole was about 75% of that recorded in the lamina. These data suggest that the petiole of the mature winter leaf of A. italicum closely co-operates with the lamina for enhancing light capture and utilization.     

两种山鹪莺的春季换羽及尾羽变化

换羽是鸟类为保证持续生存的重要过程。换羽策略与鸟类进化及对环境的适应紧密相关,研究鸟类换羽特征,对于了解鸟类的分类、系统发育、进化历史及其对环境的适应性等方面都有重要意义。2007年3月至9月,在广东肇庆市江溪村对黄腹山鹪莺(Prinia flaviventris)和纯色山鹪莺(P.inornata)的春季换羽进行了研究。通过设置雾网捕捉2种山鹪莺,对捕捉到的成体进行体重及身体量度的测量;对飞羽及尾羽进行标记:初级飞羽以翅尖的第一枚羽毛标记为"P1",次级飞羽以翅中部最外一枚标记为"S1",向内依次递增标记;尾羽以中央两根最长尾羽为"T1",分别向两侧递增标记为"T2~T5"。采用单因素方差分析(One way ANOVA)对不同月份山鹪莺的体重值进行差异性检验,对体重与月份进行Pearson相关分析,对尾羽的长度和宽度进行Pearson偏相关分析(控制变量:体长)。研究结果表明:1)两种山鹪莺换羽期为3至5月,持续时间约为60 d;2)两种山鹪莺春季换羽仅更换尾羽,换羽模式均为离心型,即中央一对尾羽最先开始替换,然后向两侧由内到外逐次更替;3)两种山鹪莺的尾羽长度和宽度同步变化,但绝大部分山鹪莺非繁殖期尾羽长度与繁殖期尾羽长度之比大于非繁殖期尾羽宽度与繁殖期尾羽宽度之比,即繁殖期尾羽相对较宽;4)两种山鹪莺换羽期间体重大致呈现下降趋势,但变化不显著(P0.05)。推测两种山鹪莺通过增加食物的摄入来抵抗换羽期和繁殖期重叠而导致的能量消耗,这可能与该地区丰富的食物资源有关,并在一定程度上体现了两种山鹪莺换羽策略对环境的适应性。     

Intranuclear Inclusions in Leaf Mesophyll Cells of Davidia involucrata

The ultrastructure of intranuclear inclusions in leaf mesophyll cells of Davidia involucrata was investigated with electron microscopy. Intranuclear inclusions occur generally in the cells of young and mature leaves. They consist of numerous bundles aggregated by several fibres (diameter about 10 nm), sometimes a few of bundles turn to tubules enveloped by fibres. Authors suggested that it is a new subtype (F2) of intranuclear fibrillar inclusion.     

两种热带雨林树苗对环境光强变化的生理响应和适应机制

干季末雨季初以西双版纳热带雨林中木奶果和玉蕊2种树苗为材料,研究了将生长于12.5%自然光（相当于小林窗的光强）和36%自然光（相当于大林窗的光强）下的这2种树苗分别移至36%自然光和12.5%自然光下之后各自叶片最大净光合速率（Pmax）、叶绿素荧光参数、光合色素含量、比叶重（LMA）以及叶片悬挂角（MA）的变化过程,探讨了2种植物幼苗在生长环境光强改变后其形态和生理生态特性做出的相应调整以适应新的光环境的过程与机制。结果表明,这2种树苗均不适宜生长在大林窗的强光环境下,但木奶果对光环境的增强表现出一定的耐受力,光合适应潜力强于玉蕊,2种树苗对低光环境都能较好地适应;新叶的生成在整株植物对生长光环境变化的适应过程中也起到至关重要的作用。     

甘蓝型油菜生殖生长期叶片和角果光合与产量关系的研究

以11个不同适生区甘蓝型油菜品种为材料,研究了油菜生殖生长期植株叶片和角果的光合气体交换参数、光合色素含量、光合关键酶蛋白含量、主要农艺性状及其与产量的关系,探讨影响叶片(角果)光合效率及单株籽粒产量的主要因子,为油菜高产高光效品种的系统评价提供理论依据。结果显示:(1)油菜植株叶片与角果的净光合速率间相关性较小,但叶片净光合速率远大于角果。(2)叶片净光合速率与其叶绿素a+b含量及气孔导度呈不显著的正相关关系(相关系数较大),与其光合关键酶PEPC、RuBisCO蛋白含量相关系数较小或呈不显著负相关;角果(皮)净光合速率与其叶绿素a、b含量、类胡萝卜素含量及气孔导度相关性较强;光合色素含量是影响叶片、角果净光合速率的第一主因子。(3)单株叶面积、角果数及角果表面积与籽粒产量显著正相关关系,是影响籽粒产量的第一主因子;叶片净光合速率和角粒数是影响籽粒产量的第二主因子;单株生物学产量与叶面积呈显著正相关关系,角果表面积、叶面积及叶片净光合速率是影响生物学产量的第一、二主要因子。研究表明,油菜高产高光效品种的综合评价指标应首选单株角果数、叶片面积,其次选择叶片净光合速率、叶片和角果皮的叶绿素含量以及角粒数。     

增强UV-B辐射和干旱对春小麦光合作用及其生长的影响

在室外盆栽条件下研究了UV-B辐射和土壤干旱对春小麦 '和尚头'生长和光合作用的影响.结果显示:(1)干旱、UV-B辐射、干旱+UV-B(复合)处理均可使叶片类黄酮含量增加,且干旱+UV-B处理增加显著高于其他处理(P<0.05).UV-B辐射和干旱单独处理均能显著降低叶片光合色素含量,但UV-B辐射的副作用大于干旱,复合处理对光合色素的影响介于UV-B和干旱之间.(2)各处理间的光合速率日均值大小次序为:对照>UV-B+干旱>UV-B>干旱;增强UV-B对净光合速率的抑制作用大于干旱,而UV-B+干旱处理的抑制作用较二者单独处理有所减轻.(3)UV-B辐射和干旱单独处理后总生物量比对照减少15%,且抑制作用为:干旱>UV-B>复合处理; UV-B辐射和干旱胁迫不但影响春小麦的生物量,而且影响小穗特征和产量.研究表明,UV-B辐射和干旱之间存在交互作用,说明一种胁迫可以减缓(轻)另外一种胁迫对春小麦的抑制作用.     

Optimization of the Leaf Mesophyll Structure in Alloploid and Diploid Wheat Species

Comparative analysis of the indices of plant growth and mesostructure of the photosynthetic apparatus was carried out with ten wheat (Triticum L.) species of various origins. Wheat alloploid forms (tetra- and hexaploids with the chromosome numbers of 28 and 42) exceeded the diploid forms (the chromosome number of 14) 2.3–2.4-fold by their absolute growth rate (AGR). As a result, the alloploid species developed a larger assimilation area; this change involved the internal reorganization of leaf phototrophic tissues and an increase in the cumulative internal assimilation area. In addition, the alloploid species manifested a higher correlation between the surface areas of cell and chloroplast membranes caused by a decrease in the cell number per the unit leaf area, a relative increase of the number of composite multifaveolate cells, a considerable expansion (in volume and surface area) of mesophyll cells, and an increase in chloroplast size and numbers. The decreased ratio between the characteristics of the cell membrane and chloroplast envelope presumes that CO₂ diffusion via cell and chloroplast membranes in the leaves was better balanced in the alloploid wheat species than in the diploid forms. All wheat species did not notably differ in their plastid–cytoplasm ratio (cell volume corresponding to one chloroplast and cell surface area per one chloroplast) and the ratio of surface area of cells to cell volume. The discriminant analysis revealed the indices of leaf growth and mesophyll structure instrumental in distinguishing between the diploid and alloploid species: leaf area, AGR, and cell size and number. The change in the latter indices optimized the structure of leaf phototrophic tissues in tetraploid and hexaploid species; as a result, the internal assimilation area was expanded and, consequently, leaf CO₂ conductance was increased.     

小麦突变体返白系生长后期某些生理变化

返白过程之后,返白系随着叶色的复绿,植株的代谢机能开始恢复,叶绿素含量上升,光合作用增强,叶片内可溶性糖含量上升,呼吸速率高于其祖先矮变１号;复绿初期返白系气孔阻力高于矮交１号,蒸腾速率则低于矮变１号。复绿后,以上各项指标都逐渐变化,达到矮变１号的水平。之后,返白系的蒸腾速率高于矮变１号,气孔阻力低于矮变１号,叶绿素含量及光合速率均高于矮变１号,近白系和矮变互号的呼吸速率在５月９～２５日间有上升趋势,但近白系呼吸速率较高。在生长后期,返白系的根系有向土壤深层分布的趋势。分析认为返白系在生长后期有一个补偿性生长阶段,通过改善植株水分状况,提高同化能力,降低消耗来保证生长和结实的需要。     

Regulation of photosynthetic carbon metabolism during phosphate limitation of photosynthesis in isolated spinach chloroplasts

Intact chloroplasts isolated from spinach were illuminated in the absence of inorganic phosphate (Pi) or with optimum concentrations of Pi added to the reaction medium. In the absence of Pi photosynthesis declined after the first 1–2 min and was less than 10% of the maximum rate after 5 min. Export from the chloroplast was inhibited, with up to 60% of the ¹⁴C fixed being retained in the chloroplast, compared to less than 20% in the presence of Pi. Despite the decreased export, chloroplasts depleted of Pi had lower levels of triose phosphate while the percentage of total phosphate in 3-phosphoglycerate was increased. Chloroplast ATP declined during Pi depletion and reached dark levels after 3–4 min in the light without added Pi. At this point, stromal Pi concentration was 0.2 mM, which would be limiting to ATP synthesis. Addition of Pi resulted in a rapid burst of oxygen evolution which was not initially accompanied by net CO₂ fixation. There was a large decrease in 3-phosphoglycerate and hexose plus pentose monophosphates in the chloroplast stroma and a lesser decrease in fructose-1,6-bisphosphate. Stromal levels of triose phosphate, ribulose-1,5-bisphosphate and ATP increased after resupply of Pi. There was an increased export of ¹⁴-labelled compounds into the medium, mostly as triose phosphate. Light activation of both fructose-1,6-bisphosphatase and ribulose-1,5-bisphosphate carboxylase was decreased in the absence of Pi but increased following Pi addition.It is concluded that limitation of Pi supply to isolated chloroplasts reduced stromal Pi to the point where it limits ATP synthesis. The resulting decrease in ATP inhibits reduction of 3-phosphoglycerate to triose phosphate via mass action effects on 3-phosphoglycerate kinase. The lack of Pi in the medium also inhibits export of triose phosphate from the chloroplast via the phosphate transporter. Other sites of inhibition of photosynthesis during Pi limitation may be located in the regeneratige phase of the reductive pentose phosphate pathway.Abbreviations FBP Fructose-1,6-bisphosphate - FBPase Fructose-1,6-bisphosphatase - MP Hexose plus pentose monophosphates - PGA 3-phosphoglycerate - Pi inorganic orthophosphate - RuBP ribulose-1,5-bisphosphate - RuBPCase ribulose-1,5-bisphosphate carboxylase - TP Triose Phosphate     

Changes in Size and Number of Mesophyll Cells, Nitrogen Content and Photosynthesis with Leaf Order in Brassica spp.

Numbers of mesophyll cells per unit leaf area decreased progressivelyfrom an upper leaf with a width of 3 cm towards the lower leaves.Enlargement of mesophyll cell size with leaf order accountedfor an increase or maintenance of mesophyll cell surface areaper unit leaf area. Increase of photosynthetic rates was correlatedwith increases of mesophyll cell surface area and nitrogen contentper unit leaf area. Therefore, in spite of an increase in cellsurface area to volume ratio with increase of mesophyll cellsize, it appears that increase of mesophyll cell surface areaand nitrogen content per unit leaf area enables a high rateof photosynthesis to be maintained. Brassica, photosynthesis, mesophyll surface area, nitrogen content, cell size, mesophyll resistance, leaf age     

The different fates of mitochondria and chloroplasts during dark-induced senescence in Arabidopsis leaves

Senescence is an active process allowing the reallocation of valuable nutrients from the senescing organ towards storage and/or growing tissues. Using Arabidopsis thaliana leaves from both whole darkened plants (DPs) and individually darkened leaves (IDLs), we investigated the fate of mitochondria and chloroplasts during dark-induced leaf senescence. Combining in vivo visualization of fates of the two organelles by three-dimensional reconstructions of abaxial parts of leaves with functional measurements of photosynthesis and respiration, we showed that the two experimental systems displayed major differences during 6 d of dark treatment. In whole DPs, organelles were largely retained in both epidermal and mesophyll cells. However, while the photosynthetic capacity was maintained, the capacity of mitochondrial respiration decreased. In contrast, IDLs showed a rapid decline in photosynthetic capacity while maintaining a high capacity for mitochondrial respiration throughout the treatment. In addition, we noticed an unequal degradation of organelles in the different cell types of the senescing leaf. From these data, we suggest that metabolism in leaves of the whole DPs enters a 'stand-by mode' to preserve the photosynthetic machinery for as long as possible. However, in IDLs, mitochondria actively provide energy and carbon skeletons for the degradation of cell constituents, facilitating the retrieval of nutrients. Finally, the heterogeneity of the degradation processes involved during senescence is discussed with regard to the fate of mitochondria and chloroplasts in the different cell types.     

4种槭树叶功能性状及其关系对季节变化的响应

以牡丹江地区的白牛槭（Acer mandshuricum）、茶条槭（Acer tataricum subsp. ginnala.）、糖槭（Acer saccharum）、五角槭（Acer pictum subsp. mono）4种槭树为研究对象,分别于春季、夏季和秋季进行取样,测定叶片性状指标（叶厚度、气孔长度、气孔宽度、气孔密度、叶脉密度、比叶面积及色素质量分数）,分析叶片各性状的季节变化趋势,并探讨色素与叶性状间在不同季节下的关系。结果如下（：1）4种槭树均表现为在夏季具有较高的叶厚度、较低的比叶面积和气孔密度,在秋季具较高的比叶面积和叶脉密度、较低的叶厚度。（2）4种槭树均为在夏季有较高的叶绿素a、b,在秋季色素质量分数均降低,季节变化区间分别为叶绿素a 77.40%～98.80%,叶绿素b 85.60%～99.53%,类胡萝卜素4.29%～78.52%。（3）色素与叶性状关系密切,季节动态下色素与比叶面积、气孔密度、叶脉密度正相关,与叶厚度、气孔长度、气孔宽度负相关（P<0.05）,但不同季节相关性略有差异。4种彩叶植物的叶片在应对不同季节的气候条件时形成了不同的构建策略...     

Pigments and Gas Exchange Characteristics in Leaves of Chlorophyll Mutants of Pisum sativum

Quantitative and qualitative characteristics of pigment composition and gas exchange were studied in chlorophyll mutants of pea, Pisum sativum L.: chlorotica 2004 and 2014. The mutant 2004 had light-green color, whereas the mutant 2014 has yellow-green leaves and stems; they contained about 80 and 50% of chlorophyll, respectively, compared to the initial line. cv. Torsdag. Leaves of the mutant 2004 had significantly lower carotene content and accumulated more lutein and violaxanthin. In the mutant 2014, the contents of chlorophyll and all carotenoids were reduced almost proportionally. The quantum efficiency of photosynthesis was by 29–30% lower in the mutants, and it was 1.5–2 times higher in F₁ hybrids, as compared to control plants. Our data allow us to conclude that the impairment of photosynthesis in the mutant 2014 is caused by the changed mesostructure of leaves, whereas in the mutant 2004, it may be caused by an impairment of photosystem reaction centers.