Self-fertilization in homozygous and heterozygous self-compatible almonds

In homozygous self-compatible genotypes 100% of the pollen grains are potentially able to grow through their own pistil, and thus the rate of self-fertilization could be higher than in heterozygous self-compatible genotypes. To evaluate the advantages of growing homozygous self-compatible almonds, pollen tube growth along the pistil at different times following self-pollination, and fruit set were studied in four homozygous and four heterozygous self-compatible seedlings. The results showed important differences between homozygous and heterozygous individuals for the percentages of pollen tubes in the third section of the style at 24 and 48 h, the pollen tube growth rate being higher in the homozygous. Twenty-four hours following self-pollination only the homozygous individuals showed pollen tubes in the ovary. However, at 72 and 96 h those values were similar for both genotypes, suggesting that space and availability of nutrients become the main limiting factors, overcoming the genetic interactions between pollen and pistil. In general, fruit set was similar in homozygous and heterozygous individuals. Interestingly, one of the homozygous individuals showed problems of fruit development, which might be explained by its inbred origin.     

Effects of pollen-load on fruit yield,seed production and germination in melons,cucumbers and squash

Summary

Four cultivars of each of three cucurbit species were used to examine the effects of pollen-load (i.e., the number of pollen grains deposited on the stigma of pistillate flowers) on fruit-set, seed-set, and germinability (i.e., germination percentage and germination rate) in four greenhouse experiments. Increasing pollen-load increased the number of fruit per plant in the four melon cultivars over two growing seasons, and in two non-parthenocarpic cucumbers, but had no effect on all four squash cultivars. In most cases, increasing pollen-load increased the number of fully-developed seeds, decreased the percentage of empty seeds, and tended to decrease mean seed weights. On average, melons produced 2.2 fruits per plant in the Winter, and only 0.9 fruits per plant in the Autumn. In contrast, melons produced 275 fully-developed seeds per fruit in the Autumn, but only 57 seeds in the Winter. Mean melon seed weight was higher in Autumn, and the sum of all seed yield component effects resulted a significantly higher seed yield per plant in the Autumn. Germinability of melon seeds from the Autumn season, and of squash seeds from the Winter season, were not significantly affected by pollen-load treatment. These data are contrary to the theory that microgametophyte competition has a positive effect on the vigour of the progeny. The lower germinability of melon seeds obtained by passive pollination (i.e., self-pollination in covered flowers) may be due to the fact that pollination without insect or human interference yielded only a few seeds per fruit, and, under such circumstances, there may be a survival advantage for slow and distributed germination.     

Pollen grains of heat tolerant tomato cultivars retain higher carbohydrate concentration under heat stress conditions

Exposure to high temperatures (heat stress) causes reduced yield in tomatoes (Lycopersicon esculentum), mainly by affecting male gametophyte development. Two experiments were conducted where several tomato cultivars were grown under heat stress, in growth chambers (day/night temperatures of 31/25 °C) or in greenhouses (day/night temperatures of 32/26 °C), or under control (day/night temperatures of 28/22 °C) conditions. In heat-sensitive cultivars, heat stress caused a reduction in the number of pollen grains, impaired their viability and germinability, caused reduced fruit set and markedly reduced the numbers of seeds per fruit. In the heat-tolerant cultivars, however, the number and quality of pollen grains, the number of fruits and the number of seeds per fruit were less affected by high temperatures. In all the heat-sensitive cultivars, the heat-stress conditions caused a marked reduction in starch concentration in the developing pollen grains at 3 days before anthesis, and a parallel decrease in the total soluble sugar concentration in the mature pollen, whereas in the four heat-tolerant cultivars tested, starch accumulation at 3 days before anthesis and soluble sugar concentration at anthesis were not affected by heat stress. These results indicate that the carbohydrate content of developing and mature tomato pollen grains may be an important factor in determining pollen quality, and suggest that heat-tolerant cultivars have a mechanism for maintaining the appropriate carbohydrate content under heat stress.     

Observations on the Effect of Potash Supply on the Tension of the Tracheal Contents in Fruit Trees and Bushes

Summary

The effects of pollen source on fruit set and fruit quality characteristics (xenia effects) were examined in three commercial cultivars of mandarin, Imperial, Ellenor, and Murcott. Six trees of each cultivar received six pollination treatments: three cross-pollen sources, self-pollination, bagging and bagging with emasculation. Pollen tube growth, percentage fruit set, fruit weight, seediness, sugar and acid content were assessed in all treatments. Significant xenia effects, including effects on sugar content, were found in all cultivars. `Imperial' was found to be self-incompatible as self-pollen tubes were inhibited in the upper style. This resulted in a lower fruit set in self-pollinated fruits (P<0.01), a very low fruit weight (33–55 g, compared with 92–103 g, P<0.01), and fruits containing few or no seeds. In addition, `Ellenor' and `Murcott' pollen significantly increased sugar content of fruit by between 0.9–1.6% compared with self-pollinated and unpollinated treatments (P<0.05). Widespread problems of variable production and poor fruit quality in `Imperial' may be alleviated by interplanting with appropriate pollen sources such as `Ellenor' and `Murcott'. Pollen source significantly affected fruit set, seed number and sugar content but not fruit weight of cv. Ellenor. In particular, `Murcott' pollen produced a significantly higher fruit set, relatively low seed number, and the highest mean sugar content (13.2%), significantly higher than `Imperial' pollen, bagged, and unpollinated treatments (>12.5%, P<0.01). Fruit production, seediness and sugar content of `Ellenor' mandarin may be improved by interplanting with `Murcott'. Cross-pollination significantly increased seed number of `Murcott' (15–21 seeds per fruit, compared with 13–17 seeds per fruit, P<0.01). `Murcott' could be planted in pure blocks since self-pollinated `Murcott' fruit had slightly fewer seeds than crosses, without any significant loss of size or quality. These results demonstrate the need for careful consideration of interplanting of cultivars and management of pollinators such as the honeybee, Apis mellifera L. to maximize fruit production and quality in mandarins.     

磨盘柿与甜柿杂交低结籽率的组织学研究

 通过对西村早生、禅寺丸和花御所3种甜柿自交及与磨盘柿杂交的花粉管荧光观察,磨盘柿胚囊发育的石蜡切片观察,研究了磨盘柿受精率低的原因。结果如下：①磨盘柿与3种甜柿杂交,发育种子比例（发育种子数/胚珠数）明显低于甜柿自交,且父本花粉不同,磨盘柿的结子率有较大差异;②磨盘柿柱头上附着花粉量少,发芽率低,花柱中花粉管数量少,到达基部的条数少。甜柿柱头附着的花粉量大、发芽率高,花柱中花粉管数量大,大部分可以到达子房;③磨盘柿中存在多种异常胚囊,直接或间接的影响受精的顺利进行。较低的受精比率以及大量异常胚囊的存在是导致磨盘柿结籽率低的原因。     

黄瓜未授粉子房培养获得同源四倍体

为获得稳定纯合的同源四倍体黄瓜材料,采用多种分化培养基对黄瓜(Cucumis sativus L.)未授粉子房培养形成的胚进行培养。结果共获得33个再生植株,经染色体计数后发现7株为同源四倍体植株(2n=4x=28)。利用SSR手段对获得的同源四倍体植株进行了同质性鉴定,发现均为纯合子。利用形态学观察和染色体计数法对同源四倍体单株自交后代的遗传稳定性进行了研究,结果表明自交后代倍性没有发生变异。对此类型同源四倍体植株和经秋水仙素诱导获得的同源四倍体植株分别进行了花粉可染率、花粉萌发率及自交结籽数的观察,发现前者具有高的育性,自交结籽数为15～34粒。上述结果表明,黄瓜未授粉子房培养是获得同源四倍体的一条途径,获得的稳定纯合且育性好的同源四倍体材料可作为特异资源用于黄瓜倍性育种。     

切割花柱方式对亚百系内杂交花粉管生长和结实的影响

用常规柱头授粉和切割不同长度花柱4种授粉方式对亚百系内杂交的花粉管生长和结实情况进行了研究.结果表明:同一系内各组合亲和性存在差异,亲和性较好的组合为"金色号角×多安娜"、"普瑞头×索莱尔",次之为"多安娜×普瑞头","金色号角×普瑞头","普瑞头×多安娜"为不亲和组合;同一系内组合中,采用常规柱头授粉比切割花柱授粉得到胚的比例高,所有组合花粉管均能进入子房,而且随着切割花柱长度的增加,花粉管在花柱中及进入子房的量是依次递减的,种子数目与花粉管的生长情况呈正相关;果实膨大系数不能反映果实是否结籽;所有组合中都存在胚囊不亲和现象,形成了无胚仅有胚乳的种子.     

Immunolocalization and quantification of IAA after self- and free-pollination in Olea europaea L.

In order to characterise the self-compatibility in ‘Pisa 9’, that is an improved clone of cultivar Leccino (Olea europaea L.), biological, histological and biochemical analyses were carried out. Observations were also focused on ‘Pendolino’, the main pollinator for Italian cultivars considered as being self-incompatible. After self-pollination, in ‘Pisa 9’ the majority of the pollen tubes reached the distal part of the style, entered the ovule leading to a high fruit-set percentage. These same processes were also noted in the Pendolino cultivar, though in a lesser degree. The indole acetic acid (IAA) concentration and its immunocytochemical localization were determined in pollinated flowers after self- and free-pollination and in unpollinated flowers. In both cultivars the highest IAA levels and signal intensity were observed in free-pollinated pistils, whereas after self-pollination a different behaviour emerged. In ‘Pendolino’ the immunostaining was not uniformly distributed and stopped at the style level. This finding sustained the low percentage of fruit-set obtained in the cultivar. In ‘Pisa 9’ the auxin distribution was similar to the free-pollinated pistils where the immunolocalization staining reached the ovary. The correspondence between the IAA signal in the ovary and the high percentage of fruit-set in ‘Pisa 9’ self-pollinated pistils, confirms the role of this hormone in the induction and regulation of the fertilisation process.     

梨花柱半离体培养法及品种自交不亲和基因型鉴定

 ：切取梨授粉花柱进行半离体培养的结果表明，杂交不亲和性组合从花柱基部长出花粉管的花柱比率为0～32．4％ ，且大多在16％ 以下，而杂交亲和性组合为51．6％ ～86．7％ ，与田间杂交授粉的坐果率相近，且在授粉花粉的萌发率达20％以上时，温室水培枝条促成的花与露地开花的花之间没有显著差异。应用此方法鉴定出了梨品种‘筑水’、‘喜水’及‘爱甘水’的s基因型分别为s s 、s s 、及s s 。     

Fruit set after self-pollination at different floral stages and its relation to pollen-tube growth and stylar S-RNase content in Japanese apricot (Prunus mume Sieb. et Zucc.)

Summary

To investigate fruit set after self-pollination at different floral stages, and its relationship to the S-RNase content of the style in Japanese apricot, which exhibits gametophytic self-incompatibility (GSI), the cultivar ‘Xiyeqing’ was selfand cross-pollinated at –6, –4, –2, 0 and +2 d after anthesis (DAA). At –6 and –4 DAA, the percentage fruit set was low, suggesting that the propensity to seed set was weak during this period. At –2 DAA, the percentage fruit set, after self-pollination, reached a maximum of 5.97%. Thus, the effective time of self-pollination to obtain inbred seed was –2 DAA. Soluble protein extracts of styles at each floral stage were subjected to iso-electric focussing. The results showed that S-RNase began to be synthesized from –6 DAA, reached its maximum expression 2 – 3 d before anthesis, and was degraded slowly after anthesis. The number of pollen-tubes arriving at the stylar base, as detected by fluorescence microscopy, varied at –2, 0, and +2 DAA. The number of pollen-tubes arriving at the stylar base, and the percentage fruit set after self-pollination, exhibited a positive correlation (r = 0.8615; P = 0.1), while the S-RNase content per style showed a negative relationship to fruit set percentage (r = –0.9640; P = 0.01), and to the number of pollen tubes arriving at the stylar base (r = –0.9380; P = 0.01) during this period. This implied that the S-RNase content in the style was mainly responsible for the low percentage fruit set and the low number of pollen-tubes arriving at the stylar base after self-pollination.     

花粉管通道法在番茄转基因上的应用

为提高花粉管通道法遗传转化率,现设计了自交授粉后对番茄的花柱分别进行4种依次加大切割深度并滴加外源基因的处理,待转化果实成熟后收获转化种子。对各处理的坐果率和结籽数/果进行统计分析。结果表明:随着花柱切割深度的加大,坐果率和结籽数/果均显著下降;对T1代植株进行PPT抗性筛选、PCR检测阳性率后表明,不同深度切割处理对植物材料的转化率差异不显著。切除柱头+1/3花柱的处理方式进行花粉管通道法遗传转化操作,能获得较好的效果。     

A review of the practical use of gametocides on vegetable crops

Experimental observations on the use of gametocides on vegetable crops are reviewed. Out of 15 chemicals tested MH (maleic hydrazide) at 100 to 500 p.p.m. appeared most effective in inducing a high level of pollen sterility in eggplant, okra, peppers and tomato, without detrimental influence on female fertility. Mendok (2,3-dichloroisobutyrate), between 0.2 and 0.8%, also caused a high degree of pollen sterility, but was accompanied by an adverse influence on plant vigour and fruit-set.     

Sind Pollenspritzungen oder Pollendispenser Alternativen zur herkömmlichen Bestäubung der Apfelbäume durch Bienen?

The efficacy of different methods of applying cv. ‘Golden Delicious‘ pollen to ‘Cox Orange‘ apple trees inside insect-proof cages was investigated: (1) spraying pollen suspended in water directly into the trees while they were in bloom (treatment A); (2) pollen transfer by honeybees (treatment B) or by bumblebees (treatment C), both of which had to pass through a dispenser loaded with cv. ‘Golden Delicious‘ pollen; (3) transfer by honeybees of pollen from cv ‘Golden Delicious‘ trees bearing compatible pollen and maintained in pots within the same cages (treatment D). Naturally pollinated cv. ‘Cox Orange‘ apple trees outside the cages in the orchard served as controls. For methods A–C normal commercially available ‘Golden Delicious‘ pollen was used for hand pollination, and its efficacy was assessed with reference to the amount of fruit that set. The fruit-set at the time of harvesting differed significantly (Nemenyi test) with the different methods of pollination: 1.0% (±2.0) of the blossoms ripened to yield marketable apples after treatment A, 6.1% (±5.2) after treatment B, 4.9% (±4.6) after treatment C, and 20.4% (±11.5) after treatment D, while the corresponding figure for the control trees was 7.3% (±2.8) and that for hand pollination, 41,9%. The low fruit-set after an aqueous suspension of cv. ‘Golden Delicious‘ pollen was sprayed on the test trees shows that this procedure did not result in adequate pollination. The density of pollen grains was determined on filter papers during spraying and was an average of 3 (±2.6, range 0.0–8.6) pollen grains/cm². When the pollen dispensers were used, the fruit-set was lower than on the hand-pollinated control trees. Despite the success of manual pollination with exogenous cv. ‘Golden Delicious‘ pollen, pollen spraying to enhance pollination, as specified in current instructions, cannot be recommended for commercial apple growing in Germany.     

Effect of pistil age and pollen parent on pollen tube growth and fruit production of pistachio

Female pistachio (Pistacia vera) trees were hand pollinated with pollen from three different male genotypes 0,1,2,3 and 4 d after anthesis. Results were measured by mature fruit set and by fluorescence microscopy of pollen germination and tube growth in the pistil. Maximum pollen tube growth and fruit set of split nuts was achieved following pollination within two days of anthesis. Three day old pistils supported pollen tube growth, but fruit set was low. Four day old pistils supported little pollen tube growth or fruit set. Significant differences were also apparent between pollen parents, with low pollen tube growth and fruit set following interspecific pollination with P. atlantica pollen. All pollen tubes were observed to penetrate chalazogamously, and parthenocarpic production of blank fruits occurred in both unpollinated and pollinated treatments. The results indicate that for optimum fruit production of pistachio, pollen transfer must be achieved within 2 d of anthesis and pollination by P. atlantica should be avoided.     

‘金坠梨’自交亲和性突变机制的初步研究

 自交不亲和性品种鸭梨的芽变品种‘金坠梨’自花授粉能结实, 但其自交亲和性突变机制至今不祥。本研究结果表明, 鸭梨自花授粉结实率仅2% , 自花花粉管在花柱中上部已经停止生长, 而金坠梨自花授粉结实率高达76% , 自花的花粉管能正常生长至花柱基部; 鸭梨花柱能够接受金坠梨花粉并受精结实, 而金坠梨花柱却与鸭梨花粉杂交不亲和; 进一步鉴定出了鸭梨和金坠梨基于S-RNase基因的S基因型, 发现两者S基因型相同, 均为S₂₁S₃₄ ; 通过克隆两品种S-RNase基因cDNA全长序列并进行比较分析发现, 该两品种的1对雌蕊S-RNase基因在核苷酸序列上完全相同, 且S-RNase基因均正常表达, 表达量没有明显差异, 从分子水平上证实了金坠梨在花柱方面和鸭梨并无差异, 可能是花粉S 基因发生突变, 导致了自交不亲和性功能的丧失, 表现出自花授粉能够结实。     

温敏型核雄性不育系番茄T4育性的研究

以温敏型核雄性不育系番茄T4及对照First为试材,通过调查花粉发芽率、自交结实率、果实种子数以及采用Tricine-SDS-PAGE电泳方法分析叶片及花药蛋白质的变化,研究T4的育性转化,并分析其在可育和不育条件下花粉发芽率、自交结实率、果实种子数、叶片及花药蛋白质的差异。结果表明：28 ℃/18 ℃（昼/夜）处理的T4花粉发芽率、自交结实率最高,果实种子数最多,与对照First差异不显著,表明此时T4恢复部分育性|28 ℃/24 ℃和28 ℃/12 ℃处理的T4花粉发芽率、自交结实率和果实种子数与对照差异均达到极显著水平,表现为不育。不同温度处理的T4花药蛋白质与叶片蛋白质差异均达到显著水平|28 ℃/24 ℃和28 ℃/12 ℃处理的T4叶片蛋白质与对照差异显著,但28 ℃/18 ℃处理的差异不明显。     

Effective pollination period in durian (Durio zibethinus Murr.) and the factors regulating it

The effective pollination period (EPP) of durian was determined by both delayed and bud pollination, during which reproductive factors affecting the EPP, e.g., stigma receptivity, pollen tube growth in the style, and ovule longevity were studied histologically. This study was conducted in three distinct locations in Thailand, namely, the Chantaburi Horticultural Research Center and two private orchards in Chantaburi and Trat provinces. Results from artificial pollination revealed that at anthesis, the durian flower is receptive and has a high fruit set ratio. A mean fruit set of 50% was obtained at anthesis in the private orchard in Chantaburi province. However, the EPP of durian was found to be very short, lasting for only one night; the fruit set from pollination on the morning after anthesis ranged from 0% to 3.4%. No fruit set occurred following pollination 24 or more hours after anthesis. When compared with the flowers of other fruit species, the durian flower has a unique feature in that it blooms overnight; the following morning, there is abscission of all parts of the flower, except the gynoecium. Thus, EPP appears to be synchronized with flower longevity. On the other hand, the durian flower was receptive several hours before anthesis. The results of chemical tests, including the hydrogen peroxide test and Perex-Test^®, for the evaluation of stigma receptivity appeared to be in agreement with the EPP. However, fluorescent microscopy revealed that pollen could germinate even in the stigmas pollinated 48 h after anthesis, but the number of pollen tubes at the top of the style rapidly decreased from 34.6 (at anthesis) to 0.5 (48 h after anthesis). A correlation test demonstrated a higher correlation coefficient between the fruit set and the number of pollen than that between the fruit set and the result of Perex-Test^®. This indicated that pollen tube penetration or elongation in the style was inhibited, probably due to the deterioration of nutritional support from the pistil to the pollen tubes; this can be a limiting factor of the EPP in durian.     

四倍体西瓜低稔性胚胎发育研究

试验以二倍体自交为主要对照，四倍体与二倍体正反交为辅助对照，研究了四倍体西瓜自交低稔性的胚胎发育。通过镜检观察表明：1．四倍体西瓜自交花粉萌发率低，花粉管在柱头与花柱中生长出现异常现象，在花柱中生长缓慢，授粉后12h到达花柱基部。2．四倍体西瓜有少数结构不正常胚囊，但所占比率低于10％，不是稔性低的主要原因。3．四倍体自交双受精过程正常，但花粉管进入的胚囊数少，受精率仅35．8％。4．四倍体自交只有少数胚能正常发育，形成有活力种胚；大部分胚由于游离核或细胞化胚乳的异常解体，在原胚或球形胚阶段败育；少数胚分化到心形胚、鱼雷胚后，由于细胞化胚乳过早解体，胚停止分化而败育。     

Germination and growth of sponge gourd (Luffa cylindrica) pollen tubes and FTIR analysis of the pollen tube wall

Emergence of multiple pollen tubes from single pollen grains occurred both in vitro and in vivo in sponge gourd (Luffa cylindrica (L.) Roem). The frequency with which pollen grains produced multiple pollen tubes in vivo (7.2%) was lower than that under in vitro conditions (14.9%). In pollen grains germinated in vitro, the total length of the multiple pollen tubes was greater than that of single pollen tubes, but individual tubes among the multiple tubes did not reach the same length as single tubes. Moreover, the growth of the single pollen tubes continued for a longer period in vitro than that of the multiple tubes. Fluorescence microscopy showed that callose was present throughout the pollen tube wall except in the apical part of growing pollen tubes, and nuclei moved into the longest of the multiple tubes. Results of Fourier transform infrared microspectroscopy indicated that abnormal cell wall components (peaks at 800–1000 cm⁻¹) were more frequent in multiple pollen tubes lacking nuclei, and the pectin content (1733 cm⁻¹) in multiple pollen tubes was much lower than that in single pollen tubes. These findings suggested that there were significant differences in pollen tube growth and wall composition between single and multiple pollen tubes, and that multiple pollen tubes had much less opportunity than single pollen tubes to reach the embryo sac and achieve double fertilization.     

Pollen-tube growth behaviour in ‘Chanee’ and ‘Monthong’ durians (Durio zibethinus L.) after selfing and reciprocal crossing

Summary

Two durian cultivars, ‘Monthong’ and ‘Chanee’, were investigated with respect to post-pollination processes in the pistil and the percentages of fruit set after self-pollination or reciprocal crossing. Pollen grains from each cultivar germinated normally on both stigmas and grew downwards healthily. The percentage of penetrated ovules exceeded 40% in all treatments. However, fruit set after self-pollination in ‘Chanee’ was extremely low. The percentage of fruit set in ‘Chanee’ 35 d after self-pollination (DAP) was 0% in 2002 and 2003, while that of ‘Monthong’ was 6.9% in 2002, and 23.6% in 2003. The percentage of fruit-set after cross-pollination was significantly higher. On the basis of pollen-tube growth behaviour and the non-synchronisation of fruit drop between self-pollination and the two cross combinations, it may be that ‘Monthong’ and ‘Chanee’ durians possess post-zygotic barriers to selfing, especially in ‘Chanee.’