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.     

Fruit set evaluation for self-compatibility selection in almond

Self-compatibility was assessed in 19 almond selections by genetic and physiological means, such as PCR with specific primers for the S_f allele, pollen tube growth, and fruit set after self-pollination and in bagged branches. Although all genotypes possessed the S_f allele and showed a similar pollen tube growth after self-pollination than after cross-pollination with cross-compatible pollen, fruit sets showed a different behaviour between years, ranging from 16.2 to 24.7%, as well as between treatments, with the highest after self-pollination. The differences between genotypes could be due to the genetic constitution of each genotype, where inbreeding may reduce set by the accumulation of deleterious genes in different members of a progeny. Flower morphology may also affect sets in bagged branches. Thus, in addition to bud density, flower sterility, pollination success and environmental conditions, other traits must be taken into account when evaluating yield in self-compatible almond cultivars, such as the inbreeding effect and the effective autonomous self-pollination.     

Influence of self-pollination in fruit quality of autogamous almonds

Due to the several advantages expected from growing self-compatible almond cultivars, breeding programmes have recently introduced self-compatibility as an important trait. However, doubts have arisen regarding the capability of the newly obtained self-compatible almonds to produce good yields in monovarietal plantations, and the commercial quality of the fruits from self-pollination. For this reason, in the last years several studies have been conducted to evaluate fruit set and fruit traits following self- and cross-pollination of self-compatible almonds. Their results showed inconsistencies for fruit set and for some of the fruit traits studied. Thus, while some studies showed no differences between both pollination types for any of the fruit traits, others clearly showed important differences with the detriment of self-pollination for commercially important fruit traits. The fact that some of these studies evaluated a low number of individuals and/or fruit traits, implies the need of a more complete study. In this work, 10 fruit traits were studied in 26 self-compatible almonds following self-pollination by bagging and open pollination treatments. In general, and despite a few individuals showed differences between both pollination types for two of the traits, the results showed no influence of self-pollination in fruit quality.     

Physiological Breakdown in Stored Monarch Plums

Summary

Several pollination studies carried out on different, self-incompatible almond cultivars and seedlings have shown the presence of variable levels of fruit set following self-pollination that could be attributed to partial self-incompatibility (PSI). PSI is an intermediate reproductive behaviour, described in some angiosperm species, which indicates that self-incompatibility is a quantitative and plastic trait. The present study was performed to substantiate the occurrence of PSI in almond by studying ten cultivars that are traditionally considered to be self-incompatible (four of which had previously shown fruit set after self-pollination). These cultivars were analysed by microscopic observations of the progression of pollen tubes through the pistil following controlled self-pollination, determinations of fruit set after bagging flower buds, and molecular identification of the parentage of the fruits obtained using consensus PCR-primers for Prunus S-RNase alleles. The results showed that, in nearly all cases, the pollen tubes did not enter the ovary and, from a total of 5,349 bagged flower buds, only 17 fruits were obtained. In all cases, PCR analysis of the plants obtained after germination of these seeds showed a band corresponding to an S-RNase allele not present in the maternal progenitor, clearly indicating that they could only have arisen from cross-pollination.Therefore, the low fruit set values observed in some of the cultivars studied were not due to a breakdown in the self-incompatibility response that confers PSI, but to very low rates of contamination with foreign pollen. These results corroborate the self-incompatibility phenotype of the cultivars studied here, and highlight the importance of ascertaining the identity of the parentage in any progeny obtained after bagging.     

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.     

梨不同花龄自花与异花授粉的花柱内花粉管生长及坐果率的比较

对自交不亲和强度不同的梨品种丰水和菊水的不同花龄花进行自花授粉和丰水×菊水异花授粉后,用荧光显微镜观察花粉萌发及生长特性。结果表明,开花当天及以后的自花和异花授粉花粉在柱头上均有较高的萌发率;自花和异花花粉管在花柱内的生长速度及停止生长的位置不同,丰水自花授粉后花粉管生长的短且慢,菊水自花花粉管生长的长且快,而异花授粉的花粉管生长最快。自花授粉后,不同花龄对花粉管生长影响表现为:开花4d前的蕾期授粉以及开花4d后的延迟授粉,花粉管生长长度显著的长。开花6d前的各种授粉组合,花粉管生长均较差。这与田间授粉坐果率的高低基本一致,即整体表现为各个花龄的授粉都以异花授粉坐果率最高,其次为菊水自花授粉,丰水自花授粉坐果率最低。另外,自花授粉中,蕾期授粉和延迟授粉(开花2d后除外)坐果率都有提高,而异花授粉中蕾期授粉和延迟授粉的坐果率却有所下降。     

‘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。     

果梅花粉原位萌发及花粉管生长特性的研究

以软条红梅为试材,分别于白花授粉和异花授粉后的1、3、6、12、24、48、72、96、120 h切取花柱,用FAA固定液处理、荧光染色后压片观察,结果表明:异花和自花花粉都能在柱头上萌发,但在授粉后的48 h之内异花花粉的萌发率显著高于自花花粉的萌发率,如在授粉6 h后,异花花粉萌发率高达58％,而自花花粉的萌发率仅为23％。花柱内异花花粉管生长速度明显比自花的快,在授粉后花粉管到达花柱上部、中部及基部的数目均是异花高于白花。如授粉24 h后异花花粉管平均有30余根穿过花柱上部,约有14根到达中部,有2根到达基部;而自花授粉的花粉管分别仅有18、7和0根,且白花授粉时在72 h内均未见有花粉管到达花柱基部,主要在花柱中部前后停止生长。结果表明软条红梅自花授粉的花粉管主要是在花柱中部被抑制而停止生长,从而不能完成受精,表现出典型的配子体型自交不亲和性。     

Gametophytic self-incompatibility causes seedlessness in ‘Kagzi Kalan’ lemon (Citrus limon)

The present study aimed to study the flower and pollen structure, pollen viability, in vitro pollen germination of ‘Kagzi Kalan’ lemon (Citrus limon (L.) Osbeck), and in vivo pollen tube growth in self- and cross pollination to understand the mechanism of seedlessness. The results revealed that Kagzi Kalan had tetra-colporate spherical shaped pollen of uniform size. The results of Acetocarmine and FDA test and in vitro germination indicated normal pollen viability and germinability in Kagzi Kalan. In vivo pollen tube growth showed > 50% pollen germination on stigma in all treatments though a greater number of pollen tubes at the mid style, base of the style, and near the ovule was found in cross pollination. Contrary to this, despite optimum pollen germination (53.51–70.37%) in self-pollination treatments, none of the pollen tubes reached the base of the style due to abnormal growth of pollen tubes, viz. curvatures, inhibition of pollen tube growth, and callose deposition. The inhibition of pollen tubes at the mid style under self-pollination treatments, and production of seeded fruits under cross pollination treatments, indicate the presence of self-incompatibility and the site of inhibition of pollen tubes. Thus, gametophytic self-incompatibility (SI) caused seedlessness in Kagzi Kalan by blocking fertilization in the ovary.     

Characterization of progenies derived from pollination of pomegranate cv. Malase-Tourshe-Saveh using fruit traits and RAPD molecular marker

Fruit traits and molecular markers (RAPD) were used to survey genetic similarities and inheritance pattern of offspring, derived from self- and open pollination of pomegranate cv. Malase-Tourshe-Saveh (MTS) as well as progenies derived from cross between ‘MTS’ and ‘Narm-Daneh’ (ND) a soft-seed cultivar in the present study. Clustering based on fruit traits, divided the accessions firstly into two major groups, sweets and sour or sweet–sours. Members of sub-clusters were different in fruit characters, and seed softness also was affecting the grouping of individuals. Offspring of ‘MTS’ × ’ND’ showed somehow seed softness with varying degrees compared to other individuals. In RAPD analysis, by using 26 polymorphic primers, 325 fragments were produced from 39 individuals, among which 70 reproducible, polymorphic bands were scored for data analysis. NTsys and Bootstrap software were used for RAPD data analysis and respective dendrogram depicted by Jaccard's similarity coefficients using UPGMA method. The similarity coefficients were ranging from 0.2 to 0.94 and the lowest was obtained between pollen parent (ND cv.) and a genotype from open pollination of MTS cultivar. The highest similarity coefficient (0.94) was observed between two offspring both from self-pollination of MTS cultivar. In corresponding dendrogram, pollen parent was separated from other genotypes and laid individually in a sub-cluster, while the mother plant clustered with its progenies. In addition, some marker–trait associations were observed, especially for seed softness.     

不同李品种花粉对杏李坐果率的影响

以风味皇后和恐龙蛋2个杏李品种为试材,研究了大石早生、黑宝石、小黄李和蓝宝石4个李品种花粉对其坐果率的影响。结果表明：风味皇后和恐龙蛋2个杏李品种的自花授粉坐果率均为0,说明2品种自花不实,属异花结实果树。用大石早生和黑宝石的花粉为风味皇后授粉,坐果率分别为13.33%和5.83%,均极显著地高于风味皇后自花授粉的坐果率,且均能达到生产上要求的产量,认为上述2个李品种均可作为风味皇后的授粉树。而以小黄李和蓝宝石2个李品种为风味皇后授粉及该研究的4个李品种为恐龙蛋授粉,坐果率均为0,认为小黄李和蓝宝石2个李品种不能作为风味皇后的授粉树;而该研究的4个李品种不能作为恐龙蛋的授粉树。     

Screening Capsicum species of different origins for high temperature tolerance by in vitro pollen germination and pollen tube length

Successful fruit set depends on several reproductive processes including pollen germination and tube growth processes. An experiment was conducted to determine the effects of temperature on pollen germination characteristics and to identify species/genotypic differences in Capsicum using the cumulative temperature response index (CTRI) concept. Pollen was collected from plants of seven genotypes from five Capsicum species, adapted to various parts of the world and grown outdoors in large pots. The pollen was subjected to in vitro temperatures ranging from 15 to 50 °C at 5 °C intervals. Pollen germination and tube lengths were recorded for all species after 24 h of incubation at the respective treatments. Species/genotypes differed significantly for in vitro pollen germination percentage and pollen tube length with mean values of 78% and 734 μm, respectively. The mean cardinal temperatures (T_min, T_opt, and T_max) averaged over genotypes, were 15.2, 30.7, and 41.8 °C for pollen germination and 12.2, 31.2, and 40.4 °C for pollen tube growth. The CTRI of each species/genotype calculated as the sum of eight relative individual stress response values, such as maximum pollen germination, maximum pollen tube length; T_min, T_opt, and T_max temperatures of pollen germination, and pollen tube lengths, identified species tolerance to high temperatures. Capsicum annum cv. Mex Serrano from Mexico was identified as tolerant, C. chacoense cv. 1312 and C. spp. cv. Cobanero from Argentina and Guatemala, respectively as intermediate and C. frutescens cv. Early Spring Giant from China, C. annum cv. Long Green from South Korea, C. spp. cv. NM89C130 and C. pubescens cv. 90002 from Guatemala as sensitive to high temperatures. The tolerant species/genotypes can be used in breeding programs to develop new genotypes that can withstand high temperature conditions both in the present climate and particularly in a future warmer climate.     

Rain effect on pollen–stigma adhesion and fertilization in almond

The fact that rainy weather negatively affects production in almond is well-known by growers. However, as far as we know, no previous study has been carried out in this species to determine if the rain is able to wash off pollen grains from the stigma surface and consequently affect fertilization efficiency. To answer this question, flowers of the self-compatible almond cultivar ‘Antoñeta’ were emasculated on branches of trees in the field, pollinated by hand with pollen of the cultivar ‘Marcona’, and sprayed with water to simulate the rain effect at 4, 8, 24 and 48 h after pollination. A control for which no treatment was applied was also included in the assay. Seven days after spraying the flowers, the number of germinated pollen grains on the stigma was recorded in 10 pistils for each treatment by fluorescent microscopic observation. In addition, for each treatment the initial and final fruit set were determined at 30 and 60 days after pollination, respectively. The following year additional assays were performed in the field and in the laboratory in order to complete the study with earlier treatment times. Thus, an assay of rain simulation in the field at 0 and 2 h, and other consisting on immersing a branch with flowers and shaking it in a water container in the laboratory at 0, 30, 60 and 120 min after pollination were performed. One sample more was immersed, shaken, then pollinated and again immersed and shaken. The results from field assays showed that adhesion of pollen grains to the stigma was very quick and strong, and the treatments did not significantly affect pollen–stigma adhesion and subsequent fruit set. On the other hand, laboratory results showed that all washing treatments decreased the number of germinated pollen grains on the stigma, mainly when the flowers were immersed before pollination. In conclusion, the results showed that the simulated rain was not able to completely wash off pollen grains from the stigma surface, although it seems to affect adhesion in forthcoming pollinations.     

Studies on the Nutrition of Tulips and Narcissi

Summary

We explored the effects of pollination method (hand cross-, hand self-, automatic self-, and open-pollination) and pollen source on fruit set and growth in four red-skinned pitaya (Hylocereus spp.) cultivars [‘Vietnam White’ (‘VNWhite’), ‘Chaozhou 5’, ‘Orejona’, and ‘F11’] in Taiwan.‘VN-White’ has white flesh, while the other three cultivars have red flesh. There were no significant differences in pollen viability or germination rate among the four cultivars, irrespective of whether the pollen was collected at night (approx. 20.30 h) or on the following morning (approx. 08.30 h).The results also indicated that ‘VN White’ was fully self-compatible and exhibited a high fruit set percentage (80 - 96%) following all pollination treatments. This cultivar produced the largest fruit from both hand self- and openpollination, compared to the three other cultivars tested. ‘Chaozhou 5’ was partly self-compatible, and ‘Orejona’ and ‘F11’ were completely self-incompatible. Hand cross-pollination significantly increased the fruit set percentages and mean fruit fresh weights (FWs) in ‘Chaozhou 5’ and ‘Orejona’. Pollen source also significantly affected the fruit set percentage and fruit FW. ‘VN-White’ (after self-pollination) and ‘Chaozou 5’ (after crossing with ‘VN-White’) gave superior fruit set percentages and fruit FWs. Reciprocal crosses between ‘Orejona’ and ‘F11’ also resulted in high fruit set percentages as well as large fruit in both cultivars. Therefore, the source of pollen and the method of pollination can affect fruit production in some cultivars of pitaya. Self-compatibility in ‘VN-White’ concurs with the morphology of its flowers in which the anthers lie in close proximity to the stigma.The distance between the anthers and the stigma may be used an indicator of whether hand pollination is necessary for a pitaya cultivar.     

Effects of low temperatures on sexual reproduction of ‘Tainong 1’ mango (Mangifera indica)

Prevailing ambient temperature during the reproductive phase is one of important factors for seed and fruit set in different plant species. In mango (Mangifera indica L.), natural low temperatures during flowering induced seedless fruits. Here the sexual reproduction process of ‘Tainong 1’ mango at low temperatures (diurnal maximum temperature < 20 °C) was studied. For comparison, we also examined this process at “normal” temperatures (diurnal maximum ranging from 25 to 30 °C, diurnal average temperature > 20 °C). Results showed: natural low temperatures significantly affected pistil and male gametophyte development, resulting in pollen grains with low viability. Meiotic chromosomal irregularities, including univalents, multivalents, laggards, bridges and micronuclei were detected at higher incidences and significantly greater proportions of nucleolus fragmentation and dissolution were detected when temperatures were low. Pollen tube growth was retarded under low temperature stress, either in vivo or in vitro. The virtual absence of sexual reproduction of ‘Tainong 1’ mango at low temperatures appears to be due largely to slow growth of pollen tube in vivo and to a low rate of successful fertilization.     

中国原产果梅自交亲和变异品种花粉决定基因SFB的插入突变

 果梅是配子体自交不亲和树种,但在长期进化过程中也出现了自交亲和品种。以果梅典型的自交不亲和品种‘南高’和自交亲和品种‘甲州小梅’为对照,采用田间自交授粉试验对原产于中国的‘四川白梅’和‘长农17’两个果梅品种进行了自交亲和性鉴定,结果表明：其自花授粉坐果率分别为30.73%和16.27%,属于自交亲和品种。进一步通过AS-PCR分析发现花粉SFB基因存在一段插入序列,造成了分子水平的基因突变。推测该基因的突变使‘四川白梅’和‘长农17’SFB功能发生改变,从而自交亲和。     

紫花含笑与含笑、深山含笑和阔瓣含笑杂交亲和性分析

以紫花含笑（Michelia crassipes）为母本,含笑（M. figo）、深山含笑（M. maudiae）和阔瓣含笑（M. platypetala）为父本,研究其杂交亲和性。采用离体培养法对父本花粉生活力进行检测,利用荧光显微镜观察不同杂交组合花粉萌发和花粉管伸长情况,并调查种间杂交坐果率和杂种萌发特性。结果表明：紫花含笑、含笑和深山含笑的花粉萌发率达65%以上,而阔瓣含笑的花粉萌发率较低,为29.07%。荧光显微观察发现,紫花含笑 × 含笑、紫花含笑 × 深山含笑的花粉萌发率和花粉管生长速度比紫花含笑自交快,且花粉管能正常伸长完成授精;而紫花含笑 × 阔瓣含笑的花粉虽能在柱头表面萌发,但花粉萌发和花粉管生长速度均慢于紫花含笑自交,且出现花粉管膨大、花粉管停止生长、柱头和花柱内胼胝质堆积等现象。紫花含笑 × 含笑、紫花含笑 × 深山含笑的坐果率和种子萌发率均达80%以上,表明杂交亲和性较好;而紫花含笑 × 阔瓣含笑的坐果率仅有11.1%,且杂种胚败育,受精前障碍可能是影响其杂交的主要原因之一。     

寒富苹果授粉花柱的荧光显微观察与自交亲和性分析

以寒富苹果为试材,进行自花和异花授粉后花朵和花序坐果率、平均种子数调查试验和荧光显微观察,结果表明,寒富苹果自花授粉的花朵坐果率高达92.8%,花序坐果率为98.3%,平均种子数为7.9粒;略低于异花授粉的96.6%、100%和9.5粒。自花授粉8 h后花粉开始萌发,花粉管能够正常生长,48 h花粉管伸入花柱中部,并在72 h后通过花柱基部,进入子房室。而异花授粉后8 h花粉管开始进入花柱,24 h花粉管伸入花柱中部,48 h花粉管穿过花柱的基部并进入子房室。     

Pollen load affects fruit set,size, and shape in cherimoya

Cherimoya (Annona cherimola Mill.) is a subtropical fruit crop that exhibits protogyny dichogamy and for which the original pollinators are not present in the main producing countries. Under such circumstances the achievement of profitable yields depends on hand pollination. The present work explores the effects of the amount of pollen applied on pollen–pistil interaction and on fruit set, size, shape and growth. Pollen dilution with Lycopodium spores reduced fruit set and size and favoured the appearance of misshapen fruits, whereas the application of double amount of pollen did not improve fruit size and increased fruit set only the first year. Pollen load did not affect fruit growth model, which always followed a double sigmoid pattern. Nevertheless, the slopes of the curves during the two rapid growth phases were higher when a larger amount of pollen grains was applied. Seed index (seed number per 100 g of fresh fruit weight) rose slightly as pollination level increased.     

Pollen germination as affected by pollen age in cherimoya

Cherimoya (Annona cherimola (Mill.)) is a subtropical fruit tree, which is cultivated in a good range of subtropical regions. In most of these areas the crop relies on hand pollination. However, following this practice, erratic fruit set is often produced, which could be related to problems in pollen handling. Indeed, very little is known of the time that the pollen remains viable and on which is the best stage to collect the anthers or pollen from the flower. The aim of this work is to evaluate pollen germinability prior and after anther dehiscence and also how the age of pollen affects pollen vigor, understood as speed of germination. Pollen samples at different times following anther dehiscence were germinated in vitro and in vivo. Pollen up to 90 min following dehiscence performed as well as freshly dehisced pollen. However, the pollen taken 120 min following dehiscence, showed a clear reduction in vigor and germinated much slower in vivo. To overcome this short pollen germinability, pollen was taken from anthers 30 and 5 h prior to natural anther dehiscence and compared with pollen taken at anther dehiscence and 20 h later. However, a reduction in germination rate was obtained in pollen taken prior to anther dehiscence. The narrow stage at which pollen can be collected together to its ephemeral germinability explains erratic results obtained following hand pollination in this crop and these results provide the clues for an adequate pollen handling.