Scion Interaction Research Articles

Oxidative stress associated with rootstock–scion interactions in pear/quince combinations during early stages of graft development

Exposing a plant to stress situations, such as grafting, generally triggers antioxidant defense systems. In fruit tree grafting, quince (Cydonia oblonga) is widely used as a rootstock for pear (Pyrus communis L.), but several economically important pear cultivars are incompatible with available quince rootstocks. In this study, grafts were established using an in vitro callus graft system mimicking the events taking place in fruit trees. In vitro grown callus from pear [P. communis L. cv. ‘Conference’ (Co) and cv. ‘William’ (Wi)] and quince (C. oblonga Mill. clone ‘BA29’) was used to establish the compatible homografts ‘Co/Co’, ‘Wi/Wi’ and ‘BA29/BA29’, the compatible heterograft ‘Co/BA29’ and the incompatible heterograft ‘Wi/BA29’. The main objective was to determine whether specific isoforms of genes involved in oxidative stress [superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT)] are differentially expressed at the graft interface from compatible and incompatible unions throughout 3 weeks after grafting. Reactive oxygen species (ROS) levels and programmed cell death were also evaluated in the course of graft development. Genes differentially expressed between compatible and incompatible heterografts were identified. Transcript levels of six antioxidant genes (SOD1, SOD3, APX3, APX6, CAT1 and CAT3) were down-regulated 10 days after grafting (DAG) in the incompatible heterograft in comparison to the compatible one. Likewise, SOD enzymatic activities were significantly higher at 1 and 10 days after wounding in the compatible cultivar ‘Co’ than in the incompatible one ‘Wi’. These findings, together with live cell imaging of ROS-specific probes, ultrastructural mitochondrial changes and DNA fragmentation related to apoptotic processes, give indications that within incompatible rootstock/scion interfaces, either the level of ROS is increased or there is a less efficient detoxification system.

Genotypic Effect of Rootstock and Scion on Grafting Success and Growth of Kola (Cola nitida) Seedlings

Kola (Cola nitida) is an important economic cash crop for many West and Central African countries. It has several medicinal uses in the pharmaceutical industries and also plays a major role in traditional marriages among Islamic communities across West and Central Africa. The crop is extensively cultivated in Nigeria and Ghana. However, it exhibit signs of total and partial sterility as well as self incompatibility when propagated from seeds in most cases. Therefore, grafting is seen as a method of choice in addressing the problem stated above. Though grafting accounts for some degree of success, there is the need to assess genotypic and physiological factors that account for high or low grafting success. Genetic and physiological factors (such as rootstock age) affecting grafting success and growth in kola (C. nitida) were investigated in two separate experiments. In experiment I720 kola seedlings were raised from unselected kola nuts and sown at two monthly intervals. Four groups of seedlings (180/group) i.e. 6, 8, 10 and 12 months old were thus produced. Three different scions (A1, A12 and JB1) measuring (5-10 cm) were grafted onto the four age groups of rootstocks, namely, 6, 8, 10 and 12 months. Experiment II consisted of 540 seedlings raised from three main crosses (JX1/9 × JX1/11 * B1/142 × B1/151, JX1/9 × JX1/11 * B2/177 × B2/156 and JX1/9 × JX1/11 * GX1/46 × GX1/53). Grafting was done after six months using the same set of scions as described in experiment I. Experimental design used was 3 × 4 and 3 × 3 factorial designs in completely randomised design with three replicates for experiment I and II respectively. The fixed effects were the different genotype and age of rootstock at grafting whilst the response variable was the percentage of successful grafting two months as well as growth at six monthly intervals. Results from the study showed that grafting onto 6 months old stocks gave the highest percentage success and growth of grafts followed by 8, 10 and 12 months old rootstock in that order in both trial years. The study revealed also a significant rootstock and scion interaction (P < 0.05). We conclude that successful grafting in kola depends on rootstock genotype such as JX1/9 × JX1/11 * GX1/46 × GX1/53 and has been proven suitable for use in future kola propagation studies. Nonetheless, suitable rootstock with high grafting success does not translate into vigorous scion growth.

Rootstock Scion Interaction and Effects on Vine Vigor, Phenology, and Cold Hardiness of Interspecific Hybrid Grape Cultivars (Vitis spp.)

Scion-rootstock interactions were analyzed to test the interaction between environment and above-ground vine phenology. The experiment employed ‘Marechal Foch’ and ‘Vidal Blanc’ as reciprocally grafted, own-rooted, and self-grafted vines. Results suggest that genetically complex phenological factors were under the control of the scion cultivar. The effect of the scion on fruit composition was related to differences in yield between the cultivars. Other effects are secondary in nature as a result of vine vigor and shoot density. Factors potentially under specific root influence, (e.g., fruit-set, water status, nutrition, soil pH, salinity, or root pests) were not limiting in this experiment.

Genome-wide identification and expression analysis of MAPK and MAPKK gene family in Malus domestica

MAPK signal transduction modules play crucial roles in regulating many biological processes in plants, which are composed of three classes of hierarchically organized protein kinases, namely MAPKKKs, MAPKKs, and MAPKs. Although genome-wide analysis of this family has been carried out in some species, little is known about MAPK and MAPKK genes in apple (Malus domestica). In this study, a total of 26 putative apple MAPK genes (MdMPKs) and 9 putative apple MAPKK genes (MdMKKs) have been identified and located within the apple genome. Phylogenetic analysis revealed that MdMAPKs and MdMAPKKs could be divided into 4 subfamilies (groups A, B, C and D), respectively. The predicted MdMAPKs and MdMAPKKs were distributed across 13 out of 17 chromosomes with different densities. In addition, analysis of exon–intron junctions and of intron phase inside the predicted coding region of each candidate gene has revealed high levels of conservation within and between phylogenetic groups. According to the microarray and expressed sequence tag (EST) analysis, the different expression patterns indicate that they may play different roles during fruit development and rootstock–scion interaction process. Moreover, MAPK and MAPKK genes were performed expression profile analyses in different tissues (root, stem, leaf, flower and fruit), and all of the selected genes were expressed in at least one of the tissues tested, indicating that the MAPKs and MAPKKs are involved in various aspects of physiological and developmental processes of apple. To our knowledge, this is the first report of a genome-wide analysis of the apple MAPK and MAPKK gene family. This study provides valuable information for understanding the classification and putative functions of the MAPK signal in apple.

Rootstock scion somatogenetic interactions in perennial composite plants.

The ancient plant production practice of grafting which instantly imparts new physiological properties to the desirable scion still remains shrouded in mystery. Yet, grafting remains a widely used technique in the production of several horticultural species. In a composite grafted plant, rootstocks control many aspects of scion growth and physiology including yield and quality attributes as well as biotic and abiotic stress tolerance. Broadly, physical, physiological, biochemical and molecular mechanisms have been reviewed to develop an integrated understanding of this enigmatic process that challenges existing genetic paradigms. This review summarizes the reported mechanisms underlying some of the economically important traits and identifies several key points to consider when conducting rootstock scion interaction experiments. Study of the somatogenetic interactions between rootstock and scion is a field that is ripe for discovery and vast improvements in the coming decade. Further, utilization of rootstocks based on a better understanding of the somatogenetic interactions is highly relevant in the current agricultural environment where there is a need for sustainable production practices. Rootstocks may offer a non-transgenic approach to rapidly respond to the changing environment and expand agricultural production of annual and perennial crops where grafting is feasible in order to meet the global food, fiber and fuel demands of the future.

Interação enxerto e porta-enxerto na incidência da resinose do cajueiro

A expansão do cajueiro-anão-precoce no Brasil vem promovendo baixa diversidade genética dos genótipos usados como enxerto e porta-enxerto, ensejando vulnerabilidade da cultura às vicissitudes bióticas como a resinose (Lasiodiplodia theobromae), principal doença do cajueiro no semiárido nordestino. Estima-se que cerca de meio milhão de mudas de cajueiro-anão-precoce sejam produzidas anualmente, sendo a grande maioria delas produzida de propágulos enxertados sobre plântulas oriundas de sementes do clone CCP 06. A principal estratégia de manejo da resinose é o plantio de clones resistentes. Entretanto, entre os aspectos que contribuem para sucessivas epidemias da resinose, destaca-se a falta de estudos de interações genotípicas entre enxerto e porta-enxerto. Este estudo objetivou avaliar o efeito de combinações de clones de cajueiro-anão-precoce usados como enxerto e porta-enxerto na incidência da resinose. Sementes de plantas de polinização aberta de seis clones selecionados foram usadas para produção de porta-enxerto. Os clones comerciais CCP 76 (suscetível) e BRS 226 (resistente) foram usados como enxertos. O experimento foi realizado obedecendo ao delineamento de blocos ao acaso, no esquema fatorial 2 x 6, com quatro repetições e nove plantas por parcela do tipo quadrada, sob condições de elevada pressão da doença, em Pio IX-PI. Três anos após o plantio definitivo, a incidência (I) e a severidade (S) (escala de 0 a 4) da resinose foram superiores no clone CCP 76 (I = 97% e S=2,10) em relação ao BRS 226 (I = 33% e S=0,36), independentemente do porta-enxerto. O clone CP 06 como porta-enxerto foi o único que reduziu a incidência e a severidade da resinose, independentemente do genótipo do enxerto. Este clone foi capaz de reduzir a severidade da resinose do clone CCP 76 (S=2,10) como enxerto em quase 30%.

EFFECTS OF GRAFTING ON TEA 1. GROWTH, YIELD AND QUALITY

SUMMARYTrials in Kenya have shown that yields of tea clones can be increased significantly by grafting onto suitable rootstocks, with the best combinations giving profitable yield increases compared to straight cuttings. However, stock × scion interactions were significant, and not all clones gave useful responses to grafting even onto the best rootstocks, so combinations must be tested individually before commercial planting is considered. The effect of grafting was to increase the number of shoots harvested, with little change in mean shoot weight. Grafting had little or no effect on quality of the tea produced. Attempts to find a method of identifying good rootstocks without testing them in grafting trials were inconclusive.

The Effect of Grafting on the Flowering of Near‐Isogenic Lines of Soybean

Grafting of soybean [Glycine max (L.) Merr.] genotypes differing in time to flower has been used to study translocation of flowering hormones and also as a tool to facilitate crossing. Our objective was to use Y‐shaped, grafted soybean plants to examine the mobility of the flowering stimulus. We grafted plants of ‘Harosoy’ (L58‐266, homozygous for the e1e2E3e5 genotype) and four isolines of Harosoy [L62‐667 (e1e2e3e5), L71‐802 (E1e2e3e5), L84‐307 (e1E2e3e5), and L84‐337 (e1e2e3E5)], differing by single maturity genes. The scion was reciprocally grafted on one of the branches, leaving the second branch as a stock. Ungrafted and self‐grafted controls were included, and plants were grown in growth chambers under short‐ (12‐h) and long‐day (20‐h) photoperiods. All treatments flowered at the same time under short‐day photoperiod. Under long‐day photoperiod, the greatest delay of flowering was observed in lines containing the E1 and E3 alleles. The stock and scion flowered independently of each other and no stock × scion interaction occurred. Hypothesizing that leaving full foliage on the plants could have been a reason for the lack of mutual effect of scion and stock, we performed a second experiment where one, two, four, eight, and all leaves were maintained on the scion. The scion and stock affected each other only slightly, and only when one or two leaves were present on a scion. The location of the first flowering node suggested the promotion of flowering in the isogenic line containing the late E3 allele.

Influência de porta-enxertos no crescimento de clones de seringueira no Estado de São Paulo

Este trabalho foi instalado na Estação Experimental de Agronomia de Pindorama, SP, com a finalidade de avaliar a interação enxerto vs. porta-enxertos de seringueira, Hevea brasiliensis (Willd. ex Adr. de Juss.) Müell. Arg. Os clones utilizados foram IAN 873, RRIM 600, RRIM 701, PB 235, PR 107 e GT 1, enxertados em seis diferentes porta-enxertos provenientes de sementes ilegítimas dos clones IAN 873, RRIM 600, RRIM 701, PB 235, GT 1 e de sementes não selecionadas. O delineamento utilizado foi o de blocos ao acaso, com parcelas subdivididas, tendo os porta-enxertos como tratamentos e os clones (enxertos) como subtratamentos, em quatro repetições. Os resultadosmostram que no período de avaliação o porta-enxerto GT 1 e IAN 873 foram os que produziram os maiores perímetros por planta, sendo 10,20 % maior que o de sementes não selecionadas. Paralelamente, os enxertos em vigor mostraram que os clones PB 235, RRIM 600 e PR 107 apresentaram melhor desempenho, com um perímetro do caule 8,12% maior que o dos clonesRRIM 701 e GT 1,notadamente os de menor vigor. A interação enxerto vs. porta-enxerto não foi significativa.

Grape rootstock - scion interactions on shoot growth and cane maturing

Interaction between the rootstock and scion varieties (clones) was examined. Berlandieri x Riparia T. K. 5BB, Berlandieri x Riparia T.5C being the most widely used varieties in Hungary, Fercal, Ruggeri 140 being recently used on special soil conditions ; Georgikon 28 a new established variety and Berlandieri x Riparia T. 8B GK 10 clone were the rootstocks used. The V. vinifera L. varieties were a clone of Italian Riesling and two new hybrids from the same cross population f ( Noble Italian Riesling X Ezerjó) X ( Noble Italian Riesling X Pinot Gris ) }. This study presents the results how the growth habit depends on different scion/stock combinations in the first three years.&#x0D; Shoot growth characters were observed during the initial years after plantation in the vineyard until we got the first yields. Our results did not agree with those of Pospisilova (1977) that the anticipated vigour of shoot growth will appear later in the vineyard only. However we agree with Zimmerman (1970), who showed that the differences are caused by the rootstocks in the growth habit of vines during the first two years already. The differences in shoot elongation decreased similarly to the rootstocks in the first year of fruit production. It shows us that the intense root development caused vigorous shoot growth, which we think to be a rootstock effect. When the vegetative and generative development are balanced already, the effect of scions in shoot elongation became stronger than the effect of rootstock.&#x0D; We also found great differences in the maturation of wood each year from planting of the vineyard to the year of fruit production.&#x0D; During the first years the differences of cane maturation were greater according to the scion varieties, the means were significantly different. In the first ripening year the differences dwindled or increased due to the rootstocks. This means that the effect of the rootstock on cane maturation became stronger in the first year of fruit production.&#x0D;

Rootstock effects on scion growth and reproduction in 8-year-old grafted loblolly pine

Contributions of sites, rootstocks, and scion clones (and the interactions between these factors) to scion growth and reproduction were studied in loblolly pine (Pinus taeda L.). Twenty-five full-sib families were used as rootstocks. Six scion clones were grafted on them in all combinations. Study sites were three seed orchards in the southeastern United States; trees were measured 8 years after grafting. Scion elongation, diameter at breast height (DBH) of the main leader, crown diameter, cone counts, and number of male and female strobili were measured at all sites. Crown diameter and tree height were combined into a crown volume index. Highly significant differences existed among scion clones for all traits. When analyzed over all three sites, the only trait with significant rootstock effects was DBH. There were significant rootstock × scion interactions for total scion elongation, crown volume index, and DBH and significant site × scion interactions for strobili counts and cone count. In analyses by clone, rootstock effects were expressed differently in the different clones. There were significant rootstock effects for three traits in each of three clones and no effects at all in two clones. For all traits the largest variance component was for either site or scion clone. Components for rootstocks were small or zero. These results show that the scion clone and site have more control on scion growth and reproduction of grafted loblolly pine than the rootstock. The study did not identify full-sib families that (as rootstocks) would signficantly reduce scion elongation or signficantly increase cone production, for all six scion clones at all three sites.

Rootstock and scion effects on carbohydrates and mineral nutrients in loblolly pine

Variation in scion physiology caused by rootstock families, scion clones, and the rootstock–scion interactions were studied in loblolly pine (Pinustaeda L.). Ten full-sib families were used as rootstocks, and six scion clones were grafted on the rootstocks in all combinations. The trees were measured during and after the 2nd year after grafting; the traits measured were needle carbohydrate (starch, sucrose, and hexoses) concentrations and needle N, P, K, Ca, and Mg concentrations. These traits were measured in early fall and early spring. There were highly significant differences among scion clones for all traits. Rootstocks significantly affected hexoses in fall, total sugars in spring, P, K, Ca, and Mg in fall, and Ca and Mg in spring. For most traits the largest variance component was within each rootstock-scion combination; next largest were those for scion clones. Variance components for rootstocks were small or negative for most traits, indicating that the scion has more control than the rootstock on scion physiology of young grafted loblolly pine.