Peach Breeding Research Articles

Multi-omics analysis unravels chemical roadmap and genetic basis for peach fruit aroma improvement

Selection of fruits with enhanced health benefits and superior flavor is an important aspect of peach breeding. Understanding the genetic interplay between appearance and flavor chemicals remains a major challenge. We identify the most important volatiles contributing to consumer preferences for peach, thus establishing priorities for improving flavor quality. We quantify volatiles of a peach population consisting of 184 accessions and demonstrate major reductions in the important flavor volatiles linalool and Z-3-hexenyl acetate in red-fleshed accessions. We identify 474 functional gene regulatory networks (GRNs), among which GRN05 plays a crucial role in controlling both red flesh and volatile content through the NAM/ATAF1/2/CUC (NAC) transcription factor PpBL. Overexpressing PpBL results in reduced expression of PpNAC1, a positive regulator for Z-3-hexenyl acetate and linalool synthesis. Additionally, we identify haplotypes for three tandem PpAATs that are significantly correlated with reduced gene expression and ester content. We develop genetic resources for improvement of fruit quality.

The Impact of Peach Rootstocks and Winter Cover Crops on Reproduction of Ring Nematode

Two peach rootstocks (‘Guardian’ and ‘MP-29’) and ten winter cover crops (rye, wheat, barley, triticale, oat, Austrian winter pea, crimson clover, balansa clover, hairy vetch, and daikon radish) were evaluated in a greenhouse environment to determine their suitability to host ring nematode, Mesocriconema xenoplax. Each crop was inoculated with 500 ring nematodes, and the experiments were terminated 60 days after inoculation. The reproduction factor (ratio of final and initial nematode population) ranged from 0 to 13.8, indicating the crops greatly varied in their host suitability to ring nematode. ‘Guardian’ has been known to tolerate ring nematode; however, results from the current study suggest the tolerance statement is anecdotal. Another peach rootstock, ‘MP-29’, was also a good host for ring nematode, suggesting an urgency to develop ring nematode-resistant peach rootstocks. Wheat supported the least to no nematode reproduction while pea supported the greatest reproduction. The rest of the cover crops were poor to good hosts to ring nematodes. Although planting cover crops in peach orchards is not common, employing non or poor host crops can help suppress nematodes in addition to having soil health benefits. Furthermore, peach breeding programs should focus on finding and introgressing ring nematode resistance in commercial rootstocks.

Ester-related volatile compounds reveal the diversity and commonalities of different types of late-ripening peaches.

To recognize the key ester-related volatile compounds, 5 types of peaches including 54 late-ripening peach materials were examined by headspace solid-phase microextraction coupled with gas chromatography-mass spectrometry and E-nose. Here, a large number of esters were identified to be released by ripe peach fruits and were mainly characterized by fruity, green, and fatty notes. The variety and content of esters had greatly changed within or between cultivars, indicating that the fruit volatiles were highly differentiated depending on the specific genotypes and cultivation conditions. The ester types showed that fatty acid-derived C6 alcohols and methyl-/ethyl- short-chain alcohol were the main ester precursors, which were more likely to be utilized and well selected by alcohol acyltransferases, whereas the preference of acyl donors was not observed. The common peach type, which exhibited a unique volatile profile, displayed broader diversity and more abundant characteristics in ester-related volatiles than the other four types. A total of 19 key esters were identified as the main components and the content of most esters showed no significant difference among different peach types. Some key esters had even been enriched in nectarines. Moreover, the multiple discriminant analysis revealed a possible relationship between peach types and the domestication of the peach evolution. This study investigated ester-related volatiles released by different types of peach fruits and can be further used to evaluate the peach qualities, providing an important reference for peach breeding and processing.

Ppe.RPT/SSC-1: from QTL mapping to a predictive KASP test for ripening time and soluble solids concentration in peach

Genomic regions associated with ripening time (RPT) and soluble solids concentration (SSC) were mapped using a pedigreed population including multiple F1 and F2 families from the Clemson University peach breeding program (CUPBP). RPT and SSC QTLs were consistently identified in two seasons (2011 and 2012) and the average datasets (average of two seasons). A target region spanning 10,981,971–11,298,736 bp on chromosome 4 of peach reference genome used for haplotype analysis revealed four haplotypes with significant differences in trait values among different diplotype combinations. Favorable alleles at the target region for both RPT and SSC were determined and a DNA test for predicting RPT and SSC was developed. Two Kompetitive Allele Specific PCR (KASP) assays were validated on 84 peach cultivars and 163 seedlings from the CUPBP, with only one assay (Ppe.RPT/SSC-1) needed to predict between early and late-season ripening cultivars and low and high SSC. These results advance our understanding of the genetic basis of RPT and SSC and facilitate selection of new peach cultivars with the desired RPT and SSC.

Genome sequencing revealed the red-flower trait candidate gene of a peach landrace.

Peach (Prunus persica) is an economically important fruit crop globally and an excellent material for genomic studies. While considerable progress has been made in unveiling trait-associated genes within cultivars and wild relatives, certain novel genes controlling valuable traits in peach landraces, such as the red-flowering gene, remained unclear. In this study, we sequenced and assembled the diploid genome of the red-flower landrace 'Yingzui' (abbreviated as 'RedY'). Multi-omics profiling of red petals of 'RedY' revealed the intensified red coloration associated with anthocyanins accumulation and concurrent decline in flavonols. This phenomenon is likely attributed to a natural variant of Flavonol Synthase (FLS) harboring a 9-bp exonic insertion. Intriguingly, the homozygous allelic configurations of this FLS variant were only observed in red-flowered peaches. Furthermore, the 9-bp sequence variation tightly associated with pink/red petal color in genome-wide association studies (GWAS) of collected peach germplasm resources. Functional analyses of the FLS variant, purified from procaryotic expression system, demonstrated its diminished enzymatic activity in flavonols biosynthesis, impeccably aligning with the cardinal trait of red flowers. Therefore, the natural FLS variant was proposed as the best candidate gene for red-flowering trait in peach. The pioneering unveiling of the red-flowered peach genome, coupled with the identification of the candidate gene, expanded the knowledge boundaries of the genetic basis of peach traits and provided valuable insights for future peach breeding efforts.

Discovery of candidate genes related to carotenoid accumulation based on yellow sarcocarp bud mutation peach resource

The carotenoid composition and content in the yellow sarcocarp peach are a direct indicator of quality. Therefore, discoveries regarding the identification of candidate genes related to carotenoid accumulation and their regulatory mechanisms would be beneficial for yellow sarcocarp peach breeding. In this study, the white sarcocarp peach cultivar ‘21shiji’ (21SJ) and its unique yellow sarcocarp bud mutation individual (21BM) were used for carotenoid determination and candidate gene discovery based on UPLC-APCI-MS/MS and RNA-seq. In total, 11 carotenoid compositions showed significant differences between ‘21SJ’ and ‘21BM’, including four carotenes and seven xanthophylls. Furthermore, the accumulation of β-carotene, zeaxanthin, β-cryptoxanthin, antheraxanthin, violaxanthin, and capsanthin showed different tendencies between ‘21SJ’ and ‘21BM’ during the ripening stage and influenced ‘21BM’ yellow sarcocarp formation. Using transcriptome analysis, we found that the differential expression of candidate genes PpZEP, PpVDE1, PpCCD4, and PpCCS were major influencing factors. Two transfactors, PpbHLH14 and PpMYB73, were significantly related to PpZEP, PpVDE1, PpCCD4, and PpCCS expression and carotenoid accumulation after weighted gene co-expression network analysis. The identified structural genes and transcription factors in this study will further enrich carotenoid accumulation regulatory mechanism in peach and will provide an important theoretical reference for yellow sarcocarp peach breeding.

The Development of Molecular Markers for Peach Skin Blush and Their Application in Peach Breeding Practice

Peach is an economically important fruit tree crop worldwide. The external color of the fruit governs the peach price, especially in fruits with different degrees of blush. Molecular marker-assisted breeding has become a necessary part of modern breeding practices, increasing their efficiency. Although the key related genes responsible for peel coloration have been found in peach, corresponding molecular markers have not been widely used in peach breeding. The development of molecular markers for peach peel color needs to be advanced and implemented in practice. This study aimed to explore the variation related to peach skin color and to develop molecular markers linked to these variants that can be used in breeding. By analyzing the expression of anthocyanin synthesis-related and regulatory genes, we confirmed that MYB10.1 is a key gene controlling skin color. We further identified that 5243 bp insertion and 483 bp deletion in the MYB10.1 promoter was highly associated with peach skin color phenotypes. In addition, we identified one transposon insertion mutation at the −2706 bp position of the MYB10.1 promoter associated with the non-red fruit skin trait and developed a molecular marker for validation. The insertion size amplified from the ‘ShiYuBaiTao’ genome DNA was approximately 3.5 kb. However, it explained a lower percentage of the non-red skin phenotype variance in peach, at 36.1%, compared to MYB10.1-2/MYB10.1-2 in this study. Based on these results, we propose that MYB10.1-2/MYB10.1-2 should not only be the only non-red skin genotype assessed but should also be combined with other molecular makers to increase the prediction accuracy of peach skin color.

Genomic analysis provides insights into the westward expansion of domesticated peaches in China

Peach, an economically important model plant of the Rosaceae family, has been domesticated and cultivated in China for approximately 5 000 years. The Hexi Corridor, an important corridor connecting east-central China and the Tarim Basin, is the starting point of the Silk Road that links China and the Eurasian region. As a globally distributed fruit tree, the spread of peach was accomplished through historical trade routes in the Hexi Corridor and the Tarim Basin. However, knowledge of peach genetic diversity in these regions remains limited. In this study, we examined the relationships and the spread history of domesticated peaches through sequencing and genomic analysis of 161 peach accessions collected from Northwest China, including 43 from the Hexi Corridor and 104 from the Tarim Basin. The results indicate that peach landraces in the Hexi Corridor and the Tarim Basin are derivatives of peaches from the east and south of China (ESC). Notably, the genetic diversity of accessions from both the Hexi Corridor and the Tarim Basin was lower than that of ESC accessions. Reduction of diversity (ROD) and linkage disequilibrium (LD) analyses detected a genetic bottleneck in peaches from these regions. Additionally, these peaches have undergone varying degrees of selection from natural environment. Moreover, genes responsive to biotic and abiotic stresses were under selection, which could be the result of the climate change of Northwest China after the Last Glacial Maximum (LGM). Our findings provide a better understanding of the genetic basis of peach migration in Northwest China. Furthermore, this study expands the available genomic data for peaches and provides critical information for future peach breeding programs.

Interactive Effect of Cultivars, Crop Years and Rootstocks on the Biochemical Traits of Prunus persica (L.) Batsch Fruits.

Peach fruit is one of the most economically widespread temperate fruits, whose productivity, and nutritional and sensory qualities are determined by interactions among several environmental and genetic factors, rootstocks, agronomic practices and pedo-climatic conditions. In recent years, climate change has prompted peach breeding programs to use specific rootstocks that are well adapted to unusual soil and climate characteristics, thus improving the plant's adaptability and fruit quality. The aim of this work was to assess the biochemical and nutraceutical profile of two different peach cultivars, considering their growth on different rootstocks over three crop years. An analysis was carried out evaluating the interactive effect of all factors (i.e., cultivars, crop years and rootstocks) revealing the advantages or disadvantages on growth of the different rootstocks. Soluble solids content, titratable acidity, total polyphenols, total monomeric anthocyanins and antioxidant activity in fruit skin and pulp were analyzed. An analysis of variance was performed to assess the differences between the two cultivars considering the effect of rootstock (one way) and crop years, rootstocks and their interaction (two ways). In addition, two principal component analyses were performed separately on the phytochemical traits of the two cultivars to visualize the distributions of the five peach rootstocks during the three crop years. The results showed that fruit quality parameters are strongly dependent on cultivars, rootstocks and climatic conditions. All these aspects could be useful for the choice of rootstock in relation to agronomic management, making this study a valuable tool for choosing the best rootstock, considering simultaneously more factors affecting peaches' biochemical and nutraceutical profile.

Multiple-statistical genome-wide association analysis and genomic prediction of fruit aroma and agronomic traits in peaches.

'Chinese Cling' is an important founder in peach breeding history due to the pleasant flavor. Genome-wide association studies (GWAS) combined with genomic selection are promising tools in fruit tree breeding, as there is a considerable time lapse between crossing and release of a cultivar. In this study, 242 peaches from Shanghai germplasm were genotyped with 145 456 single-nucleotide polymorphisms (SNPs). The six agronomic traits of fruit flesh color, fruit shape, fruit hairiness, flower type, pollen sterility, and soluble solids content, along with 14 key volatile odor compounds (VOCs), were recorded for multiple-statistical GWAS. Except the reported candidate genes, six novel genes were identified as associated with these traits. Thirty-nine significant SNPs were associated with eight VOCs. The putative candidate genes were confirmed for VOCs by RNA-seq, including three genes in the biosynthesis pathway found to be associated with linalool, soluble solids content, and cis-3-hexenyl acetate. Multiple-trait genomic prediction enhanced the predictive ability for γ-decalactone to 0.7415 compared with the single-trait model value of 0.1017. One PTS1-SSR marker was designed to predict the linalool content, and the favorable genotype 187/187 was confirmed, mainly existing in the 'Shanghai Shuimi' landrace. Overall, our findings will be helpful in determining peach accessions with the ideal phenotype and show the potential of multiple-trait genomic prediction to improve accuracy for highly correlated genetic traits. The diagnostic marker will be valuable for the breeder to bridge the gap between quantitative trait loci and marker-assisted selection for developing strong-aroma cultivars.

Ppe.CR.1 DNA test for predicting chilling requirement in peach

Chilling requirement (CR) is an important agronomic trait controlling the floral bud break for proper flowering in peach. Even though it has been widely researched and several peach CR quantitative trait loci (QTLs) have been identified, no diagnostic DNA tests validated in the U.S. peach breeding germplasm are available for this trait. Breeders and growers need a simple DNA test to predict the CR of peach cultivars for their particular environment. Therefore, we developed a quick and reliable Kompetitive Allele Specific PCR (KASP) DNA test using haplotype information from 9K IPSC genotype data of the U.S. peach germplasm integrating four CR-associated SNP markers from the previously reported CR QTL region on linkage group 1. Four KASP assays (Ppe.CR.1-1 to -4) were developed and validated on 77 peach cultivars, and nine accessions from two F2 populations, with 96 and 74% accuracy in determining expected CR genotype (compared to SNP array) and predicting phenotype, respectively. Furthermore, the Ppe.CR.1 showed 80% accuracy in predicting the precise CR phenotype in the Clemson University peach breeding material. Only one Ppe.CR.1 KASP assay (Ppe.CR.1-1) is needed to distinguish between haplotypes with CR lower and higher than 800 chilling hours, and two Ppe.CR.1 assays (Pp.CR.1-1 and -4), are capable of distinguishing low, moderate, and high CR alleles. Coupled with the crude DNA extraction, the Ppe.CR.1 DNA test provides a low-cost option for breeders and growers to predict CR in peach material with more than 70% accuracy.

Inheritance of Fruit Red-Flesh Patterns in Peach.

Fruit color is an important trait in peach from the point of view of consumer preference, nutritional content, and diversification of fruit typologies. Several genes and phenotypes have been described for peach flesh and skin color, and although peach color knowledge has increased in the last few years, some fruit color patterns observed in peach breeding programs have not been carefully described. In this work, we first describe some peach mesocarp color patterns that have not yet been described in a collection of commercial peach cultivars, and we also study the genetic inheritance of the red dots present in the flesh (RDF) and red color around the stone (CAS) in several intra- and interspecific segregating populations for both traits. For RDF, we identified a QTL at the beginning of G5 in two intraspecific populations, and for CAS we identified a major QTL in G4 in both an intraspecific and an interspecific population between almond and peach. Finally, we discuss the interaction between these QTLs and some other genes previously identified in peach, such as dominant blood flesh (DBF), color around the stone (Cs), subacid (D) and the maturity date (MD), and the implications for peach breeding. The results obtained here will help peach germplasm curators and breeders to better characterize their plant materials and to develop an integrated system of molecular markers to select these traits.

Progresso genético em 53 anos do Programa de Melhoramento de pessegueiro da Embrapa: cultivares para consumo fresco

Abstract A peach breeding program started in 1963, at the Experiment Station of Pelotas, nowadays Embrapa Clima Temperado, whose primary aim was developing cultivars adapted to mild winter conditions. Its first priority was to obtain cultivars of canning type fruits, and over the years, the fresh market cultivars acquired equal importance. This article analyzes the data of 84 fresh market cultivars, obtained in Pelotas, from 1964 to 2017, focusing on the following parameters: time of ripening, fruit development period, average fruit mass, number of fruits per tree, productivity per plant and total soluble solids. First, the data were tabulated, divided into two periods (1964-1984 and 1985-2017), and the descriptive statistical analysis was performed, followed by an analysis via mixed models and estimates of genetic progress via meta-analysis. The main results revealed a reduced fruit development period of the fresh market peaches belonging to that program. It was also observed a significant spread of the time of ripening (end of September or beginning of October until January), with a slight tendency for earliness. Genetic gain was observed for yield corresponding to 1.17 and 2.25% per year, for 1964-1984 and 1985-2017, respectively.

Starting from scratch: fourteen years of peach breeding program at Clemson University

Starting from scratch: fourteen years of peach breeding program at Clemson University

Machine learning methods for efficient and automated in situ monitoring of peach flowering phenology

Accurate knowledge of peach flowering phenology is essential for scheduling precise irrigation and managing artificial pollination for breeding. However, in situ monitoring of peach flowering phenology is laborious and challenging. This study divided peach flowering phenology into eight stages covering inflorescence emergence and flowering using BBCH scales. Web-connected recording cameras and weather stations automatically-collected flower images and meteorological data from three peach cultivars. Daily variables, including area proportion of specific color ranges in the images, temperature, illuminance and heat/chilling requirement data were applied for training and testing four machine learning models: random forest (RF), support vector machine (SVM), naïve Bayes (NB), and k-Nearest Neighbors (KNN). Grid tuning and 10-fold cross-validations were conducted on these models to determine the optimal method for identifying peach flowering phenological stages. The RF model obtained highest optimal F1 score of 98.82 % (harmonic average of model accuracy and recall) among the models on the testing set. The area proportion of specific color ranges in the real-time images are essential for model performance. Heat requirement data (biological growth time and growing degree days) can improve the overall accuracy. The classification accuracy at different BBCH phenological stages of the three cultivars is acceptable for real-time monitoring of peach flowering phenology. These are applicable for peach breeding, heat stress management, and irrigation scheduling. The RF model also shows acceptable accuracy with flower images and public meteorological data input, which reveals the extendibility for phenology monitoring of other trees or crops.

Profiling of naturally occurring proanthocyanidins and other phenolic compounds in a diverse peach germplasm by LC-MS/MS

Peach fruits are rich in phenolic compounds and have considerable health benefits. In this study, 19 proanthocyanidins (PACs) and 37 other phenolic compounds are identified and evaluated in the mature fruits of 217 peach accessions using LC-QTRAP-MS/MS and LC-QTOF-MS analyses. Total PAC quantities ranged from 18.93 to 697.52 μg/g fresh weight with a variance of 36.8-fold, and accounted for 11.2 % − 85.6 % of total phenolics content. Kaempferol-3-O-rutinoside (0.001–0.968 μg/g), isorhamnetin-3-O-rutinoside (0.001–0.300 μg/g), taxifolin (0.006–0.078 μg/g), luteoloside (0.002–0.068 μg/g), prunin (0.043–33.333 μg/g), phlorizin (0.018–1.100 μg/g), and trans-piceid (0.013–0.472 μg/g) were also highly diverse. The fruit ripening period, breeding background and fruit type significantly influenced the PACs and phenolic glycosides. This study presents a complete profile of PACs and other major phenolics in 217 peach germplasms, and is expected to aid future peach breeding procedures targeted at producing plants rich in specific phenolics.

Breeding Peaches for Brown Rot Resistance in Embrapa

Brown rot, caused by Monilinia spp., is the main stone fruit disease. Major efforts to detect sources of resistance are being applied by several breeding programs worldwide. The main objective of this study was to seek sources of brown rot resistance, as well as to study the segregation, estimate the heritability, verify the possible existence of the maternal effect, and estimate the genetic advances. For this purpose, 20 parents and 303 seedlings, representing 16 breeding families, and ‘Bolinha’ (control) have been phenotyped for fruit reaction to brown rot using wounded and non-wounded inoculation procedures in 2015–2016, 2016–2017, and 2017–2018 growing seasons. Wounded fruits were very susceptible to brown rot incidence, however, the incidence and severity of non-wounded fruits showed high variability among the evaluated genotypes. Conserva 947 and Conserva 1600 and their progeny, had lower disease incidence and severity than most of the evaluated genotypes. Genetic gain estimation was −5.2 to −30.2% (wounded fruits) and between −15.0 to −25.0% (non-wounded fruits) for brown rot resistance. Selected genotypes were equal to or better than ‘Bolinha’ in relation to brown rot resistance, with several of them far superior in fruit quality than ‘Bolinha’, demonstrating the progress of the Embrapa Peach Breeding Program.

Analysis of the free amino acid content and profile of 129 peach (Prunus persica (L.) Batsch) germplasms using LC-MS/MS without derivatization

Free amino acids (FAAs) are essential for fruit flavor and function. In this study, mature fruits of 129 germplasms grown in China were employed to fully comprehend the variability in the FAA composition of peaches (Prunus persica (L.) Batsch). A brief sample preparation process, based on formic acid/water/methanol extraction, was performed. Using the HSS T3 column, 24 FAAs were successfully separated. These FAAs were analyzed using LC-MS/MS without derivatization. A total of 20 FAAs were detected in peaches. Asparagine was the most abundant FAA (368.04–6090.79 μg/g FW) in peach fruit, followed by aspartic acid (29.00–409.51 μg/g FW), glutamic acid (45.33–290.13 μg/g FW), alanine (22.39–805.21 μg/g FW), glutamine (12.05–322.62 μg/g FW), serine (17.81–323.35 μg/g FW), and threonine (10.9–109.04 μg/g FW). Other proteinaceous amino acids, including arginine, glycine, histidine, isoleucine, leucine, lysine, phenylalanine, proline, tryptophan, tyrosine, valine, cis-4-hydroxy-proline, and a specialized non-proteinaceous amino acid, γ-aminobutyric acid, were identified and quantified in the peach germplasm. By comparing the FAA content of various germplasms, middle- and late- maturing peaches were found to possess more asparagine, proline, and cis-4-hydroxy-proline than early-maturing peaches. These essential results could markedly augment peach breeding programs and provide a comprehensive understanding of the peach germplasm resources.

Parameter estimation and selection efficiency under Bayesian and frequentist approaches in peach trials

Identification of stable and high-yielding genotypes is a real challenge in peach breeding, since genotype-by-environment interaction (GE) masks the performance of the materials. The aim of this work was to evaluate the effectiveness of parameter estimation and genotype selection solving the linear mixed models (LMM) under frequentist and Bayesian approaches. Fruit yield of 308 peach genotypes were assessed under different seasons and replication numbers arranged in a completely randomized design. Under the frequentist framework the restricted maximum likelihood method to estimate variance component and genotypic prediction was used. Different models considering environment, genotype and GE effects according to the likelihood ratio test and Akaike information criteria were compared. In the Bayesian approach, the mean and the variance components were assumed to be random variables having a priori non-informative distributions with known parameters. According the deviance information criteria the most suitable Bayesian model was selected. The full model was the most appropriate to calculate parameters and genotypic predictions, which were very similar in both approaches. Due to imbalance data, Cullis’s method was the most appropriate to estimate heritability. It was calculated at 0.80, and selecting above 5% of the genotypes, the realized gain of 14.80 kg tree1 was attained. Genotypic frequentist and Bayesian predictions showed a positive correlation (r = 0.9991; P = 0.0001). Since the Bayesian method incorporates the credible interval for genetic parameters, genotypic Bayesian prediction would be a more useful tool than the frequentist approach and allowed the selection of 17 high-yielding and stable genotypes.

Selection of genotypes of peach rootstock resistant to Meloidogyne incognita

The aim of this study was to evaluate the genotypes developed by the Peach Breeding Program at the Federal University of Viçosa, as regards to resistance to M. incognita. Six rootstocks genotypes propagated by cuttings (713-07, 713-13, 913-3, 913-6, 913-11 and 913-17) and two rootstocks propagated by seeds (‘Okinawa’ and hybrid between scion cultivars Aurora 2 x Aurora 1), were evaluated. The experimental design was randomized block design with five replicates and one plant per experimental units. After establishing the plants in pot, maintained in a greenhouse, this were inoculated with 11.000 juveniles + eggs of M. incognita. Evaluations were performed at 140 days after inoculation. The roots were evaluated and the number of galls and egg mass in the roots were determined. The eggs were extracted from each plant for quantification and determination of the Reproduction Factor (RF) of the nematode. The peach genotypes 913-3, 913-6, 913-11, 913-17 and 713-7 showed an immune reaction to M. incognita. Genotype 713-13 showed susceptible reaction to M. incognita. The hybrid between scion cultivars Aurora 2 x Aurora 1 confirmed susceptible.