Guillermo Padilla

Genetic diversity in a germplasm collection of Brassica rapa subsp rapa L. from northwestern Spain

In Galicia (northwestern Spain), Brassica rapa subsp. rapa L. includes turnips, turnip greens, and turnip tops. The objectives of this study are (i) to determine the genetic diversity and morphological resemblances among the B. rapa landraces of northwestern Spain in order to have information relative to the resources preserved, and (ii) to evaluate their agronomic characteristics, considering the three potential products that can be harvested. A collection of 120 landraces was evaluated for 34 morphological and agronomical traits by an augmented design at two locations. Two landraces were the most promising for turnips production (MBG-BRS0183 and MBG-BRS0256), two showed the best characteristics for turnip greens (MBG-BRS0082 and MBG-BRS0184), and three were the most appropriate landraces for turnip tops production (MBG-BRS0143, MBG-BRS0173 and MBG-BRS0401). Landraces were classified into five clusters (A–E) using the Ward–MLM (Modified Location Model) strategy: (A) included plants with the worst agronomic potential, (B) included most of the turnip populations with rosette growth habit, (C) included turnip populations without rosette growth habit, having more vigorous plants than cluster B, (D) gathered the most vigorous local varieties, with the highest early vigor, fresh matter content per leaf, and number of secondary stems per plant, and (E) landraces characterized by their earliness, large flowering periods, high numbers of secondary stems, and large seed weights. As conclusion, landraces evaluated in this work displayed enough variability to differentiate among appropriate populations for each one of the distinct crops. Their classification, using the Ward–MLM strategy, grouped accessions with similar characteristics into homogeneous categories.

The nabicol: A horticultural crop in northwestern Spain

Nabicol (B. napus L. var. pabularia) is a traditional crop in the Northwest of Iberian Peninsula (South of Galicia and North of Portugal) where it is grown during the winter season on small farms and gardens using traditional varieties. A collection of 36 populations of nabicol from Galicia (northwestern Spain) was evaluated during 2002 and 2003 in two locations and two growing seasons (spring/summer and autumn/spring) for 28 agronomic and morphological traits. The objectives of this study were to: (i) evaluate a collection of nabicol landraces from northwestern Spain, (ii) determine the suitability of this germplasm as a summer crop and (iii) study the genetic diversity among local populations. Significant differences were observed among populations for most traits. Genotype × environment interaction was significant for most of them. Spring/summer growing season could be recommended for growing nabicol but resistance to Lepidoptera pests attacking Brassica crops should be improved. Most populations had an agronomic value similar to the commercial variety. The most promising variety for horticultural use was MBG-BRS0063, which showed the highest yield. Morphological and agronomic data were subjected to cluster analysis and four groups were defined with a group clustering most populations. The low genetic diversity could be explained because populations were collected in close geographical areas and the selection made by farmers was always for a horticultural use. These results give information about the diversity and breeding value of the nabicol Spanish germplasm, which could be useful in breeding programs.

Incidence of the Major Brassica Pests in Northwestern Spain

ABSTRACT Kale (Brassica oleracea L. acephala group) crops are common in northwestern Spain, where they are severely damaged by different insect pests. The damage notably affects the value of this crop because it is freshly consumed and fresh processed. The objective of this work was to determine the abundance and relative importance of the main Lepidoptera pests of Brassica crops for 6 yr at five localities in northwestern Spain and to relate the seasonal changes of larval populations and environmental conditions. Pheromone traps were used as a method of monitoring adults. Larval populations were monitored on kales by counting the larvae for several years and locations at different sample dates. Five species were found: Mamestra brassicae (L.); imported cabbageworm, Pleris rapae (L.); Pieris brassicae (L.); diamondback moth, Plutella xyllostella (L.); and Autographa gamma L. Proportions of each insect fluctuated over the years and in the different locations. M. brassicae was the most abundant (48.5% of the total of Lepidoptera species) followed by P. xyllostella (25%) and P. rapae (15%). The use of pheromone traps combined with plant sampling permitted the detection of two generations of M. brassicae. However, adult counts were not correlated to the number of larvae on plants.

LOXL2 Is Highly Expressed in Cancer-Associated Fibroblasts and Associates to Poor Colon Cancer Survival

Purpose: Cancer-associated fibroblasts (CAF) are major mediators in tumor microenvironment. We investigated the changes in protein expression in colon cancer–associated fibroblasts compared with normal fibroblasts (NF) in the context of searching for prognostic biomarkers, particularly for stage II patients. Experimental Design: CAFs and NFs isolated from colon cancer patients were used to identify differentially expressed proteins using quantitative proteomics. Stromal expression of deregulated proteins was analyzed by IHC. Prognostic impact was studied using external gene-expression datasets for training, then quantitative PCR and IHC for validation in different cohorts of patients. Combined datasets were used for prediction of risk assessment at stages II and III. Results: A desmoplastic signature composed of 32 proteins, highly specific for stromal components in colon cancer, was identified. These proteins were enriched for extracellular matrix organization components, TGFβ signaling pathway, fibrosis, and wound-healing proteins. The expression in CAFs of 11 upregulated proteins and four downregulated proteins, selected for biomarker validation, was verified by orthogonal techniques. LOXL2 displayed a high prognostic impact by using external independent datasets and further validation in two different cohorts of patients. High expression of LOXL2 was associated with higher recurrence P = 0.001 HR, 5.38 [95% confidence interval (CI), 1.70–17.01] and overall survival P = 0.001 HR, 8.52 (95% CI, 1.90–38.29). IHC analysis revealed a prognostic value for LOXL2 in stage II patients. Conclusions: We identified LOXL2 to be associated with the outcome of colon cancer patients. Furthermore, it can be used to stratify patients at stages II and III for further therapeutic decisions. Clin Cancer Res; 21(21); 4892–902. ©2015 AACR.

Characterization of fall and spring plantings of Galician cabbage germplasm for agronomic, nutritional, and sensory traits

Twenty one landraces of cabbage (Brassica oleracea var. capitata L.) and two of Tronchuda cabbage (B. oleracea var. tronchuda Bailey) from Galicia (north–western Spain) along with five commercial hybrids of cabbage and one commercial variety of Tronchuda cabbage were evaluated in this study in two planting dates, autumn/winter for an early harvest and spring/summer for a late harvest. Data were recorded on morphologic, agronomic, nutritional, and sensory traits. The objectives were to assess the characteristics of the Galician cabbage landraces and to compare their agronomic value with that of the commercial hybrids available in local markets, at two planting dates. Four cabbage landraces and the two Tronchuda cabbage landraces showed no head formation. At the autumn/winter season, commercial hybrids showed poor adaptation, with more plants lost after transplanting, less early vigor, and yield than the head forming landraces. However, for characters related to crop uniformity (head appearance, days to harvest, and synchrony of production), commercial hybrids did better than landraces. Regarding the sensory and nutritional values, in the autumn/winter season, accessions were tenderer, sweeter, had a better flavour, and showed higher levels of crude protein and less of crude fibre than in the spring/summer season. Landraces had higher calcium contents compared to commercial varieties. Local landraces MBG-BRS0425, MBG-BRS0452, MBG-BRS0536, and MBG-BRS0537 stood out for the most interesting traits in the autumn/winter season growing period and they could be included in breeding programs to obtain hybrids suitable to grow in this planting period.

Genetic Transformation of Fruit Trees

Since the twentieth century, classical breeding strategies have been used to produce improved fruit trees. However, breeders have to deal with many problems due to their long juvenile period, open pollination, self-incompatibility, hetererozygosity and the time involved before selected phenotypes can be properly evaluated. Transformation with genes that mediate horticulturally important traits is a truly revolutionary approach for improving perennial species, as it implies that superior cultivars can be modified for a specific trait without otherwise altering the integrity of the clone. This review discusses the progress that has been made using transformation technologies to address important breeding objectives of perennial fruit species and also underlines the current limitations of this technology.

Molecular evidence of outcrossing rate variability in Brassica napus

A leafy crop of Brassica napus L. called nabicol has been grown by farmers in northwestern Spain for many years, being an important horticultural product during the winter season. A collection of landraces of a Brassica napus leafy crop called nabicol is kept at ‘Misión Biológica de Galicia’ (CSIC-Spain) which can be used to search for desirable characteristics or to produce new commercial varieties to release in the market. The assessment of the mating system of nabicol landraces is particularly important to carry on adequate breeding and genetic conservation programs. The objective of this work is to estimate the outcrossing rate in nabicol under controlled pollinator conditions using SSRs. Pairs of flowering plants taken from nabicol landrace MBG-BRS0039 were placed in separated isolation cages and bumble bees (Bombus sp.) were released for facilitating the crosses between plants. A seed sample from each plant in the cross was analyzed by SSRs that were polymorphic in the parental population. We found that the crop is partially allogamous and that there is genetic variation for the outcrossing rate among individuals. Several consequences for the maintenance and genetic improvement of the crop are discussed. The existence of genetic variability for this trait is a valuable tool that will allow us to study the genetic mechanisms underlying the mating system of this crop.

Maize Stem Response to Long-Term Attack by Sesamia nonagrioides

Plants defend themselves against herbivores by activating a plethora of genetic and biochemical mechanisms aimed at reducing plant damage and insect survival. The short-term plant response to insect attack is well understood, but less is known about the maintenance of this response over time. We performed transcriptomic and metabolomics analyses in order to identify genes and metabolites involved in the long-term response of maize to attack by the corn borer Sesamina nonagrioides. To determine the role of elicitors present in caterpillar secretions, we also evaluated the response of maize stem challenged with insect regurgitates. The integrative analysis of the omics results revealed that the long-term response in maize is characterized by repression of the primary metabolism and a strong redox response, mainly mediated by germin-like proteins to produce anti-nutritive and toxic compounds that reduce insect viability, and with the glutathione–ascorbate cycle being crucial to minimize the adverse effects of reactive oxygen species (ROS) on the plant. Our results suggest that different defense mechanisms are involved in the long-term response compared to those reported during the early response. We also observed a marginal effect of the caterpillar regurgitates on the long-term defensive response.