Contribution of anther color to interaction between plants and flower-visiting arthropods – usefulness of bioresource stocks

It is very difficult to provide strong evidence of how flower characteristic that may serve to attract pollinators, improve plant fitness. We propose to use the natural variation that we have observed within our wild tomato (Solanum pimpinellifolium) plant stocks to investigate the effect of anther color on attracting flower-visiting arthropods which act as pollinators. By looking at within-species variation, we can vary anther color while keeping other factors like petal color and other genetically controlled variables constant. We believe that our proposed study makes a significant contribution to the literature because it will allow us to clearly determine the contribution of anther color in attracting pollinators.

Efeito alelopático de Solanum pimpinellifolium L. sobre a germinação e crescimento inicial de Lactuca sativa e Bidens pilosa

Alelopatia é a interferência causada por substâncias químicas produzidas por plantas em organismos da comunidade, acarretando tanto efeitos benéficos quanto prejudiciais. Devido ao grande potencial alelopático do gênero Solanum, o objetivo do presente trabalho foi avaliar o efeito alelopático dos extratos hexânico, metanólico e de acetato de etila de folhas de Solanum pimpinellifolium L. sobre a germinação de Lactuca sativa e Bidens pilosa. Os extratos foram obtidos por maceração à temperatura ambiente por 7 dias. Depois foram secos e diluídos para as concentrações 1,0; 2,0 e 5,0 mg/mL. Em seguida, 100 sementes de cada espécie foram distribuídas em placas de Petri umedecidas com as diferentes concentrações de cada extrato e colocadas para germinar sob luz constante em câmara de germinação tipo BOD. Os bioensaios foram monitorados diariamente, obtendo-se ao final de 7 dias a porcentagem de germinação e o índice de velocidade de germinação (IVG). Dos três extratos analisados, o obtido pela extração com acetato de etila apresentou melhor desempenho, diminuindo a velocidade e a porcentagem de germinação em todas as concentrações e na concentração 5,0 mg/mL apresentou apenas 7% de germinação para L. sativa. O extrato hexânico diminuiu a velocidade e a porcentagem de germinação de B. pilosa em todas as concentrações. As análises fitoquímicas realizadas por meio de técnica de cromatografia em camada delgada (CCD) nos extratos de folha de Solanum pimpinellifolium identificaram quatro grupos químicos: flavonoides, saponinas, alcaloides e mono e diterpenos, sendo apenas esta última classe presente em todos os extratos analisados.

Ralstonia solanacearum type III effector RipJ triggers bacterial wilt resistance in Solanum pimpinellifolium

Ralstonia solanacearum causes bacterial wilt disease in solanaceous crops. Identification of avirulence type III secreted effectors recognized by specific disease resistance proteins in host plant species is an important step towards developing durable resistance in crops. In the present study, we show that R. solanacearum effector RipJ functions as an avirulence determinant in Solanum pimpinellifolium LA2093. 10 candidate avirulence effectors were shortlisted based on the effector repertoire comparison between avirulent Pe_9 and virulent Pe_1 strain. Infection assays with transgenic Pe_1 strain individually carrying a candidate avirulence effector from Pe_9 revealed that only RipJ elicits strong bacterial wilt resistance in S. pimpinellifolium LA2093. Furthermore, we identified that several RipJ natural variants do not induce bacterial wilt resistance in S. pimpinellifolium LA2093. RipJ belongs to the YopJ family of acetyltransferases. Our sequence analysis indicated the presence of partially conserved putative catalytic residues. Interestingly, the conserved amino acid residues in the acetyltransferase catalytic triad are not required for effector-triggered immunity. In addition, we show that RipJ does not auto-acetylate its lysine residues. Our study reports the identification of the first R. solanacearum avirulence protein that triggers bacterial wilt resistance in tomato. We expect that our discovery of RipJ as an avirulence protein will accelerate the development of bacterial wilt-resistant tomato varieties in the future.

Ensilado biológico de pescado y su efecto sobre el crecimiento de plantas de tomate silvestre (Solanum pimpinellifolium L.) y comercial (S. lycopersicum L.)

Plantas de tomate silvestre (Solanum pimpinellifolium L.) y comercial (S. lycopersicum L.) fueron mantenidas con solución hidropónica y con ensilado biológico de pescado, evaluando el crecimiento del tallo principal, número de ramas y porcentaje de materia seca. Las plantas de tomate silvestre que fueron regadas con el ensilado de pescado tuvieron un mayor crecimiento del tallo principal así como del número de ramas, mientras que ambas especies generaron un mayor porcentaje de materia seca en hojas. Estos resultados permiten sugerir que el nitrógeno del ensilado de pescado sería el componente importante para el mayor crecimiento de la parte aérea de estas plantas.

Genome of Solanum pimpinellifolium provides insights into structural variants during tomato breeding

Solanum pimpinellifolium (SP) is the wild progenitor of cultivated tomato. Because of its remarkable stress tolerance and intense flavor, SP has been used as an important germplasm donor in modern tomato breeding. Here, we present a high-quality chromosome-scale genome sequence of SP LA2093. Genome comparison identifies more than 92,000 structural variants (SVs) between LA2093 and the modern cultivar, Heinz 1706. Genotyping these SVs in ~600 representative tomato accessions identifies alleles under selection during tomato domestication, improvement and modern breeding, and discovers numerous SVs overlapping genes known to regulate important breeding traits such as fruit weight and lycopene content. Expression quantitative trait locus (eQTL) analysis detects hotspots harboring master regulators controlling important fruit quality traits, including cuticular wax accumulation and flavonoid biosynthesis, and SVs contributing to these complex regulatory networks. The LA2093 genome sequence and the identified SVs provide rich resources for future research and biodiversity-based breeding.

An Acylsucrose-Producing Tomato Line Derived from the Wild Species Solanum pimpinellifolium Decreases Fitness of the Whitefly Trialeurodes vaporariorum

A combination of biological control and host plant resistance would be desirable for optimally controlling the greenhouse whitefly, Trialeurodes vaporariorum in tomato crops. Whitefly settlement preference, oviposition, and survivorship were evaluated on ABL 10-4 and ‘Moneymaker’, two nearly-isogenic tomato lines with, and without, whitefly-resistance traits based on type IV leaf glandular trichomes derived from the tomato wild species Solanum pimpinellifolium, respectively. Significantly reduced preference of T. vaporariorum adult whiteflies for ABL 10-4 leaves was observed. Moreover, T. vaporariorum altered its abaxial–adaxial settling performance on leaves of ABL 10-4 plants. A significantly lower tendency to settle on abaxial leaf surface was observed in ABL 10-4 compared to Moneymaker plants. Furthermore, T. vaporariorum deposited fewer eggs and exhibited a significantly reduced egg to adult survivorship in ABL 10-4 than in Moneymaker plants. Therefore, reduced fitness and distorted performance were observed for T. vaporariorum on ABL 10-4 tomato plants supporting that type IV leaf glandular trichomes might protect them from this pest and, indirectly, from the viruses it transmits.

Adaptation to Water and Salt Stresses of Solanum pimpinellifolium and Solanum lycopersicum var. cerasiforme

Solanum pimpinellifolium and Solanum lycopersicum var. cerasiforme represent a valuable tool for tomato breeding, particularly for tolerance to abiotic stresses. Water stress and salinity are major constraints to tomato’s cultivation, and for which limited genetic variability has been reported within the cultivated species. We evaluated four accessions of S. pimpinellifolium and four of S. l. var. cerasiforme for their adaptation to water deficit and salinity. The CO2 assimilation rate, stomatal conductance, substomatal CO2 concentration, transpiration rate, and leaf chlorophyll concentration were evaluated, as well as morphological and agronomic traits. The accessions showed a remarkable inter- and intra-species response variability to both stresses. Two S. pimpinellifolium accessions and one S. l. var. cerasiforme showed unaltered physiological parameters, thus indicating a good adaptation to water deficit. Two S. l. var. cerasiforme accessions showed an interesting performance under salt stress, one of which showing also good adaptation to water stress. In general, both stresses showed a negative impact on leaf size and fruit fresh weight, especially in the big-sized fruits. However, flowering, fruit setting and earliness remained unaltered or even improved when compared to control conditions. Stressed plants yielded fruits with higher ° Brix. Response to stresses seemed to be linked to origin environmental conditions, notwithstanding, variability was observed among accessions of the same region.

Genome of Solanum pimpinellifolium provides insights into structural variants during tomato breeding

Solanum pimpinellifolium (SP) is the wild progenitor of cultivated tomato. Because of its remarkable stress tolerance and intense flavor, SP has been used as an important germplasm donor in modern breeding of tomato. Here we present a high-quality chromosome-scale genome sequence of SP LA2093. Genome comparison identifies more than 92,000 high-confidence structural variants (SVs) between LA2093 and the modern cultivar, Heinz 1706. Genotyping these SVs in ~600 representative tomato accessions unravels alleles under selection during tomato domestication, improvement and modern breeding, and discovers numerous novel SVs underlying genes known to regulate important breeding traits such as fruit weight and lycopene content. Expression quantitative trait locus (eQTL) analysis detects hotspots harboring master regulators controlling important fruit quality traits, including cuticular wax accumulation and flavonoid biosynthesis, and novel SVs contributing to these complex regulatory networks. The LA2093 genome sequence and the identified SVs provide rich resources for future research and biodiversity-based breeding.