Molecular evidence and ecological niche modeling reveal an extensive hybrid zone among three Bursera species (section Bullockia)

The genus Bursera, includes ~100 shrub and trees species in tropical dry forests with its center of diversification and endemism in Mexico. Morphologically intermediate individuals have commonly been observed in Mexican Bursera in areas where closely related species coexist. These individuals are assumed to result from interspecific hybridization, but no molecular evidence has supported their hybrid origins. This study aimed to investigate the existence of interspecific hybridization among three Mexican Bursera species (Bullockia section: B. cuneata, B. palmeri and B. bipinnata) from nine populations based on DNA sequences (three nuclear and four chloroplast regions) and ecological niche modeling for three past and two future scenario projections. Results from the only two polymorphic nuclear regions (PEPC, ETS) supported the hybrid origin of morphologically intermediate individuals and revealed that B. cuneata and B. bipinnata are the parental species that are genetically closer to the putative hybrids. Ecological niche modeling accurately predicted the occurrence of putative hybrid populations and showed a potential hybrid zone extending in a larger area (74,000 km2) than previously thought. Paleo-reconstructions showed a potential hybrid zone existing from the Last Glacial Maximum (~ 21 kya) that has increased since the late Holocene to the present. Future ecological niche projections show an increment of suitability of the potential hybrid zone for 2050 and 2070 relative to the present. Hybrid zone changes responded mostly to an increase in elevational ranges. Our study provides the first insight of an extensive hybrid zone among three Mexican Bursera species based on molecular data and ecological niche modeling.

Interspecific hybridization in natural sturgeon populations of the Eastern Black Sea: the consequence of drastic population decline?

The eastern part of the Black Sea and its tributaries are suitable habitats for several sturgeon species, among which Acipenser gueldenstaedtii, A. stellatus, A. nudiventris, A. persicus, A. sturio, and H. huso are well documented. However, different threats have led these species to a dramatic decline, all of them are currently listed as Critically Endangered, and some Locally Extinct, in that area. We tested 94 wild sturgeon samples from the Black Sea and Rioni River by analyzing the mitochondrial Control Region and nuclear markers for hybrid identification. The data analyses (1) assessed mitochondrial diversity among samples, (2) identified their species, as well as (3) indicated instances of hybridization. The data collected, besides confirming a sharp decrease of catches of Beluga and Stellate sturgeon in recent years, also revealed four juvenile hybrids between Russian and Stellate sturgeon, providing the first evidence of natural interspecific hybridization in the Rioni. The present communication raises concerns about the status of sturgeon species in this area and underlines the urgent need for conservation programs to restore self-sustaining populations.

Genetic Analysis of Various Traits in Oilseed Brassicas

Background: The combining ability and manifestation of heterosis within and among the species of oilseed brassicas (B. campestris, B. napus and B. juncea) were studied for yield and yield related traits in 12F1 combinations. Methods: All crosses (12F1) along with their parents (7 parents) were sown in randomized complete block design (RCBD) with three replications. Result: The analysis of variance showed extensive variability among the genotypes. The physical appearance of interspecific crosses was intermediate. B. campestris showed significant GCA effects among lines and B. juncea among testers for seed yield per plant. General combining behaviour of B. campestris was better as compared to B. napus and B. juncea. The SCA effects were higher within species than among the species. This also revealed that within the species B. juncea had more SCA (17.45) than B. napus (9.82) and B. campestris (8.01) for seed yield. The SCA showed the improvement of B. Juncea, is the best than other two species. It is also concluded that to obtain better yield, crossing within the species is more appropriate than among the species. Moreover, to introduce novel traits in brassica species is possible through interspecific hybridization.

Analysis of genetic variability in F2 interspecific hybrids of mung bean (Vigna radiata) using inter-retrotransposon amplified polymorphism marker system

Fatmawati Y, Setiawan AB, Purwantoro A, Respatie DW, Teo CH. 2021. Analysis of genetic variability in F2 interspecific hybrids of mung bean (Vigna radiata) using inter-retrotransposon amplified polymorphism marker system. Biodiversitas 22: 4880-4889. Mung bean (Vigna radiata L. Wilczek) categorized as one of the pivotal annual crops of Vigna genera is commonly cultivated in rotation with the cereal crops during the drought season. Conversely, to ameliorate its stunted productivity, the interspecific hybridization technique has been introduced between the mung bean and the common bean to promote genetic improvement with the breeding projects in Indonesia. However, since mung bean is a self-pollinated crop and has a narrow genetic base, the selection and improvement of a specific trait using marker-assisted selection is more challenging. Hence, a precautionary investigation is imperative to evaluate the progenies resulting from interspecific hybridization using an ideal marker. This study aimed to investigate the genetic variability of the F2 population of the interspecific mung bean hybrids using retrotransposon-based markers, particularly Inter-Retrotransposon Amplified Polymorphism (IRAP) markers. In this study, we identified retrotransposon from the mung bean genome and determined the Long Terminal Repeat (LTR) sequence using the LTR Finder. The IRAP primers were designed from a conserved region of the LTR sequence. One hundred of the F2 interspecific hybrids generated from the crossing between mung bean and common bean were successfully discriminated by IRAP markers. The IRAP marker showed high heterozygosity and moderate Polymorphic Information Content (PIC) values. The IRAP markers were able to detect genetic variability in the F2 progenies resulting from the interspecific hybridization. Cluster analysis showed that 100 of the F2 progenies were grouped into three clusters. This study demonstrated that retrotransposon-based markers can offer an effective approach for evaluating the segregation in the F2 population of intercross hybrids in the mung bean.