bims-plasge 2025-06-29 papers

Issue of 2025–06–29
two papers selected by
Vera S. Bogdanova, ИЦиГ СО РАН

Am Nat. 2025 Jul;206(1): 16-30

Cytoplasmic Male Sterility Declines in the Presence of Resistant Nuclear Backgrounds.

Fanny Laugier, Kévin Béthune, Florian Plumel, Céline Froissard, Jean-Marc Donnay, Timothée Chenin, François Rousset, Patrice David.

AbstractGenomic conflicts arise when different genes in a genome are selected for opposite phenotypic effects. One well-known conflict occurs in plants, between mitochondrial genes causing cytoplasmic male sterility (CMS) and their nuclear suppressors, called restorers of male fertility. The evolution of CMS-restorer polymorphisms has been modeled many times, but empirical validations remain indirect. Here we use a new biological model, a freshwater snail, to directly observe evolutionary trajectories. In this species, CMS-associated mitogenomes coexist with male-fertile ones in populations. Models predict such a coexistence when nuclear restorers make CMS mitogenomes less fit than male-fertile ones, thus preventing the fixation of CMS. During 11 generations of experimental evolution, we observed rapid decreases in the frequency of CMS mitogenomes in a restorer-rich nuclear background, with an estimated ∼20% fitness disadvantage, consistent with theoretical conditions for the maintenance of cytonuclear polymorphism. In parallel, in an ancillary experiment, eggs laid by isolated snails carrying CMS showed a reduced hatching rate. Although significant, this reduction did not reach 20%, suggesting that fitness differentials in populations are enhanced by competition or rely on unmeasured traits. Our study illustrates the speed at which evolution can proceed in the context of cytonuclear conflicts over sex allocation.

Keywords: Physa acuta; cost; cytoplasmic male sterility; experimental evolution; restoration

DOI: https://doi.org/10.1086/735820

Discov Agric. 2025 ;3(1): 93

Effect of cultivar selection on symbiotic nitrogen fixation and yield traits of pea cultivars in intercropping with wheat.

Chathuranga De Silva, Pramod Rathor, Thomas D Warkentin, Hari P Poudel, Malinda S Thilakarathna.

In recent decades, agricultural practices have shifted from diverse cropping systems to monocropping, leading to soil degradation, nutrient depletion, and reduced biodiversity, which threaten long-term productivity and ecosystem sustainability. This study aimed to explore how legume cultivar selection influences pea (Pisum sativum L.)-wheat (Triticum aestivum L.) intercropping, focusing on symbiotic nitrogen (N) fixation, yield, seed N, and land productivity. A greenhouse experiment was conducted using various pea cultivars that were released in different decades [Century (1960), Trapper (1970), CDC Golden (2002), CDC Amarillo (2012), and CDC Spectrum (2016)] under monocropping and intercropping with wheat to evaluate the yield parameters and symbiotic N fixation capabilities of pea. The old, long-vined pea cultivars (Century and Trapper) had higher seed dry weight (62.9-66.3%), number of pods (82.7-100%) and number of seeds (126.9-163.5%) than the newer, moderate vine length cultivars (CDC Golden, CDC Amarillo and CDC Spectrum) under intercropping. On the other hand, the companion wheat crop had a greater yield (29.8-69.9%) and seed N (31.1-65.5%) when intercropped with the newer pea cultivars. Intercropping enhanced N fixation (0.7-7.5%) in peas across cultivars; however, the older cultivars contributed more to the overall system's N fixation and N carry-over compared to the newer cultivars. While the harvest index, land equivalent ratio (LER), and N-based LER (LERN) of intercropped wheat were not significantly higher than mono-cropped wheat, the increased partial LER and LERN for wheat highlight intercropping benefits. Overall, newer pea cultivars enhanced pea-wheat intercropping by improving productivity and resource efficiency, highlighting the importance of legume cultivar selection in intercropping.
Graphical abstract:

Keywords: Breeding; Cereals; Legume; Monocropping; Nitrogen; Rhizobia

DOI: https://doi.org/10.1007/s44279-025-00261-0