bims-plasge 2024-09-15 papers

J Genet Genomics. 2024 Sep 04. pii: S1673-8527(24)00233-9. [Epub ahead of print]

PPR21 is involved in the splicing of nad2 introns via interacting with PPR-SMR1 and SPR2 and is essential to maize seed development.

Yan-Zhuo Yang, Xin-Yuan Liu, Song Gao, Shu-Guang Zhang, Bao-Cai Tan.

Pentatricopeptide repeat (PPR) proteins are a large group of eukaryote-specific RNA-binding proteins that play pivotal roles in plant organelle gene expression. Here, we report the function of PPR21 in mitochondrial intron splicing and its role in maize kernel development. PPR21 is a typical P-type PPR protein targeted to mitochondria. The ppr21 mutants are arrested in embryogenesis and endosperm development, leading to embryo lethality. Null mutations of PPR21 reduce the splicing efficiency of nad2 intron 1, 2, and 4 and impair the assembly and activity of mitochondrial complex I. Previous studies show that the P-type PPR protein EMP12 is required for the splicing of identical introns. However, our protein interaction analyses reveal that PPR21 does not interact with EMP12. Instead, both PPR21 and EMP12 interact with the small MutS-related (SMR) domain-containing PPR protein 1 (PPR-SMR1) and the short P-type PPR protein 2 (SPR2). PPR-SMR1 interacts with SPR2, and both proteins are required for the splicing of many introns in mitochondria, including nad2 intron 1, 2, and 4. These results suggest that a PPR21-(PPR-SMR1/SPR2)-EMP12 complex is involved in the splicing of nad2 introns in maize mitochondria.

Keywords: Intron splicing; PPR-SMR1; PPR21; SPR2; maize (Zea mays); mitochondrion; seed development

DOI: https://doi.org/10.1016/j.jgg.2024.08.010

Plant J. 2024 Sep 09.

Cryptic cytoplasmic male sterility-causing gene in the mitochondrial genome of common japonica rice.

Kinya Toriyama, Yuko Iwai, Shinya Takeda, Ayumu Takatsuka, Keisuke Igarashi, Tomoyuki Furuta, Sunlu Chen, Yoshitaka Kanaoka, Yuji Kishima, Shin-Ichi Arimura, Tomohiko Kazama.

Cytoplasmic male sterility (CMS) is an agronomically significant trait that causes dysfunction in pollen and anther development. It is often observed during successive backcrossing between distantly related species. Here, we show that Asian japonica cultivars (Oryza sativa) exhibit CMS when the nucleus is replaced with that of the African rice Oryza glaberrima. The CMS line produced stunted anthers and did not set any seeds. Mitochondrial orf288 RNA was detected in the anthers of CMS lines but not in fertility restorer lines. The mitochondrial genome-edited japonica rice that was depleted of orf288 did not exhibit male sterility when backcrossed with O. glaberrima. These results demonstrate that orf288 is a CMS-causing gene. As orf288 commonly occurs in the mitochondrial genomes of japonica rice, these results indicate that common japonica rice cultivars possess a cryptic CMS-causing gene hidden in their mitochondrial genomes.

Keywords: Oryza sativa; TALEN; cytoplasmic male sterility; mitochondrial gene; orf288

DOI: https://doi.org/10.1111/tpj.17028

Plants (Basel). 2024 Sep 02. pii: 2454. [Epub ahead of print]13(17):

Identification of Sources of Resistance to Aphanomyces Root Rot in Pisum.

Sara Rodriguez-Mena, Diego Rubiales, Mario González.

Aphanomyces root rot (ARR), caused by Aphanomyces euteiches, is one of the most devastating diseases that affect the production of peas. Several control strategies such as crop rotation, biocontrol, and fungicides have been proposed, but none provides a complete solution. Therefore, the deployment of resistant cultivars is fundamental. ARR resistance breeding is hampered by the moderate levels of resistance identified so far. The available screening protocols require post-inoculation root assessment, which is destructive, time-consuming, and tedious. In an attempt to address these limitations, we developed a non-destructive screening protocol based on foliar symptoms and used it to identify new sources of resistance in a Pisum spp. germplasm collection. Accessions were root inoculated separately with two A. euteiches isolates, and leaf symptoms were assessed at 5, 10, 14, 17, and 20 days after inoculation (DAI). Although the majority of accessions exhibited high levels of susceptibility, thirty of them exhibited moderate resistance. These thirty accessions were selected for a second experiment, in which they were inoculated with both A. euteiches isolates at two inoculum doses. The objective of this second trial was to confirm the resistance of these accessions by evaluating root and biomass loss, as well as foliar symptoms, and to compare root and foliar evaluations. As a result, a high correlation (R2 = 0.75) between foliar and root evaluations was observed, validating the foliar evaluation method. Notably, accessions from P.s. subsp. humile exhibited the lowest symptomatology across all evaluation methods, representing valuable genetic resources for breeding programs aimed at developing pea varieties resistant to ARR.

Keywords: Aphanomyces euteiches; aerial evaluation; pea; root disease

DOI: https://doi.org/10.3390/plants13172454