Paeonia ludlowii (Stern & Taylor) D.Y.Hong, an endangered species, is indigenous to Tibet, China and propagated only by seed under natural conditions. Its natural reproduction is constrained by low fecundity. Excess seed abortion is a key factor restricting its natural reproduction, cultivation, introduction, and protection. Understanding the specific origin and occurrence of aborted ovules is important for the protection of offspring. Using serial sectioning analysis, we studied the process of pollination and fertilization of P. ludlowii and examined the characteristics of aborted ovules, developmental differences after flowering of normal and aborted ovules, and their ratios at different positions in P. ludlowii ovaries. During pollination, fertilization, and seed development, ovule abortion was frequent, with a random abortion position. There were three types of abortion, namely, abnormal pistil, sterile ovules, and embryo and endosperm abortions. Of these, embryo and endosperm abortions could be divided into early abortion and middle abortion. The early aborted ovules stopped growing on day 12, the endoblast and endosperm in the embryo sac aborted gradually. Furthermore, the shape of the embryo sac cavity changed. The volume of aborted ovules was significantly different from that of fertile ovules. At ripening, the external morphology of different types of aborted seeds was significantly different. The possible reasons for the abortion of the ovules are also discussed.

Background: Paeonia ludlowii (Stern & G. Taylor D.Y. Hong) belongs to the peony group of the genus Paeonia in the Paeoniaceae family and is now classified as a “critically endangered species” in China. Reproduction is important for this species, and its low fruiting rate has become a critical factor limiting both the expansion of its wild population and its domestic cultivation. Results: In this study, we investigated possible causes of the low fruiting rate and ovule abortion in Paeonia ludlowii. We clarified the characteristics of ovule abortion and the specific time of abortion in Paeonia ludlowii, and used transcriptome sequencing to investigate the mechanism of abortion of ovules in Paeonia ludlowii. Conclusions: In this paper, the ovule abortion characteristics of Paeonia ludlowii were systematically studied for the first time and provide a theoretical basis for the optimal breeding and future cultivation of Paeonia ludlowii.

The DNA amplified fragment length polymorphism (AFLP) fingerprinting approach was used to identify a shell color-linked marker in the noble scallop Chlamys nobilis Reeve. The marker B1f176 was linked completely to the gene for bright-orange shell color with no recombination in the progeny we sampled. This marker was amplified in bright-orange parents and all orange progeny, but was absent in all of the brownish purple progeny. Nevertheless, AFLP markers are not feasible for large-scale application. Thus, we converted B1f176 into a sequence-characterized amplified region (SCAR) marker that we designated as SCAR Orange-142. The marker Orange-142, like the AFLP band from which it was derived, amplified a robust band in only the bright-orange scallops, both in F1 and F2 families as well as in a test group obtained from a seafood market. These results indicate that Orange-142 is tightly linked to the gene for orange shell color. In all but 1 of 10 F2 families derived from bright-orange F0 grandparents...

Introduction: Paeonia ludlowii is a rare and endangered plant species with a high application value. However, its low cultivation success rate in China has severely limited its protection, development, and utilization. In addition to natural factors, microorganisms in the rhizosphere play an important role in determining its cultivation success.Methods: In this study, growth indexes and soil physicochemical properties of both wild (origin: Nyingchi) and cultivated (introduction: Luanchuan) species of P. ludlowii were measured during the flowering, fruiting, and autumn foliage stages. ITS high-throughput sequencing technology was employed to detect rhizosphere soil fungi, and the diversity, community structure, functional prediction, molecular network, and ecological processes of the microbial community assembly were examined by multidirectional analysis.Results and discussion: The results indicated that: both wild and cultivated P. ludlowii species were able to flower and fruit normally, although the wild species had a higher number of flowers and fruits and higher soil available phosphorus and available potassium contents than those of the cultivated species. Ascomycota and Basidiomycota were the dominant rhizosphere soil fungal phyla in both P. ludlowii species. However, our network analysis showed that Ascomycota as the key fungal phylum of the wild species, whereas the cultivated species lacked key fungi. The community assembly mechanisms of rhizosphere soil fungi in both wild and cultivated species were primarily stochasticity, with no significant differences between them. Based on the results of FUNGuild and molecular network analyses, cultivated species had a higher proportion of fungi, such as Soil Saprotroph, that can easily cause diseases. Additionally, the network connections among fungi were weaker in the cultivated species than those in the wild species, which increased the cultivated species susceptibility to external environmental interferences. Therefore, from a soil microorganism perspective, this study suggests that, after the introduction and cultivation of P. ludlowii, if rhizosphere soil fungi fail to gradually form a close network relationship and instead promote the growth of pathogenic fungi, the fungal ecosystem would become vulnerable.