Pecan is an important horticultural nut crop originally from North America and now widely cultivated in China for its high ecological, ornamental and economic value. Currently, there are over one hundred cultivars grown in China, including introduced American cultivars and Chinese seedling breeding cultivars. Molecular markers were used to assess the genetic diversity of these cultivars and to identify the pedigrees of fine pecan plants with good characteristics and no cultivar-related data. A total of 77 samples grown in China were studied, including 14 introduced cultivars, 12 domestic seedling breeding cultivars, and 49 fine pecan plants with no cultivar data, together with Carya cathayensis and Juglans nigra. A total of 77 ISSR and 19 SSR primers were prescreened; 10 ISSR and eight SSR primers were selected, yielding a total of 94 amplified bands (100% polymorphic) in the range of 140–1,950 bp for the ISSR and 70 amplified bands (100% polymorphic) in the range of 50–350 bp for SSR markers. Genetic diversity analyses indicated Chinese-grown pecan cultivars and fine plants had significant diversity at the DNA level. The dengrograms constructed with ISSR, SSR or combined data were very similar, but showed very weak grouping association with morphological characters. However, the progeny were always grouped with the parents. The great diversity found among the Chinese cultivars and the interesting germplasm of the fine pecan plants analyzed in this study are very useful for increasing the diversity of the pecan gene pool. All 77 accessions in this study could be separated based on the ISSR and SSR fingerprints produced by one or more primers. The results of our study also showed that ISSR and SSR techniques were both suitable for genetic diversity analyses and the identification of pecan resources.

A previous report showed that both Pyruvate decarboxylase (PDC) genes were significantly upregulated in kiwifruit after waterlogging treatment using Illumina sequencing technology, and that the kiwifruit AdPDC1 gene was required during waterlogging, but might not be required during other environmental stresses. Here, the function of another PDC gene, named AdPDC2, was analyzed. The expression of the AdPDC2 gene was determined using qRT-PCR, and the results showed that the expression levels of AdPDC2 in the reproductive organs were much higher than those in the nutritive organs. Waterlogging, NaCl, and heat could induce the expression of AdPDC2. Overexpression of kiwifruit AdPDC2 in transgenic Arabidopsis enhanced resistance to waterlogging and heat stresses in five-week-old seedlings, but could not enhance resistance to NaCl and mannitol stresses at the seed germination stage and in early seedlings. These results suggested that the kiwifruit AdPDC2 gene may play an important role in waterlogging resistance and heat stresses in kiwifruit.

The sucrose nonfermenting 1-related protein kinase (SnRK) plays an important role in responding to abiotic stresses by phosphorylating the target protein to regulate various signaling pathways. However, little is known about the characteristics, evolutionary history, and expression patterns of the SnRK family in black raspberry (Rubus occidentalis L.) or other Rosaceae family species. In this study, a total of 209 SnRK genes were identified in 7 Rosaceae species and divided into 3 subfamilies (SnRK1, SnRK2, and SnRK3) based on phylogenetic analysis and specific motifs. Whole-genome duplication (WGD) and dispersed duplication (DSD) were considered to be major contributions to the SnRK family expansion. Purifying selection was the primary driving force in the SnRK family evolution. The spatial expression indicated that the RoSnRK genes may play important roles in different tissues. In addition, the expression models of 5 RoSnRK2 genes in response to abiotic stresses were detected by qRT-PCR. The proteins encoded by RoSnRK2 genes localize to the cytoplasm and nucleus in order to perform their respective functions. Taken together, this study provided an analysis of the SnRK gene family expansion and evolution, and contributed to the current knowledge of the function of 5 RoSnRK2 genes, which in turn expanded understanding of the molecular mechanisms of black raspberry responses to abiotic stress.

Drought severely affects the growth and production of pecan (Carya illinoinensis), while genes conferred drought adaptation are yet to be fully elucidated. Here, an in-depth exploration of the two different RNA-seq projects regarding drought stress (designated as P1 and P2) was performed via weighted gene co-expression network analysis. For the two projects, there existed one pair of modules (P1 turquoise module and P2 blue module) that was probably associated with drought resistance, as the paired modules both exhibited an increased expression profile with increasing water shortage stress and were annotated to be involved in oxidative stress response and the signaling pathways of abscisic acid and jasmonic acid. There were 441 and 1258 hub genes in the P1 turquoise module and P2 blue module, respectively, among which, 140 were overlapped and thus were recognized as core drought responsive genes. An additional drought stress experiment was conducted for RT-qPCR validation, and the results showed that the 20 core genes selected for detection were highly responsive to water deficit. Together, our results will be helpful for understanding the molecular mechanism of drought response and improving drought resistance in pecan.