Transcriptomic Analysis of the Pistacia vera (L.) Fruits Enable the Identification of Genes and Hormone-Related Gene Linked to Inflorescence Bud Abscission

Abstract

Pistacia vera (L.) is an alternate bearing species. The tree produces axillary inflorescence buds every year. Still, they abscise in “ON” overloaded shoots, causing a limited production in the following “OFF” year, causing a significant and unfavorable production fluctuation. In this work, we carried out de novo discovery and transcriptomic analysis in fruits of “ON” and “OFF” shoots of the cultivar Bianca. We also investigated whether the fruit signaling pathway and hormone biosynthesis directly or indirectly linked to the premature fall of the inflorescence buds causing alternate bearing. We identified 1536 differentially expressed genes (DEGs) in fruits of “ON” vs. “OFF” shoots, which are involved primarily in sugar metabolism, plant hormone pathways and transcription factors. The premature bud abscission linked to the phenomenon is attributable to a lack of nutrients (primarily sugar) and the possible competition between the same branches’ sinks (fruits vs. inflorescence buds). Hormone pathways are involved as a response to signals degradation and remobilization of carbon and nutrients due to the strengthening of the developing embryos. Genes of the secondary metabolism and transcription factors are also involved in tailoring the individual branches response to the nutritional stress and sink competition. Crosstalk among sugar and various hormone-related genes, e.g., ethylene, auxin, ABA and cytokinin, were determined. The discovery of putative biomarkers like callose synthase 5, trehalose-6-phosphate synthase, NAD(P)-linked oxidoreductase and MIOX2, Jasmonate, and salicylic acid-related genes can help to design precision farming practices to mitigate the alternate bearing phenomenon to increase farming profitability. The aim of the analysis is to provide insight into the gene expression profiling of the fate of “ON” and “OFF” fruits associated with the alternate bearing in the pistachio.

In a nutshell: pistachio genome and kernel development

“…Further, we identified homologs of LEC1 and WRI1, known to act together to regulate seed oil content in other plant species 25,31 , to be candidate regulators of fatty acid biosynthesis in pistachio 37 . Benny and colleagues 35,36 Environmental temperature was recorded using HOBO temperature and light sensors data logger (Onset, United States) placed in the orchards at three separate locations. Growing degree days were calculated with the equation 10 :…”

“…The lull in fruit growth identified as Stage II may function to generate resources from photosynthesis that can be used to support kernel growth in Stage III 34 . This growth pattern may also help explain why some pistachio nuts continue their development without a kernel ( i.e., “blanks”) and why the trees drop their buds in early summer ( i.e., bud abscission), leading to alternate bearing years 35,36 . Transcriptome and hormone analysis at the transition to seed growth (Stage II to III) will be essential to further elucidate these phenomena.…”

NGS transcriptomic analysis uncovers the possible resistance mechanisms of olive to Spilocea oleagina leaf spot infection

“…Arabidopsis WRKY46, WRKY70, and WRKY53, partially involved in the SA-signaling pathway, positively regulate basal resistance against P. syringae, playing synergetic roles in plant basal defense (Hu et al, 2012;Caarls et al, 2015). However, some WRKY TFs (e.g., WRKY6-like, Benny et al, 2020b) and JUNGBRUNNEN 1-like (Thirumalaikumar et al, 2018) have an important role in combined abiotic and biotic stress responses (Bai et al, 2018). SARD1 is a master transcription factor in plant immunity, induced by SA accumulation.…”

“…GO terms with p-values <=0.05 were considered as significant. The approaches used have already been employed for the analysis of highly complex physiological traits in other species ( Benny et al., 2020a ; Benny et al., 2022 ).…”

Interactive effect of branch source-sink ratio and leaf aging on photosynthesis in pistachio

“…Pistachio trees have marked annual changes in the source-sink ratio within the branch that strongly affect productivity. A heavy fruit load will precipitate abscission of the reproductive buds and later cause early leaf senescence (Marino and Marra, 2019;Benny et al, 2020;Benny et al, 2022). The result in the following season within the individual branch is no fruit or alternate bearing, and less shoot growth due to decreased NSC reserves (Barone et al, 2014).…”