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

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.

Two new species of Begonia (sect. Platycentrum, Begoniaceae) from the Central Highlands of Vietnam: B. villosula and B. lophura

Two new species of Begonia L., namely Begonia villosula T.S.Hoang & C.W.Lin and B. lophura T.S.Hoang & C.W.Lin, from the Central Highlands of Vietnam, are described and illustrated. They are assigned to Begonia sect. Platycentrum based on several characters including axillary inflorescence, 4-tepaled staminate flower and 5-tepaled pistillate flower with bilocular ovary, each with two placentae. Begonia villosula resembles B. thomsonii, but it is different in its leaf margins crenate to crenulate (vs. irregularly serrulate), stamens 80–120 (vs. 35–70), pistillate flower 4-tepaled (vs. 5-tepaled) and ovary hirsute (vs. villous). Begonia lophura is somewhat similar to B. pavonina, but it is different in having widely ovate (vs. ovate) and abaxially red hirsute (vs. glabrous) leaves, bracts persistent (vs. caducous), tepals hirsute (vs. glabrous) in both of staminate and pistillate flowers, capsule scabrous (vs. glabrous) and abaxial wing strongly swollen (vs. thin, not swollen). The conservation status of the two new species are assessed as Vulnerable according to the IUCN Red List criteria.

Description of a new natural Sonneratia hybrid from Hainan Island, China

Here, we describe, illustrate and compare a new natural hybrid, Sonneratia × zhongcairongii Y. S. Wang & S. H. Shi (Sonneratiaceae), with its possible parent species. Based on its morphological characteristics and habitat conditions, this taxon is considered to represent a sterile hybrid between S. alba and S. apetala. In China, the new hybrid is only reported in the mangrove forest in Dongzhai Harbour, Hainan Island. It has intermediate characteristics with its parents by elliptical leaf blades, peltate stigma, terminal or axillary inflorescence with 1–3 flower dichasia, cup – shaped calyx (4–6 calyx lobes) and no petals. We also provide a key for the identification of Sonneratia species.

Ophiochloa bryoides (Poaceae, Paniceae), a New Grass Species from Central Brazil

Ophiochloa bryoides, a new species in the Brazilian endemic genus Ophiochloa, is described and illustrated. It is similar to O. hydrolithica, the only currently known species in this genus, from which it differs because of its diminutive annual habit, the absence of an axillary inflorescence, and the occurrence of a single apical seta on the lower lemma. The affinity of Ophiochloa with Axonopus is briefly discussed. Ophiochloa bryoides, uma nova espécie de Ophiochloa, um gênero endêmico do Brasil, é descrita e ilustrada. A espécie é relacionada à O. hydrolithica, a única espécie conhecida desse gênero, da qual difere pelo hábito anual, pelo tamanho diminuto, pela ausência de uma inflorescência axilar, e pela ocorrência de uma única seta apical no lema inferior. A afinidade de Ophiochloa com Axonopus é discutida brevemente.

Disruption of an RNA helicase/RNAse III gene in Arabidopsis causes unregulated cell division in floral meristems

Arabidopsis thaliana floral meristems are determinate structures that produce a defined number of organs, after which cell division ceases. A new recessive mutant, carpel factory (caf), converts the floral meristems to an indeterminate state. They produce extra whorls of stamens, and an indefinite number of carpels. Thus, CAF appears to suppress cell division in floral meristems. The function of CAF is partially redundant with the function of the CLAVATA (CLV) and SUPERMAN (SUP) genes, as caf clv and caf sup double mutants show dramatically enhanced floral meristem over-proliferation. caf mutant plants also show other defects, including absence of axillary inflorescence meristems, and abnormally shaped leaves and floral organs. The CAF gene was cloned and found to encode a putative protein of 1909 amino acids containing an N-terminal DExH/DEAD-box type RNA helicase domain attached to a C-terminal RNaseIII-like domain. A very similar protein of unknown function is encoded by a fungal and an animal genome. Helicase proteins are involved in a number of processes, including specific mRNA localization and mRNA splicing. RNase III proteins are involved in the processing of rRNA and some mRNA molecules. Thus CAF may act through some type of RNA processing event(s). CAF gives rise to two major transcripts of 2.5 and 6.2 kb. In situ hybridization experiments show that CAF RNA is expressed throughout all shoot tissues.

Gibberellin- and Cytokinin-induced Growth and Flowering Responses in Rudbeckia hirta L.

BA and GA4+7, were applied to vegetative, mature Rudbeckia hirta plants at the beginning of long days (LD). There were no synergistic effects, but BA inconsistently affected branching and had no effect on flowering. Floral initiation of the terminal inflorescence was promoted by GA4+7, although axillary inflorescences were not. Increasing GA4+7 levels decreased the time to terminal inflorescence anthesis. However, the interval between the terminal and second axillary inflorescence anthesis was increased. The net result was no significant effect on the time to second axillary inflorescence anthesis. Gibberellins may enhance the LD effect on the apical meristem of Rudbeckia, but axillary meristems, which initiate later, remained unaffected. Chemical names used: benzyladenine (BA), gibberellin4+7, (GA4+7).