Tropical Plant Biology

Carrara, Scott; Dornelas, Marcelo Carnier

2020 Tropical Plant Biology

doi: 10.1007/s12042-020-09274-z

Several studies involving the TCP family have been carried out in the last two decades since the first members were discovered and the family was defined. The domain that names the family was well characterized and we know that the protein is a transcription factor that forms a non-canonical bHLH type structure capable of binding to the DNA molecule and promoting interactions between proteins. In recent years it has become clear that members of this family have a key role in the integration of several endogenous and exogenous signals for the control of various aspects of plant development, mainly in the establishment of plant architecture through the control of branching and the transition to reproduction, therefore, being a gene family with great economic potential and possible an important role on the evolution of angiosperms.

Barbosa, Naira Costa Soares; Dornelas, Marcelo Carnier

2020 Tropical Plant Biology

doi: 10.1007/s12042-020-09272-1

Plants undergo distinct phase transitions during their post-embryonic development and progresses from the juvenile to the adult and reproductive phases. These transitions are characterized by morphological and molecular changes and are differently influenced by gibberellins (GAs) and cytokinins (CKs). GAs are notably known to either induce or repress phase transition and flowering in diverse plant species. This GA-mediated modulation is ultimately related to the behavior of the DELLA transcriptional regulators. CKs influence phase transitions by promoting meristem cell divisions and flowering stimulation. Moreover, CKs and GAs can mutually repress each other or have complementary functions in processes such as branching and flowering. Therefore, the effects observed such as flower formation and vegetative growth is modulated by the co-regulation exerted by the cross-talk of both GA and CK pathways. We review the roles of GA and CK in phase transitions at the molecular level in model species such as Arabidopsis and the genes that are modulated by both GA and CK pathways. Additionally we point out perspectives of the conservation of these molecular pathways in tropical plants.

Nan, Hong; Lin, Yang-Lei; Liu, Jin; Huang, Hui; Li, Wei; Gao, Li-zhi

2020 Tropical Plant Biology

doi: 10.1007/s12042-020-09268-x

The multigene family WRKY is plant-specific transcription factors, which is involved in numerous aspects of plant growth and development. Here, we report a genome-wide search for the rubber tree WRKY (HbWRKY) genes and their expression profiles at various tissues including latexes. We also present a comprehensive overview of whole HbWRKY gene family, including gene structure, chromosomal locations, conserved protein domains, gene duplications and phylogenetic inferences. We identify a total of 108 full-length HbWRKY genes, which were classified into the three major subgroups. The genome-scale syntenic analysis showed that WGDs might have played a major role in the evolution of the HbWRKY gene family. Our further real-time reverse transcription-PCR (qRT-PCR) experiments validated that the HbWRKY genes are divergently expressed and gene expression divergence seemingly existed among the duplicated WRKY genes, suggesting a fundamentally functional divergence of the duplicated WRKY paralogs in rubber tree. We also investigated the gene expression profiling of the HbWRKYs under salt stress, to which the majority of genes differentially responded. This study acquires a new insight into the evolution of the HbWRKYs, which will help further functional characterization of theses candidate genes in rubber tree.

Zhang, Mo; Jin, Yukun; Ma, Yiyong; Zhang, Qi; Wang, Qi; Jiang, Nan; Zhao, He; Qu, Jing; Guan, Shuyan; Wang, Piwu

2020 Tropical Plant Biology

doi: 10.1007/s12042-020-09270-3

Leaf angle (LA) and leaf orientation value (LOV) are two crucial traits constituting the plant architecture (PA) of maize. Screening of quantitative trait loci (QTLs) and candidate genes (CGs) related to leaf angle and leaf orientation value provides the molecular basis for the improvement of maize plant architecture. In this study, we utilized genotyping by sequencing (GBS) on 179 maize recombined inbred lines (RILs) obtained by crossing two inbred lines with significant variation in leaf angle and leaf orientation value. A total of 4235 markers were used for the construction of the genetic linkage map. The total length of the genetic map was 1514.57 cM with the average genetic distance between each marker of 0.36 cM. On association of this map with phenotypic data from four environments, nine QTLs associated with leaf angle and nine QTLs associated with leaf orientation value were identified, explaining 78.89% and 59.71% of the phenotypic variation of leaf angle and leaf orientation value, respectively. Two QTLs explained greater than 10% of the phenotypic variation and three QTLs controlling both leaf angle and leaf orientation value were screened. Three candidate genes were identified as the most possible genes associated with leaf angle and leaf orientation value by screening the annotations of genes underlying these crucial QTLs. These were Zm00001d019053 might be associated with leaf angle, Zm00001d028164 and Zm00001d025352 might be associated with leaf angle and leaf orientation value, respectively. Expression analysis of candidate genes from parents and subsets also confirmed the significant variation in expression. Differences in DNA of the inbred lines with different phenotype were identified based on analysis of allelic variations in the candidate genes. These results not only enrich QTLs and candidate genes associated with leaf angle and leaf orientation value of maize, but also provide references for the improvement of plant architecture and molecular marker-assisted breeding.

Yoosomboon, Phatcharom; Sojikul, Punchapat; Viboonjun, Unchera; Narangajavana, Jarunya

2020 Tropical Plant Biology

doi: 10.1007/s12042-020-09271-2

The major challenge of cassava cultivation is phytopathogen damage and lack of resistant cultivars. Investigating the defense mechanism in cassava should provide insights into the development of new disease control strategies. Colletotrichum gloeosporioides f. sp. manihotis (CAD) is a fungal pathogen that causes cassava anthracnose disease, which is a serious disease worldwide, affecting cassava production and yield loss. Syntaxins contribute to mediate vesicles fusion in trafficking pathway by specifically forming as ternary SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) complex to transport defense components to site of microbe infection between the plasma membrane and plant cell wall. The function of syntaxins is largely unknown in resistance to Colletotrichum spp. in cassava. To manipulate resistance against Colletotrichum spp., the role of syntaxin genes and plant hormones; salicylic acid (SA) and jasmonic acid (JA) in triggering various responses to biotic stress was studied. All syntaxin genes in cassava genome were identified, and gene expression was investigated in CAD-resistant (HB60) and -susceptible (HN) cultivars of cassava. MePR1 was highly up-regulated in HB60 upon CAD infection. SA-pretreatment induced MeSYP121 expression and coexisted with delayed development of disease symptoms in HB60. In contrast, the different expression patterns of both genes were demonstrated in HN, and JA-pretreatment could not induce CAD-resistance. Altogether, the results suggest the role of SA-induced syntaxin gene expression to mediate vesicle trafficking and trigger defense-associated factors for more disease resistance in cassava. This investigation could be useful for the development of effective crop protection strategies and plant disease management in modern agriculture.

Zhou, Lixia; Yarra, Rajesh; Cao, Hongxing; Zhao, Zhihao

2020 Tropical Plant Biology

doi: 10.1007/s12042-020-09273-0

Oil palm (Elaeis guineensis Jacq.) is the key vegetable oil yielded crop and widely distributed in the southern region of China. The present study aimed at analyzing the genetic diversity and population structure of 223 oil palm accessions collected from four provinces of China by using the sequence-related amplified polymorphism (SRAP) markers. A set of 33 SRAP molecular markers were employed to analyze genetic diversity as well as population structure across 223 oil palm accessions. Out of 514 amplified bands, 487 (94.75%) bands were found to be polymorphic. The PIC value (polymorphic information content) of detected bands was from 0.38 to 0.51, with 0.46 of average. The STRUCTURE analysis categorized the 223 oil palm accessions into three subpopulations. The UPGMA based clustering classified them into three major clusters. The correlation between the population subdivisions and the genetic relationships among oil palm accessions was revealed by UPGMA and Bayesian STRUCTURE analyses. The principal coordinate analysis also confirmed a similar grouping of accessions as revealed by the UPGMA dendrogram and STRUCTURE analysis. AMOVA analysis also revealed the variance of 24% among subpopulations and 76% within subpopulations. The present investigation provided valuable information on population structure and genetic diversity of oil palm populations in China for molecular breeding research in oil palm.