Combining ability analysis in bitter gourd (Momordica charantia L.) for potential quality improvement

Combining ability analysis provides useful information for the selection of parents, also information regarding the nature and magnitude of involved gene actions. Crops improvement involves strategies for enhancing yield potentiality and quality components. Targeting the improvement of respective characters in bitter gourd, combining ability and genetic parameters for 19 characters were estimated from a 6×6 full diallel analysis technique. The results revealed that the variances due to general combining ability (GCA) and specific combining ability (SCA) were highly significant for most of the important characters. It indicated the importance of both additive and non-additive gene actions. GCA variances were higher in magnitude than SCA variances for all the characters studied indicating the predominance of the additive gene effects in their inheritance. The parent P2 (BG 009) appeared as the best general combiner for earliness; P1 (BG 006) for number of fruits, average single fruit weight and fruit yield; P4 (BG 027) for node number of first female flower and days to seed fruit maturity; P3 (BG 011) for fruit length and thickness of the fruit flesh; P5 (BG 033) for 100-seed weight; and P6 for number of nodes per main vine. The SCA effect as well as reciprocal effect was also significant for most of the important characters in different crosses.

A new species (Begonia giganticaulis) of Begoniaceae from southern Xizang (Tibet) of China

Begonia giganticaulis, a huge new species in Begonia sect. Platycentrum of Begoniaceae from southern Xizang (Tibet) of China, is described. Morphologically, it is mostly similar to B. longifolia and B. acetosella, but clearly differs from the former mainly by its dioecious and taller plants, sparse hairs on abaxial veins, longer inflorescence, unique shape of fruits, and differs from the latter mainly by its late and longer flowering time, 6-tepals of female flower and 3-loculed ovary. The phylogenetic analyses also support the separation of the new species from other taxa. Based on the current data, its conservation status is assigned to Endangered (B2a) according to the IUCN Red List Categories and Criteria.

Genome-Wide Identification and Characterization of Melon bHLH Transcription Factors in Regulation of Fruit Development

The basic helix-loop-helix (bHLH) transcription factor family is one of the largest transcription factor families in plants and plays crucial roles in plant development. Melon is an important horticultural plant as well as an attractive model plant for studying fruit ripening. However, the bHLH gene family of melon has not yet been identified, and its functions in fruit growth and ripening are seldom researched. In this study, 118 bHLH genes were identified in the melon genome. These CmbHLH genes were unevenly distributed on chromosomes 1 to 12, and five CmbHLHs were tandem repeat on chromosomes 4 and 8. There were 13 intron distribution patterns among the CmbHLH genes. Phylogenetic analysis illustrated that these CmbHLHs could be classified into 16 subfamilies. Expression patterns of the CmbHLH genes were studied using transcriptome data. Tissue specific expression of the CmbHLH32 gene was analysed by quantitative RT-PCR. The results showed that the CmbHLH32 gene was highly expressed in female flower and early developmental stage fruit. Transgenic melon lines overexpressing CmbHLH32 were generated, and overexpression of CmbHLH32 resulted in early fruit ripening compared to wild type. The CmbHLH transcription factor family was identified and analysed for the first time in melon, and overexpression of CmbHLH32 affected the ripening time of melon fruit. These findings laid a foundation for further study on the role of bHLH family members in the growth and development of melon.

VviPLATZ1 is a major factor that controls female flower morphology determination in grapevine

Plant genetic sex determinants that mediate the transition to dioecy are predicted to be diverse, as this type of mating system independently evolved multiple times in angiosperms. Wild Vitis species are dioecious with individuals producing morphologically distinct female or male flowers; whereas, modern domesticated Vitis vinifera cultivars form hermaphrodite flowers capable of self-pollination. Here, we identify the VviPLATZ1 transcription factor as a key candidate female flower morphology factor that localizes to the Vitis SEX-DETERMINING REGION. The expression pattern of this gene correlates with the formation reflex stamens, a prominent morphological phenotype of female flowers. After generating CRISPR/Cas9 gene-edited alleles in a hermaphrodite genotype, phenotype analysis shows that individual homozygous lines produce flowers with reflex stamens. Taken together, our results demonstrate that loss of VviPLATZ1 function is a major factor that controls female flower morphology in Vitis.

Rafflesia zollingeriana Koord.: a Reinstatement

Rafflesia zollingeriana Koord. was one of Rafflesia that distributed in Java. Although it has been stated as a different species, R. zollingeriana is sometimes still regarded as a synonym of R. patma. In addition, there are several contradictions in description of R. zollingeriana. Therefore, further investigation is needed. This study attempts presents a full the description of the R. zollingeriana female flower. In this study, a full description of female flower of R. zollingeriana and pictures of important characters such as ramenta, annulus, perigone lobes, disc, processes, bractea are presented. This study is also compared the morphology of R. zollingeriana and R. patma, to confirm their differences in size, opening of diaphragm, blotches and warts pattern on perigone lobes and diaphragm, annulus, and ramenta.

Transcriptome profiling based on Illumina- and SMRT-based RNA-seq reveals circadian regulation of key pathways in flower bud development in walnut

Flower bud development is a defining feature of walnut, which contributes to the kernel yield, yield stability, fruit quality and commodity value. However, little is known about the mechanism of the flower bud development in walnut. Here, the stages of walnut female flower bud development were divided into five period (P01-05) by using histological observation. They were further studied through PacBio Iso-Seq and RNA-seq analysis. Accordingly, we obtained 52,875 full-length transcripts, where 4,579 were new transcripts, 3,065 were novel genes, 1,437 were consensus lncRNAs and 20,813 were alternatively spliced isoforms. These transcripts greatly improved the current genome annotation and enhanced our understanding of the walnut transcriptome. Next, RNA sequencing of female flower buds at five periods revealed that circadian rhythm-plant was commonly enriched along with the flower bud developmental gradient. A total of 14 differentially expressed genes (DEGs) were identified, and six of them were confirmed by real-time quantitative analysis. Additionally, six and two differentially expressed clock genes were detected to be regulated by AS events and lncRNAs, respectively. All these detected plant circadian genes form a complex interconnected network to regulate the flower bud development. Thus, investigation of key genes associated with the circadian clock could clarify the process of flower bud development in walnut.

Transcriptome-based analysis of the hormone regulation mechanism of gender differentiation in Juglans mandshurica Maxim

Juglans mandshurica Maxim is a hermaphroditic plant belonging to the genus Juglans in the family Juglandaceae. The pollination period of female flowers is different from the loose powder period of male flowers on the same tree. In several trees, female flowers bloom first, whereas in others, male flowers bloom first. In this study, male and female flower buds of J. mandshurica at the physiological differentiation stage were used. Illumina-based transcriptome sequencing was performed, and the quality of the sequencing results was evaluated and analyzed. A total of 138,138 unigenes with an average length of 788 bp were obtained. There were 8,116 differentially expressed genes (DEGs); 2,840 genes were upregulated, and 5,276 genes were downregulated. The DEGs were classified by Gene Ontology and analyzed by Kyoto Encyclopedia of Genes and Genomes. The signal transduction factors involved in phytohormone synthesis were selected. The results displayed that ARF and SAUR were expressed differently in the auxin signaling pathway. Additionally, DELLA protein (a negative regulator of gibberellin), the cytokinin synthesis pathway, and A-ARR were downregulated. On April 2nd, the contents of IAA, GA, CTK, ETH and SA in male and female flower buds of two types of J. mandshurica were opposite, and there were obvious genes regulating gender differentiation. Overall, we found that the sex differentiation of J. mandshurica was related to various hormone signal transduction pathways, and hormone signal transduction plays a leading role in regulation.

Delineating the genetic regulation of cannabinoid biosynthesis during female flower development in Cannabis sativa

Cannabinoids are predominantly produced in the glandular trichomes on cannabis female flowers. There is little known on how cannabinoid biosynthesis is regulated during female flower development. We aim to understand the rate-limiting step(s) in the cannabinoid biosynthetic pathway. We investigated the transcript levels of cannabinoid biosynthetic genes as well as cannabinoid contents during 7 weeks of female flower development. We demonstrated that the enzymatic steps for producing CBG, which involve genes GPPS, PT and OAC, could be rate limit cannabinoid biosynthesis. Our findings further suggest that cannabinoid synthases, CBDAS and THCAS in a hemp and medical marijuana variety respectively, are not critical for cannabinoid biosynthesis. The cannabinoid biosynthetic genes are generally upregulated during flower maturation, which indicate glandular trichome development. MeJA can potentially increase cannabinoid production. We propose that biweekly application of 100 μM MeJA staring from flower initiation would be efficacious for promoting cannabinoid biosynthesis.